State University of Medan

In tropical peatland regions, direct chlorination of peat water is a common household practice to improve clarity and ensure microbial safety. However, this simple treatment can produce toxic disinfection by-products (DBPs) due to the high organic matter and acidity of peat water. This perspective examines the dual nature of chlorination—its effectiveness in removing bacteria and reducing color, versus its role in generating hazardous halogenated compounds. Chlorine reacts with humic and fulvic substances, yielding trihalomethanes, haloacetic acids, and other DBPs with mutagenic and carcinogenic potential. In the absence of controlled dosing and residual monitoring, households often use excessive chlorine, allowing prolonged reactions and increasing DBP concentrations. Field observations in Indonesian peatland communities indicate that chlorination is typically guided by visual cues rather than quantitative control, leading to a false sense of safety. The paper highlights the urgent need for risk awareness, simple pre-treatment steps to remove precursors, and practical dosing guidance to balance microbial and chemical safety. Future efforts should emphasize locally appropriate technologies such as biochar filtration, natural coagulants, or hybrid UV-chlorination systems. Ensuring safe drinking water for peatland populations requires integrating scientific understanding, community education, and policy action to reduce DBP exposure without compromising microbial protection.

This study investigates the catalytic specificity of sulfonated palm kernel shell (PKS)-derived biochar for the esterification of free fatty acids (FFA) in high-acid crude palm oil (HACPO). Biochar was prepared by pyrolysis (500 °C, 5 h, N2), activated with KOH (2 M, 1:4 w/v, 90 °C, 5 h) and HCl (1 M, 1:4 w/v), and sulfonated with concentrated H2SO4 (1:4 mass ratio, 100 °C, 5 h). Comprehensive characterization using FTIR, XPS, XRD, and N2 physisorption revealed that KOH activation generated substantial microporosity (BET surface area 251.85 m2/g), which was subsequently blocked by the grafted –SO3H groups after sulfonation, causing the surface area to collapse to 4.95 m2/g. XPS confirmed the exclusive presence of covalently bound aromatic –SO3H groups (S 2p at 168.7 eV) with no residual sulfate impurities. The resulting catalyst exhibited a competitive acid site density of 2.80 mmol g⁻1 and achieved an 84.44

The high content of free fatty acids (FFA) in vegetable oils, such as oleic acid, requires an effective acid catalyst for the esterification process in biodiesel production. This investigation endeavors to synthesize sulfonated polystyrene-divinylbenzene resin (PS-DVB-S) as a heterogeneous catalyst through the polymerization of styrene and divinylbenzene, succeeded by sulfonation to yield solid acid catalyst properties. Characterization was conducted via Fourier Transform Infrared Spectroscopy (FTIR), which confirmed the successful sulfonation through the detection of the – SO3H group absorption band within the range of 1018–1021 cm⁻¹, in contrast, thermogravimetric analysis (TGA) indicates that increasing the concentration of sulfonic acid groups reduces the thermal stability of the resin at elevated temperatures. The catalytic activity assessment in the oleic acid esterification reaction effectively diminished the acid number of oleic acid from 199.71 mg KOH/g to 20.78 mg KOH/g when utilizing the PS-DVB-S/D catalyst, achieving the highest FFA conversion rate of 89.59

A supercapacitor is an exciting breakthrough in the field of energy because it has a storage capacity that is greater than ordinary capacitors. Graphene is one of the most widely used supercapacitor materials because it has a high specific surface area. The purpose of this research is to analyze the effect of temperature on the structure of graphene material and the capacitive properties of graphene material as a supercapacitor electrode by the microwave-assisted solvothermal method using graphite, tartaric acid, and methanol as its main ingredients. The temperature variation of thermal shock in the furnace used in the synthesis process is 600, 700, and 800 °C. The material produced from the synthesis process was characterized using XRD, FTIR, and SEM tests. For supercapacitor performance, CV testing is carried out. It was found that the higher the temperature of the thermal shock applied, the more energy was given to widen the distance between the layers in the graphite to produce amorphous graphene, with a thin morphology and a low oxygen functional group. The highest capacitance values are for thermal shock temperatures at 800 °C (141,659 F/g), 700 °C (124,848 F/g), and 600 °C (111,240 F/g), respectively. This indicates that optimizing the thermal shock process can significantly enhance the supercapacitor’s energy storage capacity. Further research could explore the effects of varying heating durations and cooling rates to fine-tune the material properties for even better performance.

In this study, sodium titanate (NTO) nanorods were synthesized using a hydrothermal and template method, followed by calcination at various temperatures (800 degrees C-1000 degrees C), to evaluate their potential as anode materials for sodium-ion batteries (SIBs). X-ray diffraction (XRD) confirmed that NTO calcined at 950 degrees C (NTO950) exhibited the highest crystallinity, dominated by the Na2Ti6O13 phase, with sharp diffraction peaks at (200) and (310). Fourier-transform infrared spectroscopy (FTIR) confirmed the removal of hydroxyl groups and the presence of Ti-O and Ti-O-Ti vibrations, indicating enhanced structural integrity. BET analysis revealed an optimal mesoporous structure, with a specific surface area of 14.30 m(2)/g, a pore volume of 0.037 cc/g, and an average pore radius of 1.7 nm, facilitating efficient ion diffusion. Scanning and transmission electron microscopy (SEM/TEM) images displayed a uniform nanorod morphology, promoting enhanced ionic conductivity. Electrochemical characterization demonstrated that all NTO samples exhibited pseudocapacitive behavior, with NTO950 showing superior sodium-ion storage properties due to the synergy between Na2Ti6O13 and rutile TiO2. Cyclic voltammetry (CV) analysis revealed redox peaks at similar to 0.7 V and similar to 1.0 V, corresponding to Na+ intercalation/deintercalation, while galvanostatic charge-discharge (GCD) measurements confirmed NTO950's high discharge capacity and excellent cycling stability, achieving a Coulombic efficiency of 95% over 50 cycles. Electrochemical impedance spectroscopy (EIS) analysis showed that NTO950 exhibited the lowest charge transfer resistance (Rct) before and after cycling, with the highest sodium-ion diffusion coefficient (DNa+) of 10.7 & times; 10(-14) cm(2)/s after 50 cycles, confirming superior Na+ transport kinetics. These findings demonstrate that the optimized calcination strategy enhances the electrochemical performance of NTO, making NTO950 a promising anode material for high-performance sodium-ion batteries.