Photocatalytic Elimination of Cr(VI) in Aqueous Solution by Using ZSM-5 Zeolite as Catalyst and Urea as Coexisting Organic Contaminants

Abstract

The photocatalytic reduction of Cr ( VI ) to Cr ( III ) in aqueous solutions without or with urea (a model organic contaminant) using ZSM-5 zeolite as catalyst under UV illumination was studied. The used ZSM-5 zeolite has the characteristics of pure ZSM-5 zeolite crystalline structure, with the point of zero charge (pHPZC) value of pH = 3.7–3.9. The effects of illumination time, mass content of ZSM-5 zeolite, urea concentrations, Cr ( VI ) initial concentrations and ionic strength on the photocatalytic reduction of Cr ( VI ) to Cr ( III ) were investigated. The results indicated that both the increase of urea concentration and the mass content of ZSM-5 zeolite can improve the photocatalytic reduction of Cr ( VI ) to Cr ( III ) under UV illumination. The results are important to understand the photocatalytic reduction of Cr ( VI ) to Cr ( III ) in natural environment with organic contaminant.