Vol. 3 No. 1 (2025): March

The adsorption capability of Ni/Al LDH modified with gambier leaf extract was evaluated for the removal of Rhodamine B (RhB), Malachite Green (MG), and Methylene Blue (MB) dyes from aqueous solutions. UV-Vis spectroscopy analysis revealed that Ni/Al-Gambier Leaf Extract exhibited a higher efficiency in cationic dye removal compared to unmodified Ni/Al LDH. The removal percentages of RhB, MG, and MB using unmodified Ni/Al LDH were 6.00%, 40.05%, and 14.73%, respectively. However, after modification with Gambier Leaf Extract, these values significantly improved to 25.62%, 39.48%, and 31.06%, respectively. This enhancement was attributed to the polyphenolic functional groups present in the gambier leaf extract, which strengthened electrostatic interactions and promoted dye adsorption. These findings indicate that incorporating gambier leaf extract into Ni/Al LDH enhances its adsorption performance, making it a promising material for improving dye removal in wastewater treatment.

This study investigates the hydrothermal carbonization (HTC) process of Dimocarpus longan peel for the development of a selective and regenerable adsorbent for cationic dye removal. The hydrochar was synthesized at 190°C with varying carbonization durations (4–12 hours) and characterized using XRD and FTIR analysis. XRD analysis revealed the formation of an amorphous carbon phase, particularly at longer HTC durations, with the most optimized structure observed at 10 hours. FTIR spectra confirmed that hydrothermal carbonization preserved the primary functional groups while modifying their intensity. Adsorption experiments using a binary dye system (malachite green-MG and rhodamine B-RhB) demonstrated that the hydrochar exhibited higher selectivity for MG, achieving a removal efficiency of 81.78%, compared to 41.88% for RhB. Desorption studies indicated that ethanol and acetone were the most effective desorbing agents, with desorption efficiencies of 18.99% and 18.14%, respectively, while water and acidic conditions showed minimal dye release. Regeneration tests revealed a gradual decline in adsorption capacity over three cycles, with removal efficiencies decreasing from 73.23% to 42.17%, indicating partial loss of adsorption sites and possible structural degradation. These findings suggest that Dimocarpus longan peel-derived hydrochar, particularly at 10-hour HTC processing, is a promising adsorbent for selective cationic dye removal. However, further optimization of regeneration techniques is necessary to improve its reusability and long-term performance.

Water pollution due to synthetic dye waste is a serious environmental problem, so an effective method is needed to overcome it, including using adsorption. In this study, Ni/Al-Cs materials were synthesized and characterized to evaluate their selectivity towards Rhodamine B (RhB), Malachite Green (MG), and Methylene Blue (MB) dyes. Adsorption selectivity tests were conducted using UV-Vis spectroscopy to determine changes in dye concentration before and after interaction with the material. Results showed that Ni/Al-Cs had the highest adsorption capacity towards MG, followed by MB and RhB.  With its selective adsorption properties, Ni/Al-Cs material has the potential to be used as an effective adsorbent in the treatment of dye effluents in aquatic environments, especially MG dye.

Oxidation desulfurization (ODS) is an effective method to remove sulfur compounds from fuels by converting them into more polar oxidized forms that are easier to extract. In this study, H₅PV₂Mo₁₀O₄₀/TiO₂ catalysts were synthesized and characterized using FT-IR spectroscopy. The FT-IR spectra confirmed the successful impregnation of polyoxometalate into the TiO₂ matrix, indicated by the appearance of Ti-O and O-Ti-O vibrations, while the typical H₅PV₂Mo₁₀O₄₀ peaks remained detectable. The performance of the H₅PV₂Mo₁₀O₄₀/TiO₂ catalyst in the desulfurization of 4-methyldibenzothiophene (4-MDBT) was studied based on variations in reaction time, catalyst mass, temperature, and amount of H₂O₂. The optimal conditions obtained were a reaction time of 2 hours, a catalyst mass of 0.05 g, a temperature of 60°C, and a volume of H₂O₂ of 5 mL, with a maximum sulfur conversion of 99.0%. These results indicate that H₅PV₂Mo₁₀O₄₀/TiO₂ has potential as an efficient ODS catalyst.

This study aims to synthesize and characterize the H₃[α-PMo₁₂O₄₀].nH₂O-TiO₂ composite as a heterogeneous catalyst for cyclohexane oxidation using H₂O₂. FT-IR and XRD characterization showed the interaction between POM and TiO₂, with an increase in TiO₂ ratio leading to a decrease in POM crystallinity. Reaction optimization showed that the POM-1.00TiO₂ catalyst gave the highest conversion of 99.95% at 80°C, 2 hours reaction time, 3 mL H₂O₂ volume, and 0.1 g catalyst mass. GC analysis confirmed the formation of cyclohexanol and cyclohexanone, with the optimized conditions resulting in a balanced selectivity of 35.51% for cyclohexanol and 34.69% for cyclohexanone, demonstrating the catalyst's effectiveness in cyclohexane oxidation.