Optimized fabrication of Cu-doped ZnO/calcined CoFe‒LDH composite for efficient degradation of bisphenol a through synergistic visible-light photocatalysis and persulfate activation: Performance and mechanisms

A novel magnetically separable Cu/ZnO/CoFe‒CLDH composite, whose synthesis was optimized using the Taguchi approach, was optimally synthesized by hydrothermally coupling Cu-doped ZnO and calcined CoFe-LDH. The synthesized Cu/ZnO/CoFe‒CLDH was applied to construct a synergistic process of integrating visible-light photocatalysis (VPC) with persulfate activation (PSA) and to degrade bisphenol A (BPA). Various characterizations proved that Cu/ZnO/CoFe‒CLDH possessed excellent physicochemical, optoelectronic and magnetic properties, thereby enhancing the catalytic performance. The Cu/ZnO/CoFe‒CLDH composite achieved highly efficient BPA degradation during the synergistic VPC‒PSA process, and its reaction rate constant (0.74 h-1) was 6.17-, 4.11-, and 2.85-fold higher than that of Cu/ZnO, CoFe‒CLDH, and Cu/ZnO/CoFe‒CLDH (VPC only), respectively. Moreover, the effects of the catalyst dosage, initial pollutant concentration, solution pH, persulfate dosage and coexisting ions on BPA degradation were comprehensively investigated. Radical-trapping experiments revealed that the contributions of ·OH, SO4·‒, ·O2-, and 1O2 involved in BPA degradation. Based on the intermediates identified by LC/MS, the main BPA degradation pathways were determined, the overall trend of which reflects a decreasing ecotoxicity. This study verified the effectiveness of the synergistic VPC‒PSA process with Cu/ZnO/CoFe‒CLDH, which could be used as a new reference for removing organic micropollutants from water.