Solid-waste-recycled CuO/CN S-scheme heterojunctions for efficient photocatalytic antibiotic degradation.

With the increasing severity of antibiotic pollution, the development of effective green photocatalysts for the degradation of organic pollutants in water has attracted extensive attention. Herein, we have prepared CuO/CN S-scheme heterogeneous photocatalysts recycling Cu resources from Cu-containing electroplating sludges. By mediating the acid leaching process, copper in electroplating sludges was dissolved selectively, while other metal species were retained in the residues. The CuO/CN S-scheme heterojunction not only effectively suppressed the recombination of photogenerated charge carriers of CN, but also preserved the strong reducing electrons of CN and the strong oxidizing holes of CuO, retaining the outstanding redox ability of CuO/CN. Therefore, CuO/CN photocatalysts exhibited good catalytic performance in the degradation of tetracycline (over 95% in 2 h). In addition, CuO/CN S-scheme heterojunctions achieved a high mineralization rate (45% in 2 hours), thus reducing secondary pollution during the degradation. This work provides a reliable direction for designing novel S-scheme heterojunction photocatalytic materials by using metal sources in solid waste.