<![CDATA[Rapid industrialization in Indonesia has increased the generation of coal fly ash (CFA) from coal-fired power plants, while domestic greywater from laundry activities is commonly discharged without adequate treatment. These environmental challenges require integrated and resource-efficient solutions. This study investigates the valorization of CFA as a low-cost support material for TiO2 photocatalysts synthesized using the sol–gel method to simultaneously degrade organic pollutants and promote hydrogen evolution using real laundry greywater as the reaction medium. CFA was characterized through Loss on Ignition (LOI), X-ray fluorescence (XRF), and slurry pH analysis. Pretreatment involved sequential washing, mild acid neutralization, drying, and calcination prior to sol–gel synthesis. The resulting TiO2/CFA composite was immobilized on stainless steel using brush coating, calcined at 400oC, and tested in a closed batch reactor under UV irradiation. The greywater was coarsely filtered and adjusted to pH 6.0–7.5 before treatment. Characterization confirmed the suitability of CFA as a catalyst support, with an LOI of 1.66%, SiO2 content of 47.64%, Al2O3 content of 18.17%, and a slurry pH decrease from 11.25 to approximately 8.0 after pretreatment. After six hours of UV irradiation, organic content decreased from 97.9 to approximately 45.1 mg/L, corresponding to an overall removal efficiency of 53.96 ± 0.12%. However, without control experiments, this removal reflects combined effects of photocatalysis, photolysis, and adsorption. An MQ-2 sensor detected reducing gas accumulation under nitrogen-purged anaerobic conditions, but the gas identity remains unconfirmed due to the sensor's non-selectivity and requires verification using GC-TCD. The findings demonstrate the potential of CFA as a functional TiO2 support for integrated greywater treatment and photocatalytic hydrogen evolution, while quantitative hydrogen analysis and advanced catalyst characterization are recommended for further investigation. Keyword: Coal fly ash, TiO2-Based Photocatalyst, Sol–Gel Synthesis, Photocatalytic Hydrogen Evolution, Greywater, Permanganate Index, Organic Degradation.]]>
