Synchronous removal of tetracycline and copper (II) over Z‑scheme BiVO4/rGO/g-C3N4 photocatalyst under visible-light irradiation

The combined pollution of heavy metals and organic pollutants in water body has become one of vital environmental issues. Herein, a series of BiVO4/rGO/g-C3N4 nanocomposites were synthesized for concurrent removals of organic pollutant and heavy metal. Results showed that using the optimized photocatalyst BiVO4/rGO/g-C3N4-28, tetracycline (TC) removal of 87.3% and copper (Cu (II)) removal of 90.6% were achieved under visible-light irradiation within 3 h, respectively; much higher than those using BiVO4 and g-C3N4. More importantly, synergistic effect of TC and Cu (II) removals occurred on the surface of BiVO4/rGO/g-C3N4 in the TC-Cu (II) coexistence condition. Additionally, the ·OH and ·O2ˉ were the most important active species for TC oxidation, while photogenerated electrons were the most responsible for Cu (II) reduction. Results of various characterizations and electron spin resonance test demonstrated that BiVO4/rGO/g-C3N4 was a Z-scheme photocatalyst. Based on the identified intermediates, possible degradation pathways and mechanisms for photocatalytic degradation of TC were proposed. This study advances the development and mechanism of photocatalysts for collaborative removal of pollutants.