Hydrothermal synthesis of SnO2/ZnS nanocomposite as a photocatalyst for degradation of Rhodamine B under simulated and natural sunlight

A novel nanocomposite, SnO2/ZnS, was successfully synthesized via a one-step hydrothermal method. The composite was characterized by several techniques such as XRD, SEM, TEM, XPS and UV-vis spectrum, and utilized for photocatalytic degradation of refractory dye Rhodamine B (RhB) under simulated and natural sunlight. It was found that the composite prepared at the molar ratio of n(SnCl4 center dot 5H(2)O)/n(Zn(NO3)(2)center dot 6H(2)O)= 1.5 and hydrothermal temperature of 180 degrees C showed the highest photocatalytic activity. The photocatalytic degradation of RhB reached the maximum of 95% at the 1 g/L SnO2/ZnS dosage, 10 mg/L initial RhB concentration, 4.59 initial solution pH and 23 degrees C. The RhB photocatalytic degradation fitted well to the first-order kinetics model, and the increased SnO2/ZnS dosage, decreased initial RhB concentration and optimal initial solution pH were responsible for the increase of RhB photocatalytic degradation rate. The composite also displayed stable performance during 5 runs of reuse. Quenching tests demonstrated that the dominant active species generated in SnO2/ZnS-RhB-H2O-simulated sunlight system was O-2(center dot-); nevertheless, h(+) and (OH)-O-center dot also contributed to RhB degradation. The formation mechanism of the SnO2/ZnS nanosphere and RhB photocatalytic degradation mechanism were proposed. Moreover, the composite has proved to have the high efficiency for the degradation of RhB under natural sunlight irradiation. (C) 2015 Published by Elsevier B.V.