Oxidation degradation of rhodamine B in aqueous by UV/S2O 82- treatment system

Abstract

The UV photolysis of persulfate (S2O82-) is a novel advanced oxidation technologies (AOTs), which leads to the formation of strong oxidizing radicals, sulfate radicals (SO2). The effect of oxidant S2O 82- concentration, initial dye concentration, initial pH of solution, and various inorganic anions (Cl-,H 2PO4-, and HCO3-) were investigated using Rhodamine B (RhB), a kind of xanthene dye, as a model pollutant. With the increase of oxidant S2O82-, more SO4•- produced to attack RhB molecules and result in the increase of RhB degradation. While the improvement was not sustained above a critical value, beyond which degradation rate does not increase. Initial pH of solution had great effect on the RhB degradation rate during UV/S2O82- system. SO4•- is rather stable in acidic solutions, while increasing system pH results in the transformation of SO 4•- to •OH. The effects of three inorganic anions (Cl-,H 2PO4-, and HCO3-) all had some negative effect on the degradation of RhB. Based on the RhB solution changes of the UV-vis absorption intensity during the UV/S2O 82- treatment, decolorization of RhB accompanied the destruction of aromatic ring structures of RhB molecules. © 2012 Xiaoyang Chen et al.