ChemEngineering

20 pages, 1462 KB

Open AccessReview

Sustainable Solutions in Sodium-Ion Battery Cathode Materials: A Mini-Review of Strategies for Upgraded Performance Through Modification Techniques

by Mudhar A. Al-Obaidi, Farhan Lafta Rashid, Ahmed K. Ali, Mohammed Mahdi, Ahmad Al Astal and Iqbal M. Mujtaba

ChemEngineering 2025, 9(6), 143; https://doi.org/10.3390/chemengineering9060143 - 12 Dec 2025

Abstract

Sodium-ion batteries (SIBs) have arisen as a potential alternative to lithium-ion batteries (LIBs) as a result of the abundant availability of sodium resources at low production costs, making them in line with the United Nations Sustainable Development Goals (SDGs) for affordable and clean [...] Read more.

Sodium-ion batteries (SIBs) have arisen as a potential alternative to lithium-ion batteries (LIBs) as a result of the abundant availability of sodium resources at low production costs, making them in line with the United Nations Sustainable Development Goals (SDGs) for affordable and clean energy (Goal 7). The current review intends to comprehensively analyse the various modification techniques deployed to improve the performance of cathode materials for SIBs, including element doping, surface coating, and morphological control. These techniques have demonstrated prominent improvements in electrochemical properties, such as specific capacity, cycling stability, and overall efficiency. The findings indicate that element doping can optimise electronic and ionic conductivity, while surface coatings can enhance stability in addition to mitigating side reactions throughout cycling. Furthermore, morphological control is an intricate technique to facilitate efficient ion diffusion and boost the use of active materials. Statistically, the Cr-doped NaV_1−xCr_xPO₄F achieves a reversible capacity of 83.3 mAh/g with a charge–discharge performance of 90.3%. The sodium iron–nickel hexacyanoferrate presents a discharge capacity of 106 mAh/g and a Coulombic efficiency of 97%, with 96% capacity retention over 100 cycles. Furthermore, the zero-strain cathode Na₄Fe₇(PO₄)₆ maintains about 100% capacity retention after 1000 cycles, with only a 0.24% change in unit-cell volume throughout sodiation/desodiation. Notwithstanding these merits, this review ascertains the importance of ongoing research to resolve the associated challenges and unlock the full potential of SIB technology, paving the way for sustainable and efficient energy storage solutions that would aid the conversion into greener energy systems. Full article

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31 pages, 1765 KB

Open AccessArticle

Synergistic Effects of Rosemary and Carrot Extracts as Green Corrosion Inhibitors for Carbon Steel Protection in Acidizing Operations of Petroleum Industry

by Sedigheh Ghanbari Daryaee, Azizollah Khormali, Akram Taleghani and Majid Mokaber-Esfahani

ChemEngineering 2025, 9(6), 142; https://doi.org/10.3390/chemengineering9060142 - 10 Dec 2025

Abstract

Corrosion of carbon steel in acidic media remains a critical challenge during acidizing operations. This study evaluates carrot and rosemary extracts—individually and in combination—as green corrosion inhibitors for carbon steel in 1 M HCl. Inhibition performance was assessed using weight loss, potentiodynamic polarization [...] Read more.

Corrosion of carbon steel in acidic media remains a critical challenge during acidizing operations. This study evaluates carrot and rosemary extracts—individually and in combination—as green corrosion inhibitors for carbon steel in 1 M HCl. Inhibition performance was assessed using weight loss, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), SEM/EDS, and adsorption isotherms. Weight-loss measurements showed inhibition efficiencies of 59.5% (carrot) and 85.7% (rosemary) at 800 ppm, while their 30/70 mixture achieved a markedly higher efficiency of 99.6%. PDP results confirmed this trend, with corrosion current density decreasing from 892 μA/cm² (blank) to 13.4 μA/cm² for the mixture, corresponding to 98.5% efficiency. In addition, EIS analysis revealed a substantial increase in charge-transfer resistance from 41.1 ohm.cm² (blank) to 174.9 ohm.cm² (carrot), 266.9 ohm.cm² (rosemary), and 1868.1 ohm.cm² for the 30/70 mixture, confirming superior barrier formation. Moreover, temperature-dependent tests showed only a 5% efficiency loss for the mixture and an average 6% decrease for the single extracts between 25–45 °C, indicating good thermal stability. Also, SEM images demonstrated severe surface damage in the blank sample, while carrot-, rosemary-, and mixture-treated surfaces showed progressively smoother morphologies. EDS analysis confirmed this trend, with Fe content increasing from 65.78% (blank) to 90.16% (carrot), 91.88% (rosemary), and 94.59% for the mixture. Furthermore, FTIR and GC–MS identified oxygenated functional groups and major phytochemicals responsible for adsorption. Adsorption data followed the Langmuir model, and Gibbs free energy values from −25 to −31 KJ/mol indicated spontaneous mixed physisorption–chemisorption. Overall, the 30/70 carrot–rosemary mixture consistently achieved the highest corrosion protection across all tests, confirming strong synergistic adsorption and demonstrating its potential as a high-performance, eco-friendly inhibitor for acidic environments. Full article

16 pages, 1926 KB

Open AccessArticle

Investigation of the Effects of Sodium Caseinate/Xanthan Gum Complexes on the Stability and Sustained Release of Acid Double Emulsions Using Box–Behnken Design

by Houria Bouziane, Soumia Seddari and Nadji Moulai-Mostefa

ChemEngineering 2025, 9(6), 141; https://doi.org/10.3390/chemengineering9060141 - 9 Dec 2025

Abstract

This study investigates the formulation and optimization of acid-stable water-in-oil-in-water (W/O/W) double emulsions stabilized by sodium caseinate (NaCN)–xanthan gum (XG) complexes, with the aim of developing a natural biopolymer-based delivery system exhibiting controlled release behavior. The emulsions were prepared at pH 4, and [...] Read more.

This study investigates the formulation and optimization of acid-stable water-in-oil-in-water (W/O/W) double emulsions stabilized by sodium caseinate (NaCN)–xanthan gum (XG) complexes, with the aim of developing a natural biopolymer-based delivery system exhibiting controlled release behavior. The emulsions were prepared at pH 4, and the effects of NaCN concentration, XG concentration, and primary fraction (PF) on the encapsulation efficiency (EE) and droplet size (DS) were systematically evaluated using response surface methodology (RSM) based on a Box–Behnken design (BBD). Microscopic and rheological analyses confirmed the formation of a rigid interfacial film around the droplets, leading to improved emulsion stability over one month of storage at 4, 25, and 40 °C. The release kinetics of chlortetracycline (CTC), used as a model drug, followed a Fickian diffusion mechanism, indicating efficient control of the release rate by the NaCN/XG interfacial complex. The optimized formulation (NaCN = 0.652%, XG = 0.339%, PF = 10%) yielded an encapsulation efficiency of 87.7% and a mean droplet size of 24.83 µm, demonstrating excellent predictive accuracy of the statistical model. The results highlight the potential of NaCN/XG complexes to produce acid-stable, biopolymer-based double emulsions capable of sustained release of bioactive compounds, making this system promising for food and pharmaceutical delivery applications. Full article

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24 pages, 2980 KB

Open AccessArticle

Monte Carlo Simulations as an Alternative for Solving Engineering Problems in Environmental Sciences: Three Case Studies

by Sergio Luis Parra-Angarita, Guillermo H. Gaviria, Juan F. Herrera-Ruiz and María del Carmen Márquez

ChemEngineering 2025, 9(6), 140; https://doi.org/10.3390/chemengineering9060140 - 9 Dec 2025

Abstract

Monte Carlo methods offer a fast, cost-effective approach for modeling environmental systems influenced by random variability. This study applied them to three abiotic cases: (I) water quality in a lentic surface water source, (II) sizing of a homogenization chamber for solid waste treatment, [...] Read more.

Monte Carlo methods offer a fast, cost-effective approach for modeling environmental systems influenced by random variability. This study applied them to three abiotic cases: (I) water quality in a lentic surface water source, (II) sizing of a homogenization chamber for solid waste treatment, and (III) removal of atmospheric particulate matter by rain. Deterministic models produced wide and inconsistent estimates: BOD₅ concentrations from 5.28 to 19.81 mg/L (275% relative difference), chamber volumes from 24.12 to 116.53 m³, and particulate matter reductions with up to 60 µg/m³ per month variation. Monte Carlo simulations, by contrast, captured system variability and provided more robust outputs: a design value of 94.84 m³ for the homogenization chamber, narrower ranges for BOD₅, and realistic distributions of atmospheric PM concentrations. Results show that reliance on average values introduces strong biases and mathematical incompatibilities, while the Monte Carlo approach yields quantitative predictions that are both accurate and operationally useful. This confirms its relevance as a practical tool for analyzing and designing environmental systems under uncertainty. Full article

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

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21 pages, 4086 KB

Open AccessArticle

Activated Carbons for Bone Cell Growth: Structural Properties and Biological Interactions

by Damião de Carvalho Pereira, Drielli Viana Souza, Ayres Fernando Rodrigues, Gisele Amaral-Labat, Patrícia Almeida-Mattos, Guilherme Frederico Bernardo Lenz e Silva, Flavia Lega Braghiroli, Ana Paula Ligeiro de Oliveira, José Antônio Silva Júnior, Stella Regina Zamuner, Vanessa Fierro, Alain Celzard and Rodrigo Labat Marcos

ChemEngineering 2025, 9(6), 139; https://doi.org/10.3390/chemengineering9060139 - 9 Dec 2025

Abstract

Having high porosity and biocompatibility, carbon-based materials are promising candidates for tissue engineering applications, particularly as substitutes for biological tissues. This study investigates the growth and viability of osteoblasts on four different activated carbon (AC) materials and correlates biological responses with their physicochemical [...] Read more.

Having high porosity and biocompatibility, carbon-based materials are promising candidates for tissue engineering applications, particularly as substitutes for biological tissues. This study investigates the growth and viability of osteoblasts on four different activated carbon (AC) materials and correlates biological responses with their physicochemical and morphological properties. Two materials derived from non-renewable sources—AC1, a laboratory-synthesized carbon derived from anthracite, and AC3, a commercial activated carbon (Norit GCN 830) derived from coal—and two commercial activated carbons derived from renewable sources—peat, AC2 (Norit PK1-3), and wood, AC4 (ROX 0.8)—are studied. Results showed that AC1 exhibited the highest porosity (3072 m²/g), with higher phenolic and oxygen-containing surface groups but lower cell viability. In contrast, AC2, AC3, and AC4 displayed lower porosity compared to AC1 (755, 1040, and 1083 m²/g, respectively) and fewer surface phenolic groups but sustained osteoblast proliferation. Notably, AC4 demonstrated superior performance, characterized by regions of fibrous surface, pores in the meso- and microscale range (<50 nm), and enhanced cell viability and proliferation. AC2 also showed favorable results, ranking second for cell growth support. These findings suggest that biomass-derived ACs, particularly AC4 and AC2, provide favorable environments for osteoblast viability and proliferation. AC costs were estimated at 15 to 38 times lower than those for hydroxyapatite and bioceramics, which are widely used for bone cell growth. Thus, ACs made from renewable sources are promising candidates for tissue engineering applications, offering sustainable and effective alternatives for biomedical use. Full article

(This article belongs to the Special Issue Recent Advances in Applied Activated Carbon Research)

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9 pages, 1141 KB

Open AccessArticle

A Practical Approach for Measuring Chemical Oxygen Demand (COD) of Fats, Oils, and Grease (FOG) Using Tween 80 in Wastewater

by Naveed Ahmed and Andrea Straub

ChemEngineering 2025, 9(6), 138; https://doi.org/10.3390/chemengineering9060138 - 5 Dec 2025

Abstract

This study aims to estimate the organic load of oily wastewater by using Chemical Oxygen Demand (COD) measurements, addressing the analytical challenges posed by the hydrophobic, nonpolar, and often emulsified nature of Fats, oil and grease (FOG). This study established a reproducible and [...] Read more.

This study aims to estimate the organic load of oily wastewater by using Chemical Oxygen Demand (COD) measurements, addressing the analytical challenges posed by the hydrophobic, nonpolar, and often emulsified nature of Fats, oil and grease (FOG). This study established a reproducible and practical methodology for measuring COD in wastewater containing FOG at a laboratory scale, utilizing the nonionic surfactant T80 as a solubilizing and emulsifying agent. Precise gravimetric methods were employed to measure the mass of T80 (indirectly from volume (100–1400 µL/L)) added, and its correlation with COD was established. A strong linear relationship (R² = 0.993–0.998) between T80 concentration and COD confirmed its stability and suitability as a calibration standard. Experiments with sunflower (1–4 mL/L) and rapeseed oils (1–3 mL/L) showed that COD increased linearly with oil concentration and stabilized after prolonged mixing (96–120 h), indicating complete emulsification and micellar equilibrium. Even under T80 overdose conditions, COD retained linearity (R² > 0.99), though absolute values were elevated due to excess surfactant oxidation. Temperature variation (5 and 20 °C) and mild heating of coconut fat (30–32 °C) showed no significant effect on COD reproducibility, indicating that mixing time and surfactant dosage are the dominant factors influencing measurement accuracy. Overall, the study establishes T80 as a reliable surfactant for solubilizing oily matrices, providing a consistent and repeatable approach for COD assessment of wastewater containing FOG. The proposed method offers a practical basis and a step towards environmental monitoring and process control in decentralized and industrial wastewater treatment systems. Full article

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

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26 pages, 6347 KB

Open AccessArticle

Physicochemical Study of Water Contamination for Health Risks and Environmental Implications: A Case Study of Barite Mining Sites

by David Oluwasegun Afolayan, Hassan Abubakar Adamu, Seun Isaiah Olajuyi and Olumide Samuel Oluwaseun Ogunmodimu

ChemEngineering 2025, 9(6), 137; https://doi.org/10.3390/chemengineering9060137 - 5 Dec 2025

Abstract

Mining is associated with specific heavy metals (HMs), including cadmium (Cd), lead (Pb), copper (Cu), iron (Fe), and other toxic metals. These metals contaminate water and accumulate in both children and adults at varying concentrations, resulting in severe health implications. This paper examines [...] Read more.

Mining is associated with specific heavy metals (HMs), including cadmium (Cd), lead (Pb), copper (Cu), iron (Fe), and other toxic metals. These metals contaminate water and accumulate in both children and adults at varying concentrations, resulting in severe health implications. This paper examines the impact of barite mining on water quality, human well-being, and the environment. It evaluates the health implications of natural and anthropogenic activities on the selective liberation of heavy metals at mining sites. The potential environmental impact on mining communities in the extreme dry (April), early or mid-rainy (July), and optimum rainy (October) seasons of the year is also elucidated. Ponds within six barite mining sites were analysed using an Atomic Absorption Spectrometer (AAS) to identify these metals in water samples. The implications of HM concentrations on the well-being of the young and adults were examined and assessed using relevant mathematical expressions, and the outcome was compared with national and international environmental standards. Results show that the ponds within the barite mining sites are contaminated with copper (Cu), barium (Ba), cadmium (Cd), lead (Pb), and iron (Fe). The HM concentration exceeds the reference dose (RfD) or tolerable daily intake (TDI) stated by global and national standards for water quality and healthy living. Statistical assessments indicated that the non-carcinogenic risks of Pb and Cd are higher in children than in adults. In addition to mining, farming activities may increase HM contamination within the areas. It is anticipated that existing policy frameworks and water laws will be reviewed to support efforts for the early detection of HMs in water through medical examinations, water quality assessments, and non-carcinogenic risk (NCR) assessments. Full article

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18 pages, 4076 KB

Open AccessArticle

Preparation and Mechanism of pH-Responsive Cellulose Fabric via HRP-Catalyzed Grafting of Ferulic Acid

by Jinfang Zhang, Shujun Chen, Cheng Lv, Shanshan Liu, Xinggang Shan, Hailong Chen, Chen Liu, Yujing Bian and Jiangfei Lou

ChemEngineering 2025, 9(6), 136; https://doi.org/10.3390/chemengineering9060136 - 4 Dec 2025

Abstract

To develop a novel pH-responsive multifunctional wound dressing, this study designed a ferulic acid (FA)–cellulose-grafted polymer that leverages the pH-responsive properties of FA. This polymer enables the rapid detection of pH fluctuations in wound environments and effectively monitors acute inflammatory changes. This study [...] Read more.

To develop a novel pH-responsive multifunctional wound dressing, this study designed a ferulic acid (FA)–cellulose-grafted polymer that leverages the pH-responsive properties of FA. This polymer enables the rapid detection of pH fluctuations in wound environments and effectively monitors acute inflammatory changes. This study innovatively employed FA as the functional compound, horseradish peroxidase (HRP)/ascorbic acid (AA) as the catalytic system, and hydrogen peroxide as the initiator, successfully achieving a grafting reaction between cellulose and FA. Through optimized experiments, the optimal amounts of the FA, AA, HRP enzyme, and hydrogen peroxide were determined. Under these optimal conditions, the K/S value of the FA-grafted fabrics exceeded one, with a grafting rate surpassing 1%. The structure of the cellulose–FA was characterized by FT-IR, HPLC, and ¹H NMR, and the possible grafting mechanisms were analyzed. Subsequently, FA-grafted fabric samples were immersed in solutions with varying pH levels, and the material’s pH responsiveness was analyzed through color changes. When the solution’s pH shifted from 3 to 12, the grafted fabric exhibited significant color variations. Consequently, FA-grafted cellulose shows great potential for monitoring skin wound acidity/alkalinity changes and detecting inflammatory responses. Full article

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19 pages, 2131 KB

Open AccessArticle

Agri-Food Residues into N-Doped Hydrochar for Peroxymonosulfate Activation in Wastewater Treatment

by Silvia Escudero-Curiel, Xacobe M. López-Rodríguez, Aida M. Díez, Marta Pazos and Ángeles Sanromán

ChemEngineering 2025, 9(6), 135; https://doi.org/10.3390/chemengineering9060135 - 3 Dec 2025

Abstract

This study investigates the valorization of two agri-food residues, specifically olive pomace (alperujo, A) and banana peel (B), into efficient N-doped carbon-based catalysts for polluted wastewater treatment. The residues were converted into hydrochar (HA and HB), which were subsequently N-doped using polyethylenimine (PEI) [...] Read more.

This study investigates the valorization of two agri-food residues, specifically olive pomace (alperujo, A) and banana peel (B), into efficient N-doped carbon-based catalysts for polluted wastewater treatment. The residues were converted into hydrochar (HA and HB), which were subsequently N-doped using polyethylenimine (PEI) in combination with cross-linkers (glutaraldehyde (GTA) or 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)) to optimize their catalytic properties. The enhanced hydrochars were utilized as catalysts for the removal of organic pollutants from water by activation of peroxymonosulfate (PMS). Characterization techniques, including CHNS, FTIR, XPS, SEM and electrochemical analysis, were employed to understand the physicochemical properties of the materials. The catalytic activity was evaluated using Reactive Black 5 (RB5) as a model pollutant, with the N-doped alperujo-derived hydrochar cross-linked with EDC (N-HA-EDC) showing the best performance, achieving 80% removal in 60 min and an adsorption capacity of 97 mg/g. The versatility of this functionalization approach was assessed through tests with three pharmaceuticals, corroborating the adaptability and efficacy of the catalyst and demonstrating its potential for wastewater treatment applications. This study provides insights into the development of sustainable, cost-effective carbocatalysts, aligning with circular economy and zero waste principles. Full article

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17 pages, 1613 KB

Open AccessArticle

Optimizing the Bleaching Conditions for Mechanically Extracted and Solvent-Extracted Hempseed Oil

by Preston C. Wilson, Md. Sanaul Huda, Roque Evangelista, Clairmont L. Clementson, Sean Liu, Bingcan Chen and Ewumbua Monono

ChemEngineering 2025, 9(6), 134; https://doi.org/10.3390/chemengineering9060134 - 2 Dec 2025

Abstract

Hemp (Cannabis sativa) seed oil is recognized as a valuable oil due to its beneficial fatty acid profile, which includes a favorable balance of omega-6 and omega-3 fatty acids, making it highly desirable for edible and bioproduct applications. Crude hempseed oil [...] Read more.

Hemp (Cannabis sativa) seed oil is recognized as a valuable oil due to its beneficial fatty acid profile, which includes a favorable balance of omega-6 and omega-3 fatty acids, making it highly desirable for edible and bioproduct applications. Crude hempseed oil contains high concentrations of chlorophyll, carotenoids, and other amphiphilic compounds that can negatively affect its appearance, stability, and downstream processing. Therefore, bleaching is a crucial step in removing these pigments after the degumming and neutralization processes. To optimize the bleaching process, a Box–Behnken response surface methodology was employed, focusing on three factors: time (15, 30, 45 min), temperature (100, 120, 140 °C), and bleaching earth concentration (2.5, 5, and 7.5% w/w). The key response variables were β-carotene, chlorophyll content, and antioxidant activity. For chlorophyll removal, bleaching earth concentration accounted for 83.82% and 81.84% of the variation in the solvent-extracted and mechanically extracted oils, respectively. For β-carotene, the bleaching earth concentration accounted for over 93% of the variation in both types of oil. The optimal bleaching earth concentrations were determined to be 4.87% and 5.36% for the solvent-extracted and mechanically extracted oils, respectively, to achieve the target chlorophyll level of ≤150 ppb. Mechanically extracted oil had lower antioxidant activity after bleaching compared to solvent-extracted oil. The addition of bleaching earth, up to 5%, removed polar antioxidants, further lowering the oil’s antioxidant capacity. These findings suggest that optimizing bleaching conditions can significantly affect both pigment removal and the antioxidant profile of the final product. Full article

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15 pages, 2675 KB

Open AccessArticle

Formation of Films on a Metal Surface by Inhibitors with Assessment of Their Protective Properties

by Balzhan Kabylbekova, Nadezhda Vysotskaya, Abibulla Anarbaev, Roza Spabekova, Karim Kurbanbekov, Gulnur Kaldybekova and Zhakhongir Khussanov

ChemEngineering 2025, 9(6), 133; https://doi.org/10.3390/chemengineering9060133 - 21 Nov 2025

Abstract

An effective approach to maintaining uninterrupted coolant flow in heat supply systems—and thereby reducing energy consumption—is to prevent the formation of corrosion-scale deposits on the inner surfaces of metal pipes. This is typically achieved by performing anti-corrosion treatment on the coolant. However, the [...] Read more.

An effective approach to maintaining uninterrupted coolant flow in heat supply systems—and thereby reducing energy consumption—is to prevent the formation of corrosion-scale deposits on the inner surfaces of metal pipes. This is typically achieved by performing anti-corrosion treatment on the coolant. However, the efficiency of this method depends on several factors, including pipe conditions, water flow rate, and water composition. To inhibit corrosion and scale formation on the internal surfaces of pipelines, specific inhibitors are used to create protective films on the metal surface. For strong adhesion of these films, preliminary chemical cleaning of the metal surface with low-concentration acid solutions is essential. This cleaning is usually performed in circulation mode for several hours. The activated surface enhances inhibitor adhesion, leading to the formation of films with improved protective properties. The quality of the anticorrosive films was evaluated using a JSM-6490LV scanning electron microscope equipped with INCAEnergy energy-dispersive microanalysis systems, HKL-Basic structural analysis, ContrAA-300 atomic adsorption spectrometer, and potentiostat IPC-Pro MF. Full article

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19 pages, 6474 KB

Open AccessArticle

Dissolution Behavior and Kinetics of Copper Sulfide Concentrate in Choline Chloride DES

by Mojtaba Ghadamgahi, Abolfazl Babakhani, Hossein Shalchian, Ghasem Barati Darband and Hamid Reza Shiri

ChemEngineering 2025, 9(6), 132; https://doi.org/10.3390/chemengineering9060132 - 20 Nov 2025

Abstract

This study presents a comprehensive investigation of copper extraction from chalcopyrite concentrate using choline chloride–malonic acid (ChCl:Ma) deep eutectic solvent (DES) through an integrated experimental and modeling approach. The work began with determination of the deep eutectic temperature (38 °C) for the ChCl:Ma [...] Read more.

This study presents a comprehensive investigation of copper extraction from chalcopyrite concentrate using choline chloride–malonic acid (ChCl:Ma) deep eutectic solvent (DES) through an integrated experimental and modeling approach. The work began with determination of the deep eutectic temperature (38 °C) for the ChCl:Ma system, which guided the selection of the optimal 1:1 molar ratio to ensure minimal viscosity and maximum solvent stability. The operating temperature range (50–80 °C) was strategically chosen based on TGA analysis confirming the solvent’s thermal stability below 120 °C, ensuring no solvent degradation during leaching experiments. Response Surface Methodology (RSM) with Central Composite Design (CCD) optimization revealed temperature and leaching time (24–72 h) as statistically significant parameters affecting copper recovery, with a highly predictive quadratic model (R² = 0.99, p < 0.0001). Kinetic analysis using the shrinking core model identified a diffusion-controlled mechanism through a sulfur layer, supported by low activation energies (Cu = 29.09 kJ/mol, Fe = 38.16 kJ/mol). Comprehensive characterization showed preferential chalcopyrite dissolution with direct conversion to elemental sulfur (XRD), formation of metalchlorocomplexes (UV-Vis), and excellent solvent thermal properties (TGA). These findings demonstrate ChCl:Ma DES as an effective medium for chalcopyrite processing, with a systematic methodology providing insights for sustainable non-aqueous metal recovery systems. Full article

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17 pages, 1981 KB

Open AccessArticle

Experimental Investigation of the Two-Phase Loop Thermosyphon Working with Low-GWP Mixtures for Heat Reclaim

by Michał Sobieraj, Dariusz Ksionek, Michał Kamiński and Filip Karczmarczyk

ChemEngineering 2025, 9(6), 131; https://doi.org/10.3390/chemengineering9060131 - 18 Nov 2025

Abstract

The application range of a two-phase loop thermosyphon (TPLT) includes electronics cooling and heating and ventilation (HVAC) systems. Combining data center heat removal with HVAC systems can be beneficial in terms of reducing energy use and greenhouse gas emissions. The thermal resistance of [...] Read more.

The application range of a two-phase loop thermosyphon (TPLT) includes electronics cooling and heating and ventilation (HVAC) systems. Combining data center heat removal with HVAC systems can be beneficial in terms of reducing energy use and greenhouse gas emissions. The thermal resistance of the TPLT is the most important parameter affecting its heat transfer ability. This study presents the first experimental characteristics of the TPLT, working with novel low Global Warming Potential (GWP) fluids, including the evaporating and condensing performance. The operation of the TPLT is evaluated with pure fluids R600a, R32, and their mixture R600a/R32 at heat sink temperature in the range of 25 °C to 35 °C under heat input from 50 W to 225 W. The novel mixture presents the highest temperature at the evaporator outlet. Pure fluids R600a and R32 show the highest heat transfer coefficients and the lowest thermal resistance. The flow visualization is performed to study the boiling flow patterns. Empirical correlations are employed to predict the boiling-heat transfer coefficients. Thermal characteristics are obtained for further development of TPLT operating with environmentally friendly fluids. Full article

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18 pages, 2994 KB

Open AccessArticle

Theoretical Design of Acridone-Core Energetic Materials: Assessment of Detonation Properties and Potential as Insensitive, Thermally Stable High-Energy Materials

by Jelena Tamuliene and Jonas Sarlauskas

ChemEngineering 2025, 9(6), 130; https://doi.org/10.3390/chemengineering9060130 - 13 Nov 2025

Abstract

In this study, we investigated the impact of incorporating energetic substituents such as –NO₂, –NH₂, –Cl, –F, N-methyl-N-nitro (CH₃–N–NO₂), and picryl on the detonation performance and stability of acridone-based compounds. The B3LYP/cc-pVTZ approach was applied [...] Read more.

In this study, we investigated the impact of incorporating energetic substituents such as –NO₂, –NH₂, –Cl, –F, N-methyl-N-nitro (CH₃–N–NO₂), and picryl on the detonation performance and stability of acridone-based compounds. The B3LYP/cc-pVTZ approach was applied to investigate the influence of substitutions on the stability and detonation properties of acridone derivatives. The results obtained exhibit the significant influence of both the type and position of substituents on the energetic performance and stability of the compounds studied. Notably, the acridone derivative bearing a picryl group and four –NH₂ substituents exhibited energetic properties superior to those of 2,4,6-trinitrotoluene (TNT). Its calculated velocity lies in the range [7.45–7.66] km/s, and its detonation pressure is [22.49–24.36] GPa; however, its stability is lower than that of core compounds. This reduction, however, is dependent on both the nature and number of substituents introduced. Full article

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40 pages, 6064 KB

Open AccessArticle

Numerical Simulation of the Isoparaffins Dehydrogenation Process in Fluidized Bed Reactor: From Laboratory to Industry

by Sergei A. Solovev and Olga V. Soloveva

ChemEngineering 2025, 9(6), 129; https://doi.org/10.3390/chemengineering9060129 - 12 Nov 2025

Abstract

A numerical model was developed to simulate a fluidized bed reactor for isobutane dehydrogenation. First, we constructed a hydrodynamic model of catalyst particle fluidization and a kinetic model for three chemical reactions in a simple lab-scale reactor (H = 70 cm, D = [...] Read more.

A numerical model was developed to simulate a fluidized bed reactor for isobutane dehydrogenation. First, we constructed a hydrodynamic model of catalyst particle fluidization and a kinetic model for three chemical reactions in a simple lab-scale reactor (H = 70 cm, D = 2.8 cm). Experimental studies and numerical simulation of the laboratory reactor were carried out at four temperatures: 550, 575, 600, and 625 °C. The product yield results from the computational fluid dynamics simulation show a close match to the experimental data. The optimal process temperature in the laboratory reactor is 575 °C, at which the isobutylene yield is ~46.03 wt%. With decreasing temperature, the isobutylene yield decreases, and it rises as temperature increases. However, with rising temperature, the total yield of by-products increases on average to 20 wt%. We compared the CFD simulation results for two laboratory reactor models: a 3D model and a 2D axisymmetric model. For gas phase fractions, absolute deviations ranged from 0.01 to 1.12%, while relative deviations were between 0.006% and 0.114%. However, there are differences in the solid-phase particle dynamics. Second, we applied the constructed CFD model to simulate an industrial-scale reactor (H = 23.81 m, D = 4.6 m). In addition to its size, the industrial reactor differs from the laboratory reactor in its heating principle. In this configuration, the gas, preheated to 550 °C, and the catalyst particles, at 650 °C, are fed into the entire volume. The objective of this study is to test the performance of the model, which was verified on a laboratory reactor, for simulating an industrial reactor. Temperature fields and zones of reaction product formation are analyzed. The average isobutylene yield is ~31.88 wt%, which is consistent with the operation of real reactors but lower than the results for the laboratory reactor at all temperatures. The industrial reactor is more challenging to heat uniformly. It contains many internal elements that affect the movement of the gas–solid system. Overall, the model developed for the laboratory reactor has proven to be suitable for CFD modeling of an industrial reactor. Full article

(This article belongs to the Special Issue The Applications of Computational Fluid Dynamics in Transport Phenomena)

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42 pages, 2905 KB

Open AccessReview

A Review on the Mixing Quality of Static Mixers

by Lukas von Damnitz and Denis Anders

ChemEngineering 2025, 9(6), 128; https://doi.org/10.3390/chemengineering9060128 - 12 Nov 2025

Abstract

Static mixers are widely used devices for efficient fluid mixing, homogenization, and enhancement of heat transfer, with applications ranging from chemical processing and pharmaceutical manufacturing to wastewater treatment. This review provides a structured overview of mixing processes and the key metrics used to [...] Read more.

Static mixers are widely used devices for efficient fluid mixing, homogenization, and enhancement of heat transfer, with applications ranging from chemical processing and pharmaceutical manufacturing to wastewater treatment. This review provides a structured overview of mixing processes and the key metrics used to assess mixing quality in static mixers. Conceptual models such as dispersive versus distributive mixing and the classification into macro-, meso-, and micromixing are introduced as a basis for understanding mixing phenomena. Subsequently, a comprehensive set of quantitative measures, including G-value, residence time distribution, intensity of segregation, coefficient of variation, striation-based descriptors, Lyapunov exponent, extensional efficiency, and shear rate, is discussed in detail. Correlations and relationships among these measures are highlighted to facilitate their application in characterizing mixing quality in static mixers. By systematically summarizing the theoretical background, definitions, and interconnections of mixing quality measures, this review aims to provide researchers and engineers with a clear framework for evaluating and comparing mixing quality in static mixers, thereby supporting both academic studies and practical design considerations. Full article

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28 pages, 9180 KB

Open AccessArticle

Optimized Synthesis Strategy of Mxene-Loaded Graphitic Carbon Nitride (g-C₃N₄) for Enhanced Photocatalytic Degradation of Rhodamine B

by Bayazid Bustami, Parvej Rahman Alif, Md Mahfuzur Rahman, Mohaiminul Islam and Alam S. M. Nur

ChemEngineering 2025, 9(6), 127; https://doi.org/10.3390/chemengineering9060127 - 10 Nov 2025

Abstract

Developing efficient photocatalysts is essential for sustainable wastewater treatment and tackling global water pollution. Graphitic carbon nitride (g-C₃N₄) is a promising material because it is active under visible light and chemically stable. However, its practical application is limited by [...] Read more.

Developing efficient photocatalysts is essential for sustainable wastewater treatment and tackling global water pollution. Graphitic carbon nitride (g-C₃N₄) is a promising material because it is active under visible light and chemically stable. However, its practical application is limited by fast recombination of charge carriers and a low surface area. In this study, we report a simple hydrothermal method to synthesize exfoliated porous g-C₃N₄ (E-PGCN) combined with Ti₃C₂ MXene to form a heterojunction composite that addresses these issues. Various characterization techniques (FTIR, XRD, XPS, SEM, BET) confirmed that adding MXene improves light absorption, increases surface area (53.7 m²/g for the composite versus 21.4 m²/g for bulk g-C₃N₄ (BGCN)), and enhances charge separation at the interface. Under UV-visible light irradiation with Rhodamine B (RhB) as the model pollutant, the E-PGCN/Ti₃C₂ MXene composite containing 3 wt% MXene demonstrated an impressive degradation efficiency of 93.2%. This performance is superior to BGCN (66.6%), E-PGCN (82.5%), and E-PGCN/Ti₃C₂ MXene-5 wt% composites (81%). This is due to the excess Mxene which caused agglomeration and reduced activity. Scavenger studies identified electron radicals as the dominant reactive species, with optimal activity at pH ~4.5. This enhanced performance, 1.4 times greater than BGCN and 1.13 times higher than E-PGCN, is ascribed to the synergistic interplay between the excellent electrical conductivity of MXene and the porous structural features of E-PGCN. This work highlights the importance of morphological engineering and heterojunction design for advancing metal-free photocatalysts, offering a scalable strategy for sustainable water purification. Full article

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20 pages, 3238 KB

Open AccessArticle

CFD Simulation of High Gas Flow Rate in Large-Scale Rotating Packed Beds

by Seyedmohsen Hosseini and Renzo Di Felice

ChemEngineering 2025, 9(6), 126; https://doi.org/10.3390/chemengineering9060126 - 7 Nov 2025

Abstract

Rotating packed beds (RPBs) have recently attracted significant attention as a promising approach to intensify the performance of traditional packed columns. Although many lab-scale experimental and numerical studies on RPBs are available in the literature, there is a scarcity of operational data for [...] Read more.

Rotating packed beds (RPBs) have recently attracted significant attention as a promising approach to intensify the performance of traditional packed columns. Although many lab-scale experimental and numerical studies on RPBs are available in the literature, there is a scarcity of operational data for large-scale RPBs. In this research, high gas flow rates in large-scale RPBs are investigated using computational fluid dynamics (CFD) simulation to predict the dry pressure drop in a rotating bed. A 2D geometry with periodic boundary conditions was applied to simulate the turbulent gas flow in a rotating packed bed. The simulation results provide valuable insights into the gas flow dynamics within rotating beds, highlighting the pressure and velocity variations that occur at high rotational speeds. A semi-empirical correlation successfully replicated the results obtained in this study and can be utilized to predict the pressure drop in large-scale RPBs under operating conditions similar to those studied in this research. Full article

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21 pages, 3667 KB

Open AccessArticle

Modeling of Hydrodynamics of Agglomeration of Low-Grade Phosphorites in the Presence of Phosphate-Siliceous Shales and Oil Sludge

by Saltanat Tleuova, Zhunisbek Turishbekov, Ayaulym Tileuberdi, Dana Pazylova, Iskandarbek Iristaev, Mariyam Ulbekova and Nurila Sagindikova

ChemEngineering 2025, 9(6), 125; https://doi.org/10.3390/chemengineering9060125 - 7 Nov 2025

Abstract

The purpose of this study is to develop a multiphysical model of agglomeration of low-grade phosphorites with the addition of phosphate-siliceous shales and oil sludge. To achieve these tasks, a numerical approach was used in the COMSOL Multiphysics environment, based on solving the [...] Read more.

The purpose of this study is to develop a multiphysical model of agglomeration of low-grade phosphorites with the addition of phosphate-siliceous shales and oil sludge. To achieve these tasks, a numerical approach was used in the COMSOL Multiphysics environment, based on solving the related problems of heat transfer and hydrodynamics during heat treatment of the material. A laboratory vertical tubular furnace made of heat-resistant quartz glass with electric heating was used to study the effect of the temperature field and the velocity of gases on the degree of sintering and the dynamics of phosphorous agglomerate formation under various technological conditions. It has been established that the optimal temperature for the agglomeration process is a layer temperature of 950–1000 °C at a gas flow rate of 1.5–2 m/s, which ensures the formation of durable granules and minimizes sintering heterogeneity. The maximum sintering layer height of the test charge reaches 210–230 mm at pressures of 0.015–0.027 MPa. A comparison of the numerical simulation results with experimental data showed a good agreement, which confirms the practical significance of the proposed model for the design and optimization of industrial processes of agglomeration of phosphorous raw materials. Modern physical and chemical analyses have established the phase, microstructural, and element-by-element characteristics of the studied phosphate-siliceous shale and the product of agglomeration firing. The results of modeling the hydrodynamics of the charge agglomeration process can be recommended to increase the efficiency of processing phosphate-containing waste and reduce energy consumption. Full article

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