Photo-Catalytic Activity of ZnO Supported on H-ZSM-5 Zeolite to Reduce Cr(VI) from Aqueous Solutions

Aims: The application of photocatalytic processes to remove heavy metals in aqueous solutions and industrial wastewater are regarded as extremely effective, clean and without producing waste methods. The goal of the present study was to investigate the photocatalytic activity of ZnO based on H-ZSM-5 zeolite support.
ZnO/H-ZSM-5 composite synthesized by impregnation method successfully, and photo-reduction of Cr(VI) was investigated via this composite in present of UV light irradiation. The prepared composite was characterized by X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). Data was analyzed by repeated measurement statistical test.
Findings: ZnO/H-ZSM-5 (79.5%) had better removal photo-reduction activity than pure H-ZSM-5 (8.7%; p=0.003) zeolite and ZnO (58.8%; p=0.003). The initial concentration of Cr(VI) was a highly influential factor in photo-reduction of Cr(VI); In the way that when the initial concentration increased from 10 to 40mg/l, the photo-reduction percentage decreased from 92.5 to 57.7% in constant operational conditions (p=0.001).
ZnO/H-ZSM-5 composite has higher removal photo-catalytic activity than pure ZnO and HZSM-5 zeolite. Photo-reduction of Cr(VI) by ZnO/H-ZSM-5 composite is an efficient technology for the treatment of water and wastewater containing high concentration of Cr(VI).