Research On Synthesis, Characterization And Photocatalytic Degradation Of Azo Dyes By ZnBiSbO₅

A large amount of printing and dyeing wastewater is discharged from China’s textile printing plants annually, which is very harmful to the environment. Meanwhile the application of the photocatalysis under visible light irradiation in dyeing wastewater has become a hot issue in the field of catalysis, and the development of efficient semiconductor catalysts responsed to visible light is the key to photocatalysis research.In this paper, a new catalyst ZnBiSbO5 has been synthesized by a high temperature solid phase sintering method, which is active under visible light irridiation. Through screening the optimum calcination process ZnBiSbO5 has been determined to be calcined at 1000℃ for 5 hours. By characterization means of SEM, TEM, XRD, DRS, EDS, XPS, FTIR, BET and Zeta potential, relative characterization information of ZnBiSbO5 has been given. The particles of ZnBiSbOs are irregular and the particle size distribution is among from 200 nm to 3μm. The compound ZnBiSbO5 is of high purity and well crystallized as one kind of pyrochlore structure with a cubic crystal system, lattice parameters a= b=c=10.413897 A, whose space group is Fm3m 225. ZnBiSbO5 can strongly absorb visible light for its band gap Eg= 2.62 eV.We select direct red 4BS (disazo) and direct dark green B (three azo) as the target contaminants for the widely usage of azo dyes in reality. Photocatalisis experiments had been conducted with ZnBiSbOs as phtocatalyst under visible light irridiation. The influences of operating conditions and the inorganic salts concentration in dye aqueous on the photocatalytic efficiency of azo dye molecules had been studied. Besides recycling efficiency of the catalyst and phytotoxicity reaction of treated dye solution had been also reserched. Firstly ZnBiSbOs performed excellent during the degradation process of azo molecules under visible light. Secondly the effects of inorganic ions NaCl and Na2SO4 towards degradation was complex. Thirdly the structure of ZnBiSbOs was stable and ZnBiSbOs had high recycling rates. Lastly the treated dye solution had a lower concentration of harmful substances, resulting a lower phytotoxicity. Besides, ZnBiSbOs performed better during photocatalysis degradation than N-TiO2.