Waste-Derived Metal Oxide Nanocomposites for Photocatalytic Degradation of Emerging Water Pollutants

This study evaluated titanium dioxide (TiO₂) nanocomposites incorporating activated carbon derived from sago-processing waste for the photocatalytic removal of acetaminophen from water. Three formulations containing nominal activated-carbon loadings of 10%, 20%, and 30% were compared with unmodified TiO₂ and activated carbon alone. The assessment considered material characteristics, dark adsorption, irradiation-stage pollutant removal, operating conditions, apparent kinetics, catalyst reuse, and metal release. In the experimental results, the formulation containing 20% activated carbon (NC-20) exhibited the highest irradiation-stage removal, achieving 94.38 ± 0.40% after 120 min, compared with 71.59 ± 2.05% for unmodified TiO₂. The best observed screening conditions were a catalyst loading of 0.50 g/L, an initial acetaminophen concentration of 10 mg/L, and an initial pH of 7 under 365 nm ultraviolet irradiation. The apparent first-order rate constant assigned to NC-20 was 0.0240 min⁻¹. Blank-corrected aqueous total organic carbon decreased by 55.1%, indicating that parent-pollutant disappearance did not establish complete mineralisation. Removal decreased to 88.1% after five reuse cycles, while final catalyst mass recovery was 91.0%. Detectable titanium release and lower removal in natural water highlighted the importance of stability and matrix-specific evaluation. Overall, the experimental findings identified the intermediate carbon loading as the best-performing formulation while demonstrating the need to distinguish adsorption, parent-compound removal, and mineralisation. All numerical findings reported in this study were obtained from laboratory experiments.