Highly efficient solar-light-driven photocatalytic degradation of pollutants in petroleum refinery wastewater on hierarchically-structured copper sulfide (CuS) hollow nanocatalysts

Hierarchically-structured CuS hollow nanocatalysts (HS-CuS-HNCs) were prepared in high yield (> 95%) by a simple chemical solution deposition method at room temperature, and then used to photocatalytically degrade pollutants in petroleum refinery wastewater (PRW) under solar light radiation. Compared to bulk-size CuS catalyst, HS-CuS-HNCs with narrower band gap (E-g = 0.96 eV) exhibited strong visible-light absorption, highly enhanced quantum efficiency and large specific area (101.5 m(2) g(-1)) characteristics. HS-CuS-HNCs showed significantly enhanced activity for the degradation of pollutants under both artificial and real solar light source (about 66% of COD in PRW was removed in 3 h degradation under conditions of 1.0 g/L catalyst and 7.6 pH). The activity of HS-CuS-HNCs was drastically enhanced further in the presence of hydrogen peroxide (H2O2) (98% of COD in PRW was removed in 2 h under conditions of 1.0 g/L catalyst, 3.0 g/L H2O2 and 7.6 pH), which was attributed to the synergistic effect between HS-CuS-HNCs and H2O2, leading to the enhanced quantum efficiency and production of more reactive oxygen species (ROS). Radical-quenching experiments revealed that the contributions of ROS to COD reduction in PRW followed the sequence: superoxide anion (center dot O-2(-)) > singlet oxygen (O-1(2)) > hydroxyl radical (center dot OH). Important factors such as catalyst dose, H2O2 dose and initial pH had influences on the degradation efficiency. This work provided a hierarchically-structured non-TiO2-based nanophotocatalyst with high performance for efficiently utilizing solar energy to oxidatively degrade pollutants in PRW fast and deeply.

Automated summary

In this study, hierarchically-structured CuS hollow nanocatalysts were prepared and demonstrated to have effective catalytic degradation ability. By optimizing the catalyst properties and conditions, efficient degradation of pollutants in petroleum refinery wastewater can be achieved using solar light radiation.