Improved visible-light-driven activity of micro graphite/BiOI nanocomposite for effective removal of xanthate from wastewater

Abstract

The visible light responsive micro-powder graphite (Mic-g)/BiOI nanocomposite was prepared by hydrothermal method to effectively remove the xanthate residue in sulfide ore flotation wastewater. The effects of different weight ratios of graphite in composites on photocatalytic activity were investigated. Under visible light, the 5wt% Mic-g/BiOI composite exhibited the highest degradation efficiency (94.36%) and the largest rate constant (0.02273 min−1) which was about 4.3 times higher than that of pure BiOI. The enhanced photocatalytic activity was mainly due to the synergy of a good contact interface between BiOI and graphite with good conduction resulting in the carriers’ rapid transfer. In addition, the mechanism of enhanced photocatalytic activity during the reaction was also investigated. The free radical trapping experiment demonstrated that the main active species in the photocatalytic process are •OH. This work provides a simple and effective approach to synthesizing the visible-light-driven photocatalyst with high efficiency for xanthate wastewater treatment.