Hexavalent chromium reduction and Rhodamine B degradation by visible-light-driven photocatalyst of stannum indium sulfide-samarium vanadate

Abstract In this study, a flower-like SnIn 4 S 8 /SmVO 4 heterostructure was synthesized by applying a hydrothermal approach and used as a visible-light-driven photocatalyst to remove hexavalent chromium (Cr 6+ ) and Rhodamine B (RhB). The process design and optimization were carried out by response surface methodology (RSM). An artificial neural network (ANN) was also used to determine the relative importance of operational factors. Under RSM-based optimal conditions, the Cr 6+ and RhB removal efficiency reached 90.93 and 97.57%, respectively. Process modeling by ANN revealed pH as the most influential factor in Cr 6+ and dye removal. The predominant photocatalytic activity of SnIn 4 S 8 /SmVO 4 was attributed to its Z-scheme structure, leading to the significant separation of charge carriers and conserving the redox capacity of the photogenerated electron-holes. Kinetic studies revealed that the SnIn 4 S 8 /SmVO 4 could achieve considerable rate constants of 0.036 and 0.080 min −1 to remove Cr 6+ and RhB, respectively. Furthermore, the catalyst’s reusability was confirmed under optimal conditions.