Degradation of diphenhydramine by the photocatalysts of ZnO/Fe2O3 and TiO2/Fe2O3 based on clinoptilolite: Structural and operational comparison

The photocatalysts of TiO2/Fe2O3 and ZnO/Fe2O3 based on clinoptilolite natural zeolite were synthesized by impregnation route and sol-gel methods The synthesized photocatalysts were characterized by XRD, XRF, EDX, FE-SEM, FT-IR, BET and UV-vis DRS analyses. The results of XRD, FT-IR, and EDX confirmed the presence of Fe2O3, TiO2, and ZnO nanoparticles on the surface of clinoptilolite. The FE-SEM results confirmed deposition of TiO2/Fe2O3 and ZnO/Fe2O3 on the surface of zeolite. The approximate particle size of TiO2/Fe2O3 and ZnO/ Fe2O3 was 47 and 34 nm, respectively. According to the XRF results, the synthesized nanoparticles had Fe3+/ TiO2 and Fe3+/ZnO molar ratios of 0.06 in TiO2/Fe2O3/Zeolite and ZnO/Fe2O3/Zeolite, respectively. Based on BET analysis, the surface area of TiO2/Fe2O3/Zeolite and ZnO/Fe2O3/Zeolite was about 112 and 289 m(2)/g, respectively. UV-vis DRS analysis confirmed that both TiO2/Fe2O3/Zeolite and ZnO/Fe2O3/Zeolite have high absorbtion capacity at visible light region. The performance of these two photocatalysts in degradation of diphenhydramine (DPH) from contaminated water was evaluated by investigating the effects of operational factors such as concentration of the contaminant (1-100 mg/l), photocatalysts (0.5-2 g/l), irradiation time (45-180 min), and pH (4-10). The results of the photocatalytic experiments revealed that the ZnO/Fe2O3/ Zeolite had a more effective performance in degrading DPH, compared to TiO2/Fe2O3/Zeolite. Under the optimal conditions, the efficiency of DPH degradation with TiO2/Fe2O3/Zeolite (DPH: 50 mg/l, hydrogen peroxide: 50 mg/l, irradiation time: 120 min, photocatalyst: 0.5 g/l, pH = 5) and ZnO/Fe2O3/Zeolite (DPH: 50 mg/l, hydrogen peroxide: 50 mg/l, irradiation time: 100 min, photocatalyst: 0.5 g/l, pH = 10) was 80 and 95%, respectively.