ASEAN Journal of Chemical Engineering

Effect of Dye Combination and Acidity on Efficiency of Dye-Sensitized Solar Cells

2026-05-04T17:25:45+07:00

A Dye-Sensitized Solar Cell (DSSC) is a solar cell technology that converts solar radiation into electrical energy. Dyes play a pivotal role in DSSCs by absorbing sunlight and converting it into electrical energy. The development of natural dyes is driven by numerous negative impacts associated with the utilization of synthetic dyes. The objective of this study is to evaluate the performance of a combination of natural dyes from two sources under neutral and alkaline pH conditions. The performance parameters measured included Isc, Voc, and efficiency. The efficiency values obtained from the dyes (a), (b), and (c), respectively, were 2.02%, 2.55%, and 3.02% at neutral pH, and 1.92%, 2.73%, and 2.58% at base pH condition. Dye efficiency was higher in neutral pH conditions than in base pH conditions. The combination of dye (c) Clitoria ternatea/aquadest and Pandan leaf/methanol showed the best efficiency, reaching 3.02%.

Comparative Analysis and Kinetic Modeling of Acetone-Butanol-Ethanol (ABE) Production in Batch and Continuous Fermentation Using Clostridium acetobutylicum with the Monod-Inhibited Model

2026-05-04T17:25:45+07:00

Biobutanol is a competitive alternative to conventional fossil fuels, and its sustainable production can be optimized through Acetone, Butanol, and Ethanol (ABE) fermentation using Clostridium acetobutylicum. This process typically results in a weight ratio of acetone, butanol, and ethanol of 3:6:1. A critical challenge in ABE fermentation is butanol toxicity, which inhibits Clostridium growth. To address this, continuous fermentation is utilized to prevent butanol accumulation by facilitating its continuous removal from the reactor. This study focused on optimizing butanol production through both batch and continuous fermentation processes, varying the initial glucose concentration in batch experiments. Batch fermentation was conducted at glucose concentrations of 30, 40, 50, and 60 gL^-1, with the highest butanol yield and productivity observed at 40 gL^-1, producing 0.13 g _butanol. g _glucose^-1 and 0.083 gL^-1h^-1, respectively. The maximum growth rate of Clostridium acetobutylicum was 0.14 h^-1 under these conditions. Significantly, a mathematical model based on the Monod inhibition equation was developed to describe the kinetics of ABE fermentation. This model achieved an R² value of 0.66 and an SSE of 0.0165, providing a robust framework for predicting fermentation outcomes across varying conditions. Continuous fermentation, initiated at a glucose concentration of 20 gL^-1and a dilution rate of 0.15 h^-1, yielded 0.23 g _butanol g _glucose^-1 and a productivity of 0.093 gL^-1h^-1. These results confirm that continuous fermentation is more advantageous for maintaining high-efficiency ABE fermentation, as supported by the predictive accuracy of the developed kinetic model.

Stability and Kinetic Study of Immobilized Carbonic anhydrase into PVDF Membrane

2026-05-05T05:12:32+07:00

Carbonic anhydrase (CA) is a highly efficient biocatalyst for accelerating CO₂ hydration and has attracted significant interest for enzyme-assisted carbon mineralization and post-combustion CO₂ capture. However, the practical deployment of CA is hindered by its limited stability and non-recyclability under industrially relevant conditions. In this study, CA was immobilized onto a hydrophobic poly(vinylidene fluoride) (PVDF) membrane via glutaraldehyde-mediated covalent crosslinking to develop a robust enzymatic membrane platform for CO₂ mineralization applications. The immobilized enzyme showed greater enhanced thermal and pH stability than free CA, demonstrating improved resilience under conditions relevant to mineral carbonation processes. Enzymatic kinetics were systematically evaluated using p-nitrophenyl acetate as a model substrate, revealing a low apparent Michaelis constant (K_m = 7.45 mmol L⁻¹) and a maximum reaction rate (V_m = 0.76 µmol min⁻¹), indicative of strong enzyme–substrate affinity within the membrane-confined microenvironment. Scanning electron microscopy confirmed homogeneous enzyme distribution and stable attachment within the PVDF pore structure. While employing a conventional immobilization strategy, this work provides quantitative insight into the stability–kinetics relationship of membrane-immobilized CA. It establishes a baseline membrane architecture for future development of advanced enzyme-assisted CO₂ mineralization and membrane contactor systems.

Production of Bio-hydrocarbon through Oxidative Decarboxylation of Fatty Acids Using Biomimetic Catalysis

2026-05-04T17:25:46+07:00

The increasing global energy demand, coupled with the depletion of fossil-based resources, necessitates the development of sustainable, plant-based alternatives to mitigate CO₂ emissions, a leading driver of climate change. Fatty acids derived from renewable sources, such as crude palm oil (CPO) and coconut oil, offer a promising solution due to their molecular structure, which shares key characteristics with hydrocarbons while also featuring a carboxyl functional group. In the pursuit of hydrocarbon production, the removal of this carboxyl group is essential, typically achieved through processes such as decarbonylation or hydrodeoxygenation. This study explores the oxidative decarboxylation of fatty acids, utilizing a biomimetic catalytic approach under relatively mild conditions—atmospheric pressure and moderate temperatures. Air served as the oxidant, with manganese (Mn) as the catalyst and copper (Cu) as the co-catalyst. Reactions were conducted at 110°C to 150°C, with a fatty acid-to-catalyst mass ratio of 13:0.1 to 13:1, using dimethyl sulfoxide as the solvent and air supplied at 1 liter per minute. The results indicate that myristic acid exhibits a higher degree of conversion compared to lauric acid. Lauric acid conversion ranged between 27.70% and 34.49%, while myristic acid conversion ranged from 26.70% to 52.70%. The resulting product was analyzed according to the ASTM D-86 method, with the decarboxylation of lauric acid yielding a boiling range of 98°C to 250°C—within the typical range for gasoline and aviation turbine fuel. This approach offers a promising, energy-efficient route to bio-hydrocarbon production under mild aerobic conditions, contributing to the global transition towards renewable energy sources.

Removal of Chloride in Saline Water by Bismuth Oxide Nanoparticles

2026-05-04T17:25:46+07:00

Climate change intensifies saltwater intrusion in coastal and delta regions, notably the Mekong Delta, thereby increasing the concentration of chloride ions (Cl^-) in water. Elevated Cl^-concentrations pose serious environmental challenges, inhibiting plant growth and impacting human health. While various conventional methods for chloride treatment exist, challenges persist concerning high cost, complex procedures, and secondary waste. Therefore, developing a simple, cost-effective, and highly efficient method using novel adsorbent materials is imperative. The primary objective of this study was to prepare and evaluate the efficacy of bismuth oxide nanoparticles (Bi₂O₃) as a novel, highly effective adsorbent for the removal of Cl^- from saline water sources. Bi₂O₃nanoparticles were synthesized using the solid dispersion evaporation technique with sorbitol as a support. FTIR, XRD, SEM, and EDX were used to characterize the physicochemical and structural properties of the material. The Cl^- removal capacity was systematically studied under diverse operational conditions, including contact time, solution pH, adsorbent dosage, initial Cl^- concentration, and temperature, to determine appropriate adsorption conditions. The material was also subjected to adsorption-desorption cycling tests to evaluate its regeneration potential and long-term durability. The kinetic study showed that the Bi₂O₃material reached adsorption equilibrium efficiently after 90 minutes. The maximum Cl^- adsorption capacity was 40.89 mg/g at an optimum solution pH of 4, under optimized conditions (initial Cl^-concentration of 50 mg/L, 25 °C). Other investigated factors significantly influenced the adsorption kinetics and capacity. Crucially, the Bi₂O₃ adsorbent maintained its high removal efficiency over 10 regeneration cycles, confirming its excellent durability and potential for real-world applications. The results clearly demonstrate that the synthesized Bi₂O₃nanoparticles have excellent potential as a robust, high-performing adsorbent for Cl^- removal, suggesting a viable and practical solution to the challenges posed by saltwater intrusion.

Effects of Different Solvents on Natural Dye Extraction from Clitoria ternatea

2026-05-04T17:25:46+07:00

Dyes worldwide are drawing attention to the health risks they pose, thereby beckoning radical change toward better alternatives. Synthetic dyes are large, complex molecules that are resistant to biodegradation, leading to various environmental issues. The trend in natural products has been toward natural dyes, particularly those derived from flowering parts, such as the flowers of Clitoria ternatea, which produce blue colors due to anthocyanins. This research aims to extract anthocyanins from Clitoria ternatea using two solvents: distilled water and ethanol. The most efficient solvent for the extraction of natural dyes from Clitoria ternatea was determined by focusing on two key parameters: extraction time and pH. The total anthocyanin content was determined using UV-Vis spectroscopy; the presence of functional groups was analyzed by Fourier Transform Infrared Spectroscopy (FTIR); and the color attributes of Clitoria ternatea were assessed using a chroma meter. The results showed that distilled water consistently yielded higher anthocyanin content than ethanol, with the highest value at 60 minutes of extraction. FTIR analysis confirmed the presence of key functional groups associated with anthocyanins, while color analysis indicated that higher anthocyanin content corresponded to darker and more intense blue coloration. These findings demonstrate that distilled water is a more effective and environmentally friendly solvent for anthocyanin extraction. The information presented may serve as a basis for further research on the extraction of natural dyes, advancing the process and enabling the creation of new natural products.

Disentangling membrane wetting, compaction, and fouling during ultra-low-pressure liquid filtration using a phase-inverted PVDF membrane

2026-05-04T17:25:47+07:00

This study disentangles membrane wetting, compaction, and fouling during ultra-low-pressure filtration using phase-inverted polyvinylidene fluoride (PVDF) membranes. Pressure-stepping tests (0.04-0.11 bar) and repeated one-hour filtration cycles at 0.07 bar, each followed by 10 min of relaxation, were performed with clean water and river water to separate the hydraulic contributions of the three phenomena. With clean water, permeability increased most strongly in the 4-7 kPa range and then approached a plateau, indicating progressive pore wetting. During repeated clean-water filtration, permeability declined because of compaction but recovered from 337.72 to 372.10 L m^-2 h^-1 bar^-1 after the first relaxation, confirming that part of the compaction was reversible. River water showed consistently lower permeability and only partial recovery (217.40 to 299.30 L m^-2 h^-1 bar^-1 after the first relaxation), demonstrating the superimposed effect of fouling. The results show that wetting dominates the initial pressure response, compaction governs time-dependent permeability loss under clean water, and fouling becomes decisive in natural water filtration. This mechanistic separation provides a practical basis for pressure optimization, relaxation scheduling, and fouling control in ultra-low-pressure membrane processes.

Physicochemical Properties of Starch-Chitosan Film with Lemongrass Essential Oil

2026-05-04T17:25:48+07:00

Biopolymer films integrated with natural antimicrobial represent a sustainable strategy for enhancing food safety and shelf life. This study characterizes a functional starch-chitosan (S-CH) film incorporated with lemongrass essential oil (LEO). GCMS identified α-citral as the primary antimicrobial component of the LEO. The film was prepared using the casting technique, and the influence of LEO concentration on mechanical properties, hydrophobicity and surface morphology were determined. The findings show that the tensile strength and elongation at break of the S-CH-LEO films were lower than those of the S-CH film, making them brittle and less stretchy. The incorporation of LEO from 0.05% to 0.15% had increased tensile strength and elongation at break from 0.143 MPa to 0.873 MPa and from 3.81% to 8.63%, respectively. The hydrophobicity of S-CH-LEO films increased with the increase in LEO, as evidenced by a higher water contact angle range between 52.30° and 84.80°. S-CH-LEO 0.15% film was the best formulation, with a tensile strength of 0.873 MPa, an elongation at break of 8.63%, and a contact angle of 71.50°. This study shows that S-CH-LEO films improve moisture resistance, a critical factor for extending the food shelf life. Therefore, despite the lower tensile strength and elongation at break, the resulting improvements in water resistance and functional bioactivity suggest that S-CH-LEO films are viable solution for active food packaging applications.

Electrodialysis Process Application for Pigment Wastewater Treatment Using Ion Exchange Membranes

2026-05-05T04:58:02+07:00

Electrodialysis (ED) is an efficient technique for treating high-salinity industrial effluents. This study examined the removal efficiencies of sodium chloride (NaCl), sodium acetate (C₂H₃NaO₂), and acetic acid (CH₃COOH) using electrodialysis. The procedure utilized a cation exchange membrane type MK-40 and an anion exchange membrane type MA-40. The impact of operational parameters, including electrolysis time, initial concentration, and applied current, was examined. The findings indicated that the removal efficiency improved over time, reaching 70% for NaCl at an initial concentration of 0.086 M and an applied current of 1 A. The elimination efficiency of C₂H₃NaO₂ attained a maximum value of 97% at a concentration of 0.036 M and an applied current of 1 A. The maximum removal efficiency of acetic acid was 71%, achieved at a starting concentration of 0.033 M with an applied current of 1 A. The findings indicated that the current efficiency peaked at elevated initial concentrations of all examined contaminants, whereas increasing the applied current significantly enhanced removal efficiency. Consequently, electrodialysis is an efficient technique for removing certain contaminants from industrial effluents.

Evaluation of Geometrical Factors toward the Efficiency of Natural Gas Ejector-Booster System by CFD Simulation

2026-05-04T17:25:49+07:00

The geometrical parameters of the ejector significantly affect its performance in boosting the flow from low-pressure gas wells. Several studies have identified that primary nozzle exit position (NXP), primary nozzle exit diameter (D_p), and mixing tube diameter (D_mt) are among the most influential factors. In this study, computational fluid dynamics (CFD) simulation is used to investigate the effect of these parameters on the entrainment ratio and isentropic efficiency of the ejector, especially by analyzing the velocity and pressure field inside the ejector. After model construction and validation against published data, we found that the optimum ejector is achieved at geometry configuration of NXP/D_t = 6.346, D_mt/D_t = 2.615, and D_p/D_t= 1.275. The maximum entrainment ratio and corresponding ejector efficiency at optimum geometry are 76.3% and 29.6%. The optimum geometry is obtained when the double choking flow forms inside the mixing chamber as indicated by the velocity and pressure profiles. These findings align with our previous study, further emphasizing the impact of flow profiles on ejector performance.

Microwave-Assisted Sustainable Extraction and Characterization of Chitosan from Hermetia Illucens

2026-05-04T17:25:49+07:00

Chitosan holds considerable industrial significance due to its versatile physicochemical and bioactive properties. With growing attention to sustainability and circular economy principles, recent research has increasingly explored alternative and renewable sources of chitosan, most notably the black soldier fly (Hermetia illucens), as a promising substitute for conventional crustacean-based materials. Chitosan was successfully synthesized for the first time through a rapid, efficient, and simplified approach involving microwave irradiation across all three fundamental extraction stages: demineralization, deproteinization, and deacetylation. A comparative study was carried out between this microwave-assisted method and traditional thermal processing. The structural and physicochemical characteristics of the resulting chitosan were thoroughly evaluated using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), and particle size analysis (PSA). The microwave-assisted process yielded chitosan with a degree of deacetylation (DD) of 76.01% in just 24 minutes, whereas the conventional heating method required up to 6 hours to achieve a comparable DD of 76.48%. This represents a remarkable reduction in processing time—approximately 1/15 of the conventional duration—highlighting the microwave-assisted technique as a significantly more energy-efficient, timesaving, and environmentally sustainable strategy for valorizing Hermetia illucens-derived biowaste.

Cassava Starch-Based Biocomposites Reinforced with Zinc Oxide and Spent Coffee Ground Cellulose: A Comparative Study and TOPSIS Evaluation

2026-05-04T17:25:52+07:00

The accumulation of synthetic plastic waste and depletion of fossil resources have driven the search for sustainable alternatives, such as biodegradable bioplastics. This study explores the use of cellulose derived from spent coffee grounds (SCG) and zinc oxide (ZnO) as reinforcing fillers in cassava starch-based bioplastics fabricated via solution-casting methods. Various formulations were developed using SCG cellulose (1%, 1.5%, and 2% with 10%, 15%, and 20% glycerol) or ZnO (1%, 1.5%, and 2% with 10% and 15% glycerol) The resulting films were evaluated for their mechanical, barrier, and optical properties, followed by structural analysis using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). Results showed that SCG-based cellulose significantly improved tensile strength (up to 1.87 MPa) but reduced transparency (to 46.38%), while ZnO-enhanced films exhibited higher light transmittance (up to 70.28%). FTIR confirmed hydrogen bonding interactions between the filler and the starch matrix, and XRD revealed differences in crystallinity, with cellulose showing semi-amorphous characteristics and ZnO contributing to higher peak intensity. SEM analysis supported these findings, indicating a more compact and continuous matrix in ZnO films. A multi-criteria decision-making analysis using the TOPSIS method identified the optimal cellulose-based formulation as 2% SCG cellulose with 20% glycerol, which achieved a tensile strength of 1.87 MPa, transparency of 46.40, and a water vapor permeability (WVP) of 2.318 × 10-6 g/m·day·Pa. These findings demonstrate the potential of SCG and ZnO as functional additives in biodegradable packaging materials and support the circular economy by valorizing organic waste.

Gum Rosin Properties Upgrading as Water Dispersed Tackifier for Wet Adhesive and Pressure Sensitive Adhesive (PSA)

2026-05-04T17:25:53+07:00

In this research, gum rosin, as one of the non-wood forest products obtained from the resin tapping of pine trees, is modified by applying a modification process consisting of an esterification reaction with glycerol, a Diels-Alder reaction using maleic anhydride, and further esterification with polyethylene glycol 400 (PEG-400) to make it more stable to oxidation. It has a lower softening point and viscosity, making it suitable for use as a tackifier to enhance the tackiness of renewable, eco-friendly adhesives based on natural rubber/latex. Pressure-sensitive adhesives (PSA) and wet glue were produced using natural rubber as the elastomer and a mixture of modified gum rosin and water as the tackifier, with various compositions. It is found that PSA and wet glue produced with a tackifier-latex ratio of 30:70 and a gum rosin-to-water ratio of 60:40 exhibit the best adhesion performance and are suitable for application on wood and paper substrates. The wet glue also exhibits superior adhesion performance compared to commercial wood and paper glue.

Adsorption of CO₂ with Thermally Activated Serpentine: Experimental and CFD Simulations in a Fixed-bed Reactor

2026-05-05T05:17:07+07:00

Thermally activated serpentine, abundant in Mg-silicate, shows potential for CO₂ extraction using mineral carbonation. This study aims to evaluate the performance of thermally activated serpentine for CO₂ capture in a fixed-bed reactor by combining breakthrough experiments with CFD simulations. The serpentine was thermally activated at 750 °C for 1.5 hours. CO₂ adsorption using three gas flow rates (0.1, 0.5, and 1.0 SLPM) with two variations of adsorbent mass (15 g and 30 g). The results show that the thermal activation of serpentine surface area, micro-porosity, and Mg content, thereby significantly enhancing the material’s capacity and adsorption rate. The breakthrough curve shows that at a flow rate of 0.1 SLPM, the CO₂ capture capacity is 2.81 mg/g, while a at 0.5 SLPM, it provides a good balance between adsorption rate and capacity. Conversely, at 1.0 SLPM, the process is limited by transport, resulting in a steeper, faster breakthrough curve. Kinetic modeling revealed that the Clark and Yoon-Nelson models were better suited to describing the experimental data than Thomas model (R² > 0.99). The integrated experimental and simulation approach provides a strong quantitative basis for predictive design and scale-up of fixed-bed reactors for CO₂ capture. Overall, thermally activated serpentine has proven to be an effective sorbent for CO₂ capture in gas-solid systems, and the validated CFD model provides valuable insights for more efficient reactor design and optimization of operational conditions at an industrial scale.

Recent Trends in Non-conventional Starches for Wastewater Treatment Applications

2026-05-04T17:25:54+07:00

Coagulation and flocculation are essential processes in water and wastewater treatment. However, commonly used commercial coagulants pose environmental and health risks due to residual metal content and the large volumes of sludge they produce. As a sustainable alternative, starch-based biocoagulants have attracted increasing research interest due to their biodegradability, cost-effectiveness, and lower sludge generation, with some studies reporting up to 5-fold lower sludge volumes than with conventional chemical coagulants. Among these, non-conventional starches offer a promising solution because of their diversity, regional availability, and lack of competition with the food supply. This review explores extraction methods, modification strategies, and characterization techniques for structural and mechanistic validation. Reported studies revealed excellent pollutant removal performance under optimal conditions, including turbidity (98.91%), TSS (90.7%), COD (84.96%), color (100%), and selected metals (100%). Normalized removal efficiencies ranged from1.855% per mg/L for turbidity, 0.541% per mg/L for COD, and 1.7778% per mg/L for TSS, depending on the starch source and wastewater type. Mechanisms such as charge neutralization and interparticle bridging have also been identified. Despite challenges such as composition variability, high dosage requirements, and scalability issues, techno-economic assessments suggest potential industrial applicability. Overall, non-conventional starch-based biocoagulants hold considerable promise for sustainable wastewater treatment applications.