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Growth of a Single Bubble Due to Super-Saturation: Comparison of Correlation-Based Modelling with CFD Simulation
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Combustion Air Humidifier for a Biomass Boiler with Flue Gas Condensation
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An Upgraded FOS/TAC Titration Model Integrating Phosphate Effects for Accurate Assessments of Volatile Fatty Acids and Alkalinity in Anaerobic Media
Journal Description
ChemEngineering
ChemEngineering
is an international, peer-reviewed, open access journal on the science and technology of chemical engineering, published bimonthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, ESCI (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Engineering, Chemical) / CiteScore - Q1 (General Engineering )
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 29.6 days after submission; acceptance to publication is undertaken in 5.7 days (median values for papers published in this journal in the first half of 2025).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
3.4 (2024);
5-Year Impact Factor:
3.1 (2024)
Latest Articles
Bitumen Extraction from Bituminous Sands by Ultrasonic Irradiation
ChemEngineering 2025, 9(5), 109; https://doi.org/10.3390/chemengineering9050109 - 10 Oct 2025
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This paper discusses the efficiency of ultrasonic-assisted bitumen extraction from bituminous sands of the Beke deposit (Mangistau region, Kazakhstan) using alkaline aqueous solutions. The process parameters, including ultrasonic frequency (22 kHz), power (up to 1500 W), solution pH (>12), and optimal NaOH concentration
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This paper discusses the efficiency of ultrasonic-assisted bitumen extraction from bituminous sands of the Beke deposit (Mangistau region, Kazakhstan) using alkaline aqueous solutions. The process parameters, including ultrasonic frequency (22 kHz), power (up to 1500 W), solution pH (>12), and optimal NaOH concentration (1 wt.%) were optimized to achieve a maximum bitumen recovery of 98 wt.% within 8 min. The most effective sand-to-solution mass ratio was determined as 1:2, while the optimal process temperature was 75 °C. The application of ultrasound significantly enhances cavitation and reagent penetration, enabling efficient separation of bitumen with minimal chemical usage. Fourier-transform infrared (FTIR) spectroscopy and GC–MS analyses revealed the presence of aromatic hydrocarbons, paraffinic and naphthenic structures, as well as sulfur- and oxygen-containing functional groups (e.g., sulfoxides, carboxylic acids). These characteristics suggest moderate maturity and a high degree of aromaticity of the organic matter. Despite suitable thermal and compositional properties, the extracted bitumen exhibits a relatively low stiffness and softening point, indicating the need for additional upgrading (e.g., oxidation) prior to use in road construction. Although standard rheological tests (e.g., dynamic shear rhinometry) were not conducted in this study, the penetration and softening point values suggest a relatively soft binder, possibly unsuitable for high-temperature paving applications without modification. Future research will focus on rheological evaluation and oxidative upgrading to meet the ST RK 1373-2013 specification requirements.
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Open AccessArticle
Use of Oil Shale as a Catalyst and Hydrogen Donor in the Processing of Heavy Hydrocarbons: Accumulation of Rare Trace Elements and Production of Light Fractions
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Murzabek Baikenov, Dariya Izbastenova, Xintai Su, Akmaral Sarsenbekova, Alfiya Khalitova, Almas Tusipkhan, Amirbek Moldabayev, Balzhan Tulebaeva, Gulzhan Baikenova and Satybaldin Amangeldy
ChemEngineering 2025, 9(5), 108; https://doi.org/10.3390/chemengineering9050108 - 9 Oct 2025
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This study presents an integrated approach to processing the heavy fraction of coal tar (HFCT) using oil shale (OS) from Shubarkol Komir JSC to simultaneously increase the yield of valuable hydrocarbon fractions and extract rare and dispersed trace elements. The lack of data
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This study presents an integrated approach to processing the heavy fraction of coal tar (HFCT) using oil shale (OS) from Shubarkol Komir JSC to simultaneously increase the yield of valuable hydrocarbon fractions and extract rare and dispersed trace elements. The lack of data on the effect of shale on the process and the kinetics of multi-component “tar + shale” systems limits the development of effective technologies. TG/DTG analysis was combined with the Friedman, Ozawa–Flynn–Wall, and Šesták–Berggren methods for the first time to evaluate the role of oil shale (OS). It was shown that the addition of 13% OS provides a sustained reduction in activation energy (~85–86 kJ/mol) and optimal conditions for hydrometallization. At 420 °C, an initial H2 pressure of 4 MPa, and a reaction time of 60 min, the yield of light fractions reaches 62.6%, and the solid residue concentrates Ti, Mo, Ge, and other rare and dispersed elements reach up to 66,000 g/t in total. The possibility of extracting Ge using the Purolite C100 sorbent has also been confirmed. The novelty of the study lies in demonstrating the donor–catalytic effect of shale and the practical prospects of solid residue as a secondary mineral raw materials.
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Open AccessArticle
Solvent-Dependent Coordination Geometry Shift in Copper(II)-D2EHPA Complexes: How Diluent Polarity Dictates Extraction Efficiency
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Fatima Ghebghoub, Djamel Barkat, Mohamed-Cherif Ben-Ameur and Mohamed-Aymen Kethiri
ChemEngineering 2025, 9(5), 107; https://doi.org/10.3390/chemengineering9050107 - 1 Oct 2025
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This study systematically investigates the solvent-dependence of copper(II) extraction using di-2-ethylhexyl phosphoric acid (D2EHPA) across a range of polar and non-polar diluents, including chloroform, dichloromethane, carbon tetrachloride, cyclohexane, 1-octanol, and methyl isobutyl ketone (MIBK). Through analysis of extraction constants and distribution coefficients at
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This study systematically investigates the solvent-dependence of copper(II) extraction using di-2-ethylhexyl phosphoric acid (D2EHPA) across a range of polar and non-polar diluents, including chloroform, dichloromethane, carbon tetrachloride, cyclohexane, 1-octanol, and methyl isobutyl ketone (MIBK). Through analysis of extraction constants and distribution coefficients at varying pH levels, it was demonstrated that solvent polarity and dipole moment critically influenced the coordination geometry and extraction efficiency of the Cu(II)-D2EHPA complex. Notably, the highest extraction efficiencies were exhibited by 1-octanol and cyclohexane. A solvent-dependent structural transition was revealed by Ultraviolet–Visible (UV) spectroscopic evidence: tetrahedral coordination was dominated in polar media, while square planar geometries prevailed in non-polar environments. These findings establish a direct correlation between diluent properties and the extractant’s performance, offering a mechanistic framework for optimizing industrial-scale copper recovery processes. The insights gained highlight the importance of solvent selection in tailoring metal extraction systems for specific applications.
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Open AccessArticle
Polyvinylidene Fluoride Membrane Modified by PEG Additive for Tofu Industrial Wastewater Treatment
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Sutrasno Kartohardjono, Michael Gabriell Owen, Sherlyta Estella, Irfan Purnawan and Woei Jye Lau
ChemEngineering 2025, 9(5), 106; https://doi.org/10.3390/chemengineering9050106 - 1 Oct 2025
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This study investigates the enhancement of polyvinylidene fluoride (PVDF) membranes with polyethylene glycol (PEG) to improve their efficacy in treating tofu wastewater through the ultrafiltration (UF) process. PVDF membranes with varying PEG concentrations of 0, 0.5, 1, and 1.5% in the dope solution
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This study investigates the enhancement of polyvinylidene fluoride (PVDF) membranes with polyethylene glycol (PEG) to improve their efficacy in treating tofu wastewater through the ultrafiltration (UF) process. PVDF membranes with varying PEG concentrations of 0, 0.5, 1, and 1.5% in the dope solution were produced, characterized via FTIR, mechanical strength, porosity, and contact angle measurements, and evaluated in wastewater treatment at varying pressures of 3, 4, and 5 bar in the UF process. The incorporation of PEG increased the membrane’s porosity from 28.2% for M-0 to 43.5% for M-1.5. The contact angle decreased from 65.3° for M-0 to 53.3° for M-1.5, indicating an increase in hydrophilicity. Elongation increased from 36.0% for M-0 to 113.5% for M-1.5; however, the tensile strength decreased from 11.8 MPa for M-0 to 5.4 MPa for M-1.5. Although PEG-modified membranes demonstrated enhanced flux, with values of 6.3 L∙m−2∙h−1 for M-0 and 15.7 L∙m−2∙h−1 for M-1.5 at a pressure of 5 bar, pure PVDF membranes (M-0) showed greater rejection rates for chemical oxygen demand (COD), total dissolve solid (TDS), total suspended solid (TSS), and turbidity at 3 bar, achieving values of 66.3%, 41.6%, 99.6%, and 99.1%, respectively. Following ultrafiltration, the pH and TDS levels conformed to Indonesian government guidelines; however, the COD levels were non-compliant, indicating the need for additional treatment. The findings suggest that PVDF/PEG ultrafiltration membranes are suitable for pre-treatment; however, nanofiltrationor reverse osmosis may be necessary to meet the stringent regulatory standards for tofu wastewater treatment. The modified M-1.5 membrane is recommended as the primary ultrafiltration membrane for tofu wastewater treatment due to its superior flux, prior to nanofiltration or reverse osmosis, to comply with the stringent regulatory standards established by the Government of the Republic of Indonesia.
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Open AccessArticle
Influence of Added Surfactants on the Rheology and Surface Activity of Polymer Solutions
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Rajinder Pal and Chung-Chi Sun
ChemEngineering 2025, 9(5), 105; https://doi.org/10.3390/chemengineering9050105 - 23 Sep 2025
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Steady-shear rheology and surface activity of surfactant–polymer solutions were investigated experimentally. Four different polymers were studied as follows: cationic hydroxyethyl cellulose, nonionic hydroxyethyl cellulose, nonionic guar gum, and anionic xanthan gum. The influence of the following four surfactants on each of the polymers
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Steady-shear rheology and surface activity of surfactant–polymer solutions were investigated experimentally. Four different polymers were studied as follows: cationic hydroxyethyl cellulose, nonionic hydroxyethyl cellulose, nonionic guar gum, and anionic xanthan gum. The influence of the following four surfactants on each of the polymers was determined: nonionic alcohol ethoxylate, anionic sodium lauryl sulfate, cationic hexadecyltrimethylammonium bromide, and zwitterionic cetyl betaine. The interaction between cationic hydroxyethyl cellulose and anionic sodium lauryl sulfate was extraordinarily strong, resulting in dramatic changes in rheological and surface-active properties. The consistency increased initially, reached a maximum value, and then fell off with the further addition of surfactant. The surface tension of surfactant–polymer solution dropped substantially and exhibited a minimum value. Thus, the surfactant–polymer solutions were much more surface-active compared with pure surfactant solutions. The interaction between anionic xanthan gum and cationic hexadecyltrimethylammonium bromide was also strong, resulting in a substantial decrease in consistency. The surfactant–polymer solution became less surface-active compared with pure surfactant solution due to the migration of surfactant from solution to polymer. The interactions between other polymers and surfactants were weak to moderate, resulting in small to modest changes in rheological and surface-active properties. Surface activity of surfactant–polymer solutions often increased due to the formation of complexes more surface-active than pure surfactant molecules.
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Open AccessArticle
Effect of Degumming and Bleaching on the Yield and Quality of Epoxidized Hempseed Oil
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Tosin Oyewole, Emily Biggane, Niloy Chandra Sarker and Ewumbua Monono
ChemEngineering 2025, 9(5), 104; https://doi.org/10.3390/chemengineering9050104 - 23 Sep 2025
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Crude hemp (Cannabis sativa L.) seed oil (HSO) has a high degree of unsaturation, which has increased its interest in many industrial applications, especially epoxy-resin production. Crude HSO is refined to remove impurities and pigments; however, refining after epoxidation (post-epoxidation refining) also
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Crude hemp (Cannabis sativa L.) seed oil (HSO) has a high degree of unsaturation, which has increased its interest in many industrial applications, especially epoxy-resin production. Crude HSO is refined to remove impurities and pigments; however, refining after epoxidation (post-epoxidation refining) also removes impurities and side products, similar to the vegetable oil refining process. Therefore, this study evaluates if it is worth refining crude HSO before epoxidation (pre-epoxidation), and to what extent pre-refining (before epoxidation) is needed to maintain yield and quality. Crude, degummed, and bleached HSOs were epoxidized at 60 °C for 5.5 h using amberlite 120H+ solid catalyst. The cumulative recovery yield, oxirane, conversion, color, and other quality parameters were analyzed before and after epoxidation of HSOs. Results showed that the recovery yield pre- and post-epoxidation of the epoxidized hempseed oils (EHSOs) ranged from 74 to 85%, with the bleached EHSO having the lowest yield. The oxirane content and epoxy conversion ranged from 8.4 to 8.6% and 99.5%, respectively. There was a significant decrease (approximately 99%) in the chlorophyll color content after epoxidation for samples that were not bleached initially with bleaching earth. Hydrogen peroxide was very effective in bleaching the HSO. Other quality parameters did not show any significant benefit from pre-epoxidation bleaching of the HSO. Therefore, it is recommended to directly epoxidize crude HSO or degummed HSO.
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Open AccessArticle
Influence of Bioadditives on Copper Leaching from Low-Grade Raw Materials
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Bagdaulet Kenzhaliyev, Aigul Koizhanova, Tatiana Surkova, Dinara Yessimova, David Magomedov and Zamzagul Dosymbaeva
ChemEngineering 2025, 9(5), 103; https://doi.org/10.3390/chemengineering9050103 - 23 Sep 2025
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The depletion of high-grade copper ore reserves in Kazakhstan, coupled with the increasing proportion of refractory ores and the high costs of extraction and processing, necessitates the development of efficient and economically viable technological solutions. In this context, biogeotechnology has gained considerable attention.
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The depletion of high-grade copper ore reserves in Kazakhstan, coupled with the increasing proportion of refractory ores and the high costs of extraction and processing, necessitates the development of efficient and economically viable technological solutions. In this context, biogeotechnology has gained considerable attention. Recently, alternative approaches based on the use of natural organic compounds—so-called bioreagents—have been introduced into the field of bioleaching. The present study aimed to investigate the effect of amino acids, aliphatic alcohols, and alcohol-based industrial by-products, used as bioadditives, on the bioleaching of copper. The results demonstrated that the influence of amino acids on copper bioleaching decreased in the following order: glycine > leucine > cysteine > histidine > asparagine. Furthermore, the addition of fusel oils, a mixture of aliphatic alcohols, to the bioleaching pulp enhanced copper recovery, achieving extraction efficiencies exceeding 90%.
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Open AccessArticle
Techno-Economic Analysis of Hybrid Adsorption–Membrane Separation Processes for Direct Air Capture
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Paul de Joannis, Christophe Castel, Mohamed Kanniche, Eric Favre and Olivier Authier
ChemEngineering 2025, 9(5), 102; https://doi.org/10.3390/chemengineering9050102 - 22 Sep 2025
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Direct air capture (DAC) has recently gained interest as a carbon dioxide removal (CDR) method to reduce atmospheric CO2. DAC is mainly studied through standalone separation technologies, especially adsorption and absorption. Hybrid DAC, combining separation technologies, is rarely investigated and is
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Direct air capture (DAC) has recently gained interest as a carbon dioxide removal (CDR) method to reduce atmospheric CO2. DAC is mainly studied through standalone separation technologies, especially adsorption and absorption. Hybrid DAC, combining separation technologies, is rarely investigated and is the main topic of this work. This study investigates hybrid DAC using adsorption for pre-concentration up to a few percent or tens of percent depending on the case studied and membrane separation to concentrate the CO2 stream to high purity (>90%). Adsorption regeneration by temperature swing adsorption (TSA) and vacuum thermal swing adsorption (VTSA) are compared, and VTSA regeneration achieved higher pre-concentration outlet CO2 purity (15–30%) than TSA regeneration (1–10%). Membrane separation is studied depending on inlet CO2 purity and outlet-required purity (90 or 95%), which influence the energy requirement and cost of capture. For all cases studied, the cost of capture remained high (>1700 €/tCO2) with a high energy requirement (>2 MWhe/tCO2 and >27 GJ/tCO2). The adsorption pre-concentration step accounted for the majority (>80%) of the energy requirement and cost of capture, and future work should be focused on preferentially improving adsorption step performance.
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Open AccessArticle
Recovery of Light Rare Earth Elements from Coal Ash via Tartaric Acid and Magnesium Sulfate Leaching
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Ardak Karagulanova, Burcu Nilgun Cetiner, Kaster Kamunur, Lyazzat Mussapyrova, Aisulu Batkal, Zhannur Myltykbayeva and Rashid Nadirov
ChemEngineering 2025, 9(5), 101; https://doi.org/10.3390/chemengineering9050101 - 19 Sep 2025
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Coal ash is a promising secondary resource for rare earth element (REE) recovery, yet efficient processing under environmentally benign conditions remains challenging. This study demonstrates that tartaric acid, when combined with MgSO4 as a salt additive, enables effective extraction of light REEs
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Coal ash is a promising secondary resource for rare earth element (REE) recovery, yet efficient processing under environmentally benign conditions remains challenging. This study demonstrates that tartaric acid, when combined with MgSO4 as a salt additive, enables effective extraction of light REEs (La, Ce, Nd). REE recoveries improved from ~40% without salt to nearly 65% under optimized conditions. Kinetic modeling indicated a surface-reaction–controlled mechanism with activation energies of 20–22 kJ/mol, consistent with SEM evidence of particle erosion and size reduction. These findings highlight the potential of organic-salt leaching systems as alternatives to mineral acid processes, offering both effective REE recovery and reduced environmental impact.
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Open AccessArticle
Influence of Carboxylated Styrene–Butadiene Rubber on Gas Migration Resistance and Fluid Loss in Cement Slurries
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Guru Prasad Panda, Thotakura Vamsi Nagaraju, Gottumukkala Sri Bala and Saride Lakshmi Ganesh
ChemEngineering 2025, 9(5), 100; https://doi.org/10.3390/chemengineering9050100 - 19 Sep 2025
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The majority of downhole monitoring methods currently available for well cement projects, which are used to assess the quality of cement placement and monitor well integrity over time, are primarily qualitative in nature and rely on surface signs. Obviously, there is a need
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The majority of downhole monitoring methods currently available for well cement projects, which are used to assess the quality of cement placement and monitor well integrity over time, are primarily qualitative in nature and rely on surface signs. Obviously, there is a need for a practical quantitative downhole monitoring method to ensure proper cement placement and long-term performance. One potential resolution to address this enduring problem would involve enhancing the designs of the cement slurry and transforming the cement into durable downhole logging equipment, thereby facilitating real-time observation of operations. To address this issue, in this work, carboxylated styrene butadiene rubber (XSBR) polymer-treated cement was used to understand the gas migration and fluid loss mechanism. The experimental findings indicate that the electrical resistivity of polymer-treated cement is significantly influenced by applied loads and stresses. The unconfined compressive strength test with XSBR-blended cement showed a significant improvement from 22.5 MPa to 33.31 MPa when XSBR increased from 0% to 3%. Additionally, in the high pressure and high temperature (HPHT) chamber, the latex polymer used as a migration additive control, the total fluid loss is found to be about 59.2 mL under 30 min of testing. Also, to emulate the accuracy, nonlinear predictive models based on the resistivity index correlation were developed to forecast polymer-treated cement performance for all the tests performed in this study. Hence, the utilization of polymer-treated cement systems proves to be a valuable method for monitoring the placement and post-placement performance of cement, as well as for visualizing real-time operational issues associated with cementing. This will also allow operators to provide immediate solutions, saving time and operational costs.
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(This article belongs to the Special Issue The Applications of Computational Fluid Dynamics in Transport Phenomena)
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Valorization of an Industrial Pollutant Residue as a Teaching Tool: Extraction of Al3+ from Aluminum Saline Slag
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Alejandro Jiménez, Raquel Trujillano, Sophia Korili, Antonio Gil and Miguel Ángel Vicente
ChemEngineering 2025, 9(5), 99; https://doi.org/10.3390/chemengineering9050099 - 15 Sep 2025
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Aluminum is the most used non–ferrous metal. It can be recycled saving several natural resources, but generates large amounts of residues with a complex composition—still containing a valuable amount of aluminum, although also including contaminant compounds. The laboratory-scale valorization of an industrial aluminum
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Aluminum is the most used non–ferrous metal. It can be recycled saving several natural resources, but generates large amounts of residues with a complex composition—still containing a valuable amount of aluminum, although also including contaminant compounds. The laboratory-scale valorization of an industrial aluminum residue is here used as a powerful didactic resource in Inorganic and Analytical Chemistry and related fields such as Chemistry, Chemical Engineering, Environmental Engineering, Materials Engineering, and related university degrees, since concepts like acid-base properties (particularly amphoterism), redox reactions, speciation diagrams, or solubility–precipitation concepts are applied. The students are encouraged to look for information on the topic, to teamwork, and to elaborate a well-written laboratory report. At the same time, this laboratory work introduces them to advanced laboratory techniques and to incorporate concepts of Circular Economy and various Sustainable Development Goals, educating the students with respect to the environment. Although focused on University studies, this manuscript also contains excellent ideas for secondary teachers to motivate STEM vocations, particularly for Chemistry and Chemical and Environmental Engineering, and is also ideal for being included in the preparation of future Secondary School teachers.
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Open AccessArticle
Simultaneous Determination of Four Fatty Acids in Coix Seeds via Gas Chromatography
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Qiang Ai, Hui Wang, Chenghong Xiao, Changgui Yang, Shanmin Song, Mingxiang Zhang, Jiandong Tang and Yang Lei
ChemEngineering 2025, 9(5), 98; https://doi.org/10.3390/chemengineering9050098 - 11 Sep 2025
Abstract
The aim of this study was to establish a method named simultaneous determination for the content of four fatty acids in Coix seeds and provide a reference for the quality control of this type of medicinal ingredient. The contents of four fatty acids
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The aim of this study was to establish a method named simultaneous determination for the content of four fatty acids in Coix seeds and provide a reference for the quality control of this type of medicinal ingredient. The contents of four fatty acids in Coix seeds were determined via gas chromatography, and the method was subsequently validated. The linear ranges of palmitic acid, stearic acid, oleic acid and linoleic acid were 282.50–2825.00, 262.00–1572.00, 425.20–2976.75 and 304.50–1218.00 µg/mL, respectively. The RSD values of precision, repeatability and stability were less than 3.00% (n = 6), with recoveries of 98.82–102.05% (RSD 2.22–4.60%, n = 6). The contents of palmitic acid, stearic acid, oleic acid and linoleic acid in the 24 batches of Coix seeds were 0.11–0.32%, 0.06–0.08%, 0.35–1.17% and 0.31–0.73%, respectively. Oleic acid had the highest content, followed by linoleic acid, palmitic acid, and stearic acid. The detection method established in this experiment was implemented rapidly and accurately, was reproducible, and could simultaneously determine the contents of four fatty acids in Coix seeds. This study provides a reference for evaluating the quality of Coix seeds obtained from different habitats.
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(This article belongs to the Special Issue Advances in Sustainable and Green Chemistry)
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Mathematical Modeling and Design of a Cooling Crystallizer Incorporating Experimental Data for Crystallization Kinetics
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Panagiotis A. Michailidis and Argyris Panagopoulos
ChemEngineering 2025, 9(5), 97; https://doi.org/10.3390/chemengineering9050097 - 2 Sep 2025
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Crystallization is one of the approximately twenty unit operations and is considered to be among the most important due to the large number of chemical compounds it produces, as well as due to the enormous quantities of these substances being manufactured around the
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Crystallization is one of the approximately twenty unit operations and is considered to be among the most important due to the large number of chemical compounds it produces, as well as due to the enormous quantities of these substances being manufactured around the world. This article aims to present a mathematical model for the shortcut design of a cooling crystallization unit consisting of the crystallizer and auxiliary equipment, such as an evaporator with its preheater and condenser, a heat pump that acts as the cooling system of the crystallizer, and a crystallizer pressure regulator modeled as an expansion valve. The model estimates an extensive series of variables, including mass and volume flow rates of the streams, heat duties of each piece of equipment, sizing variables such as heat transfer areas of heat exchangers and volumes of the vessels, and product flow rates for each specific feed. It embraces equations for the calculation of a series of stream properties, such as density, specific heat capacity, and latent heat of vaporization. For the sizing of the crystallizer, which is the main equipment of the unit, both flow rates and crystallization kinetics are taken into account. The latter is estimated by experimental data taken in a laboratory crystallizer and includes the crystal’s growth rate as a function of residence time.
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Open AccessArticle
Feasibility Study on Using Calcium Lignosulfonate-Modified Loess for Landfill Leachate Filtration and Seepage Control
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Jinjun Guo, Wenle Hu and Shixu Zhang
ChemEngineering 2025, 9(5), 96; https://doi.org/10.3390/chemengineering9050096 - 2 Sep 2025
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Prolonged exposure to landfill leachate can weaken the impermeability of liner systems, leading to leachate leakage and the contamination of surrounding soil and water. To improve loess impermeability to enable its use as a liner material, this study uses synthetic landfill leachate to
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Prolonged exposure to landfill leachate can weaken the impermeability of liner systems, leading to leachate leakage and the contamination of surrounding soil and water. To improve loess impermeability to enable its use as a liner material, this study uses synthetic landfill leachate to investigate its effects on loess permeability via a series of laboratory tests. This study focused on the influence of varying dosages of calcium lignosulfonate (CLS) on loess permeability, along with its capacity to adsorb and immobilize heavy metal ions. Microscale characterization techniques, including Zeta potential analysis, X-ray fluorescence spectroscopy (XRF), and scanning electron microscopy (SEM), were employed to investigate the impermeability mechanisms of CLS-modified loess and its adsorption behavior toward heavy metals. The results indicate that the permeability coefficient of loess decreases significantly with increasing compaction, while higher leachate concentrations lead to a notable increase in permeability. At a compaction degree of 0.90, the permeability coefficient was reduced to 8 × 10−8 cm/s. In contrast, under conditions of maximum leachate concentration, the permeability coefficient rose markedly to 1.5 × 10−4 cm/s. Additionally, increasing the dosage of the compacted loess stabilizer (CLS) effectively reduced the permeability coefficient of the modified loess to 7.1 × 10−5 cm/s, indicating improved impermeability and enhanced resistance to contaminant migration. With the prolonged infiltration time of landfill leachate, the removal efficiency of Pb2+ gradually decreases and stabilizes, while the Pb2+ removal efficiency of the modified loess increased by approximately 40%. CLS-modified loess, through multiple mechanisms, reduces the fluid flow pathways and enhances its adsorption capacity for Pb2+, thereby improving the soil’s protection against heavy metal contamination. While these results demonstrate the potential of CLS-modified loess as a sustainable landfill liner material, the findings are based on controlled laboratory conditions with Pb2+ as the sole target contaminant. Future work should evaluate long-term performance under field conditions, including seasonal wetting–drying and freeze–thaw cycles, and investigate multi-metal systems to validate the broader applicability of this modification technique.
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Open AccessArticle
Economic Evaluation During Physicochemical Characterization Process: A Cost–Benefit Analysis
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Despina A. Gkika, Nick Vordos, Athanasios C. Mitropoulos and George Z. Kyzas
ChemEngineering 2025, 9(5), 95; https://doi.org/10.3390/chemengineering9050095 - 2 Sep 2025
Abstract
As academic institutions expand, the proliferation of laboratories dealing with hazardous chemicals has risen. While the physicochemical characterization equipment employed in these academic chemical laboratories is widely recognized, its usage presents a notable risk to researchers at various levels. This paper presents a
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As academic institutions expand, the proliferation of laboratories dealing with hazardous chemicals has risen. While the physicochemical characterization equipment employed in these academic chemical laboratories is widely recognized, its usage presents a notable risk to researchers at various levels. This paper presents a simplified approach for evaluating the effects of the implementation of prevention investments in regard to working with nanomaterials on a lab scale. The evaluation is based on modeling the benefits (avoided accident costs) and costs (safety training), as opposed to an alternative (not investing in safety training). Each scenario analyzed in the economic evaluation reflects a different level of risk. The novelty of this study lies in its objective to provide an economic assessment of the benefits and returns from safety investments—specifically training—in a chemical laboratory, using a framework that integrates qualitative insights to explore and define the context alongside quantitative data derived from a cost–benefit analysis. The Net Present Value (NPV) was evaluated. The results of the cost–benefit analysis demonstrated that the benefits exceed the cost of the investment. The findings from the sensitivity analysis highlight the significant influence of insurance benefits on safety investments in the specific case study. In this case study, the deterministic analysis yielded a Net Present Value (NPV) of €280,414.67, which aligns closely with the probabilistic results. The probabilistic NPV indicates 90% confidence that the investment will yield a positive NPV ranging from €283,053 to €337,356. The cost–benefit analysis results demonstrate that the benefits outweigh the costs, showing that with an 87% training success rate, this investment would generate benefits of approximately €6328 by preventing accidents in this study. To the best of the researchers’ knowledge, this is the first study to evaluate the influence of safety investment through an economic evaluation of laboratory accidents with small-angle X-ray scattering during the physicochemical characterization process of engineered nanomaterials. The proposed approach and framework are relevant not only to academic settings but also to industry.
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(This article belongs to the Special Issue New Advances in Chemical Engineering)
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Uncertainty and Global Sensitivity Analysis of a Membrane Biogas Upgrading Process Using the COCO Simulator
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José M. Gozálvez-Zafrilla and Asunción Santafé-Moros
ChemEngineering 2025, 9(5), 94; https://doi.org/10.3390/chemengineering9050094 - 1 Sep 2025
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Process designs based on deterministic simulations without considering parameter uncertainty or variability have a high probability of failing to meet specifications. In this work, uncertainty and global sensitivity analyses were applied to a biogas upgrading membrane process implemented in the COCO simulator (CAPE-OPEN
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Process designs based on deterministic simulations without considering parameter uncertainty or variability have a high probability of failing to meet specifications. In this work, uncertainty and global sensitivity analyses were applied to a biogas upgrading membrane process implemented in the COCO simulator (CAPE-OPEN to CAPE-OPEN), considering both controlled and non-controlled scenarios. A user-defined model code was developed to simulate gas separation membrane stages, and a preliminary study of membrane parameter uncertainty was performed. In addition, a unit generating combinations of uncertainty factors was developed to interact with the simulator’s parametric tool. Global sensitivity analyses were carried out using the Morris method and Sobol’ indices obtained by Polynomial Chaos Expansion, allowing for the ranking and quantification of the influence of feed variability and membrane parameter uncertainty on product streams and process utilities. Results showed that when feed variability was ±10%, its effect exceeded the uncertainty of the membrane parameters. Uncertainty analysis using the Monte Carlo propagation method provided lower and upper tolerance limits for the main responses. Relative gaps between tolerance limits and mean product flows were 8–9% at a feed variability of 5% and 14–18% at a feed variability of 10%, while relative tolerance gaps resulting from composition were smaller (0.4–1.2%).
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Ethanol Fermentation by Saccharomyces cerevisiae and Scheffersomyces stipitis Using Sugarcane Bagasse Selectively Delignified via Alkaline Sulfite Pretreatment
by
João Tavares, Abdelwahab Rai, Teresa de Paiva and Flávio da Silva
ChemEngineering 2025, 9(5), 93; https://doi.org/10.3390/chemengineering9050093 - 27 Aug 2025
Abstract
Bioethanol from sugarcane bagasse is a promising second-generation biofuel due to its abundance as a sugar industry by-product. Herein, enzymatic hydrolysate obtained from sugarcane bagasse pretreated with optimized hydrothermal alkaline sulfite (HAS) was evaluated for its fermentability using Saccharomyces cerevisiae PE-2 and Scheffersomyces
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Bioethanol from sugarcane bagasse is a promising second-generation biofuel due to its abundance as a sugar industry by-product. Herein, enzymatic hydrolysate obtained from sugarcane bagasse pretreated with optimized hydrothermal alkaline sulfite (HAS) was evaluated for its fermentability using Saccharomyces cerevisiae PE-2 and Scheffersomyces stipitis CBS 5773. The HAS pretreatment achieved a high delignification rate (63%), resulting in a cellulose- and hemicellulose-enriched substrate (55% and 27%, respectively). While the cellulose content remained relatively constant, hemicellulose content was reduced by 25%, with significant removal of acetyl groups (80%) and arabinan groups (39%). The pretreated bagasse exhibited high digestibility, applying 10 FPU (filter paper unit) cellulase together with 10 CBU (cellobiose unit) β-glucosidase per gram of dry bagasse in the hydrolysis step, yielding 72% glucan and 66% xylan conversion within 72 h. The resulting hydrolysate was efficiently fermented by S. cerevisiae and S. stipitis, achieving ethanol yields of 0.51 and 0.43 g/g of sugars, respectively. The fermentation kinetics were comparable to those observed in a synthetic medium containing pure sugars, demonstrating the effectiveness of HAS pretreatment in generating readily fermentable, carbohydrate-rich substrates. HAS pretreatment enabled improved conversion of sugarcane bagasse into fermentation-ready sugars, constituting a potential resource for bioethanol synthesis applying both S. cerevisiae and S. stipitis in the future.
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(This article belongs to the Special Issue Catalytic Reactions and Development of (Bio)Chemical Processes for Synthesizing Value Added Compounds)
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Open AccessArticle
Research on Deep Separation Technology of Multi–Source By–Products in Coking Coal
by
Andile Khumalo, Chuanzhen Wang, Tao Tan and Md. Shakhaoath Khan
ChemEngineering 2025, 9(4), 92; https://doi.org/10.3390/chemengineering9040092 - 18 Aug 2025
Cited by 1
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This study proposes considering the effective re–benefication of coal middlings and other such considered waste materials as a way to ensure that clean coal in coal by–products can be extracted and effectively utilized, saving costs and reducing coal waste. To quantify the clean–coal
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This study proposes considering the effective re–benefication of coal middlings and other such considered waste materials as a way to ensure that clean coal in coal by–products can be extracted and effectively utilized, saving costs and reducing coal waste. To quantify the clean–coal yield and ash reduction that can be achieved by re–beneficiating four typical by–product streams from the Guobei Coal Preparation Plant (6 Mt a−1) were used for the study. Coking–coal middlings, flotation tailings, and pressure–filter cakes from preparation plants still contain 30–60% combustible matter. Re–beneficiation techniques have been considered to recover this often-wasted coal, reduce waste rock disposal, and cut greenhouse–gas emissions per ton of clean coal produced. Representative samples (n = 4) were collected, sample size–classified as (fine coal particles ≤0.5 mm and coarse particles ≥) and subjected to (i) magnetite removal, (ii) laboratory froth flotation (diesel 507 g t−1, sec–octanol 103 g t−1), and (iii) fine and large particle density separation at 1.3–1.8 g cm−3 ZnCO3 media. Clean–coal yield and ash were measured for each stream and the coal’s particle liberation was examined by SEM. Crushing, grinding and liberation equipment and techniques that aid in the treatment of coal and the re–beneficiation of coal middlings and tailings. The key findings recorded during the experiment are as follows: Flotation of <0.5 mm fractions delivered 46.9–58.3% clean–coal yield at 10.3–17.0% ash. Density separation of 0.5–1.0 mm middlings peaked at 1.4–1.5 g cm−3, yielding 34.2% clean coal at 15–18.4% ash. Scanning Electron Microscope analysis confirmed partial liberation as results from re–grinding + second flotation which increased yield by a further 8–12%. A calculated theoretical examination of the preliminary cost–benefit analysis indicates ≈36 CNY t−1≈9 million CNY a−1 in saved disposal costs alone. savings in disposal and 0.25 Mt a−1 additional clean coal for the Guobei plant. The research presented in this paper highlights the current work by Anhui University of Science and technology in collaboration with Guobei coal preparation plant and the results therein achieved.
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Open AccessArticle
Exploring the Physicochemical and Toxicological Study of G-Series and A-Series Agents Combining Molecular Dynamics and Quantitative Structure–Activity Relationship
by
Michail Chalaris, Antonios Koufou, Sotiria Anastasiou, Pantelis-Alexandros Roupas and Georgios Nikolaou
ChemEngineering 2025, 9(4), 91; https://doi.org/10.3390/chemengineering9040091 - 18 Aug 2025
Abstract
This study explores the physicochemical and toxicological properties of six G-series and A-series chemical warfare agents (Sarin, Soman, Tabun, A230, A232, and A234) using an integrated computational approach combining molecular dynamics (MD) simulations and Quantitative Structure–Activity Relationship (QSAR) modeling. For the A-series nerve
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This study explores the physicochemical and toxicological properties of six G-series and A-series chemical warfare agents (Sarin, Soman, Tabun, A230, A232, and A234) using an integrated computational approach combining molecular dynamics (MD) simulations and Quantitative Structure–Activity Relationship (QSAR) modeling. For the A-series nerve agents, both Ellison–Hoenig and Mirzayanov structural proposals were examined. MD simulations (10 ns, NPT ensemble) provided key thermodynamic properties, including density, molar heat capacity, and diffusivity. Simulated densities for G-agents (e.g., Sarin: 1.09 g/cm3, Soman: 1.03 g/cm3) and A-agents (e.g., A230: 1.608 g/cm3, Ellison–Hoenig model) closely matched experimental data. Heat capacities ranged from 258 to 462 J/mol·K, and self-diffusion coefficients revealed lower mobility for A-agents, especially under the Ellison–Hoenig configurations. QSAR modeling focused on lipophilicity (LogP) and acute toxicity (LD50). Predicted LD50 values ranged from 0.012 to 0.017 mg/kg for G-agents and up to 1.23 mg/kg for A-agents. A-234 showed the highest lipophilicity (LogP = 2.97) and toxicity (LD50 = 0.51 mg/kg) within its group. Additional descriptors, such as molecular weight and polar surface area, supported toxicity predictions. Strong correlations emerged between MD-derived properties and QSAR outputs, validating the integrated approach. The combined use of MD and QSAR techniques provided a comprehensive view of the agents’ environmental behavior and toxicological impact, supporting safer assessment strategies and reinforcing the importance of multidisciplinary modeling for chemical threat mitigation.
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(This article belongs to the Topic Artificial Intelligence and Automation in Chemical Engineering)
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Open AccessArticle
Bio-Based Nanocellulose Piezocatalysts: PH-Neutral Mechanochemical Degradation of Multipollutant Dyes via Ambient Vibration Energy Conversion
by
Zhaoning Yang, Zihao Yang, Xiaoxin Shu, Wenshuai Chen, Jiaolong Liu, Keqing Chen and Yanmin Jia
ChemEngineering 2025, 9(4), 90; https://doi.org/10.3390/chemengineering9040090 - 15 Aug 2025
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Piezoelectric catalytic technology has attracted much attention in the field of dye wastewater treatment, in which inorganic piezoelectric materials have been widely studied. Its core mechanism involves utilizing the piezoelectric effect to generate positive and negative charges, which react with oxygen ions and
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Piezoelectric catalytic technology has attracted much attention in the field of dye wastewater treatment, in which inorganic piezoelectric materials have been widely studied. Its core mechanism involves utilizing the piezoelectric effect to generate positive and negative charges, which react with oxygen ions and hydroxyl radicals, respectively, to generate reactive oxygen species to degrade organic pollutants. Currently, while organic piezoelectric catalysts theoretically offer significant advantages such as low cost and high processability, there has been a notable lack of research in this area, which presents an innovative opportunity for the exploration of new organic piezoelectric catalytic materials. In this study, new research using natural nanocellulose (FC) suspension as an efficient organic piezoelectric catalyst is reported for the first time. The experimental results showed that the catalyst exhibited excellent degradation performance for Rhodamine B (RhB), Acid Orange 7 (AO7), and Methyl Orange (MO) under ultrasonic vibration (40 kHz, 200 W): the degradation rates reached 95.4%, 72.4%, and 31.2%, respectively, for 150 min, and the corresponding first-order reaction kinetic constants were 0.0205, 0.00858, and 0.00249 min−1, respectively. It is noteworthy that the RhB solution can achieve the optimal degradation efficiency without adjustment under neutral initial pH conditions, which significantly enhances the practical application feasibility. The experimental results showed that the catalyst, with a measurable piezoelectric coefficient (d33 = 4.4 pm/V), exhibited excellent degradation performance for Rhodamine B (RhB), Acid Orange 7 (AO7), and Methyl Orange (MO) under ultrasonic vibration (40 kHz, 200 W). This organic piezoelectric catalyst, based on renewable biomass, innovatively converts mechanical vibration energy in the environment into the power to degrade pollutants. It not only expands the application boundaries of organic piezoelectric materials but also provides a new solution for sustainable water treatment technology, demonstrating extremely promising application prospects in the field of green and environmentally friendly water treatment.
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