Photocatalytic degradation of trace carbamazepine in river water under solar irradiation.

ABSTRACT

An interesting ZnIn2S4/TiO2 composite catalyst was prepared by a hydrothermal method and thoroughly characterized. The photocatalytic degradation of trace carbamazepine (CBZ) in two river waters was primarily investigated through a batch experiment under solar irradiation, and the effects of dissolved organic matter (DOM), inorganic salt (IS), suspended solids (SS) and ultraviolet (UV) on CBZ degradation were researched. The influential degree was DOM ≈ IS ¼â€¯SS and CBZ with an initial concentration of 100 µg/L in the Bahe River water was completely degraded under a catalyst dosage of 75 mg/L and solar irradiation of 240 min. Compared with direct photolysis, the reaction rate constant enhanced 45 times and the half-life reduced to 1/82 in photocatalysis after the removal of all SS, IS and DOM. A certain adsorption capacity of composite catalyst with a specific surface area of 91.9 m2/g and a strong interaction between TiO2 and ZnIn2S4 effectively improved the photocatalytic degradation of CBZ. The increase of light intensity was confirmed to be of benefit to CBZ photocatalysis. Most of CBZ was degraded by visible light and UV effect was negligible. Although photo-etching and acidic corrosion by course products had negative effect on ZnIn2S4/TiO2, the removal of CBZ was mainly kept at 86% after five times usage of the catalyst.