Fabrication of highly efficient Bi2WO6/CuS composite for visible-light photocatalytic removal of organic pollutants and Cr(VI) from wastewater

A visible-light-driven Bi2WO6/CuS p-n heterojunction was fabricated using an easy solvothermal method. The Bi2WO6/CuS exhibited high photocatalytic activity in a mixed system containing rhodamine B (RhB), tetracycline hydrochloride (TCH), and Cr (VI) under natural conditions. Approximately 98.8% of the RhB (10 mg/L), 87.6% of the TCH (10 mg/L) and 95.1% of the Cr(VI) (15 mg/L) were simultaneously removed from a mixed solution within 105 min. The removal efficiencies of TCH and Cr(VI) increased by 12.9% and 20.4%, respectively, in the mixed solution, compared with the single solutions. This is mainly ascribed to the simultaneous consumption electrons and holes, which increases the amount of excited electrons/holes and enhances the separation efficiency of photogenerated electrons and holes. Bi2WO6/CuS can be applied over a wide pH range (2-6) with strong photocatalytic activity for RhB, TCH and Cr(VI). Coexisiting dissolved organic matter in the solution significantly promoted the removal of TCH (from 74.7% to 87.2%) and Cr(VI) (from 75.7% to 99.9%) because it accelerated the separation of electrons and holes by consuming holes as an electron acceptor. Removal mechanisms of RhB, TCH, and Cr(VI) were proposed, Bi2WO6/CuS was formed into a p-n heterojunction to efficiently separate and transfer photoelectrons and holes so as to drive photocatalytic reactions. Specifically, when reducing pollutants (e.g., TCH) and oxidizing pollutants (e.g., Cr(VI)) coexist in wastewater, the p-n heterojunction in Bi2WO6/CuS acts as a bridge to shorten the electron transport and thus simultaneously increase the removal efficiencies of both types of pollutants. (c) Higher Education Press 2020

Automated summary

A visible-light-driven Bi2WO6/CuS p-n heterojunction with high photocatalytic activity was fabricated to simultaneously remove pollutants in a mixed system containing RhB, TCH, and Cr(VI). The presence of dissolved organic matter significantly promoted the removal of TCH and Cr(VI) by accelerating the separation of electrons and holes. The p-n heterojunction formed in Bi2WO6/CuS acted as a bridge to shorten the electron transport and increase the removal efficiencies of both reducing and oxidizing pollutants in wastewater.