ChemEngineering

32 pages, 6834 KiB

Open AccessArticle

Silver-Based Catalysts on Metal Oxides for Diesel Particulate Matter Oxidation: Insights from In Situ DRIFTS

by Punya Promhuad, Boonlue Sawatmongkhon, Thawatchai Wongchang, Ekarong Sukjit, Nathinee Theinnoi and Kampanart Theinnoi

ChemEngineering 2025, 9(3), 42; https://doi.org/10.3390/chemengineering9030042 - 22 Apr 2025

Abstract

Diesel particulate matter (DPM) represents a deleterious environmental contaminant that necessitates the development of effective catalytic oxidation methodologies. This research delineates a comparative analysis of silver-supported metal oxide catalysts (Ag/Al₂O₃, Ag/TiO₂, Ag/ZnO, and Ag/CeO₂), with [...] Read more.

Diesel particulate matter (DPM) represents a deleterious environmental contaminant that necessitates the development of effective catalytic oxidation methodologies. This research delineates a comparative analysis of silver-supported metal oxide catalysts (Ag/Al₂O₃, Ag/TiO₂, Ag/ZnO, and Ag/CeO₂), with an emphasis on the effects of silver distribution and the metal-support interaction on the oxidation of DPM. An array of characterization techniques including XRD, HRTEM, XPS, H₂-TPR, TEM, GC-MS, TGA, and in situ DRIFTS was employed. The novelty of this study resides in elucidating the oxidation mechanism through a tripartite pathway and recognizing Ag⁰ as the predominant active species involved in soot oxidation. The Ag/Al₂O₃ catalyst demonstrated superior catalytic performance, achieving a reduction in the ignition temperature by more than 50 °C, attributable to the optimal dispersion of Ag nanoparticles and a balanced metal-support interaction. Conversely, an excessive interaction observed in Ag/ZnO resulted in diminished catalytic activity. The oxidation of DPM transpires through the volatilization of VOCs (<300 °C), the oxidation by reactive oxygen species, and the combustion of soot (>300 °C). This investigation offers significant contributions to the formulation of highly efficient silver-based catalysts for emissions control, with a particular focus on optimizing Ag dispersion and support interactions to enhance catalytic efficacy. Full article

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20 pages, 1654 KiB

Open AccessArticle

Environmental Dispersion of Toxic Effluents from Waste Polyethylene Fires: Simulations with ALOFT

by Giulia De Cet and Chiara Vianello

ChemEngineering 2025, 9(2), 41; https://doi.org/10.3390/chemengineering9020041 - 17 Apr 2025

Abstract

In recent years, the Italian peninsula has frequently been affected by fires in waste storage facilities, both accidental and malicious. Waste storage activities must comply with a series of regulations that require the employer to carefully assess the risks associated with the operation [...] Read more.

In recent years, the Italian peninsula has frequently been affected by fires in waste storage facilities, both accidental and malicious. Waste storage activities must comply with a series of regulations that require the employer to carefully assess the risks associated with the operation of the plant. All prevention and protection measures must be taken to reduce the risk of fires in order to safeguard both people and the environment. In addition, with new regulations coming into force in November 2022, efforts are being made to regulate waste treatment and storage facilities in terms of fire safety. This work presents simulations of the dispersion into the environment of toxic effluents produced during a polyethylene fire at a storage site, with the aid of dedicated software. Simulations were carried out using ALOFT, varying the parameters of the simulations (e.g., the burnt area, environmental characteristics, and toxic effluent investigated). In total, 24 simulations were carried out to investigate the emissions of particulate matter and volatile organic compounds in the case of polyethylene fires. The simulations showed that atmospheric stability class and wind speed had a significant impact on the dispersion. The proposed methodology can be applied both in the risk assessment and emergency phases and, eventually, as a valuable tool in post-accident analysis. Full article

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32 pages, 3317 KiB

Open AccessArticle

Recycling of Walnut Shell Biomass for Adsorptive Removal of Hazardous Dye Alizarin Red from Aqueous Solutions Using Magnetic Nanocomposite: Process Optimization, Kinetic, Isotherm, and Thermodynamic Investigation

by Vairavel Parimelazhagan, Palak Sharma, Yashaswini Tiwari, Alagarsamy Santhana Krishna Kumar and Ganeshraja Ayyakannu Sundaram

ChemEngineering 2025, 9(2), 40; https://doi.org/10.3390/chemengineering9020040 - 11 Apr 2025

Abstract

Dye wastewater poses significant risks to human health and aquatic ecosystems, necessitating efficient remediation strategies. This study developed a magnetic Fe₂O₃ nanocomposite (MNC) derived from phosphoric acid-treated walnut shell biomass carbon to remove Alizarin red S (AR) dye from polluted [...] Read more.

Dye wastewater poses significant risks to human health and aquatic ecosystems, necessitating efficient remediation strategies. This study developed a magnetic Fe₂O₃ nanocomposite (MNC) derived from phosphoric acid-treated walnut shell biomass carbon to remove Alizarin red S (AR) dye from polluted water. Characterization techniques confirmed the nanocomposite’s mesoporous structure, superparamagnetic properties (61.5 emu/g), and high crystallinity. Optimization using Response Surface Methodology (RSM) revealed a maximum adsorption efficiency of 94.04% under the following optimal conditions: A pH of 2, AR dye concentration of 85 mg/L, adsorbent dose of 1.5 g/L, and particle size of 448.1 nm. Adsorption followed pseudo-second-order (PSO) kinetics (R² = 0.9999) and Langmuir isotherm models (R² = 0.9983), with thermodynamic studies indicating spontaneous and endothermic chemisorption. The intra-particle diffusion model, Bangham, and Boyd plots describe the adsorption process, and external boundary layer diffusion of AR dye molecules in the aqueous phase limits the adsorbate removal rate. Regeneration tests demonstrated reusability over three cycles, with a desorption efficiency of 50.52% using 30 mM HCl. The MNC exhibited a maximum adsorption capacity (Q_max) of 115.35 mg/g, outperforming other adsorbents, making it an efficient and sustainable alternative solution for AR dye removal from water bodies. Full article

(This article belongs to the Special Issue Chemical Engineering in Wastewater Treatment)

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15 pages, 2620 KiB

Open AccessArticle

Research of the Process of Obtaining Monocalcium Phosphate from Unconditional Phosphate Raw Materials

by Abibulla Anarbayev, Balzhan Kabylbekova, Zhakhongir Khussanov, Bakyt Smailov, Nurlan Anarbaev and Yevgeniy Kulikov

ChemEngineering 2025, 9(2), 39; https://doi.org/10.3390/chemengineering9020039 - 2 Apr 2025

Abstract

The article presents methods for processing low-grade phosphate raw materials from the Chilisay deposit using a circulation method to produce mineral fertilizers and feed monocalcium phosphate. A study was conducted on the process of obtaining high-quality monocalcium phosphate, and optimal parameters for the [...] Read more.

The article presents methods for processing low-grade phosphate raw materials from the Chilisay deposit using a circulation method to produce mineral fertilizers and feed monocalcium phosphate. A study was conducted on the process of obtaining high-quality monocalcium phosphate, and optimal parameters for the decomposition of low-grade phosphate raw materials were determined. Based on the research, it was established that for the decomposition of phosphate raw materials, phosphoric acid with a concentration of 36–42% P₂O₅ should be used; the recycle phosphoric acid rate should be 540–560% of the stoichiometric amount required for the formation of monocalcium phosphate (MCP); the decomposition temperature should be 95–100 °C; the decomposition duration should be 40–50 min; the filtration temperature of the insoluble residue should be 85–90 °C; the crystallization temperature of MCP should be 40–45 °C; and the crystallization duration should be 85–90 min. For the sulfation of the mother solution and the production of recycle phosphoric acid, sulfuric acid with a concentration of 86–93% H₂SO₄ should be used; the sulfuric acid rate should be 95–100% of the stoichiometric amount required for the decomposition of dissolved Ca(H₂PO₄)₂. After drying the wet residue, monocalcium phosphate was obtained with the following composition: P₂O₅—55%, Ca—18.01%, H₂O—4.0%, F—0.01%, As—0.004%, Pb—0.002%. The obtained monocalcium phosphate is used in agriculture as a mineral fertilizer and feed monocalcium phosphate. Full article

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19 pages, 6273 KiB

Open AccessArticle

Enhanced Efficiency of CZTS Solar Cells with Reduced Graphene Oxide and Titanium Dioxide Layers: A SCAPS Simulation Study

by Dounia Fatihi, Giorgio Tseberlidis, Vanira Trifiletti, Simona Binetti, Eleonora Isotta, Paolo Scardi, Abderrafi Kamal, R’hma Adhiri and Narges Ataollahi

ChemEngineering 2025, 9(2), 38; https://doi.org/10.3390/chemengineering9020038 - 1 Apr 2025

Abstract

Copper zinc tin sulfide (commonly known as CZTS) solar cells (SCs) are gaining attention as a promising technology for sustainable electricity generation owing to their cost-effectiveness, availability of materials, and environmental advantages. The goal of this study is to enhance CZTS SC performance [...] Read more.

Copper zinc tin sulfide (commonly known as CZTS) solar cells (SCs) are gaining attention as a promising technology for sustainable electricity generation owing to their cost-effectiveness, availability of materials, and environmental advantages. The goal of this study is to enhance CZTS SC performance by adding a back surface field (BSF) layer. SC capacitance simulator software (SCAPS) was used to examine three different configurations. Another option is to replace the cadmium sulfide (CdS) buffer layer with a titanium dioxide (TiO₂) layer. The results demonstrate that the reduced graphene oxide (rGO) BSF layer increases the conversion efficiency by 25.68% and significantly improves the fill factor, attributed to lowering carrier recombination and creating a quasi-ohmic contact at the interface between the metal and semiconductor. Furthermore, replacing the CdS buffer layer with TiO₂ offers potential efficiency gains and mitigates environmental concerns associated with the toxicity of CdS. The results of this investigation could enhance the efficiency and viability of CZTS SCs for future energy applications. However, it is observed that BSF layers may become less effective at elevated temperatures due to increased recombination, leading to reduced carrier lifetime. This study underlines valuable insights into optimizing CZTS SC performance through advanced material choices, highlighting the dual benefits of improved efficiency and reduced environmental impact. Full article

(This article belongs to the Special Issue New Advances in Chemical Engineering)

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14 pages, 3431 KiB

Open AccessArticle

Drilling Optimization Using Artificial Neural Networks and Empirical Models

by Mohammed F. Al Dushaishi, Ahmed K. Abbas, Mortadha T. Al Saba and Jarrett Wise

ChemEngineering 2025, 9(2), 37; https://doi.org/10.3390/chemengineering9020037 - 31 Mar 2025

Abstract

A key role of drilling optimization is reducing the cost and non-productive time (NPT) for drilling operations. The rate of penetration (ROP) directly affects the overall cost and cost per foot of drilling operations and could lead to significant cost savings or expenses. [...] Read more.

A key role of drilling optimization is reducing the cost and non-productive time (NPT) for drilling operations. The rate of penetration (ROP) directly affects the overall cost and cost per foot of drilling operations and could lead to significant cost savings or expenses. Traditionally, empirical ROP modeling is used to predict bit response or estimate ROP using nearby offset data. Due to the complexity and nonlinearity of ROP, data-driven modeling, such as machine learning (ML), became more attractive. The objective of this paper is to develop an ROP data-driven artificial neural network (ANN) model using drilling and formation data collected from three nearby wells. Additionally, drilling optimization was conducted and compared with traditional empirical ROP models. The advantages and disadvantages of both methods are discussed, and the direction of future data-driven modeling is highlighted. The data-driven ANN model demonstrated strong performance when compared to the field data. The ANN model showed an RMSE and R² of 3.89 m/h and 0.93 for the training data and an RMSE and R² of 4.16 m/h and 0.92 for the testing dataset. The sensitivity analysis showed that the ANN model predicted higher ROP than the empirical models in the selected interval. Due to the limited bit wear data compared to the operational parameters, coupled simultaneous data-driven and empirical modeling is believed to be the future direction for data-driven drilling optimization. Full article

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32 pages, 3637 KiB

Open AccessReview

Comparison of Dispersing Processes of Bio-Based and Synthetic Materials: A Review

by Leah Jalowy, Dominik Nemec and Oguzhan Ilhan

ChemEngineering 2025, 9(2), 36; https://doi.org/10.3390/chemengineering9020036 - 26 Mar 2025

Abstract

The ever-growing environmental and sustainability awareness as well as the associated increased independence from petroleum has led to bio-based materials increasingly replacing synthetic, non-renewable materials in various applications, including food packaging, coatings, adhesives, and energy storage devices. Although bio-based materials offer advantages such [...] Read more.

The ever-growing environmental and sustainability awareness as well as the associated increased independence from petroleum has led to bio-based materials increasingly replacing synthetic, non-renewable materials in various applications, including food packaging, coatings, adhesives, and energy storage devices. Although bio-based materials offer advantages such as reduced toxicity and harmfulness for humans and the environment, as well as contributing to the conservation of important resources, these aspects are usually not sufficient for commercialization. Integrating bio-based materials into existing technologies is challenging due to inherent disadvantages, such as difficult processability and low moisture resistance, making it difficult to readily substitute them for synthetic materials. Consequently, surface modifications are often necessary to make bio-based materials suitable for the intended applications. This review highlights the critical role of processing methods in the successful substitution of synthetic materials with bio-based alternatives. While previous studies have primarily concentrated on material combinations and formulations of bio-based applications, often considering processing methods as secondary, this review explores the influence and importance of dispersion quality. It examines how varying dispersing methods and process parameters can impact the performance of bio-based materials, alongside addressing the specific requirements for both the materials and the dispersing processes. Furthermore, it focuses on bio-based dispersions based on lignin and polysaccharides, particularly in applications such as bio-based adhesives and binders for battery technologies. By addressing these aspects, this review aims to reveal existing research gaps and provide insights into optimizing the processing of bio-based materials for diverse applications. Full article

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22 pages, 3886 KiB

Open AccessArticle

Development of New Xanthan-Aldehyde/Gelatin Nanogels for Enhancement of Ibuprofen Transdermal Delivery: In-Vitro/Ex-Vivo/In-Vivo Evaluation

by Yacine Nait Bachir, Ramdane Mohamed Said, Mohamed Lamine Abdelli, Walid Namaoui, Meriem Medjkane, Nouara Boudjema, Halima Meriem Issaadi and Elisabeth Restrepo Parra

ChemEngineering 2025, 9(2), 35; https://doi.org/10.3390/chemengineering9020035 - 20 Mar 2025

Abstract

The aim of this study was to prepare nanogels based on gelatin and xanthan-aldehyde for the enhancement of ibuprofen transdermal delivery. Firstly, the process of formulating nanogels using the reaction of Schiff’s base was optimized using experimental designs. Secondly, the structural characterization of [...] Read more.

The aim of this study was to prepare nanogels based on gelatin and xanthan-aldehyde for the enhancement of ibuprofen transdermal delivery. Firstly, the process of formulating nanogels using the reaction of Schiff’s base was optimized using experimental designs. Secondly, the structural characterization of nanogels was performed using laser particle size, zetometry, FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-Ray Diffraction), SEM (scanning electron microscopy), and thermogravimetric analysis. Finally, the evaluation of pharmacological characteristics and formulation therapeutic efficacy were achieved using in vitro dissolution kinetics, ex vivo transdermal diffusion studies, and an evaluation of in vivo anti-inflammatory activity. The results of the experimental plan show that the formulations containing a ratio of 15:10 ibuprofen/polymer and a ratio of 1:2 gelatin/xanthan-aldehyde with a gelling time of 2 h exhibited the best results; the formulations showed a mean diameter of 179.9 ± 6.2 nm, a polydispersity index of 0.193, which confirms monodispersed particles, a zeta potential of 24.7 mV, denoting a high degree of particle stability, and an encapsulation rate of 93.78%. The FTIR spectroscopy analysis showed the formation of imine function in the nanogel, and scanning electron microscopy showed the globular and porous form of the formulation. The incorporation of ibuprofen into nanogels improved their in vitro dissolution kinetics and ex vivo transdermal diffusion. The incorporation of nanogels into a patch system for its in vivo anti-inflammatory activity has shown excellent efficiency with a percentage of edema inhibition at a dose of 25 mg and 50 mg of 38.77 ± 1.6% and 82.03 ± 9.03%, respectively, while the commercial reference gel presented inhibition values at a dose of 25 mg and 50 mg of 10.61 ± 1.71% and 37.03 ± 11.43%, respectively. Thus, the innovative pharmaceutical form of ibuprofen offers a promising model for enhancing drug bioavailability and therapeutic effects while reducing adverse effects. Full article

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20 pages, 17704 KiB

Open AccessArticle

Soft Actor-Critic Reinforcement Learning Improves Distillation Column Internals Design Optimization

by Dhan Lord B. Fortela, Holden Broussard, Renee Ward, Carly Broussard, Ashley P. Mikolajczyk, Magdy A. Bayoumi and Mark E. Zappi

ChemEngineering 2025, 9(2), 34; https://doi.org/10.3390/chemengineering9020034 - 18 Mar 2025

Abstract

Amid the advancements in computer-based chemical process modeling and simulation packages used in commercial applications aimed at accelerating chemical process design and analysis, there are still certain tasks in design optimization, such as distillation column internals design, that become bottlenecks due to inherent [...] Read more.

Amid the advancements in computer-based chemical process modeling and simulation packages used in commercial applications aimed at accelerating chemical process design and analysis, there are still certain tasks in design optimization, such as distillation column internals design, that become bottlenecks due to inherent limitations in such software packages. This work demonstrates the use of soft actor-critic (SAC) reinforcement learning (RL) in automating the task of determining the optimal design of trayed multistage distillation columns. The design environment was created using the AspenPlus^® software (version 12, Aspen Technology Inc., Bedford, Massachusetts, USA) with its RadFrac module for the required rigorous modeling of the column internals. The RL computational work was achieved by developing a Python package that allows interfacing with AspenPlus^® and by implementing in OpenAI’s Gymnasium module (version 1.0.0, OpenAI Inc., San Francisco, California, USA) the learning space for the state and action variables. The results evidently show that (1) SAC RL works as an automation approach for the design of distillation column internals, (2) the reward scheme in the SAC model significantly affects SAC performance, (3) column diameter is a significant constraint in achieving column internals design specifications in flooding, and (4) SAC hyperparameters have varying effects on SAC performance. SAC RL can be implemented as a one-shot learning model that can significantly improve the design of multistage distillation column internals by automating the optimization process. Full article

(This article belongs to the Special Issue New Advances in Chemical Engineering)

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15 pages, 2739 KiB

Open AccessArticle

Performance Assessment of Novel Soda Ash Adsorbent Biogas Sweetening: Fixed Bed Studies, Adsorption Kinetics, and Adsorption Isotherms

by Register Mrosso and Cleophas Achisa Mecha

ChemEngineering 2025, 9(2), 33; https://doi.org/10.3390/chemengineering9020033 - 17 Mar 2025

Abstract

The reliance on greenhouse gas-emitting unrenewable energy sources such as coal, natural gas, and oil, increases climate change. Transitioning to renewable energy, such as biogas, is crucial to reducing environmental degradation and global warming. The existence of impurities such as hydrogen sulfide hampers [...] Read more.

The reliance on greenhouse gas-emitting unrenewable energy sources such as coal, natural gas, and oil, increases climate change. Transitioning to renewable energy, such as biogas, is crucial to reducing environmental degradation and global warming. The existence of impurities such as hydrogen sulfide hampers the application of biogas. Utilizing natural resources for biogas purification is essential to improve access to clean energy for low-income communities. This study used soda ash derived from Lake Natron in Tanzania as a sorbent for H₂S removal. Effects of sorbent mass, flow rate, and particle size were investigated. Experimental data were analyzed using kinetic models, adsorption isotherms, and breakthrough curves. Soda ash of 280 μm particle size, a flow rate of 0.03 m³/h, and a mass of 75 g demonstrated the best performance, achieving an efficiency of 94% in removal and a sorption capacity of 0.02 g per 100 g in five repeated cycles. Freundlich and Jovanovich’s isotherms match the data with n = 0.4 and K_j = 0.003, respectively. Adsorption kinetics were best described by the intra-particle model (k_id = 0.14, c = 0.59 mg/g, and R² = 0.972). A breakthrough analysis indicated that the Yoon–Nelson model provided the best fit with an R² of 0.95. Soda ash from Lake Natron demonstrated great potential in biogas desulphurization, thus contributing to the production and access to clean energy. Full article

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16 pages, 2398 KiB

Open AccessArticle

Source Tracing of Raw Material Components in Wood Vinegar Distillation Process Based on Machine Learning and Aspen Simulation

by Siqi Liao, Wanting Sun, Haoran Zheng and Qiyang Xu

ChemEngineering 2025, 9(2), 32; https://doi.org/10.3390/chemengineering9020032 - 13 Mar 2025

Abstract

As a kind of high-oxygen organic liquid produced during biomass pyrolysis, wood vinegar possesses significant industrial value due to its rich composition of acetic acid, phenols, and other bioactive compounds. In this study, we explore the application of advanced machine learning models in [...] Read more.

As a kind of high-oxygen organic liquid produced during biomass pyrolysis, wood vinegar possesses significant industrial value due to its rich composition of acetic acid, phenols, and other bioactive compounds. In this study, we explore the application of advanced machine learning models in optimizing the dual-column distillation process for wood vinegar production, such as Random Forest algorithms. Through the integration of Aspen Plus simulation and deep learning, an adaptive control strategy is proposed to enhance the separation efficiency of key components under varying feed conditions. The experimental results demonstrate that the Random Forest model exhibits superior predictive accuracy to traditional decision tree methods, and an R² of 0.9728 can be achieved for phenol concentration prediction. This AI-driven system can provide real-time process optimization, enhancing energy efficiency, stabilizing component yields, and contributing to the advancement of sustainable practices within the biomass chemical industry. These findings are anticipated to offer valuable insights into the integration of green chemistry principles with intelligent control systems to facilitate the achievement of Industry 4.0 objectives in bio-based production. Full article

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14 pages, 2125 KiB

Open AccessArticle

Phytochemical Profiling and Antioxidant Activity of True Leaves and Cotyledons of Adenocaulon himalaicum

by Sang-Yun Lee, Nari Yoon, Neil Patrick Uy, Chung-Ho Choi and Sanghyun Lee

ChemEngineering 2025, 9(2), 31; https://doi.org/10.3390/chemengineering9020031 - 10 Mar 2025

Abstract

Adenocaulon himalaicum is widely distributed across Asia. In its early growth stages, A. himalaicum is traditionally consumed as a food source in Korea. Although previous research has identified the presence of bioactive compounds in A. himalaicum extract, suggesting its potential as a medicinal [...] Read more.

Adenocaulon himalaicum is widely distributed across Asia. In its early growth stages, A. himalaicum is traditionally consumed as a food source in Korea. Although previous research has identified the presence of bioactive compounds in A. himalaicum extract, suggesting its potential as a medicinal resource, the phytochemical profile of A. himalaicum extract has not been extensively determined. This investigation aimed to identify the phytochemicals present in the true leaf and cotyledon of A. himalaicum (TLA and CLA, respectively) and evaluate their radical-scavenging activity. By performing LC-MS/MS and HPLC, varying amounts of isochlorogenic acid A, cryptochlorogenic acid, isochlorogenic acid B, rutin, chlorogenic acid, hyperin, and neochlorogenic acid were detected in the TLA and CLA extracts. Chlorogenic acid (9.002 mg/g DW), isochlorogenic acid A (28.512 mg/g DW), and isochlorogenic acid B (12.223 mg/g DW) were the most abundant in TLA. TLA exhibited higher phytochemical content (49.737 mg/g DW), total phenolic content (45.51 mg tannic acid equivalent/g extract), and total flavonoid content (16.24 mg quercetin equivalent/g extract) than CLA. Moreover, the radical-scavenging activity of TLA was two times higher than that of CLA. The young leaf of A. himalaicum has a rich phytochemical profile and robust antioxidant activity; hence, it has potential as natural antioxidant sources for human health and valuable pharmacognosy raw materials for pharmaceutical and functional food applications. Full article

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17 pages, 4636 KiB

Open AccessArticle

Preparation and Characterization of Unactivated, Activated, and γ-Fe₂O₃ Nanoparticle-Functionalized Biochar from Rice Husk via Pyrolysis for Dyes Removal in Aqueous Samples: Comparison, Performance, and Mechanism

by Diego Barzallo, Edwuin Carrasquero, Mónica Andrade, Daniel Alejandro Heredia Jara and Paúl Palmay

ChemEngineering 2025, 9(2), 30; https://doi.org/10.3390/chemengineering9020030 - 10 Mar 2025

Abstract

This study aimed at preparing three types of biochar derived from rice husk via pyrolysis, including unactivated biochar, biochar chemically activated after with H₃PO₄, and biochar impregnated with γ-Fe₂O₃ nanoparticles. These materials were subsequently characterized using [...] Read more.

This study aimed at preparing three types of biochar derived from rice husk via pyrolysis, including unactivated biochar, biochar chemically activated after with H₃PO₄, and biochar impregnated with γ-Fe₂O₃ nanoparticles. These materials were subsequently characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis, which revealed favorable textural properties, such as an increased surface area and porosity, as well as the presence of functional groups that facilitate the adsorption of methylene blue and malachite green in aqueous solutions. Several factors that affect the adsorption capacity, including the type of material, pH effect, and adsorbent dosage, were evaluated and optimized. The adsorption behavior was analyzed using isotherm and kinetic models to better understand the mechanisms involved. Under optimal conditions, biochar@γ-Fe₂O₃ NPs emerged as the most effective material due to its high surface area, functionalized surface, and magnetic properties, allowing easy water recovery without the need for complex instrumentation. Among the kinetic models evaluated, the pseudo-second-order model exhibited the highest linear regression coefficient (R² = 0.99), supporting a chemisorption process driven by strong interactions and stable chemical bond formation between the adsorbate and the adsorbent, while equilibrium data fit well with the Sips isotherm model, indicating a combination of monolayer and multilayer adsorption mechanisms. This magnetic biochar achieved removal efficiencies of 97% for methylene blue and 95% for malachite green, demonstrating a high performance and reusability over four cycles. Moreover, a possible adsorption mechanism of MB on the magnetic biochar was proposed to explain the interaction between the dye and the adsorbent surface. Thus, this work demonstrates that magnetic biochar is a sustainable and cost-effective adsorbent for wastewater treatment, integrating circular economy principles by transforming rice husk into a high-value material. The incorporation of γ-Fe₂O₃ nanoparticles enhances adsorption while enabling magnetic recovery, providing an eco-friendly and scalable solution for dye removal. Full article

(This article belongs to the Special Issue Innovative Approaches for the Environmental Chemical Engineering)

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17 pages, 5598 KiB

Open AccessArticle

The Influence of the Geometric Properties on the Gas Holdup and Phase Surface Area for Single-Orifice Gas Distributors in a Bubble Column

by Thorsten Jonach, Tetiana Ruzova, Christian Jordan, Michael Harasek and Bahram Haddadi

ChemEngineering 2025, 9(2), 29; https://doi.org/10.3390/chemengineering9020029 - 7 Mar 2025

Abstract

The introduction of a gas phase into a liquid is used in a variety of technical applications. Based on the purpose of the application, different flow behaviors of the gas phase and specific gas phase parameters are preferred. In this study, the influence [...] Read more.

The introduction of a gas phase into a liquid is used in a variety of technical applications. Based on the purpose of the application, different flow behaviors of the gas phase and specific gas phase parameters are preferred. In this study, the influence of the diameter and shape of a single-hole orifice sparger on the gas phase behavior was investigated. For this purpose, an experimental setup of a bubble column was built, and different orifice sizes and types were installed. The two different designs that were tested were direct flat orifices and single needle-type nozzles. The flat nozzle diameter was varied from 0.5 mm to 3 mm, whereas two different needle-type nozzles with diameters of 0.5 mm and 1 mm were also tested. Through high-speed imaging and digital image processing, a contour analysis of the bubbles was performed using a special technique for image segmentation and the identification of phase inhomogeneities. The gas holdup and surface area of the gas phase were calculated at different column heights and different flow rates. The results show that smaller nozzle diameters led to a higher gas holdup and a higher phase surface than larger-diameter orifices at the middle and upper sections of the column, implying a better mass and heat transfer performance. Full article

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17 pages, 1855 KiB

Open AccessArticle

Asymptotic Solution on Spherical Floating Particle

by Jaesung Lee

ChemEngineering 2025, 9(2), 28; https://doi.org/10.3390/chemengineering9020028 - 6 Mar 2025

Abstract

The method of matched asymptotic expansions is applied to analyze the meniscus around a floating particle. The asymptotic solutions, derived while considering Fraenkel’s warning, are expressed as functions of the filling angle and contact angle. The analytical solutions accurately predict both the filling [...] Read more.

The method of matched asymptotic expansions is applied to analyze the meniscus around a floating particle. The asymptotic solutions, derived while considering Fraenkel’s warning, are expressed as functions of the filling angle and contact angle. The analytical solutions accurately predict both the filling angle and the position of the three-phase contact line, even for larger

ϵ

values. The deformed free surface profile around a single floating particle shows excellent agreement with numerical results obtained from transformed equations using the inclination angle of the deformed surface. The matched asymptotic solutions reveal two distinct steady-state interface configurations, with one stable configuration identified through vertical stability analysis. This asymptotic approach enables the construction of stability diagrams for floating conditions, helping determine the maximum floatable particle size or density ratio for sustained flotation. The methodology developed here provides a foundation for future research on buoyancy for particles of various shapes and stability under dynamic conditions. Full article

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9 pages, 9259 KiB

Open AccessCommunication

Plasma Modification of Technical Carbon with Nitrogen and Sulfur-Containing Functional Groups for Application in Catalytic Systems

by Ksenia Kharisova, Evgenii Beletskii, Oleg Levin, Ruopeng Li, Peixia Yang and Elena Alekseeva

ChemEngineering 2025, 9(2), 27; https://doi.org/10.3390/chemengineering9020027 - 3 Mar 2025

Abstract

This study presents an effective plasma treatment method for doping technical carbon by nitrogen- and sulfur-containing functional groups. Nitrogen incorporation shifted the oxygen reduction reaction onset potential by 0.25 V and increased the limiting current by 1 mA cm⁻², while sulfuration [...] Read more.

This study presents an effective plasma treatment method for doping technical carbon by nitrogen- and sulfur-containing functional groups. Nitrogen incorporation shifted the oxygen reduction reaction onset potential by 0.25 V and increased the limiting current by 1 mA cm⁻², while sulfuration showed a more pronounced effect, with a 0.31 V shift in onset potential and an increase in the limiting current to 6.23 mA cm⁻². These enhancements are attributed to the formation of additional active sites and improved surface properties. The proposed plasma-based approach is simple, scalable, and environmentally friendly, minimizing the use of hazardous reagents and eliminating the need for multistep processes. This method demonstrates the potential for industrial applications using commercially available raw materials such as technical carbon and to be extended to other carbon-based materials. Full article

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12 pages, 5349 KiB

Open AccessArticle

An Electrochemical Characterisation of Silica–Zirconia Oxide Nanostructured Materials for Fuel Cells

by Rudzani Sigwadi, Touhami Mokrani and Fulufhelo Nemavhola

ChemEngineering 2025, 9(2), 26; https://doi.org/10.3390/chemengineering9020026 - 3 Mar 2025

Abstract

Silica–zirconia nanoparticles were successfully synthesised using the precipitation process. The surface area and shape of the Si-ZrO₂ nanoparticles were investigated using BET, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (HRTEM). The HRTEM results demonstrate that silica was successfully [...] Read more.

Silica–zirconia nanoparticles were successfully synthesised using the precipitation process. The surface area and shape of the Si-ZrO₂ nanoparticles were investigated using BET, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (HRTEM). The HRTEM results demonstrate that silica was successfully integrated into ZrO₂ nanoparticles with a mixture of nanorod and nanosphere shapes. The element analysis (EDX) reveals the presence of silica (14.61%) and zirconia (1.18%) nanoparticles, as well as oxygen (83.65) on the surface. The BET results demonstrate a larger surface area of 185 m²/g and pore volume (0.14 cm³/g). The XRD measurements confirmed the transition of amorphous silica into the monoclinic phase of the zirconia nanoparticles. The electrochemical characteristics of the silica–zirconia nanoparticles were tested in a potassium chloride solution. With a large specific surface area and an appropriate pore size distribution, a pair of broad and symmetric redox peaks were centred at −0.15 V and 0.6 V. Full article

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19 pages, 1591 KiB

Open AccessArticle

Pectin Extraction Process from Cocoa Pod Husk (Theobroma cacao L.) and Characterization by Fourier Transform Infrared Spectroscopy

by Ismael Santiago-Gómez, Areli Carrera-Lanestosa, Fanny Adabel González-Alejo, Zenaida Guerra-Que, Ricardo García-Alamilla, José Luis Rivera-Armenta and Pedro García-Alamilla

ChemEngineering 2025, 9(2), 25; https://doi.org/10.3390/chemengineering9020025 - 27 Feb 2025

Abstract

The Cocoa Pod Husk (CPH) accounts for 67–76% of the total cocoa fruit weight, making it its main agro-industrial waste of cocoa production. A valorization of this waste is possible through the extraction of pectin. In this study, pectin was extracted from CPH [...] Read more.

The Cocoa Pod Husk (CPH) accounts for 67–76% of the total cocoa fruit weight, making it its main agro-industrial waste of cocoa production. A valorization of this waste is possible through the extraction of pectin. In this study, pectin was extracted from CPH powder by acid hydrolysis using citric acid and sulfuric acid. Fourier transform infrared spectroscopy (FT-IR) was employed as a qualitative and quantitative characterization technique. The FT-IR of the pectin samples showed the bands visible at 1732 and 1626 cm⁻¹ corresponding to the esterified and free carboxylic groups, respectively. These bands can be differentiated according to their degree of methyl esterification (DE) by analyzing the area under the curve. The extracted pectin showed no significant difference in yields (p ≤ 0.05) between the two acids; however, significant differences (p ≤ 0.05) were observed in DE and methoxylation percentage (MeO). According to the FT-IR results, pectin extracted with citric acid presented a lower DE (7.43%) and MeO (1.12%) compared to pectin extracted with sulfuric acid, which showed a DE of 18.15% and a 2.96% MeO. Pectin with a DE below 50% is classified as low-methylated, making it unsuitable for the food industry. However, these create a raw material that has a potential use in the pharmaceutical and bioenergy industries. Full article

(This article belongs to the Collection Green and Environmentally Sustainable Chemical Processes)

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12 pages, 3105 KiB

Open AccessArticle

Synthesis of MOFs and Characterization and Drug Loading Efficiency

by Chuang Wu and Haithm Yahya Mohammed Almuaalemi

ChemEngineering 2025, 9(2), 24; https://doi.org/10.3390/chemengineering9020024 - 24 Feb 2025

Abstract

Asthma and allergic rhinitis (AR) stand as prevalent chronic ailments impacting children within the United States. It is approximated that as many as 40% of American children exhibit symptoms indicative of AR, a condition which, if inadequately managed, could potentially lead to the [...] Read more.

Asthma and allergic rhinitis (AR) stand as prevalent chronic ailments impacting children within the United States. It is approximated that as many as 40% of American children exhibit symptoms indicative of AR, a condition which, if inadequately managed, could potentially lead to the onset of additional illnesses such as asthma, rhinosinusitis, allergic conjunctivitis, and otitis media. We have devised a universal synthetic pathway to encapsulate small molecules of montelukast sodium within Metal–Organic Frameworks (MOFs) for the treatment of asthma and AR. Two distinct Cu-MOFs, namely single linker and mixed linker MOFs, were synthesized through the solvothermal method utilizing 1,4-benzenedioic acid (BDC) and 4,4′-dipyridile as linkers. The synthesized Cu-MOFs underwent thorough examination employing various analytical techniques including BET, SEM, FTIR, and PXRD. These MOFs hold promise as potential vehicles for drug delivery applications. Various proportions of Cu-MOF-1 and Cu-MOF-2 were dispersed alongside montelukast sodium. Notably, the 1:1 ratio of both MOFs exhibited enhanced drug absorption compared to other ratios. Furthermore, Cu-MOF-2 demonstrated superior drug absorption overall when contrasted with Cu-MOF-1. This investigation also delves into the drug release dynamics from different ratios of MOFs and the drug. The drug release analysis was conducted in a phosphate-buffered saline (PBS) solution with a pH of 7.4, and the absorbance values were measured using a UV-visible spectrometer at distinct time intervals. Drug molecules are effectively encapsulated within MOFs and demonstrate controlled release through the establishment of hydrogen bonding or π–π interactions between the drug molecules and MOFs. Despite notable advancements in the utilization of MOFs for biomedical purposes, additional enhancements are necessary before they can be considered viable therapeutic modalities. Full article

(This article belongs to the Special Issue Catalytic Reactions and Development of (Bio)Chemical Processes for Synthesizing Value Added Compounds)

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