Processes

12 pages, 6973 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Enhancing the Photoelectric Properties of Flexible Carbon Nanotube Paper by Plasma Gradient Modification and Gradient Illumination

by Chen-Chen Yang, Pi-Yu Shen, Hsin-Yuan Miao, Chia-Yi Huang, Shih-Hung Lin, Jun-Hong Weng, Lakshmanan Saravanan and Jih-Hsin Liu

Processes 2024, 12(7), 1449; https://doi.org/10.3390/pr12071449 - 11 Jul 2024

Cited by 4 | Viewed by 776

Abstract

This study investigates the impact of plasma gradient modification and gradient illumination on the optoelectronic properties of buckypaper (BP), a flexible and large-scale material composed of multi-walled carbon nanotubes (MWCNTs). The BP samples were subjected to argon ion plasma treatment at varying power [...] Read more.

This study investigates the impact of plasma gradient modification and gradient illumination on the optoelectronic properties of buckypaper (BP), a flexible and large-scale material composed of multi-walled carbon nanotubes (MWCNTs). The BP samples were subjected to argon ion plasma treatment at varying power levels and durations, thereby creating different carrier concentration gradients on the surface. The photovoltage and photocurrent responses of the samples were then measured under uniform full illumination and gradient illumination conditions. The findings revealed that both plasma gradient modification and gradient illumination significantly enhanced the optoelectronic performance of BP. Notably, the combined application of these two methods yielded superior results compared to the application of either method alone. Specifically, the optimal plasma power for improving BP was found to be 20 W. Under conditions of plasma gradient modification and gradient illumination, a photovoltage of 267.76 μV was generated, which represents a 21.44 times increase, and a photocurrent of 15.69 μA, reflecting a 32.69 times enhancement. The mechanism underlying this optoelectronic effect can be attributed to the presence of π-bonds in the carbon atoms. These π-bonds are excited by photons, resulting in the generation of small voltages and currents. This study underscores the potential of BP as an optoelectronic material and introduces a novel approach to enhance its optoelectronic properties through plasma gradient modification and gradient illumination. Full article

(This article belongs to the Special Issue Multifunctional Nanomaterials for Energy: Synthesis, Characteristics, and Applications)

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17 pages, 1922 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Modeling and Optimizing Biocontrol in Wines: pH as a Modulator of Yeast Amensalism Interaction

by Benjamín Kuchen, María Carla Groff, María Nadia Pantano, Lina Paula Pedrozo, Fabio Vazquez and Gustavo Scaglia

Processes 2024, 12(7), 1446; https://doi.org/10.3390/pr12071446 - 10 Jul 2024

Viewed by 753

Abstract

The control of spoilage yeasts in wines is crucial to avoid organoleptic deviations in wine production. Traditionally, sulfur dioxide (SO₂) was used to control them; nevertheless, SO₂ influence on human health and its use is criticized. Biocontrol emerges as an [...] Read more.

The control of spoilage yeasts in wines is crucial to avoid organoleptic deviations in wine production. Traditionally, sulfur dioxide (SO₂) was used to control them; nevertheless, SO₂ influence on human health and its use is criticized. Biocontrol emerges as an alternative in wine pre-fermentation, but there is limited development in its applicability. Managing kinetics is relevant in the microbial interaction process. pH was identified as a factor affecting the interaction kinetics of Wickerhamomyces anomalus killer biocontrol on Zygosaccharomyces rouxii. Mathematical modeling allows insight into offline parameters and the influence of physicochemical factors in the environment. Incorporating submodels that explain manipulable factors (pH), the process can be optimized to achieve the best-desired outcomes. The aim of this study was to model and optimize, using a constant and a variable pH profile, the interaction of killer biocontrol W. anomalus vs. Z. rouxii to reduce the spoilage population in pre-fermentation. The evaluated biocontrol was W. anomalus against the spoilage yeast Z. rouxii in wines. The kinetic interactions of yeasts were studied at different pH levels maintained constant over time. The improved Ramón-Portugal model was adopted using the AMIGO2 toolbox for Matlab. A static optimization of a constant pH profile was performed using the Monte Carlo method, and a dynamic optimization was carried out using a method based on Fourier series and orthogonal polynomials. The model fit with an adjusted R² of 0.76. Parametric analyses were consistent with the model behavior. Variable vs. constant optimization achieved a lower initial spoilage population peak (99% less) and reached a lower final population (99% less) in a reduced time (100 vs. 140 h). These findings reveal that control with a variable profile would allow an early sequential inoculation of S. cerevisiae. The models explained parameters that are difficult to quantify, such as general inhibitor concentration and toxin concentration. Also, the models indicate higher biocontrol efficiency parameters, such as toxin emission or sensitivity to it, and lower fitness of the contaminant, at pH levels above 3.7 during biocontrol. From a technological standpoint, the study highlights the importance of handling variable profiles in the controller associated with the pH management actuators in the process without incurring additional costs. Full article

(This article belongs to the Section Biological Processes and Systems)

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19 pages, 7196 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Modeling and Simulation of the Induction Hardening Process: Evaluation of Gear Deformations and Parameter Optimization

by Pedro Maranhão Pinheiro, José Urbano Junio, Lídice Aparecida Pereira Gonçalves, José Ângelo Peixoto da Costa, Alvaro Antonio Villa Ochoa, Kleber Gonçalves Bezerra Alves, Gustavo de Novaes Pires Leite and Paula Suemy Arruda Michima

Processes 2024, 12(7), 1428; https://doi.org/10.3390/pr12071428 - 9 Jul 2024

Cited by 3 | Viewed by 1536

Abstract

This study aimed to analyze and optimize the thermal induction hardening process applied to toothed transmission gears, focusing on thermal aspects, structural deformation, and topology optimization, while exploring the feasibility of various materials and operating conditions. The research simulated thermal and deformation behavior [...] Read more.

This study aimed to analyze and optimize the thermal induction hardening process applied to toothed transmission gears, focusing on thermal aspects, structural deformation, and topology optimization, while exploring the feasibility of various materials and operating conditions. The research simulated thermal and deformation behavior using a computer model, comparing results with experimental data through the Ansys^® platform 2022 R1. The methodology encompassed thermal and deformation analyses, topology optimization to identify removable regions without compromising part integrity, and a sensitivity study to evaluate the different materials and operating conditions. This study validates the precision of computational models in predicting thermal and deformation behavior in toothed gears under thermal induction hardening, introducing topology optimizations and alternative materials, and providing novel perspectives for the more efficient and cost-effective manufacturing of these components. Comparative thermal analysis revealed a maximum relative error of less than 6% between temperatures from the computer model and experimental results, while deformation comparisons exhibited a maximum relative error of less than 7%, affirming the simulation model’s accuracy in predicting and managing deformations within acceptable thresholds. Topology optimization successfully pinpointed removable regions without compromising structural integrity, enabling the production of lighter and more economical devices. Future endeavors should concentrate on additional tests to verify the feasibility of reducing power and cooling temperature without compromising product specifications. Furthermore, it is advisable to explore alternative materials and apply the developed methodology in diverse industrial settings to generalize the findings and amplify the impact of the proposed optimizations. Full article

(This article belongs to the Special Issue Heat and Mass Transfer in Energy Engineering)

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13 pages, 3423 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Design and Characterization of a Continuous Melt Milling Process Tailoring Submicron Drug Particles

by Philip da Igreja, Tim Grenda, Jens Bartsch and Markus Thommes

Processes 2024, 12(7), 1417; https://doi.org/10.3390/pr12071417 - 7 Jul 2024

Cited by 1 | Viewed by 1647

Abstract

Solid crystalline suspensions (SCSs) containing submicron particles were introduced as a competitive solution to increase dissolution rates and the bioavailability of poorly water-soluble drugs. In an SCS, poorly water-soluble drug crystals are finely dispersed in a hydrophilic matrix. Lately, melt milling as an [...] Read more.

Solid crystalline suspensions (SCSs) containing submicron particles were introduced as a competitive solution to increase dissolution rates and the bioavailability of poorly water-soluble drugs. In an SCS, poorly water-soluble drug crystals are finely dispersed in a hydrophilic matrix. Lately, melt milling as an adapted wet milling process at elevated temperatures has been introduced as a suitable batch manufacturing process for such a formulation. In this work, the transfer from batch operation to a two-step continuous process is demonstrated to highlight the potential of this technology as an alternative to other dissolution-enhancing methods. In the first step, a powder mixture of a model drug (griseofulvin) and a carrier (xylitol) is fed to an extruder, where a uniform suspension is obtained. In the second step, the suspension is transferred to a custom-built annular gap mill, where comminution down to the submicron region takes place. The prototype’s design was based on batch grinding results and a narrow residence time distribution, intended to deliver large quantities of submicron particles in the SCS. The throughput of the mill was found to be limited by grinding media compression. By inclining the mill at an angle, the grinding media position was manipulated, such that compression was avoided. Different states of the grinding media in the grinding chamber were identified under surrogate conditions. This strategy allows the maintenance of an energy-optimized comminution without adaption of the associated process parameters, even at high throughputs. Using this new process, the production of an SCS with 80–90 % submicron particles in a single passthrough was demonstrated. Full article

(This article belongs to the Special Issue Features, Reviews and Perspectives for the 10th Anniversary of Processes)

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39 pages, 5062 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Main Composition and Visual Appearance of Milk Kefir Beverages Obtained from Four Consecutive 24- and 48-h Batch Subcultures

by Delicia L. Bazán Tantaleán, Pablo G. Del-Río, Sandra Cortés Diéguez, José Manuel Domínguez and Nelson Pérez Guerra

Processes 2024, 12(7), 1419; https://doi.org/10.3390/pr12071419 - 7 Jul 2024

Cited by 1 | Viewed by 1743

Abstract

Nowadays, there has been a significant rise in the consumption of kefir, a functional beverage touted for its perceived health benefits. To offer a high-quality beverage to consumers, it is imperative to scrutinize and fine-tune the fermentation process. This study seeks to investigate [...] Read more.

Nowadays, there has been a significant rise in the consumption of kefir, a functional beverage touted for its perceived health benefits. To offer a high-quality beverage to consumers, it is imperative to scrutinize and fine-tune the fermentation process. This study seeks to investigate the impact of fermentation time and the number of subcultures on the physicochemical, microbiological, and volatile composition, as well as the visual appearance, of kefir beverages obtained from four consecutive 24- or 48-h batch subcultures. All fermented beverages exhibited low lactose, ethanol and acids levels, with counts of viable probiotic lactic acid bacteria and yeast exceeding 10⁶ colony forming units/mL. The four kefir beverages from the 48-h batch subcultures notably showed the lowest total concentrations of volatile compounds, likely due to overfermentation and over-acidification of the beverages. This caused the separation of the whey and curd, along with the formation of large gas bubbles, negatively affecting the visual appearance of the products. These findings emphasize the importance of fine-tuning the fermentation process to ensure the production of high-quality kefir beverages that align with consumer preferences. The four beverages from the 24-h batch subcultures exhibited high microbiological and physicochemical stability during storage at 4 °C for 28 days. Full article

(This article belongs to the Section Food Process Engineering)

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11 pages, 2119 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Efficient, Facile, and Green Synthesis of Ruthenium Carboxylate Complexes by Manual Grinding

by Eleonora Aneggi, Daniele Zuccaccia, Andrea Porcheddu and Walter Baratta

Processes 2024, 12(7), 1413; https://doi.org/10.3390/pr12071413 - 6 Jul 2024

Viewed by 1262

Abstract

Recently, scientists have been developing sustainable processes, and in this context, mechanochemistry is commonly associated with green chemistry for its ability to reduce waste generation from chemical reactions. The well-known acetate complex, diacetate bis(triphenylphosphine) ruthenium(II) [Ru(OAc)₂(PPh₃)₂], is [...] Read more.

Recently, scientists have been developing sustainable processes, and in this context, mechanochemistry is commonly associated with green chemistry for its ability to reduce waste generation from chemical reactions. The well-known acetate complex, diacetate bis(triphenylphosphine) ruthenium(II) [Ru(OAc)₂(PPh₃)₂], is a versatile precursor for preparing active complexes for several catalytic reactions. This report presents an efficient and straightforward manual grinding protocol for the sustainable synthesis of ruthenium carboxylate complexes starting from the commercially available [RuCl₂(PPh₃)₃] and metal carboxylates. This work represents a novel and preliminary investigation into carboxylate precursors’ alternative solventless synthesis route based on manual grinding. To our knowledge, this is the first time [Ru(OAc)₂(PPh₃)₂] has been prepared via a mechanochemical procedure. The synthesis method has also been investigated for other alkali metal carboxylates and yields ranging from 30 to 80% were obtained. A comparison of sustainability and environmental impact between conventional solution synthesis and the grinding route has been carried out using the E-factor and Mass Productivity. While for the acetate complex E-factor and MP were only slightly better compared with the solvent method (3 vs. 4 for E-factor and ~6 vs. 5 for MP), for benzoate higher results were found (1 vs. ~4 for E-factor and 10 vs. 5 for MP). Full article

(This article belongs to the Special Issue Metal-Based Formulations for Eco-Sustainable Processes in Homogeneous and Heterogeneous Catalysis)

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37 pages, 991 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Predicting the Liquid Steel End-Point Temperature during the Vacuum Tank Degassing Process Using Machine Learning Modeling

by Roberto Vita, Leo Stefan Carlsson and Peter B. Samuelsson

Processes 2024, 12(7), 1414; https://doi.org/10.3390/pr12071414 - 6 Jul 2024

Cited by 1 | Viewed by 1596

Abstract

The present work focuses on predicting the steel melt temperature following the vacuum treatment step in a vacuum tank degasser (VTD). The primary objective is to establish a comprehensive methodology for developing and validating machine learning (ML) models within this context. Another objective [...] Read more.

The present work focuses on predicting the steel melt temperature following the vacuum treatment step in a vacuum tank degasser (VTD). The primary objective is to establish a comprehensive methodology for developing and validating machine learning (ML) models within this context. Another objective is to evaluate the model by analyzing the alignment of the SHAP values with metallurgical domain expectations, thereby validating the model’s predictions from a metallurgical perspective. The proposed methodology employs a Random Forest model, incorporating a grid search with domain-informed variables grouped into batches, and a robust model-selection criterion that ensures optimal predictive performance, while keeping the model as simple and stable as possible. Furthermore, the Shapley Additive Explanations (SHAP) algorithm is employed to interpret the model’s predictions. The selected model achieved a mean adjusted

R^{2}

of 0.631 and a hit ratio of 75.3% for a prediction error within ±5 °C. Despite the moderate predictive performance, SHAP highlighted several aspects consistent with metallurgical domain expertise, emphasizing the importance of domain knowledge in interpreting ML models. Improving data quality and refining the model framework could enhance predictive performance. Full article

(This article belongs to the Special Issue AI / Machine Learning Techniques as a Tool for Process Modeling and Product Design)

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15 pages, 3288 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Hydrothermal Co-Liquefaction of Sugarcane Bagasse and Residual Cooking Soybean Oil for Bio-Crude Production

by Matheus Venâncio de Oliveira, Maria Pelisson, Fabiane Hamerski, Luís Ricardo Shigueyuki Kanda, Fernando A. P. Voll, Luiz Pereira Ramos and Marcos Lúcio Corazza

Processes 2024, 12(7), 1371; https://doi.org/10.3390/pr12071371 - 1 Jul 2024

Cited by 1 | Viewed by 1150

Abstract

Hydrothermal co-liquefaction (co-HTL) is a process involving two sources of biomasses aiming at bio-crude production. Since there is a lack of studies performed with sugarcane bagasse and residual soybean oil, this study investigated different conditions for the co-HTL of these biomasses, with and [...] Read more.

Hydrothermal co-liquefaction (co-HTL) is a process involving two sources of biomasses aiming at bio-crude production. Since there is a lack of studies performed with sugarcane bagasse and residual soybean oil, this study investigated different conditions for the co-HTL of these biomasses, with and without the presence of ethanol as a co-solvent to maximize the bio-crude yield. All co-HTL reactions were carried out in a 300 mL Parr^® reactor at temperatures ranging from 200 to 300 °C. After the reaction, a vacuum filtration was performed to separate the bio-char, later washed with ethanol to extract heavy bio-crude, while the liquid-phase was mixed with dichloromethane to recover light bio-crude. Bio-crude yields of around 95 wt.% were obtained at 300 °C using ethanol and water as solvents. The highest bio-char yield (16.6 wt.%) was achieved when using only sugarcane bagasse as the substrate, without the presence of soybean oil. Bio-crude samples obtained at higher temperatures (280 °C and 300 °C) using ethanol as a hydrogen donor presented higher contents of both free fatty acids and fatty acid ethyl esters. This work presents a promising process to produce high-quality bio-crude using an abundant feedstock (sugarcane bagasse) in the presence of a lipid source which could cause environmental problems if poorly handled. Full article

(This article belongs to the Section Chemical Processes and Systems)

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22 pages, 9588 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

On the Feasibility of Deep Geothermal Wells Using Numerical Reservoir Simulation

by Ali Nassereddine and Luis E. Zerpa

Processes 2024, 12(7), 1369; https://doi.org/10.3390/pr12071369 - 30 Jun 2024

Cited by 1 | Viewed by 1701

Abstract

This study examines the geothermal energy extraction potential from the basement rock within the Denver–Julesburg Basin, focusing on the flow performance and heat extraction efficiency of different geothermal well configurations. It specifically compares U-shaped, V-shaped, inclined V-shaped, and pipe-in-pipe configurations against enhanced geothermal [...] Read more.

This study examines the geothermal energy extraction potential from the basement rock within the Denver–Julesburg Basin, focusing on the flow performance and heat extraction efficiency of different geothermal well configurations. It specifically compares U-shaped, V-shaped, inclined V-shaped, and pipe-in-pipe configurations against enhanced geothermal system setups. Through numerical modeling, we evaluated the thermal behavior of these systems under various operational scenarios and fracture conditions. The results suggest that while closed-loop systems offer moderate temperature increases, Enhanced geothermal system configurations show substantial potential for high-temperature extraction. This underscores the importance of evaluating well configurations in complex geological settings. The insights from this study aid in strategic geothermal energy planning and development, marking significant advancements in geothermal technology and setting a foundation for future explorations and optimizations. Full article

(This article belongs to the Special Issue Advanced Reservoir Simulation and Modelling, Thermal and Enhanced Oil Recovery Processes)

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18 pages, 4673 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Impact of Storage Conditions on Stability of Bioactive Compounds and Bioactivity of Beetroot Extract and Encapsulates

by Vesna Postružnik, Slađana Stajčić, Dragana Borjan, Gordana Ćetković, Željko Knez, Maša Knez Marevci and Jelena Vulić

Processes 2024, 12(7), 1345; https://doi.org/10.3390/pr12071345 - 28 Jun 2024

Cited by 1 | Viewed by 2001

Abstract

(1) Background: In this study, bioactive compounds (phenolics and betalains) extracted from beetroot were stabilized by encapsulation with maltodextrin and soy protein by the freeze drying method. Stability of bioactive compounds and bioactivities in a beetroot extract and encapsulates during 60 days of [...] Read more.

(1) Background: In this study, bioactive compounds (phenolics and betalains) extracted from beetroot were stabilized by encapsulation with maltodextrin and soy protein by the freeze drying method. Stability of bioactive compounds and bioactivities in a beetroot extract and encapsulates during 60 days of storage at 4 °C (without light) and at 25 °C (with and without light) were investigated. (2) Methods: Contents of bioactive compounds and bioactivity (antioxidant activity by DPPH, RP, and ABTS tests; anti-inflammatory and antihyperglycemic activity) were determined. Improvement in stability of bioactives’ content and bioactivity of prepared encapsulates in relation to the extract was observed after storage at room temperature under light conditions. (3) Results: Encapsulation with maltodextrin showed improvement in stability of all studied bioactive parameters, while an encapsulate with soy protein improved stability of bioactives and antioxidant activity compared to the extract. The encapsulated beetroot extract represents a promising food additive for functional foods due to their content of bioactive compounds and consequent bioactivities. Full article

(This article belongs to the Special Issue Advances in Green Chemistry Processes: Isolation, Characterization and Applications of Plant-Derived Bioactive Compounds)

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15 pages, 7025 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Expression, Characterization, and Immobilization of a Novel D-Lactate Dehydrogenase from Salinispirillum sp. LH 10-3-1

by Jianguo Liu, Xuejiao Jiang, Yaru Zheng, Kaixuan Li, Ruixin Zhang, Jingping Xu, Zhe Wang, Yuxuan Zhang, Haoran Yin and Jing Li

Processes 2024, 12(7), 1349; https://doi.org/10.3390/pr12071349 - 28 Jun 2024

Cited by 2 | Viewed by 1134

Abstract

Salinispirillum sp. LH 10-3-1 was newly isolated from the alkali lake water samples collected in Inner Mongolia. In this study, a gene coding for D-lactate dehydrogenase from the strain LH 10-3-1 (SaLDH) was cloned and characterized. The recombinant enzyme was a [...] Read more.

Salinispirillum sp. LH 10-3-1 was newly isolated from the alkali lake water samples collected in Inner Mongolia. In this study, a gene coding for D-lactate dehydrogenase from the strain LH 10-3-1 (SaLDH) was cloned and characterized. The recombinant enzyme was a tetramer with a native molecular mass of 146.2 kDa. The optimal conditions for SaLDH to reduce pyruvate and oxidize D-lactic acid were pH 8.0 and pH 5.0, at 25 °C. Cu²⁺ and Ca²⁺ slightly promoted the oxidation and reduction activities of SaLDH, respectively. To improve the stability of SaLDH, the enzyme was immobilized on Cu₃(PO₄)₂-based inorganic hybrid nanoflowers. The results showed that the reduction activity of the hybrid nanoflowers disappeared, and the optimum temperature, specific activity, thermostability, and storage stability of the immobilized SaLDH were significantly improved. In addition, the biotransformation of D-lactic acid to pyruvate catalyzed by SaLDH and the hybrid nanoflowers was investigated. The maximum conversion of D-lactic acid catalyzed by the immobilized SaLDH was 25.7% higher than by free enzymes, and the immobilized SaLDH could maintain 84% of its initial activity after six cycles. Full article

(This article belongs to the Special Issue Advances in Enzyme Biotechnology and Applications in Industry and Environment)

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19 pages, 4042 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

A Novel Data Mining Framework to Investigate Causes of Boiler Failures in Waste-to-Energy Plants

by Dong Wang, Lili Jiang, Måns Kjellander, Eva Weidemann, Johan Trygg and Mats Tysklind

Processes 2024, 12(7), 1346; https://doi.org/10.3390/pr12071346 - 28 Jun 2024

Viewed by 1490

Abstract

Examining boiler failure causes is crucial for thermal power plant safety and profitability. However, traditional approaches are complex and expensive, lacking precise operational insights. Although data-driven approaches hold substantial potential in addressing these challenges, there is a gap in systematic approaches for investigating [...] Read more.

Examining boiler failure causes is crucial for thermal power plant safety and profitability. However, traditional approaches are complex and expensive, lacking precise operational insights. Although data-driven approaches hold substantial potential in addressing these challenges, there is a gap in systematic approaches for investigating failure root causes with unlabeled data. Therefore, we proffered a novel framework rooted in data mining methodologies to probe the accountable operational variables for boiler failures. The primary objective was to furnish precise guidance for future operations to proactively prevent similar failures. The framework was centered on two data mining approaches, Principal Component Analysis (PCA) + K-means and Deep Embedded Clustering (DEC), with PCA + K-means serving as the baseline against which the performance of DEC was evaluated. To demonstrate the framework’s specifics, a case study was performed using datasets obtained from a waste-to-energy plant in Sweden. The results showed the following: (1) The clustering outcomes of DEC consistently surpass those of PCA + K-means across nearly every dimension. (2) The operational temperature variables T-BSH3rm, T-BSH2l, T-BSH3r, T-BSH1l, T-SbSH3, and T-BSH1r emerged as the most significant contributors to the failures. It is advisable to maintain the operational levels of T-BSH3rm, T-BSH2l, T-BSH3r, T-BSH1l, T-SbSH3, and T-BSH1r around 527 °C, 432 °C, 482 °C, 338 °C, 313 °C, and 343 °C respectively. Moreover, it is crucial to prevent these values from reaching or exceeding 594 °C, 471 °C, 537 °C, 355 °C, 340 °C, and 359 °C for prolonged durations. The findings offer the opportunity to improve future operational conditions, thereby extending the overall service life of the boiler. Consequently, operators can address faulty tubes during scheduled annual maintenance without encountering failures and disrupting production. Full article

(This article belongs to the Special Issue Industrial Process Operation State Sensing and Performance Optimization)

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15 pages, 7238 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Effect of Support on Steam Reforming of Ethanol for H₂ Production with Copper-Based Catalysts

by Ramiro Picoli Nippes, Paula Derksen Macruz, Aline Domingues Gomes, Marcos de Souza, Bruna Rodrigues Ferreira, Roberta Carolina Pelissari Rizzo-Domingues and Luiz Pereira Ramos

Processes 2024, 12(7), 1331; https://doi.org/10.3390/pr12071331 - 27 Jun 2024

Cited by 1 | Viewed by 1252

Abstract

Catalytic studies hydrogen production via steam reforming of ethanol (SRE) are essential for process optimization. Likewise, selecting the ideal support for the active phase can be critical to achieve high conversion rates during the catalytic steam reforming process. In this work, copper-based catalysts [...] Read more.

Catalytic studies hydrogen production via steam reforming of ethanol (SRE) are essential for process optimization. Likewise, selecting the ideal support for the active phase can be critical to achieve high conversion rates during the catalytic steam reforming process. In this work, copper-based catalysts were synthesized using two different supports, NaY zeolite and Nb₂O₅/Al₂O₃ mixed oxides. The materials were prepared using wet impregnation and characterized for their physicochemical properties using different analytical techniques. Differences in the catalyst morphologies were readily attributed to the characteristics of the support. The Cu/NaY catalyst exhibited a higher specific surface area (210.40 m² g⁻¹) compared to the Cu/Nb₂O₅/Al₂O₃ catalyst (26.00 m² g⁻¹), resulting in a homogeneous metal dispersion over the support surface. The obtained results showed that, at 300 °C, both the Cu/Nb₂O₅/Al₂O₃ and Cu/NaY catalysts produced approximately 50% hydrogen and 40% acetaldehyde, but with significant differences in conversion (6% and 56%, respectively). At 450 °C, a greater product distribution and a 10% higher conversion were observed when the catalyst was supported on NaY compared to Nb₂O₅/Al₂O₃. Hence, the performance of copper-based catalysts was influenced significantly by the textural properties of the support. Full article

(This article belongs to the Special Issue Processes in Biofuel Production and Biomass Valorization)

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16 pages, 2127 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Removal of Cefuroxime from Soils Amended with Pine Bark, Mussel Shell and Oak Ash

by Raquel Cela-Dablanca, Ainoa Míguez-González, Lucía Rodríguez-López, Ana Barreiro, Manuel Arias-Estévez, María J. Fernández-Sanjurjo, Esperanza Álvarez-Rodríguez and Avelino Núñez-Delgado

Processes 2024, 12(7), 1335; https://doi.org/10.3390/pr12071335 - 27 Jun 2024

Cited by 1 | Viewed by 1527

Abstract

The global increase in antibiotics consumption has caused hazardous concentrations of these antimicrobials to be present in soils, mainly due to the spreading of sewage sludge (or manure or slurry) and wastewater, and they could enter the food chain, posing serious risks to [...] Read more.

The global increase in antibiotics consumption has caused hazardous concentrations of these antimicrobials to be present in soils, mainly due to the spreading of sewage sludge (or manure or slurry) and wastewater, and they could enter the food chain, posing serious risks to the environment and human health. One of these substances of concern is cefuroxime (CFX). To face antibiotics-related environmental pollution, adsorption is one of the most widely used techniques, with cost-effective and environmentally friendly byproducts being of clear interest to retain pollutants and increase the adsorption capacity of soils. In light of this, in this work, three low-cost bioadsorbents (pine bark, oak ash, and mussel shell) were added to different soil samples (at doses of 12 and 48 t/ha) to study their effects on the adsorption of CFX. Specifically, batch experiments were carried out for mixtures of soils and bioadsorbents, adding a range of different antibiotic concentrations at a fixed ionic strength. The results showed that the addition of pine bark (with pH = 3.99) increased the adsorption to 100% in most cases, while oak ash (pH = 11.31) and mussel shell (pH = 9.39) caused a clearly lower increase in adsorption (which, in some cases, even decreased). The Freundlich and linear models showed rather good adjustment to the experimental data when the bioadsorbents were added at both doses, while the Langmuir model showed error values which were too high in many cases. Regarding desorption, it was lower than 6% for the soils without bioadsorbents, and there was no desorption when the soils received bioadsorbent amendments. These results show that the addition of appropriate low-cost bioadsorbents to soils can be effective for adsorbing CFX, helping in the prevention of environmental pollution due to this emerging contaminant, which is a result of clear relevance to environmental and human health. Full article

(This article belongs to the Topic Environmental and Health Issues and Solutions for Anticoccidials and other Emerging Pollutants of Special Concern)

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16 pages, 3483 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Analysis of Carbon Emission Reduction with Using Low-Carbon Demand Response: Case Study of North China Power Grid

by Haoran Feng, Jie Ji, Chen Yang, Fuqiang Li, Yaowang Li and Lanchun Lyu

Processes 2024, 12(7), 1324; https://doi.org/10.3390/pr12071324 - 26 Jun 2024

Cited by 1 | Viewed by 1266

Abstract

The power sector is the single industry with the largest carbon emission in China, the carbon emission of which accounts for more than 40% of China’s total carbon emissions. In relevant research on the simulation of power system operation, current studies focus more [...] Read more.

The power sector is the single industry with the largest carbon emission in China, the carbon emission of which accounts for more than 40% of China’s total carbon emissions. In relevant research on the simulation of power system operation, current studies focus more on energy conservation and economical operation, while few consider the low-carbon optimization of the power system from the perspective of carbon emissions. In addition, in relevant research on carbon reduction in the power system, current studies focus more on controlling the direct carbon emission of the source side and less on the indirect carbon emissions of the load side, which focus on the reverse effect of a user’s electricity consumption behavior on the carbon reduction goals of the power system. This article delved into a deterministic simulation model of power system operation based on time series load curves and proposed a carbon reduction mechanism called the low-carbon demand response mechanism, which guides users to actively respond and reduce the carbon emission of power systems. In addition, this article conducted an empirical analysis based on the planning data of the North China Power Grid. To minimize carbon emissions, a simulation of low-carbon optimization operation for the North China Power Grid in 2040 was carried out. Then, based on the simulation results, an analysis of the carbon reduction benefits of low-carbon demand response was carried out. Ultimately, the empirical analysis verified that low-carbon optimization operation and low-carbon demand response technology possess significant carbon reduction potential for the power system. Full article

(This article belongs to the Section Energy Systems)

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37 pages, 43915 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Microfluidic Insights into the Effects of Reservoir and Operational Parameters on Foamy Oil Flow Dynamics during Cyclic Solvent Injection: Reservoir-on-the-Chip Aided Experimental and Numerical Studies

by Ali Cheperli, Farshid Torabi and Morteza Sabeti

Processes 2024, 12(7), 1305; https://doi.org/10.3390/pr12071305 - 24 Jun 2024

Cited by 1 | Viewed by 1335

Abstract

This study examines the microfluidic characterization of foamy oil flow dynamics in heterogeneous porous media. A total of 12 microfluidic CSI experiments were conducted using reservoir-on-the-chip platforms. In addition, detailed PVT analysis was performed to characterise the heavy oil/solvent systems. Moreover, a numerical [...] Read more.

This study examines the microfluidic characterization of foamy oil flow dynamics in heterogeneous porous media. A total of 12 microfluidic CSI experiments were conducted using reservoir-on-the-chip platforms. In addition, detailed PVT analysis was performed to characterise the heavy oil/solvent systems. Moreover, a numerical model constructed with CMG software package (2021.10) has been validated against the experimental findings in this study. A clear-cut visualization study provided by microfluidic systems revealed that factors including solvent type, pressure depletion rate, and reservoir parameters have a significant impact on foamy oil flow extension. It was found that a solvent containing a higher CO₂ content demonstrated more effective performance compared with other solvent compositions, owing to its capability to reduce viscosity, enhance swelling, and offer more gas molecules due to its superior solubility. Additionally, a high pressure-depletion rate amplifies the driving force for bubble nucleation, as well as reducing the amount of time available for bubble coalescence. In addition, lower reservoir porosity impedes bubble movement and delays coalescence, thus extending the foamy oil flow. Furthermore, with the aid of a robust image analysis technique, it was discovered that utilizing 100% CO₂ as a solvent resulted in a 17% increase in oil recovery over using 50% CO₂ and 50% CH₄. Furthermore, a 6% increase in oil recovery was achieved by applying a fast pressure depletion rate as opposed to a slow pressure depletion rate. Moreover, the numerical model constructed was found to be accurate in adjusting heavy oil recovery with an average relative error of 7.7%. Full article

(This article belongs to the Special Issue Advanced Reservoir Simulation and Modelling, Thermal and Enhanced Oil Recovery Processes)

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31 pages, 6930 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Energy-Efficient Production of Microchloropsis salina Biomass with High CO₂ Fixation Yield in Open Thin-Layer Cascade Photobioreactors

by Ayşe Koruyucu, Torben Schädler, Amelie Gniffke, Konrad Mundt, Susann Krippendorf, Peter Urban, Karlis Blums, Billy Halim, Thomas Brück and Dirk Weuster-Botz

Processes 2024, 12(7), 1303; https://doi.org/10.3390/pr12071303 - 23 Jun 2024

Cited by 1 | Viewed by 1827

Abstract

Lipid production using microalgae is challenging for producing low-value-added products. Harnessing microalgae for their fast and efficient CO₂ fixation capabilities may be more reasonable since algal biomass can be utilized as a precursor for various products in a biorefinery approach. This study [...] Read more.

Lipid production using microalgae is challenging for producing low-value-added products. Harnessing microalgae for their fast and efficient CO₂ fixation capabilities may be more reasonable since algal biomass can be utilized as a precursor for various products in a biorefinery approach. This study aimed to optimize the productivity and efficiency of Microchloropsis salina biomass production in open thin-layer cascade (TLC) photobioreactors under physical simulation of suitable outdoor climate conditions, using an artificial seawater medium. Continuous operation proved to be the most suitable operating mode, allowing an average daily areal productivity of up to 27 g m⁻² d⁻¹ and CO₂ fixation efficiency of up to 100%. Process transfer from 8 m² to 50 m² TLC photobioreactors was demonstrated, but with reduced daily areal productivity of 21 g m⁻² d⁻¹ and a reduced CO₂ fixation efficiency, most probably due to increased temperatures at midday above 35 °C. An automated overnight switch-off of the circulation pumps was implemented successfully, reducing energy and freshwater requirements by ~40%. The ideal conditions for continuous production were determined to be a dilution rate of 0.150–0.225 d⁻¹, pH of 8.5, and total alkalinity of 200–400 ppm, facilitating efficient pilot-scale production of microalgal biomass in TLC photobioreactors. Full article

(This article belongs to the Topic Bioreactors: Control, Optimization and Applications - 2nd Volume)

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14 pages, 19402 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Properties of Ni-B/B Composite Coatings Produced by the Electroless Method under Semi-Technical Line Conditions

by Grzegorz Cieślak, Marta Gostomska, Adrian Dąbrowski, Tinatin Ciciszwili-Wyspiańska, Katarzyna Skroban, Anna Mazurek, Edyta Wojda, Michał Głowacki, Tomasz Rygier and Anna Gajewska-Midziałek

Processes 2024, 12(6), 1280; https://doi.org/10.3390/pr12061280 - 20 Jun 2024

Cited by 1 | Viewed by 1432

Abstract

Composite coatings have been successfully fabricated at the laboratory scale in many research centers around the world; however, it is still a major challenge to transfer the positive results of the work to the industrial scale. This paper presents the technology for the [...] Read more.

Composite coatings have been successfully fabricated at the laboratory scale in many research centers around the world; however, it is still a major challenge to transfer the positive results of the work to the industrial scale. This paper presents the technology for the production of Ni-B and Ni-B/B composite coatings on a pilot experimental semi-technical line by chemical reduction. A process scheme for the fabrication of Ni-B layers and composite coatings with a nickel–boron matrix and a dispersive phase in the form of boron nanoparticles was developed. All stages of the fabrication process were described in detail. The dispersion phase of the boron particles was characterized, and the performance properties of the Ni-B and Ni-B/B composite coatings produced on a pilot electroplating line were studied. The structure and morphology of the Ni-B/B composite coatings were characterized for comparison with nickel–boron coatings. Their mechanical and tribological properties and adhesion to the substrate were studied. The influence of the dispersion phase of boron particles on the structure and functional properties of the composite coatings was evaluated. In order to improve the performance of the fabricated coatings, a heating process at 400 °C was carried out, and the performance of Ni-B and composite Ni-B/B coatings was studied after the heat treatment operation. Full article

(This article belongs to the Special Issue Recent Advances in Functional Materials Manufacturing and Processing)

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17 pages, 4847 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Inverse Method-Based Kinetic Modelling and Process Optimization of Reverse-Phase Chromatography for Molnupiravir Synthesis

by Athanasios Kritikos, Ravendra Singh, Fernando Muzzio and George Tsilomelekis

Processes 2024, 12(6), 1273; https://doi.org/10.3390/pr12061273 - 20 Jun 2024

Viewed by 1408

Abstract

Our research addresses the shift towards continuous manufacturing in the pharmaceutical industry, focusing on optimizing chromatographic separation for the synthesis of molnupiravir. Using an inverse method with six different inlet concentrations for a single objective function, we systematically evaluated the adsorption of key [...] Read more.

Our research addresses the shift towards continuous manufacturing in the pharmaceutical industry, focusing on optimizing chromatographic separation for the synthesis of molnupiravir. Using an inverse method with six different inlet concentrations for a single objective function, we systematically evaluated the adsorption of key intermediates, i.e., hydroxylamine and isobutyrate, in an isocratic solvent, determining the relevant isotherm constants. The study systematically evaluates the effects of operational variables, including flowrate, column geometry, dispersivity coefficient, and injection volume, on chromatographic performance. Findings reveal that specific operational adjustments, such as reducing flowrates or altering column dimensions, significantly influence retention times and peak profiles, thus potentially impacting the efficiency of molnupiravir production. Utilizing the inverse method, we efficiently determined equilibrium isotherms by integrating a nonlinear chromatography model and adjusting isotherm parameters to match the observed band profiles. Our research offers critical insights into optimizing chromatographic separation performance through precise operational control, leveraging computational tools for rapid and adaptable drug development. Full article

(This article belongs to the Special Issue Application of Process Systems Engineering in Continuous Pharmaceutical and Biopharmaceutical Manufacturing)

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27 pages, 4239 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Advancing Wastewater Treatment: A Comparative Study of Photocatalysis, Sonophotolysis, and Sonophotocatalysis for Organics Removal

by Szabolcs Bognár, Dušica Jovanović, Vesna Despotović, Nina Finčur, Predrag Putnik and Daniela Šojić Merkulov

Processes 2024, 12(6), 1256; https://doi.org/10.3390/pr12061256 - 18 Jun 2024

Cited by 6 | Viewed by 1944

Abstract

Clear and sanitarily adequate water scarcity is one of the greatest problems of modern society. Continuous population growth, rising organics concentrations, and common non-efficient wastewater treatment technologies add to the seriousness of this issue. The employment of various advanced oxidation processes (AOPs) in [...] Read more.

Clear and sanitarily adequate water scarcity is one of the greatest problems of modern society. Continuous population growth, rising organics concentrations, and common non-efficient wastewater treatment technologies add to the seriousness of this issue. The employment of various advanced oxidation processes (AOPs) in water treatment is becoming more widespread. In this review, the state-of-the-art application of three AOPs is discussed in detail: photocatalysis, sonophotolysis, and sonophotocatalysis. Photocatalysis utilizes semiconductor photocatalysts to degrade organic pollutants under light irradiation. Sonophotolysis combines ultrasound and photolysis to generate reactive radicals, enhancing the degradation of organic pollutants. Sonophotocatalysis synergistically combines ultrasound with photocatalysis, resulting in improved degradation efficiency compared to individual processes. By studying this paper, readers will get an insight into the latest published data regarding the above-mentioned processes from the last 10 years. Different factors are compared and discussed, such as degradation efficiency, reaction kinetics, catalyst type, ultrasound frequency, or water matrix effects on process performance. In addition, the economic aspects of sonophotolysis, photocatalysis, and sonophotocatalysis will be also analyzed and compared to other processes. Also, the future research directions and potential applications of these AOPs in wastewater treatment will be highlighted. This review offers invaluable insights into the selection and optimization of AOPs. Full article

(This article belongs to the Special Issue 2nd Edition of Innovation in Chemical Plant Design)

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14 pages, 2009 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Hydrophobic Deep Eutectic Solvents for Ethanol, Propan-1-ol, and Propan-2-ol Recovery from Aqueous Solutions

by Dalal J. S. A. Audeh, Adriano Carniel, Cristiano Piacsek Borges, Maria Alice Zarur Coelho, Filipe Smith Buarque and Bernardo Dias Ribeiro

Processes 2024, 12(6), 1255; https://doi.org/10.3390/pr12061255 - 18 Jun 2024

Cited by 7 | Viewed by 1997

Abstract

Separating hydroalcoholic mixtures remains a significant challenge in engineering. Liquid–liquid extraction has emerged as an appealing alternative method, because it avoids the need for the large energy inputs, volatile organic compounds, and high pressures that are typically required by other separation processes. This [...] Read more.

Separating hydroalcoholic mixtures remains a significant challenge in engineering. Liquid–liquid extraction has emerged as an appealing alternative method, because it avoids the need for the large energy inputs, volatile organic compounds, and high pressures that are typically required by other separation processes. This study explores the use of hydrophobic deep eutectic solvents (HDESs) composed of terpenes and 10-undecenoic acid as extraction agents for the liquid–liquid separation of hydroalcoholic mixtures composed of alcohols (ethanol, propan-1-ol, and propan-2-ol) and water. The water content in the solvents studied was notably low, reflecting their hydrophobic nature. For the dried HDES samples, the water content ranged from 553 to 4901 ppm. In contrast, the water-saturated samples exhibited higher water contents, ranging from 7250 to 20,864 ppm. The HDES based on thymol, DL-menthol, and L-menthol displayed a eutectic point at an x_terpenes of approximately 0.67. These mixtures maintained a liquid state up to a mole fraction of terpenes around 0.75. In contrast, the HDES composed of carvacrol, fenchyl alcohol, and α-terpineol exhibited their eutectic point at an x_terpenes near 0.5. Notably, these mixtures remained in a liquid state across the entire composition range studied. The 2:1 molar ratio (HBA:HBD) presented the best values for extracting alcohols, reaching 34.04%, 36.59%, and 39.78% for ethanol, propan-2-ol, and propan-1-ol, respectively. These results show that HDES can be applied to overcome issues with existing extraction solvents, increasing the separation efficiency and making the process eco-friendly. Full article

(This article belongs to the Special Issue Green Separation and Purification Processes)

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31 pages, 7739 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Nirmatrelvir: From Discovery to Modern and Alternative Synthetic Approaches

by Michela Galli, Francesco Migliano, Valerio Fasano, Alessandra Silvani, Daniele Passarella and Andrea Citarella

Processes 2024, 12(6), 1242; https://doi.org/10.3390/pr12061242 - 17 Jun 2024

Cited by 2 | Viewed by 1993

Abstract

The global urgency in response to the COVID-19 pandemic has catalyzed extensive research into discovering efficacious antiviral compounds against SARS-CoV-2. Among these, Nirmatrelvir (PF-07321332) has emerged as a promising candidate, exhibiting potent antiviral activity by targeting the main protease of SARS-CoV-2, and has [...] Read more.

The global urgency in response to the COVID-19 pandemic has catalyzed extensive research into discovering efficacious antiviral compounds against SARS-CoV-2. Among these, Nirmatrelvir (PF-07321332) has emerged as a promising candidate, exhibiting potent antiviral activity by targeting the main protease of SARS-CoV-2, and has been marketed in combination with ritonavir as the first oral treatment for COVID-19 with the name of Paxlovid^TM. This review outlines the synthetic approaches to Nirmatrelvir, ranging from Pfizer’s original method to newer, more sustainable strategies, such as flow chemistry strategies and multicomponent reactions. Each approach’s novelty and contributions to yield and purification processes are highlighted. Additionally, the synthesis of key fragments comprising Nirmatrelvir and innovative optimization strategies are discussed. Full article

(This article belongs to the Special Issue Novel Methodologies for the Synthesis of Bioactive Molecules)

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13 pages, 6447 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Effects of Ti/Al Ratio on Formation of Ti-Al Intermetallics/TiB₂ Composites by SHS from Ti-Al-B Powder Mixtures

by Chun-Liang Yeh and Yi-Cheng Chan

Processes 2024, 12(6), 1237; https://doi.org/10.3390/pr12061237 - 16 Jun 2024

Viewed by 1270

Abstract

Ti-Al intermetallics/TiB₂ composites were prepared from elemental powder mixtures by the method of self-propagating high-temperature synthesis (SHS). Reactant mixtures were formulated to contain two parts; one group was (2Ti + 4B) to form 2TiB₂ and the other group was (Ti + [...] Read more.

Ti-Al intermetallics/TiB₂ composites were prepared from elemental powder mixtures by the method of self-propagating high-temperature synthesis (SHS). Reactant mixtures were formulated to contain two parts; one group was (2Ti + 4B) to form 2TiB₂ and the other group was (Ti + xAl) to produce Ti-Al intermetallic compounds. The content of Al ranged between x = 0.33 and 3.0, which was equivalent to the Ti/Al atomic ratio from Ti-25% Al to Ti-75% Al in the (Ti + xAl) group. The results showed that the increase of Al percentage reduced the overall combustion exothermicity and led to a slower self-sustaining combustion wave speed and a lower combustion temperature. Apparent activation energy of the Ti-Al-B solid-state combustion reaction was determined to be 114.7 kJ/mol by this study. Based on the XRD analysis, Ti-Al intermetallics/TiB₂ composites featuring Ti₃Al, TiAl, TiAl₂, and TiAl₃ as the dominant aluminide phase were respectively synthesized from the samples of Ti-25%~40% Al, Ti-50%~60% Al, Ti-71.4% Al, and Ti-75% Al. For the samples of Ti-25% Al and Ti-30% Al, Ti₃Al was the only aluminide formed. The microstructure of the composites exhibited that TiB₂ grains with a columnar shape of 2–3 μm in length were well distributed and embedded in the aluminide matrix. This study demonstrated an effective and energy-saving fabrication route for producing Ti-Al intermetallics/TiB₂ composites with different dominant aluminide phases. Full article

(This article belongs to the Special Issue Composites by Metallurgy and Combustion Synthesis)

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17 pages, 4718 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Rice Bran Valorization through the Fabrication of Nanofibrous Membranes by Electrospinning

by María Alonso-González, Manuel Felix and Alberto Romero

Processes 2024, 12(6), 1204; https://doi.org/10.3390/pr12061204 - 12 Jun 2024

Cited by 1 | Viewed by 1169

Abstract

The high production rate of fossil-based plastics, coupled with their accumulation and low degradability, is causing severe environmental problems. As a result, there is a growing interest in the use of renewable and natural sources in the polymer industry. Specifically, rice bran is [...] Read more.

The high production rate of fossil-based plastics, coupled with their accumulation and low degradability, is causing severe environmental problems. As a result, there is a growing interest in the use of renewable and natural sources in the polymer industry. Specifically, rice bran is a highly abundant by-product of the agro-food industry, with variable amounts of protein and starch within its composition, which are usually employed for bioplastic development. This study aims to valorize rice bran through the production of nanofiber membranes processed via electrospinning. Due to its low solubility, the co-electrospinning processing of rice bran with potato starch, known for its ability to form nanofibers through this technique, was chosen. Several fiber membranes were fabricated with modifications in solution conditions and electrospinning parameters to analyze their effects on the synthesized fiber morphology. This analysis involved obtaining micrographs of the fibers through scanning electron microscopy (SEM) and fiber diameter analysis. Potato starch membranes were initially investigated, and once optimal electrospinning conditions were identified, the co-electrospinning of rice bran and potato starch was conducted. Attempts were made to correlate the physical properties of the solutions, such as conductivity and density, with the characteristics of the resulting electrospun fibers. The results presented in this study demonstrate the potential valorization of a rice by-product for the development of bio-based nanofibrous membranes. This not only offers a solution to combat current plastic waste accumulation but also opens up a wide range of applications from filtration to biomedical devices (i.e., in tissue engineering). Full article

(This article belongs to the Special Issue Platform Chemicals and Novel Materials from Biomass)

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19 pages, 4211 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Exopolysaccharides Synthesized by Lacticaseibacillus rhamnosus ŁOCK 0943: Structural Characteristics and Evaluation of Biological and Technological Properties

by Magdalena Oleksy-Sobczak, Sabina Górska, Lidia Piekarska-Radzik, Sylwia Ścieszka and Elżbieta Klewicka

Processes 2024, 12(6), 1192; https://doi.org/10.3390/pr12061192 - 11 Jun 2024

Cited by 1 | Viewed by 1129

Abstract

Lactic acid bacteria can synthesize extracellular exopolysaccharides (EPSs) that have versatile physicochemical and biological properties. In this paper, the EPSs synthesized by Lacticaseibacillus rhamnosus ŁOCK 0943 were characterized. Their structure, biological, and technological activity, as well as application potential, were analyzed. Chemical analysis [...] Read more.

Lactic acid bacteria can synthesize extracellular exopolysaccharides (EPSs) that have versatile physicochemical and biological properties. In this paper, the EPSs synthesized by Lacticaseibacillus rhamnosus ŁOCK 0943 were characterized. Their structure, biological, and technological activity, as well as application potential, were analyzed. Chemical analysis showed that this strain produces mannan and β-1,6-glucan. Their emulsifying, antagonistic, and antioxidant properties, along with their prebiotic potential, were assessed. The analysis of the tested polymers’ ability to create a stable emulsion showed that their emulsifying activity depends mainly on the type of oily substance used. The analysis of the antagonistic activity revealed that these EPSs can inhibit the growth of yeasts (e.g., Candida albicans ATCC 10231) and potentially pathogenic bacteria (e.g., Clostridium acetobutylicum ŁOCK 0831, Enterococcus faecalis ATCC 29212). Moreover, EPSs positively influenced the growth of all tested probiotic bacteria. Furthermore, EPSs can be successfully used as a preservative in cosmetic products. The most effective results were obtained with the use of a 0.05% solution of a chemical preservative (bronopol) and 0.25 mg/mL of the EPSs. Full article

(This article belongs to the Section Food Process Engineering)

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19 pages, 8718 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Comparison of Mechanical, Fatigue, and Corrosion Properties of Fusion-Welded High-Strength AA6011 Alloy Using Three Filler Wires

by Mohamed Ahmed, Mousa Javidani, Alexandre Maltais and X.-Grant Chen

Processes 2024, 12(6), 1172; https://doi.org/10.3390/pr12061172 - 7 Jun 2024

Cited by 2 | Viewed by 1158

Abstract

In this study, the welding performance of three filler wires, ER4043, ER5356, and the newly developed FMg0.6, were systematically investigated in the gas metal arc welding of high-strength AA6011-T6 plates. An extensive analysis of the microstructural evolution, mechanical properties, fatigue resistance, and corrosion [...] Read more.

In this study, the welding performance of three filler wires, ER4043, ER5356, and the newly developed FMg0.6, were systematically investigated in the gas metal arc welding of high-strength AA6011-T6 plates. An extensive analysis of the microstructural evolution, mechanical properties, fatigue resistance, and corrosion behavior of different weldments was conducted. The ER4043 and FMg0.6 joints exhibited finer grain sizes in the fusion zone (FZ) than the ER5356 joint. The as-welded ER5356 and FMg0.6 joints exhibited higher hardness and tensile strength values than the ER4043 joint. The FMg0.6 joint demonstrated the highest mechanical strength among all of the joints with superior fatigue resistance under both the as-welded and post-weld heat treatment (PWHT) conditions. In the as-welded state, the ER5356 joint exhibited the lowest corrosion resistance, attributed to the precipitation of β-Al₂Mg₃ at the grain boundaries. The FMg0.6 joint, characterized by a high-volume fraction of eutectic Mg₂Si in the as-welded state, exhibited a higher corrosion rate than that of the ER4043 joint. However, the PWHT effectively improved the corrosion resistance of the FMg0.6 joint. Given its excellent tensile properties, superior fatigue properties, and satisfactory corrosion resistance, particularly with PWHT, the newly developed FMg0.6 filler has emerged as a promising candidate for welding high-strength 6xxx alloys. Full article

(This article belongs to the Special Issue Advances and Implementation of Welding and Additive Manufacturing)

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16 pages, 1576 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Edge Computing-Based Modular Control System for Industrial Environments

by Gonçalo Gouveia, Jorge Alves, Pedro Sousa, Rui Araújo and Jérôme Mendes

Processes 2024, 12(6), 1165; https://doi.org/10.3390/pr12061165 - 6 Jun 2024

Cited by 1 | Viewed by 1397

Abstract

This paper presents a modular hardware control system tailored for industrial applications. The system presented is designed with electrical protection, guaranteeing the reliable operation of its modules in the presence of various field noises and external disturbances. The modular architecture comprises a principal [...] Read more.

This paper presents a modular hardware control system tailored for industrial applications. The system presented is designed with electrical protection, guaranteeing the reliable operation of its modules in the presence of various field noises and external disturbances. The modular architecture comprises a principal module (mP) and dedicated expansion modules (mEXs). The principal module serves as the network administrator and facilitates interaction with production and control processes. The mEXs are equipped with sensors, conditioning circuits, analog-to-digital converters, and digital signal processing capabilities. The mEX’s primary function is to acquire local processing field signals and ensure their reliable transmission to the mP. Two specific mEXs were developed for industrial environments: an electrical signal expansion module (mSE) and the vibration signals expansion module (mSV). The EtherCAT protocol serves as a means of communication between the modules, fostering deterministic and real-time interactions while also simplifying the integration and replacement of modules within the modular architecture. The proposed system incorporates local and distributed processing in which data acquisition, processing, and data analysis are carried out closer to where data are generated. Locally processing the acquired data close to the production in the mEX increases the mP availability and network reliability. For the local processing, feature extraction algorithms were developed on the mEX based on a Fast Fourier Transform (FFT) algorithm and a curve-fitting algorithm that accurately represents a given FFT curve by significantly reducing the amount of data that needs to be transmitted over the mP. The proposed system offers a promising solution to use computational intelligence methodologies and meet the growing need for a modular industrial control system with reliable local data processing to reach a smart industry. The case study of acquiring and processing vibration signals from a real cement ball mill showed a good capacity for processing data and reducing the amount of data. Full article

(This article belongs to the Special Issue Recent Developments in Automatic Control and Systems Engineering)

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22 pages, 12706 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Catalytic Dehydrogenation on Ultradisperse Sn-Promoted Ir Catalysts Supported on MgAl₂O₄ Prepared by Different Techniques

by Sergio de Miguel, Jayson Fals, Viviana Benitez, Catherine Especel, Florence Epron and Sonia Bocanegra

Processes 2024, 12(6), 1161; https://doi.org/10.3390/pr12061161 - 5 Jun 2024

Viewed by 916

Abstract

Ir and IrSn catalysts with different Sn contents (0.5, 0.7 and 0.9 wt%) were prepared using MgAl₂O₄ supports synthesized using two different techniques (the citrate–nitrate combustion and coprecipitation methods). Both supports, with a spinel structure, presented low acidity and good [...] Read more.

Ir and IrSn catalysts with different Sn contents (0.5, 0.7 and 0.9 wt%) were prepared using MgAl₂O₄ supports synthesized using two different techniques (the citrate–nitrate combustion and coprecipitation methods). Both supports, with a spinel structure, presented low acidity and good textural properties. However, the support prepared by coprecipitation had higher specific surface area and pore volume than the one prepared by combustion, which would favor the dispersion of the metals to be deposited. Likewise, during the preparation of the catalytic materials, a very good interaction was achieved between the metals and both supports, which was confirmed by the presence of sub-nanometer atomic clusters in the mono- and bimetallic catalysts. Regarding the catalytic properties, while the monometallic Ir/MgAl₂O₄ samples lead to a very low conversion of n-butane and a selectivity towards hydrogenolysis products, the addition of Sn to Ir increases the conversion, decreases hydrogenolysis and therefore sharply increases the selectivity towards the different butenes. Catalysts with higher Sn loadings present better catalytic behavior. One of the roles of the Sn promoter would be to geometrically modify the Ir clusters, drastically decreasing the hydrogenolytic activity. This effect, added to the strong electronic modification of the Ir sites by the action of Sn, with probable Ir-Sn alloy formation, is responsible for the high catalytic performance of these bimetallic catalysts. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis in Chemical and Petrochemical Processes)

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27 pages, 4534 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Optimal Design of a Renewable-Energy-Driven Integrated Cooling–Freshwater Cogeneration System

by Iman Janghorban Esfahani and Pouya Ifaei

Processes 2024, 12(6), 1164; https://doi.org/10.3390/pr12061164 - 5 Jun 2024

Cited by 2 | Viewed by 1611

Abstract

This study presents a novel approach that will address escalating demands for water and cooling in regions vulnerable to climate change through the proposal of an optimal integrated cooling–freshwater cogeneration system powered by renewable energy sources. Comprising three subsystems (integrated multi-effect evaporation distillation, [...] Read more.

This study presents a novel approach that will address escalating demands for water and cooling in regions vulnerable to climate change through the proposal of an optimal integrated cooling–freshwater cogeneration system powered by renewable energy sources. Comprising three subsystems (integrated multi-effect evaporation distillation, absorption heat pump, and vapor compression refrigeration (MAV); renewable energy unit incorporating solar panels, wind turbines, batteries, and hydrogen facilities (RHP/BH); and combined heat and power (CHP)), the system aims to produce both cooling and freshwater. By recovering cooling from combined desalination and refrigeration subsystems to chill the air taken into the gas turbine compressor, the system maximizes efficiency. Through the recovery of waste heat and employing an integrated thermo-environ-economic framework, a novel objective function, termed modified total annual cost (MTAC), is introduced for optimization. Using a genetic algorithm, parametric iterative optimization minimizes the MTAC. The results reveal that under optimum conditions, the MAV, RHP/BH, and CHP subsystems account for 67%, 58%, and 100% of total annual, exergy destruction, and environmental costs, respectively. Notably, the system exhibits lower sensitivity to fuel prices than renewable energy sources, suggesting a need for future research that will incorporate dynamic product prices and greater fuel consumption to produce enhanced operational robustness. Full article

(This article belongs to the Special Issue Optimal Design for Renewable Power Systems)

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23 pages, 3458 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

New Insight into the Degradation of Sunscreen Agents in Water Treatment Using UV-Driven Advanced Oxidation Processes

by Tajana Simetić, Jasmina Nikić, Marija Kuč, Dragana Tamindžija, Aleksandra Tubić, Jasmina Agbaba and Jelena Molnar Jazić

Processes 2024, 12(6), 1156; https://doi.org/10.3390/pr12061156 - 3 Jun 2024

Cited by 2 | Viewed by 1728

Abstract

This study evaluates, for the first time, the effects of UV/PMS and UV/H₂O₂/PMS processes on the degradation of sunscreen agents in synthetic and natural water matrices and compares their effectiveness with the more conventional UV/H₂O₂. [...] Read more.

This study evaluates, for the first time, the effects of UV/PMS and UV/H₂O₂/PMS processes on the degradation of sunscreen agents in synthetic and natural water matrices and compares their effectiveness with the more conventional UV/H₂O₂. Investigations were conducted using a mixture of organic UV filters containing 4-methylbenzylidene camphor (4-MBC) and 2-ethylhexyl-4-methoxycinnamate. Among the investigated UV-driven AOPs, UV/PMS/H₂O₂ was the most effective in synthetic water, while in natural water, the highest degradation rate was observed during the degradation of EHMC by UV/PMS. The degradation of UV filters in the UV/PMS system was promoted by sulfate radical (68% of the degradation), with hydroxyl radical contributing approximately 32%, while both radical species contributed approximately equally to the degradation in the UV/H₂O₂/PMS system. The Vibrio fischeri assay showed an increase in inhibition (up to 70%) at specific stages of UV/H₂O₂ treatment when applied to natural water, which further decreased to 30%, along with an increase in UV fluence and progressive degradation. The Pseudomonas putida test recorded minor toxicity (<15%) after treatments. Magnetic biochar utilized in conjunction with UV-driven AOPs exhibited superior performance in eliminating residual contaminants, providing an efficient and sustainable approach to mitigate sunscreen agents in water treatment. Full article

(This article belongs to the Special Issue Advanced Oxidation Processes toward Challenges in Contaminants of Emerging Concern Treatment)

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13 pages, 5815 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Synthesis, Characterization, and Photocatalytic Properties of Sol-Gel Ce-TiO₂ Films

by Lidija Ćurković, Debora Briševac, Davor Ljubas, Vilko Mandić and Ivana Gabelica

Processes 2024, 12(6), 1144; https://doi.org/10.3390/pr12061144 - 1 Jun 2024

Cited by 2 | Viewed by 1719

Abstract

In this study, nanostructured cerium-doped TiO₂ (Ce-TiO₂) films with the addition of different amounts of cerium (0.00, 0.08, 0.40, 0.80, 2.40, and 4.10 wt.%) were deposited on a borosilicate glass substrate by the flow coating sol-gel process. After flow coating, [...] Read more.

In this study, nanostructured cerium-doped TiO₂ (Ce-TiO₂) films with the addition of different amounts of cerium (0.00, 0.08, 0.40, 0.80, 2.40, and 4.10 wt.%) were deposited on a borosilicate glass substrate by the flow coating sol-gel process. After flow coating, the deposited films were dried at a temperature of 100 °C for 1 h, followed by calcination at a temperature of 450 °C for 2 h. For the characterization of sol-gel TiO₂ films, the following analytic techniques were used: X-ray diffraction (XRD), differential thermal analysis (DTA), thermal gravimetry (TG), differential scanning calorimetry (DSC), diffuse reflectance spectroscopy (DRS), and energy dispersive X-ray spectroscopy (EDS). Sol-gel-derived Ce-TiO₂ films were used for photocatalytic degradation of ciprofloxacin (CIP). The influence of the amount of Ce in TiO₂ films, the duration of the photocatalytic decomposition, and the irradiation type (UV-A and simulated solar light) on the CIP degradation were monitored. Kinetics parameters (reaction kinetics constants and the half-life) of the CIP degradation, as well as photocatalytic degradation efficiency, were determined. The best photocatalytic activity was achieved by the TiO₂ film doped with 0.08 wt.% Ce, under both UV-A and solar irradiation. The immobilized catalyst was successfully reused for three cycles under solar light simulator radiation, with changes in photocatalytic efficiency below 3%. Full article

(This article belongs to the Special Issue Catalysis in Advanced Oxidation Processes for Environmental Remediation)

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25 pages, 1838 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Achievements and Challenges of Matrix Solid-Phase Dispersion Usage in the Extraction of Plants and Food Samples

by Agnieszka Zgoła-Grześkowiak, Tomasz Grześkowiak, Magdalena Ligor and Robert Frankowski

Processes 2024, 12(6), 1146; https://doi.org/10.3390/pr12061146 - 1 Jun 2024

Cited by 2 | Viewed by 1801

Abstract

A review of the application of matrix solid-phase dispersion (MSPD) in the extraction of biologically active compounds and impurities from plants and food samples with a particular emphasis on conventional and new types of sorbents has been provided. An overview of MSPD applications [...] Read more.

A review of the application of matrix solid-phase dispersion (MSPD) in the extraction of biologically active compounds and impurities from plants and food samples with a particular emphasis on conventional and new types of sorbents has been provided. An overview of MSPD applications for the isolation of organic residues from biological samples, determined using chromatographic and spectroscopic techniques, has been presented. In this study, procedural solutions that may extend MSDP applicability for the extraction such as vortex-assisted, ultrasound-assisted, microwave-assisted, and extraction with a magnetic sorbent have been discussed. Special attention has been paid to MSPD sorbents including modified silica, diatomite, magnesium silicate, alumina, carbon materials (carbon nanotubes, graphene oxide, graphene, or graphite), molecularly imprinted polymers, and cyclodextrin. An important aspect of the MSPD procedure is the use of high-purity and environmentally friendly solvents for extraction (e.g., deep eutectic solvents), with such criteria being the most important for modern analytical chemistry. Many advantages of MSPD are presented, such as high recoveries, the requirement for a smaller volume of solvent, and shorter procedure times than classical methods. Full article

(This article belongs to the Special Issue Separation and Extraction Techniques in Food Processing and Analysis)

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51 pages, 13880 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Towards Reliable Prediction of Performance for Polymer Electrolyte Membrane Fuel Cells via Machine Learning-Integrated Hybrid Numerical Simulations

by Rashed Kaiser, Chi-Yeong Ahn, Yun-Ho Kim and Jong-Chun Park

Processes 2024, 12(6), 1140; https://doi.org/10.3390/pr12061140 - 31 May 2024

Cited by 2 | Viewed by 1995

Abstract

For mitigating global warming, polymer electrolyte membrane fuel cells have become promising, clean, and sustainable alternatives to existing energy sources. To increase the energy density and efficiency of polymer electrolyte membrane fuel cells (PEMFC), a comprehensive numerical modeling approach that can adequately predict [...] Read more.

For mitigating global warming, polymer electrolyte membrane fuel cells have become promising, clean, and sustainable alternatives to existing energy sources. To increase the energy density and efficiency of polymer electrolyte membrane fuel cells (PEMFC), a comprehensive numerical modeling approach that can adequately predict the multiphysics and performance relative to the actual test such as an acceptable depiction of the electrochemistry, mass/species transfer, thermal management, and water generation/transportation is required. However, existing models suffer from reliability issues due to their dependency on several assumptions made for the sake of modeling simplification, as well as poor choices and approximations in material characterization and electrochemical parameters. In this regard, data-driven machine learning models could provide the missing and more appropriate parameters in conventional computational fluid dynamics models. The purpose of the present overview is to explore the state of the art in computational fluid dynamics of individual components of the modeling of PEMFC, their issues and limitations, and how they can be significantly improved by hybrid modeling techniques integrating with machine learning approaches. Furthermore, a detailed future direction of the proposed solution related to PEMFC and its impact on the transportation sector is discussed. Full article

(This article belongs to the Special Issue Modeling, Simulation and Control in Energy Systems)

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22 pages, 3495 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Recovery of High-Value Compounds from Yarrowia lipolytica IMUFRJ 50682 Using Autolysis and Acid Hydrolysis

by Rhonyele Maciel da Silva, Bernardo Dias Ribeiro, Ailton Cesar Lemes and Maria Alice Zarur Coelho

Processes 2024, 12(6), 1132; https://doi.org/10.3390/pr12061132 - 30 May 2024

Cited by 1 | Viewed by 1365

Abstract

This study aimed to evaluate the sequential hydrolysis of the biomass from unconventional and versatile Y. lipolytica to recover mannoproteins, carbohydrates, and other compounds as well as to determine the antioxidant activity of ultrafiltered fractions. The crude biomass underwent autolysis, and the resulting [...] Read more.

This study aimed to evaluate the sequential hydrolysis of the biomass from unconventional and versatile Y. lipolytica to recover mannoproteins, carbohydrates, and other compounds as well as to determine the antioxidant activity of ultrafiltered fractions. The crude biomass underwent autolysis, and the resulting supernatant fraction was used for mannoprotein recovery via precipitation with ethanol. The precipitate obtained after autolysis underwent acid hydrolysis, and the resulting supernatant was ultrafiltered, precipitated, and characterized. The process yields were 55.5% and 46.14% for the crude biomass grown in glucose and glycerol, respectively. The mannoprotein with higher carbohydrate content (from crude biomass grown in glycerol) exhibited a higher emulsification index of 47.35% and thermal stability (60% weight loss). In contrast, the mannoprotein with higher protein content (from crude biomass grown in glucose) showed a better surface tension reduction of 44.50 mN/m. The technological properties showed that the crude biomass and the food ingredients are feasible to apply in food processing. The fractionation of the acid hydrolysis portion allowed the evaluation of the antioxidant power synergism among the components present in the hydrolysate, mostly the protein peptide chain. The sequential hydrolysis method is viable for extracting valuable products from Y. lipolytica. Full article

(This article belongs to the Special Issue Advances in Lipid Chemistry: Extraction, Process and Analysis)

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13 pages, 4860 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Development of Macro-Encapsulated Phase-Change Material Using Composite of NaCl-Al₂O₃ with Characteristics of Self-Standing

by Shenghao Liao, Xin Zhou, Xiaoyu Chen, Zhuoyu Li, Seiji Yamashita, Chaoyang Zhang and Hideki Kita

Processes 2024, 12(6), 1123; https://doi.org/10.3390/pr12061123 - 29 May 2024

Cited by 2 | Viewed by 1484

Abstract

Developing thermal storage materials is crucial for the efficient recovery of thermal energy. Salt-based phase-change materials have been widely studied. Despite their high thermal storage density and low cost, they still face issues such as low thermal conductivity and easy leaks. Therefore, a [...] Read more.

Developing thermal storage materials is crucial for the efficient recovery of thermal energy. Salt-based phase-change materials have been widely studied. Despite their high thermal storage density and low cost, they still face issues such as low thermal conductivity and easy leaks. Therefore, a new type of NaCl-Al₂O₃@SiC@Al₂O₃ macrocapsule was developed to address these drawbacks, and it exhibited excellent rapid heat storage and release capabilities and was extremely stable, significantly reducing the risk of leakage at high temperatures for industrial waste heat recovery and in concentrated solar power systems above 800 °C. Thermal storage macrocapsules consisted of a double-layer encapsulation of silicon carbide and alumina and a self-standing core of NaCl-Al₂O_3. After enduring over 1000 h at a high temperature of 850 °C, the encapsulated phase-change material exhibited an extremely low weight loss rate of less than 5% compared with NaCl@Al₂O₃ and NaCl-Al₂O₃@Al₂O₃ macrocapsules, for which the weight loss rate was reduced by 25% and 10%, respectively, proving their excellent leakage prevention. The SiC powder layer, serving as an intermediate coating, further prevented leakage, while the use of Al₂O₃ ceramics for encapsulation enhanced the overall mechanical strength. It was innovatively discovered that the Al₂O₃ particles formed a network structure around the molten NaCl, playing an important role in maintaining the shape and preventing leakage of the composite thermal storage phase-change material. Furthermore, the addition of Al₂O₃ significantly enhanced the rapid heat storage and release rate of NaCl-Al₂O₃ compared to pure NaCl. This encapsulated phase-change material demonstrated outstanding durability and rapid heat storage and release performance, offering an innovative approach to the application of salt phase-change materials in the field of high temperature rapid heat storage and release and encapsulating NaCl as a high-temperature thermal storage material in a packed bed system. Compared with conventional salt-based phase-change materials, the developed product is expected to significantly improve the reliability and thermal efficiency of thermal storage systems. Full article

(This article belongs to the Special Issue Innovations in Phase-Change Materials for High-Temperature Heat Storage)

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11 pages, 2152 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Improving Microalgae Feasibility Cultivation: Preliminary Results on Exhausted Medium Reuse Strategy

by Luigi Marra, Elena Aurino, Francesca Raganati, Antonino Pollio and Antonio Marzocchella

Processes 2024, 12(5), 1029; https://doi.org/10.3390/pr12051029 - 19 May 2024

Cited by 1 | Viewed by 1492

Abstract

Although microalgae exploitation is very promising, process sustainability is undermined by biomass production and harvesting. Among the various bottlenecks of the production process, particular attention should be paid to the water footprint. Indeed, a huge volume of water is required in microalgae production. [...] Read more.

Although microalgae exploitation is very promising, process sustainability is undermined by biomass production and harvesting. Among the various bottlenecks of the production process, particular attention should be paid to the water footprint. Indeed, a huge volume of water is required in microalgae production. Water reuse can support both the water footprint and medium cost reduction, saving water and unconverted substrates. The present study reports preliminary results regarding the utilization of a water reuse strategy for two Chlorophyta microalgae under batch conditions. Growth parameters and chlorophyll content are monitored and the optimal amount of reused medium is assessed. The results show that 70% of the medium can be reused with no loss of specific growth rate and chlorophyll fraction for Pseudococcomyxa simplex in three consecutive batch cultivations. By contrast, a significant decline in Chlorella vulgaris growth was observed after the first cultivation in reused medium, across all tested conditions. Full article

(This article belongs to the Topic Bioreactors: Control, Optimization and Applications - 2nd Volume)

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26 pages, 4413 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Waste-to-Energy Processes as a Municipality-Level Waste Management Strategy: A Case Study of Kočevje, Slovenia

by Vladimir Prebilič, Matic Može and Iztok Golobič

Processes 2024, 12(5), 1010; https://doi.org/10.3390/pr12051010 - 15 May 2024

Cited by 1 | Viewed by 1412

Abstract

The escalating challenge of waste management demands innovative strategies to mitigate environmental impacts and harness valuable resources. This study investigates waste-to-energy (WtE) technologies for municipal waste management in Kočevje, Slovenia. An analysis of available waste streams reveals substantial energy potential from mixed municipal [...] Read more.

The escalating challenge of waste management demands innovative strategies to mitigate environmental impacts and harness valuable resources. This study investigates waste-to-energy (WtE) technologies for municipal waste management in Kočevje, Slovenia. An analysis of available waste streams reveals substantial energy potential from mixed municipal waste, biodegradable waste, and livestock manure. Various WtE technologies, including incineration, pyrolysis, gasification, and anaerobic digestion, are compared. The results show that processing mixed municipal waste using thermochemical processes could annually yield up to 0.98 GWh of electricity, and, separately, 3.22 GWh of useable waste heat for district heating or industrial applications. Furthermore, by treating 90% of the biodegradable waste, up to 1.31 GWh of electricity and 1.76 GWh of usable waste heat could be generated annually from biodegradable municipal waste and livestock manure using anaerobic digestion and biogas combustion in a combined heat and power facility. Gasification coupled with a gas-turbine-based combined heat and power cycle is suggested as optimal. Integration of WtE technologies could yield 2.29 GWh of electricity and 3.55 GWh of useable waste heat annually, representing an annual exergy yield of 2.98 GWh. Within the Kočevje municipality, this amount of energy could cover 23.6% of the annual household electricity needs and cover the annual space and water heating requirements of 10.0% of households with district heating. Additionally, CO₂-eq. emissions could be reduced by up to 20%, while further offsetting emissions associated with electricity and district heat generation by 1907 tons annually. These findings highlight the potential of WtE technologies to enhance municipal self-sustainability and reduce landfill waste. Full article

(This article belongs to the Special Issue Municipal Solid Waste for Energy Production and Resource Recovery)

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14 pages, 1276 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Screening of Metal Reduction Potential for Thermochemical Hydrogen Storage

by Jure Voglar and Blaž Likozar

Processes 2024, 12(5), 1004; https://doi.org/10.3390/pr12051004 - 15 May 2024

Viewed by 1252

Abstract

The screening of all non-radioactive metals without lanthanides for thermochemical hydrogen storage was performed based on physical chemistry calculations. The thermodynamic data were collected from the NIST (National Institute of Standards and Technology) public data repository, which was followed by calculations regarding the [...] Read more.

The screening of all non-radioactive metals without lanthanides for thermochemical hydrogen storage was performed based on physical chemistry calculations. The thermodynamic data were collected from the NIST (National Institute of Standards and Technology) public data repository, which was followed by calculations regarding the change in enthalpy, entropy, Gibbs free energy and equilibrium reaction temperature. The results were critically evaluated based on thermodynamic parameters, viable metals were identified, and their hydrogen storage densities and energy–enthalpy ratios were evaluated. The elements viable for controlled thermochemical hydrogen storage via the reversible reduction and oxidation of metal oxides and metals are manganese (Mn), iron (Fe), molybdenum (Mo) and tungsten (W). Manganese has the largest theoretical potential for hydrogen storage with reversible reduction and oxidation of metal oxides and metals. The second candidate is iron, while the other two (Mo and W) have much lower potential. More research efforts should be dedicated to experimental testing of the identified metals (Mn, Fe, Mo and W) and their different oxides for thermochemical hydrogen storage capabilities both on laboratory and pilot scales. Ferromanganese alloy(s) might also prove itself as an efficient and affordable thermochemical hydrogen storage material. Our theoretical investigation expanded the knowledge on thermochemical hydrogen storage and is accompanied with a brief literature review revealing the lack of experimental studies, especially on oxidation of metals with water vapor occurring during the hydrogen release phase of the cycle. Consequently, accurate modelling of transport, kinetics and other phenomena during hydrogen storage and release is scarce. Full article

(This article belongs to the Section Materials Processes)

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14 pages, 6077 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Comparative Analysis of Enzyme-, Ultrasound-, Mechanical-, and Chemical-Assisted Extraction of Biflavonoids from Ginkgo Leaves

by Anita Šalić, Lina Šepić, Iva Turkalj, Bruno Zelić and Dunja Šamec

Processes 2024, 12(5), 982; https://doi.org/10.3390/pr12050982 - 12 May 2024

Cited by 5 | Viewed by 1737

Abstract

The biflavonoid extraction from ginkgo (Ginkgo biloba L.) leaves using solvent-based extraction with 70% ethanol, alone and in combination with enzyme-assisted, ultrasound-assisted, mechanical-assisted, and chemically assisted methods was investigated and the influence of extraction duration was explored. The total content of polyphenols, [...] Read more.

The biflavonoid extraction from ginkgo (Ginkgo biloba L.) leaves using solvent-based extraction with 70% ethanol, alone and in combination with enzyme-assisted, ultrasound-assisted, mechanical-assisted, and chemically assisted methods was investigated and the influence of extraction duration was explored. The total content of polyphenols, flavonoids, and phenolic acids in the extracts was determined spectrophotometrically, while individual biflavonoids were identified and quantified using HPLC-DAD. Amentoflavone, bilobetin, ginkgetin, isoginkgetin, and sciadopitysin were identified in all our extracts. Among these, sciadopitysin emerged as the most prevalent biflavonoid with an amount above 1 mg g⁻¹ dw, followed by isoginkgetin. Comparative analysis of the extraction methods revealed that, except for chemically assisted extraction, similar levels of compounds were obtained after 45 min of extraction. However, enzymatic (EAE) and mechanical-assisted extraction (MAE) exhibited significantly higher individual (EAE: 19–41% higher; MAE: 22–67% higher) and total biflavonoid (EAE: 29% higher; MAE 50% higher) levels after just 5 min, suggesting their potential to abbreviate extraction duration and facilitate the efficient retrieval of target compounds. However, as extraction efficiency varies between individual biflavonoids, our findings also underscore the importance of considering specific compounds and extraction kinetics in the optimization of ginkgo leaf extraction processes. Full article

(This article belongs to the Special Issue Recent Advances in Processing Technologies for Substance Extraction, Separation, and Enrichment)

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14 pages, 4699 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Utilizing Recycled Expanded Polystyrene Plastics to Stabilize Metal–Organic Frameworks for Heterogeneous Catalysis

by Ruizhi Yin, Enxi Shen, Chenjia Liang, Dezhong Song, Samir El Hankari and Jia Huo

Processes 2024, 12(5), 961; https://doi.org/10.3390/pr12050961 - 9 May 2024

Cited by 3 | Viewed by 1624

Abstract

Polystyrene plastics present significant environmental and human health threats due to their poor recyclability and degradability. However, leveraging their properties to enhance material performance stands out as one of the most effective strategies for mitigating these issues. Here, we have employed recycled expanded [...] Read more.

Polystyrene plastics present significant environmental and human health threats due to their poor recyclability and degradability. However, leveraging their properties to enhance material performance stands out as one of the most effective strategies for mitigating these issues. Here, we have employed recycled expanded polystyrene plastics to manufacture metal–organic framework/expanded polystyrene plastic composites (MOF@EPP) using an adverse solvent precipitation method. This method simultaneously recycles EPPs and safeguards moisture-sensitive MOFs. Due to the exceptional hydrophobic properties of EPPs, HKUST−1@EPP can maintain structural integrity even when immersed in water for 30 days. This method is applicable to other moisture-sensitive MOFs, such as MOF−74(Zn) and MIL−53(Al). The HKUST−1@EPP composite also exhibits desirable heterogeneous catalytic activity in the Knoevenagel condensation reaction between benzaldehyde and acrylonitrile. The conversion rate can reach 94.9% within 4 h at 90 °C and does not exhibit a significant decrease even after six cycles, even in the presence of water. This study not only introduces a novel concept for recycling polystyrene plastics, but also offers a practical strategy for safeguarding moisture-sensitive MOFs. Full article

(This article belongs to the Special Issue Design and Synthesis of Metal-Organic Framework Materials)

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15 pages, 2463 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Efficient Removal of Water Soluble Fraction of Diesel Oil by Biochar Sorption Supported by Microbiological Degradation

by Zorica R. Lopičić, Tatjana D. Šoštarić, Jelena V. Milojković, Anja V. Antanasković, Jelena S. Milić, Snežana D. Spasić and Jelena S. Avdalović

Processes 2024, 12(5), 964; https://doi.org/10.3390/pr12050964 - 9 May 2024

Cited by 4 | Viewed by 1567

Abstract

The contamination of the water bodies by diesel oil (DO) and its water-soluble fraction (WSF) represents one of the most challenging tasks in the management of polluted water streams. This paper contains data related to the synthesis and characteristics of the plum stone [...] Read more.

The contamination of the water bodies by diesel oil (DO) and its water-soluble fraction (WSF) represents one of the most challenging tasks in the management of polluted water streams. This paper contains data related to the synthesis and characteristics of the plum stone biochar material (PmS-B), which was made from waste plum stones (PmS), along with its possible application in the sorption of the WSF of DO from contaminated water. Techniques applied in sample characterisation and comparisons were: Elemental Organic Analysis (EOA), Scanning Electron Microscopy−Energy Dispersive X-ray Spectroscopy (SEM-EDX), Fourier Transform Infrared Spectroscopy (FTIR), pH (pH_sus) and point of zero charge (pH_pzc). In order to increase the overall efficiency of the removal process, sorption and bioremediation were subsequently combined. Firstly, PmS-B was used as a sorbent of WSF, and then the remaining solution was additionally treated with a specific consortium of microorganisms. After the first treatment phase, the initial concentration of diesel WSF was reduced by more than 90%, where most of the aromatic components of DO were removed by sorption. The sorption equilibrium results were best fitted by the Sips isotherm model, where the maximum sorption capacity was found to be 40.72 mg/g. The rest of the hydrocarbon components that remained in the solution were further subjected to the biodegradation process by a consortium of microorganisms. Microbial degradation lasted 19 days and reduced the total diesel WSF concentration to 0.46 mg/L. In order to confirm the non-toxicity of the water sample after this two-stage treatment, eco-toxicity tests based on a microbial biosensor (Aliivibrio fischeri) were applied, confirming the high efficiency of the proposed method. Full article

(This article belongs to the Special Issue Thermochemical Conversion of Agricultural and Food Processing Waste)

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18 pages, 687 KiB

Open AccessFeature PaperEditor’s ChoiceReview

The Application of Sheep Wool in the Building Industry and in the Removal of Pollutants from the Environment

by Mária Porubská, Karin Koóšová and Jana Braniša

Processes 2024, 12(5), 963; https://doi.org/10.3390/pr12050963 - 9 May 2024

Cited by 4 | Viewed by 2156

Abstract

The presented review is focused on a brief overview of the scientific works on the use of sheep wool outside the textile industry that were published in recent years. The focus of the information is the on construction industry, which is a significant [...] Read more.

The presented review is focused on a brief overview of the scientific works on the use of sheep wool outside the textile industry that were published in recent years. The focus of the information is the on construction industry, which is a significant consumer of heat- and sound-insulating materials. With its properties, sheep wool can compete very well with insulators made from non-renewable resources. Other building elements can also be combined with wool, as long as they are used in appropriate conditions. Due to its chemical and physical structure, wool is extremely suitable for the adsorption removal of pollutants from the living and working environment, in native or modified form. Wool can also be used in recycling processes. However, each application must be preceded by an investigation of the optimal conditions of the given process, which offers researchers inspiration and interesting topics for research. Full article

(This article belongs to the Section Materials Processes)

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15 pages, 1873 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Ultrasonically Assisted Electrocoagulation Combined with Zeolite in Compost Wastewater Treatment

by Sandra Svilović, Nediljka Vukojević Medvidović, Ladislav Vrsalović, Senka Gudić and Ana-Marija Mikulandra

Processes 2024, 12(5), 951; https://doi.org/10.3390/pr12050951 - 8 May 2024

Cited by 1 | Viewed by 1685

Abstract

In this paper, the possibility of combining electrocoagulation (EC), ultrasound, and the addition of zeolite for wastewater treatment was investigated for the first time. The following combinations of hybrid processes were tested: electrocoagulation with zeolite (ECZ), simultaneous electrocoagulation with zeolite and ultrasound (ECZ+US), [...] Read more.

In this paper, the possibility of combining electrocoagulation (EC), ultrasound, and the addition of zeolite for wastewater treatment was investigated for the first time. The following combinations of hybrid processes were tested: electrocoagulation with zeolite (ECZ), simultaneous electrocoagulation with zeolite and ultrasound (ECZ+US), and two-stage electrocoagulation with zeolite and ultrasound (US+Z - EC), carried out with three different electrode materials. The results show that the simultaneous assistance of ultrasound in the ECZ leads to a lower increase in pH, while the temperature increase is higher. Regarding the COD, the assistance of ultrasound is only useful for Zn electrodes in the two-stage US+Z - EC, while the reduction in voltage consumption occurs for Fe and Al electrodes. Ultrasonic assistance caused more damage to the anodes, but anode consumption was reduced for Al and Zn electrodes. The total amount of zeolite that can be recovered is between 55–97%, and recovery is higher in systems with higher turbidity reduction. Good settling ability is only achieved with Al and Fe electrodes in simultaneous performance. Taguchi’s orthogonal L9 array design was applied to analyze the effects of electrode material, process type, mixing speed, and time duration on COD decrease, settling velocity, electrode, and voltage consumption. The results show that the use of ultrasound does not contribute to the desired result and generally only has a favorable effect on voltage and electrode consumption, while it has no positive effect on settling ability or COD decrease. Furthermore, although longer times and higher mixing speeds negatively impact cost due to voltage and electrode consumption, it is advisable not to choose the shortest duration and lowest speed to obtain adequate wastewater treatment quality. Full article

(This article belongs to the Special Issue Treatment and Remediation of Organic and Inorganic Pollutants)

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15 pages, 1766 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Hydrothermal Hydrolysis of Cocoa Bean Shell to Obtain Bioactive Compounds

by Marta Sánchez, Tamara Bernal, Amanda Laca, Adriana Laca and Mario Díaz

Processes 2024, 12(5), 956; https://doi.org/10.3390/pr12050956 - 8 May 2024

Cited by 3 | Viewed by 1730

Abstract

Cocoa bean shell (CBS), a by-product from the chocolate industry, is an interesting source of bioactive compounds. In this work, the effects of time and pH on the hydrothermal hydrolysis of CBS were evaluated with the aim of maximizing the extraction of antioxidant [...] Read more.

Cocoa bean shell (CBS), a by-product from the chocolate industry, is an interesting source of bioactive compounds. In this work, the effects of time and pH on the hydrothermal hydrolysis of CBS were evaluated with the aim of maximizing the extraction of antioxidant and functional compounds from this biomass. In general, all treatments tested led to improvements in the extraction of bioactive compounds compared to untreated samples. The maximum values for antioxidant activity (187 µmol TE/g CBS dw) and phenolic compounds (14.5 mg GAE/g CBS dw) were obtained when CBS was treated at pH 4 for 10 min. In addition, maximum amounts of flavonoids (10.1 mg CE/g CBS dw), tannins (6.5 mg CE/g CBS dw) and methylxanthines (9 mg/g CBS dw) were obtained under mild pH conditions (4–5). It is noteworthy that these values are higher than those reported in the literature for other vegetable substrates, highlighting the potential of CBS to be valorized as a source of different value-adding products. Full article

(This article belongs to the Special Issue Technologies for Production, Processing, and Extractions of Nature Product Compounds, 2nd Edition)

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12 pages, 8780 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Novel Ferrocene-Containing Triacyl Derivative of Resveratrol Protects Ovarian Cells from Toxicity Caused by Ortho-Substituted Polychlorinated Biphenyls

by Ivana Kmetič, Teuta Murati, Veronika Kovač, Lidija Barišić, Nina Bilandžić, Branimir Šimić and Marina Miletić

Processes 2024, 12(5), 947; https://doi.org/10.3390/pr12050947 - 7 May 2024

Viewed by 1290

Abstract

Polychlorinated biphenyls (PCBs) can induce neurotoxicity, immunotoxicity, reproductive toxicity, genotoxicity, and carcinogenicity (IARC group 1 Carcinogens). Scientific data suggest that resveratrol possesses the ability to attenuate ortho-PCB-induced toxicity. Recently, a novel ferrocene-containing triacyl derivative of resveratrol (RF) was synthesized and in this [...] Read more.

Polychlorinated biphenyls (PCBs) can induce neurotoxicity, immunotoxicity, reproductive toxicity, genotoxicity, and carcinogenicity (IARC group 1 Carcinogens). Scientific data suggest that resveratrol possesses the ability to attenuate ortho-PCB-induced toxicity. Recently, a novel ferrocene-containing triacyl derivative of resveratrol (RF) was synthesized and in this study, its potential to protect CHO-K1 cells from selected PCB congeners (75 µM) was evaluated. Cell viability/proliferation was observed by Trypan Blue (TB), Neutral Red (NR), Kenacid Blue (KB), and MTT bioassays, ROS formation by fluorescent probes, and the extent of apoptosis by flow cytometry. All applied bioassays confirmed that RF (2.5–100 μM) remarkably improves viability in PCB 153-treated cells with an increase in cell survival almost up to control levels. This effect was not determined after PCB 77 exposure, although ROS formation was decreased at RF ≥ 50 µM. Apoptosis was significant (p < 0.05) for both congeners. In PCB 77-treated cells, RF did not suppress the induction of cell death. The intended protective effect of RF was evident when cells were treated with PCB 153, and this correlates with results obtained for cell viability. Compared to resveratrol, the novel RF showed promising results in terms of improved biological activity and cell protection against PCB 153 toxicity at all concentrations tested. Full article

(This article belongs to the Special Issue Valorization of Medicinal and Aromatic Plants in Biotechnological Applications)

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15 pages, 6975 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Influence of Interfacial Tribo-Chemical and Mechanical Effect on Tribological Behaviors of TiN Film in Different Environments

by Yu Cao, Guizhi Wu, Yunfeng Wang, Yongjun Li and Huijing Xu

Processes 2024, 12(5), 923; https://doi.org/10.3390/pr12050923 - 30 Apr 2024

Viewed by 1200

Abstract

A series of experiments has been conducted to investigate the tribological properties of a TiN film sliding against GCr15 steel balls in ambient air, low vacuum and high vacuum environments. Various friction loads and sliding velocities were also applied. The TiN film displays [...] Read more.

A series of experiments has been conducted to investigate the tribological properties of a TiN film sliding against GCr15 steel balls in ambient air, low vacuum and high vacuum environments. Various friction loads and sliding velocities were also applied. The TiN film displays a steady-state friction stage after the running-in stage in all the above environments, while the durations of running-in stages are different. The steady-state friction coefficients of the TiN film were around 0.56 in ambient air and 0.3 in the high vacuum environment (1 × 10⁻⁵ mbar). In the low vacuum (1 × 10⁻² mbar) environment, a low friction coefficient (around 0.19) was attained for all the friction tests on TiN film, irrespective of the applied load and sliding velocity. In the meantime, it was noticed that the applied loads and the sliding velocities would change the duration of the running-in stage before reaching the low friction coefficient. It is revealed by the analysis of wear tracks that the metal oxides induced by the tribo-chemical effect at the friction interface play an important role in affecting the tribological behaviors of the TiN films in different environments. The Raman results show that the main component of the metal oxides is hematite (α-Fe₂O₃), and the amount of iron oxide is related to the friction environment. The composition and quantity of iron oxides produced by the interfacial tribo-chemical effect affect the tribological behavior. The results also show that the mechanical wear process at the friction interface displays a polishing effect, which would reduce the surface roughness. The mechanical wear performance varies under different loads and velocities. The tribological tests results indicate that the interfacial tribo-chemical effect and mechanical wear process should be considered together rather than individually to interpret the tribological behaviors of TiN films in different environments. Full article

(This article belongs to the Special Issue Latest Research on Advanced Material Surface Treatment Processing)

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15 pages, 1827 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Impact of Combined Electrolysis and Activated Sludge Process on Municipal Wastewater Treatment

by Miroslav Hutňan, Barbora Jankovičová, Ronald Zakhar and Nikola Šoltýsová

Processes 2024, 12(5), 868; https://doi.org/10.3390/pr12050868 - 25 Apr 2024

Viewed by 1758

Abstract

Electrochemical methods for the treatment of municipal and industrial wastewater are used either independently or in conjunction with biological methods for pretreatment or posttreatment of biologically treated wastewater. In our work, the combination of these processes was studied, where pre-electrolysis was used to [...] Read more.

Electrochemical methods for the treatment of municipal and industrial wastewater are used either independently or in conjunction with biological methods for pretreatment or posttreatment of biologically treated wastewater. In our work, the combination of these processes was studied, where pre-electrolysis was used to produce dissolved iron before the activation process. Electrolysis was also directly introduced into the activation using either iron or carbon electrodes. The surface of one iron electrode was 32.2 cm², voltage at the electrodes was 21 V, and current was 270 mA. The surface of one carbon electrode was 7.54 cm², current was 82.5 mA, and voltage at the electrodes was 21 V. Laboratory research on synthetic municipal wastewater treatment using a combination of electrolysis and activation processes showed that the use of iron electrodes increases the efficiency of phosphorus removal compared to its precipitation with iron salts. Electrolysis has shown a positive effect on the sedimentation properties of sludge and the destruction of filamentous microorganisms. Even though it negatively affected the respiration rates of activated sludge and the denitrification efficiency, it did not have a negative impact on the nitrification activity of sludge. Full article

(This article belongs to the Special Issue Municipal Wastewater Treatment and Removal of Micropollutants)

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14 pages, 5236 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Ultrasonic Plasticizing and Pressing of High-Aspect Ratio Micropillar Arrays with Superhydrophobic and Superoleophilic Properties

by Shiyun Wu, Jianjun Du, Shuqing Xu, Jianguo Lei, Jiang Ma and Likuan Zhu

Processes 2024, 12(5), 856; https://doi.org/10.3390/pr12050856 - 24 Apr 2024

Cited by 1 | Viewed by 1663

Abstract

An ultrasonic plasticizing and pressing method (UPP) that fully utilizes ultrasonic vibration is proposed for fabricating thermoplastic polymer surface microstructures with high aspect ratios (ARs). The characteristics of UPP are elucidated based on the plasticization of the raw material, the melt flow, and [...] Read more.

An ultrasonic plasticizing and pressing method (UPP) that fully utilizes ultrasonic vibration is proposed for fabricating thermoplastic polymer surface microstructures with high aspect ratios (ARs). The characteristics of UPP are elucidated based on the plasticization of the raw material, the melt flow, and the stress on the template microstructure during the forming process. Initially, the micronscale single-stage micropillar arrays (the highest AR of 4.1) were fabricated by using 304 stainless steel thin sheets with micronscale pore (through-hole) arrays as primary templates. Subsequently, anodic aluminum oxides (AAOs) with ordered nanoscale pore arrays were added as secondary templates, and the micro/nanoscale hierarchical micropillar arrays (the highest AR up to 24.1) were successfully fabricated, which verifies the feasibility and forming capability of UPP. The superiority and achievements of UPP are illustrated by comparing the prepared hierarchical micropillar arrays with those prepared in the previous work in four indexes: microstructure scale, aspect ratio, forming time, and preheating temperature of the raw material. Finally, the water contact angle (WCA) and oil droplet complete immersion time of the surface microstructures were measured by a droplet shape analyzer, and the results indicate that the prepared micropillar arrays are superhydrophobic and superoleophilic. Full article

(This article belongs to the Special Issue Micro/Nano Manufacturing Processes: Theories and Optimization Techniques)

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15 pages, 8456 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Combining Solution-Blowing and Melt-Blowing Techniques to Produce an Efficient Non-Woven Filter

by Agata Penconek, Łukasz Werner and Arkadiusz Moskal

Processes 2024, 12(5), 857; https://doi.org/10.3390/pr12050857 - 24 Apr 2024

Cited by 3 | Viewed by 1329

Abstract

New substances and particles appearing in the environment following technological development pose new challenges for separation methods. Moreover, the growing amount of waste also forces us to look for environmentally friendly solutions. One way to create filtration structures with the desired properties is [...] Read more.

New substances and particles appearing in the environment following technological development pose new challenges for separation methods. Moreover, the growing amount of waste also forces us to look for environmentally friendly solutions. One way to create filtration structures with the desired properties is to combine known techniques, thanks to which the advantages of one technique complement the deficiencies and disadvantages of another. Combining the melt-blowing and solution-blowing processes seems to be promising. Fibres created from melt-blowing will provide mechanical strength, while solution-blowing will allow the introduction of nanofibres into the structure with unique filtration and functional properties. Both methods enable working with biodegradable polymers, so the resulting filter can also be environmentally friendly after operation. Our research aimed to check whether combining two fibre production techniques (melt-blown and solution-blowing) is possible and how the joining method will affect the final product. We created a multilayer structure by placing a layer of solution-blowing nanofibres between melt-blown layers, and a mixed structure by simultaneous melt-blowing and solution-blowing. The created multilayer structure was characterised by high filtration efficiency and high-pressure drop. In contrast, the mixed structure achieved a high-quality factor and high mass of deposited droplets per 1 J of energy used for work. Full article

(This article belongs to the Special Issue 10th Anniversary of Processes: Design of the Chemical Industry of the Future)

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17 pages, 2996 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

A Linear Fit for Atomic Force Microscopy Nanoindentation Experiments on Soft Samples

by Stylianos Vasileios Kontomaris, Anna Malamou, Andreas Zachariades and Andreas Stylianou

Processes 2024, 12(4), 843; https://doi.org/10.3390/pr12040843 - 22 Apr 2024

Cited by 2 | Viewed by 2472

Abstract

Atomic Force Microscopy (AFM) nanoindentation is a powerful technique for determining the mechanical properties of soft samples at the nanoscale. The Hertz model is typically used for data processing when employing spherical indenters for small indentation depths (h) compared to the [...] Read more.

Atomic Force Microscopy (AFM) nanoindentation is a powerful technique for determining the mechanical properties of soft samples at the nanoscale. The Hertz model is typically used for data processing when employing spherical indenters for small indentation depths (h) compared to the radius of the tip (R). When dealing with larger indentation depths, Sneddon’s equations can be used instead. In such cases, the fitting procedure becomes more intricate. Nevertheless, as the h/R ratio increases, the force–indentation curves tend to become linear. In this paper the potential of using the linear segment of the curve (for h > R) to determine Young’s modulus is explored. Force–indentation data from mouse and human lung tissues were utilized, and Young’s modulus was calculated using both conventional and linear approximation methods. The linear approximation proved to be accurate in all cases. Gaussian functions were applied to the results obtained from both classic Sneddon’s equations and the simplified approach, resulting in identical distribution means. Moreover, the simplified approach was notably unaffected by contact point determination. The linear segment of the force–indentation curve in deep spherical indentations can accurately determine the Young’s modulus of soft materials at the nanoscale. Full article

(This article belongs to the Special Issue Multiscale Modeling and Control of Biomedical Systems)

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