Nitrogen-doped ZnO and TiO2 supported on activated carbon for dual pollutant degradation under UV/H2O2 process

Nitrogen-doped ZnO and TiO2 nanoparticles supported on GAC were simulated and characterized. Various techniques including SEM, EDX, XPS, Raman, and DRS were employed to confirm both the successful nitrogen doping and the effective immobilization of ZnO and TiO₂ particles onto the GAC substrate. The resulting N-ZnO/AC and N-TiO2/AC catalysts were applied in the photo-degradation of ammonia and phenol within a semi-continuous flow photocatalytic reactor. Photocatalytic activity assessments were performed on both catalysts with flow rate and pH variations. These investigations indicated that the optimal degradation of both contaminants occurred at 8 L/min flowrate and a moderate pH level. To comprehensively evaluate the impact of various independent parameters on degradation efficiency, Response Surface Methodology (RSM) was applied. Optimization of the UV/Catalyst/H2O2 process for the N-ZnO/AC catalyst was conducted using a Box-Behnken design. The predicted photo-degradation efficiency for both ammonia and phenol were found in excellent agreement. Optimization process revealed that the maximum photo-degradation efficiency was achieved under specific conditions: 120 min of irradiation time, 0.86 g L− 1 catalyst dose, an H2O2 concentration of 45 mM, an initial ammonia concentration of 96.55 ppm, and an initial phenol concentration of 10 ppm.