ASEAN Journal of Chemical Engineering

Effect of Polyaniline on the Ionic Conductivity of PVA/NaCl Composite Electrolyte Membranes

Firman Ridwan, Muhammad Akbar Husin — Sat, 30 Aug 2025 00:00:00 +0700

This study investigates the effect of polyaniline (PANI) on the ionic conductivity and performance of polyvinyl alcohol (PVA)/sodium chloride (NaCl) composite electrolyte membranes for application in aluminum-air batteries. PVA/NaCl/potato starch (PS) membranes with varying PANI concentrations (0, 1, 1.5, and 2 g) were prepared and characterized. Tensile strength tests revealed that increasing PANI content led to increased brittleness and decreased elastic properties of the membranes. Electrochemical impedance spectroscopy showed that adding 2 g of PANI resulted in the highest ionic conductivity of 1.69 mS/cm. Galvanostatic discharge tests demonstrated that the membrane with 1.5 g of PANI exhibited the longest operational time of 677 s at 1 mA and the highest initial voltage of 1.42 V. The battery with 1.5 g of PANI in the electrolyte membrane also achieved the highest electrical capacity of 0.188 mAh. However, excessive PANI content (2 g) led to a decrease in battery performance. The results suggest that the optimal PANI concentration for enhancing the performance of PVA/NaCl/PS electrolyte membranes in aluminum-air batteries is 1.5 g. This study highlights the potential of PANI as an additive for improving the ionic conductivity and performance of composite electrolyte membranes in Al-air batteries.

Recent Advances in Biodiesel Production: Ultrasound-Assisted Interesterification of Palm Oil with Methyl Acetate

Ansori Ansori, Achmad Qodim Syafaatullah, Yeni Variyana, Mahfud Mahfud — Sat, 30 Aug 2025 23:32:50 +0700

Currently, fossil fuels (non-renewable) are used continuously to meet bioenergy needs. Every year, there is an increase in bioenergy consumption, which will eventually lead to the depletion of fuel reserves. Therefore, it is necessary to have alternative and renewable fuels to substitute for the use of fossil fuels. One such application is the production of biodiesel, which serves as a substitute for diesel fuel. Biodiesel is made via the transesterification of triglycerides and methanol, with glycerol as a byproduct. The formation of glycerol holds no economic value and is deemed waste in biodiesel production, necessitating a separation process. Therefore, this research proposes an innovative method, specifically the non-alcoholic or interesterification reaction pathway, which involves three consecutive reversible reactions. In this reaction, methyl acetate is used to replace methanol, resulting in the production of triacetin instead of glycerol, which is completely soluble in biodiesel and offers a greater additional value than glycerol. To enhance the reaction rate and yield, potassium methoxide catalyst and ultrasound were used in this research. Meanwhile, to evaluate the influence of significant operational parameters on the interesterification reaction, experiments were carried out on different operating factors, namely a methyl acetate to oil molar ratio (3:1 to 25:1), reaction temperature (35 to 65 ^oC), catalysts (0.5 to 2% (w/w)), and interesterification time (1 to 30 minutes). It has been observed that the optimal yield is achieved at a 15:1 molar ratio, with a 1% catalyst amount, a reaction temperature of approximately 55 ^oC, and a reaction time of 5 minutes, resulting in a yield of 81.26%. Furthermore, a kinetic study was conducted to determine the activation of energy and rate constantly suitable for the second-order approximation. The reaction rate constant is 0.287 L/(mol.min) at an operational temperature of 55 ^oC, and the resulting activation energy is 50.50 kJ/mol.

Radiolytic Degradation of Reactive Orange-16: Degradation Pathways and Kinetics

Sat, 30 Aug 2025 23:34:44 +0700

Removal of Reactive Orange-16 (RO-16) dye, an emerging water pollutant and potential carcinogen, was investigated using gamma radiation. The radiolytic degradation process was studied in a batch reactor with a gamma-ray dose rate of 2426 Gy/h. Degradation of 96% RO-16 dye was achieved at 3.0 kGy irradiation dose (0.1 mM initial dye concentration). Twelve degradation products were predicted based on the m/z results from liquid chromatography-high resolution mass spectrometry (LC-HRMS). Among these, acetic acid and formic acid were identified. Possible degradation pathways were predicted based on the observed degradation products. The concentrations of the reactants RO-16, acetic acid, and formic acid were quantified to determine a specific kinetic model. The initial breakdown of the molecule occurred slowly, as indicated by the small k value, due to the steric hindrance of the large RO-16 molecule. As the molecule became smaller, the k value increased, indicating that the molecular breakdown process became faster, ultimately leading to the formation of end products. The formation of smaller molecular mass degradation products indicated that the gamma irradiation process is a promising alternative for the potential degradation of RO-16 dye.

Synergetic Effect of TiO2–PCC/Zeolite Nanocomposite on the Photodegradation of Phenolic Compound in Wastewater

Sat, 30 Aug 2025 23:36:20 +0700

Phenol is an organic compound commonly found in the water bodies contained polluted wastewater from industrial, agricultural, and domestic activities. This compound exhibits carcinogenic properties and can impact human health at certain concentrations. Therefore, excessive phenol must be degraded. Various techniques dealing with phenol waste have been developed, including the adsorption method. However, secondary pollutants might form after the adsorption process. One potential alternative for handling phenolic compounds in wastewater without generating secondary waste is the photocatalytic process. It has been proven that, when combined with adsorption, the degradation activity can be enhanced. In this paper, phenol degradation was investigated by carrying out degradation using a semiconductor catalyst, such as TiO₂, that synergizes with adsorbents like precipitated calcium carbonate (PCC) and zeolite. The highest phenol degradation was achieved with the variables 80% TiO₂- 20% PCC and 80% TiO₂- 20% zeolite, resulting in 74.3% and 69.22% of phenol degradation, respectively. In comparison, the TiO₂–PCC nanocomposite exhibits superior performance to the TiO₂–zeolite nanocomposite. The observation of the functional groups revealed that PCC has a larger functional group area, supporting the synergy of the adsorption-photocatalysis process compared to the TiO₂–zeolite nanocomposite.

Particle Size and Heating Rate Effects on the Pyrolysis Kinetics of Aceh Low-Rank Coal : Kinetics, Thermal Decomposition, and Thermodynamic

Fadhilah Almardhiyah, Mahidin, Khairil, Faisal Abnisa — Sat, 30 Aug 2025 23:39:15 +0700

This research aims to understand the combustion mechanism of Aceh's low rank coal by studying the kinetics of the pyrolysis reaction using the thermogravimetric method. This study was carried out by testing coal samples at various pyrolysis temperatures between 0 and 600oC by varying the coal particle sizes of 5, 10, and 15 mesh, as well as different heating rates of 20, 40, and 60 K/minutes in a nitrogen atmosphere. The data TG-DTG obtained are used to divide into three stages and calculate the mass conversion rate and analyze key parameters such as reaction rate constant, exponential factor and activation energy (E, A, and n). Thus, the pyrolysis reaction rate mechanism can be formulated as a function of temperature and time. Mathematical modeling can be compared with the kissenger, coats-Redfern, DAEM model. The findings of this investigation indicate that coal pyrolysis adheres to the first-order kinetics mechanism, exhibiting an average activation energy of 37-75 kJ/mol and a pre-exponential factor of 0.091- 1.8 x 107 min–1. Thermodynamic parameters, the average enthalpy change (ΔH), entropy change (ΔS), and free energy change (ΔG) associated with coal pyrolysis, are computed to be 2.6-7.3 kJ/mol, –332 kJ/mol/s, and 89-431 kJ/mol, respectively. A pyrolysis, yielding an optimal oil output of 57.04 wt% at 320°C. This empirical investigation has the potential to enhance the combustion properties of low-rank coal, particularly with regard to ignition efficiency and maximum weight reduction, thereby suggesting the viability of utilizing low-rank coals in co-combustion applications as a fuel source

Prediction of Slagging and Fouling Potential of Alternative Biomass Fuel as a Bagasse Substitute in Sugar Mill Boilers

Yunaidi Yunaidi, Saptyaji Harnowo — Sat, 30 Aug 2025 23:40:15 +0700

Boilers in sugar mills are generally designed to use bagasse as a biomass fuel. In their operations, some sugar mills are unable to provide sufficient bagasse for boiler fuel due to milling conditions that fall below their normal capacity, so they must supplement their fuel sources with biomass fuels other than bagasse, such as rice husk, wood, and sawdust. This situation can impact the performance of sugar mill boilers, which are designed specifically for use with bagasse fuel, as each biomass type has distinct characteristics. The results indicate that the use of rice husk biomass as an alternative fuel will not pose serious problems associated with slagging and fouling, as it has a low potential risk for these issues. However, the use of mahogany, acacia, or mixed wood biomass may increase the risk of slagging and fouling in boiler equipment. This is confirmed by the analysis of the ash residue contained in the boiler superheater pipe of the sugar mill taken as a research object, which shows the presence of high slagging indicators, including the parameters of base to acid ratio (B/A), iron content in ash, Fe+Ca, silica content, and silica to alumina ratio (S/A), as well as high fouling indicators in ash characterized by high total alkali parameters, fouling index, and sodium content in ash.

Influence of Chitosan Concentration on the Properties of Electrospun Methanol-crosslinked Chitosan/PVA Nanofibers

Sat, 30 Aug 2025 23:41:22 +0700

Polymers nanofibers are of great interest due to the growing need for advanced materials to be used in biomedical applications. This research seeks to assess how the chitosan (CS) concentration affects the electrospun methanol-crosslinked CS/polyvinyl alcohol (PVA) nanofibers’ characteristics. Polymer solution compositions containing 10%, 20%, and 30% CS were prepared and electrospun into nanofibers and then crosslinked with methanol to increase their stability. The nanofibers formed were characterized by their morphology, wettability, and crystallographic structure. According to the FESEM, the 20% CS had the largest diameter range (180-240 nm), while the smallest diameter range (120-160 nm) was noticed in the 10% CS. Nonetheless, the rats with 20% CS had the fewest beads during electrospinning. The analysis of WCA shows that the nanofibers had good wettability, as they all exhibited 31° as the lowest contact angle for the 20% CS. From the XRD, the nanofibers fabricated with 10% CS exhibited the highest peak intensity, which implies a more crystalline structure than the rest. However, the 20% CS nanofibers had a more amorphous structure, which could be useful in biomedical applications like wound dressing. The study demonstrates that the concentration of chitosan and methanol crosslinking significantly influences the electrospun nanofibers’s morphological, hydrophilic, and structural aspects.

A Highly Active Galam Wood Bark-derived Solid Acid Magnetic Catalyst with Properties Suitable for Hydrolysis Reaction

Sat, 30 Aug 2025 23:42:40 +0700

Galam wood is a specific plant that is distributed in Kalimantan, especially in lowland areas, shallow peat forests, and swamps. After removing the bark layer, galam wood becomes a valuable building material. The galam bark (GB) is a biomass waste that could be utilized as a solid acid magnetic catalyst (M-SA). Biomass-based solid acid catalysts have gained interest due to the need for sustainable and low-cost alternatives. Nevertheless, most of them have low reusability, poor acidity, or high production cost. To create carbon material, the GB was sized (± 60 mesh) and underwent hydrothermal treatment in the presence of sulfonic acid at 90 ^oC for 8, 10, and 12 h. Then, the carbon was impregnated by 10 mmol/L of iron (III) chloride hexahydrate for 5 h and calcined at 500 ^oC for 1 h. The solid acid magnetic catalyst (M-SA) was produced. Based on Field Emission Scanning Electron Microscope (FE-SEM) observation, the morphological structure of galam bark changes due to the delignification and carbonization processes. The X-Ray Diffraction (XRD) showed a 75% increase in crystallinity after delignification. Fourier Transform-Infrared (FT-IR) showed the presence of the -SO₃H group at a wavelength of 1137 cm^-1. The optimum sulfonation time was obtained for 8 h with an acid content of 0.710 mmol/g. The Energy Dispersive X-Ray (EDX) Analysis measurement showed the Fe and S content of 60.21% and 4.18% w/w, respectively. The highest total reducing sugar (TRS) hydrolysis was 1.345 mg/mL from the hydrolysis of 1% M-SA catalyst at 100 ^oC for 1 h. The stability of M-SA showed good performance for the 4^th repeated use with a decrease of only 6.5%. Solid acid magnetic catalyst from galam bark has good acid catalyst specifications and has the potential to be developed.

Production of Hydrogen with Electrolysis-Photovoltaic from Seawater Using Ni-Mo Electrodes Deposited at Cu (Ni-Mo/Cu)

Sat, 30 Aug 2025 23:43:28 +0700

The energy crisis and environmental impacts of fossil fuels encourage the development of environmentally friendly alternative energy sources. Hydrogen is a promising candidate as a future energy carrier. This research aims to optimize hydrogen production through seawater electrolysis using Ni–Mo/Cu electrodes with a photovoltaic energy source. Ni–Mo/Cu electrodes were prepared via electrodeposition at a varied durations of 2, 4, and 6 minutes. Electrode characterization was conducted using X-Ray Diffraction (XRD) and Scanning Electron Microscope-Energy Dispersive X-Ray (SEM–EDX). Photovoltaic systems were designed using fuzzy logic to optimize solar energy absorption. The electrolysis process was carried out at voltages of 10–30 V. The results showed that a 4-minute electrodeposition produced the most significant Ni–Mo layer. The highest hydrogen production rate of 0.7417 cm³/s was obtained at 25 V using a Ni–Mo/Cu electrode. These findings demonstrate the feasibility of producing hydrogen from seawater using renewable energy sources under the studied conditions.

Morphological Effect of Green Synthesis Cerium Oxide Nanoparticles Enhanced Antibacterial Activity

Sat, 30 Aug 2025 23:45:23 +0700

Cerium oxide nanoparticles (CeO₂NPs) were successfully synthesized using two methods, which are the precipitation and green synthesis. In the green synthesis approach, leaf extracts from Moringa oleifera and Uncaria gambir Roxb. acted as a natural capping and reducing agents. In contrast, ammonium hydroxide was used in the chemical precipitation method. X-ray diffraction (XRD) analysis confirmed the formation of CeO₂NPs with a cubic fluorite structure. Scanning electron microscopy (SEM) revealed that the nanoparticles had an agglomerate morphology. In contrast, transmission electron microscopy (TEM) showed that the CeO₂NPs were predominantly spherical, with average particle sizes of approximately 5-20 nm for the green synthesis method and 10-40 nm for the precipitation method. The antibacterial assays demonstrated significant activity, particularly against Staphylococcus aureus, with the inhibition zones measuring up to 11.05 mm. These findings suggest that green-synthesized CeO₂NPs hold promising potential for applications in the biomedical field due to their biocompatibility and antibacterial properties.

Synthesis and Characterization of Pelletized Coke with Tar Impregnation from Carbonization of Palm Kernel Shells as Nickel Laterite Reductant

Sat, 30 Aug 2025 23:46:36 +0700

The nickel laterite beneficiation policy supports the domestic stainless and alloy steel industries. However, reliance on imported coke for smelting remains a major challenge. The main challenge is the dependence on imports of reductant coke for the smelting process. Palm kernel shell (PKS) is a promising alternative that aligns with the carbon-neutral concept, but its pyrolyzed carbon shows low calorific value and mechanical strength for metallurgical use. This study aims to produce biocoke by converting PKS into carbon–carbon (C/C) composites using its carbon and tar products to enhance mechanical and thermoplastic properties. This study aims to produce biocoke by converting PKS into carbon–carbon (C/C) composites using its carbon and tar products to enhance mechanical and thermoplastic properties. Initial KOH activation (impregnation mass ratio 0.5) created a porous structure for tar deposition. Briquetting (30×30 mm) followed by co-carbonization (250 °C, 1 h) was conducted at various char-to-tar mass ratios. The best condition was achieved at a tar ratio of 1:2, producing composites with high fixed carbon (88.17%), low volatile matter, and compressive strength suitable for metallurgical applications. SEM analysis confirmed uniform carbon fiber distribution within the matrix. The final product also met ASTM D3173 standards with a heating value of 7,328 kcal/kg. XRD analysis of limonite ore reduction using this biocoke showed a decrease in geothite and lizardite phases and the formation of metallic phases such as Fe-Ni alloy, FeS, and wustite, especially at 900 °C and 1100 °C. These results indicate effective metallothermic reduction. C/C composite from PKS offers a sustainable, high-performance alternative to commercial coke for nickel laterite reduction, fulfilling both energy and environmental considerations.

Formic Acid Synthesis via Biomimetic Autoxidation of Carbon Dioxide and Methane (Biogas and Flare Gas) in Low-Temperature for Carbon Capture and Hydrogen Fuel Carrier Applications

Sat, 30 Aug 2025 23:47:55 +0700

The transition from fossil fuels to renewable energy sources and the utilization of CO₂ through CCU are crucial steps toward energy sustainability. Biogas, a renewable energy source primarily composed of CH₄ and CO₂, holds significant potential in this context. On the other hand, gas flaring continues to contribute to greenhouse gas emissions, yet it also presents an opportunity for utilization. Another challenge in utilizing gaseous fuels lies in their storage and transportation over long distances. This study aims to develop a liquid-phase autoxidation for CH₄ and CO₂ to produce formic acid using synthetic catalysts that mimic the function of the MMO enzyme. Formic acid can act as a future fuel solution due to its role as a liquid hydrogen carrier. In this exploratory study, four types of catalysts based on iron and copper were synthesized. These catalysts were tested in the autoxidation reaction of CH₄ and CO₂ in an ethanol solution at 65°C, followed by condensation at 20°C to obtain a distillate as the product. The results of this study indicate that the Cu,Fe-acetate catalyst exhibits the highest catalytic activity, achieving 6.81 mol HCOOH/kg catalyst·hour with a methane conversion to formic acid of 8.61%. Adding Cu to the Fe-Acetate catalyst increased its catalytic activity by 29.76%. Conversely, adding Cu to Fe-Format decreased catalytic activity by 36.54%.

Thermal Degradation Kinetics of Polyvinyl Chloride Stabilized with Palm Based Mixed Metal Carboxylates

Sat, 30 Aug 2025 23:49:03 +0700

Despite its diverse applications, especially as building materials, polyvinyl chloride (PVC) is easily degraded by heat. Thermal degradation poses a significant problem during extrusion, with the worst case being that the PVC resins cannot be formed into final products. Additionally, the degradation process releases hydrogen chloride, which is harmful to the environment. Mixed metal (Ca/Zn) carboxylates are popular PVC thermal stabilizers, offering a more environmentally friendly alternative to lead salts and a more cost-effective option than organotin, another commonly used industrial thermal stabilizer. However, conventional mixed Ca/Zn thermal stabilizers, typically based on stearic acid, remains relatively costly for PVC compounders in developing countries. Recently, we have developed a Ca/Zn thermal stabilizer from palm fatty acid distillate (PFAD), referred to as Ca/Zn Palmate. This thermal stabilizer is as effective as the conventional stearic-acid-based Ca/Zn thermal stabilizer but significantly more affordable, owing to the lower cost of PFAD. Continuing this research, we studied the thermal degradation kinetics of PVC resin stabilized with the developed palm-based mixed Ca/Zn thermal stabilizer. Degradation data were collected from dehydrochlorination tests carried out within the 170-190°C temperature range, with varying doses of Ca/Zn Palmate, Ca/Zn ratios, and co-stabilizer amounts. The degradation followed the A2 model of Avrami-Erofeev. The activation energy for unstabilized PVC was found to be 124.4 kJ/mol, while for stabilized PVC, it ranged from 128.8 to 167.2 kJ/mol. The results showed that increasing the Ca/Zn Palmate dose or the Ca/Zn ratio led to higher activation energy. The highest activation energy occurred when the co-stabilizer doses were equivalent to the dose of Zn Palmate.

Transforming Oil Palm Trunk (OPT) Waste into Black Soldier Fly (BSF) Larval Biomass: Investigating Pretreatment and Enrichment

Sat, 30 Aug 2025 23:50:00 +0700

The Indonesian government's palm oil replantation program has the potential to create an excess of oil palm trunks (OPT) in the field. Although there is an effort to obtain ethanol from the sap pressed from OPT, the OPT dregs (OPTD) remain as waste. This research investigates the potential of using OPTD as both a feed and growth medium for black soldier fly (BSF) larvae, which can be subsequently processed into animal feed. This manuscript focuses on the treatment of OPTD through maceration in water and palm oil mill effluent (POME), followed by the addition of supplementary materials, namely palm kernel meal (PKM), Azolla leaves, and solid decanter, to enhance the nutritional value and digestibility of the substrate. The effectiveness of these treatments is evaluated based on their waste-reducing capacity and the BSF larval growth. Macerating OPTD in 20% POME for 4 days was found optimal for enhancing the starch and sugar contents by 17% and 11%, respectively. The addition of PKM enhanced the growth of BSF larvae the most, resulting in a higher waste reduction index (WRI). However, it was not necessarily the most effective from the perspective of biomass conversion. The results here show that the treated OPTD mixture can serve as a viable complementary growth medium for BSF larvae.

Optimization of Acid-Catalyzed Hydrolysis of Water Hyacinth without Delignification

Sat, 30 Aug 2025 23:51:04 +0700

Water hyacinth (Eichhornia crassipes) is a rapidly proliferating invasive aquatic plant causing severe ecological disruptions and economic challenges worldwide. Its uncontrolled spread significantly affects aquatic biodiversity and local livelihoods. Although water hyacinth is rich in cellulose, conventional hydrolysis methods to convert it into valuable bioproducts, such as biofertilizer substrates, often require costly and environmentally harmful pretreatment steps, limiting its broader utilization. This study aimed to optimize acid-catalyzed hydrolysis of water hyacinth into glucose-rich hydrolysate without alkaline pretreatment. Response surface methodology (RSM) was employed to determine optimal conditions using hydrochloric acid (HCl) and sulfuric acid (H₂SO₄). Optimal hydrolysis conditions were found to be 2.36N concentration, 89.33°C, and 76.94 minutes for HCl, and 1.91N concentration, 100.03°C, and 79.66 minutes for H₂SO₄. Model validation showed high R² values of 0.82 and 0.95 for HCl and H₂SO₄, respectively. Subsequent biofertilizer fermentation experiments demonstrated that H₂SO₄-derived hydrolysate facilitated superior microbial growth compared to HCl, indicating better glucose bioavailability. Hydrolysates from HCl hydrolysis showed higher bacterial toxicity. These findings highlight the potential of optimized acid-catalyzed hydrolysis as an effective, sustainable strategy for converting invasive water hyacinth into glucose-rich substrates for biofertilizer production. This bioprocess-friendly approach not only mitigates environmental impacts but also enhances resource efficiency, contributing significantly to sustainable agricultural practices.