Enhanced degradation and toxicity evaluation of bisphenol A by ZnFe2O4@CuO Z-type heterojunction-PMS-visible light system.

The efficient degradation of bisphenol A (BPA) is a key challenge in the field of environmental remediation, and traditional methods commonly suffer from low efficiency and the risk of secondary pollution. In this study, a magnetically recoverable ZnFe2O4@CuO heterojunction photocatalyst was constructed by coprecipitation-calcination method, which was used to activate peroxymonosulfate (PMS) to degrade BPA under visible light. This Z-scheme heterojunction is advantageous for charge separation, with ZnFe2O4 as the substrate. Its magnetic properties enable the catalyst to recover quickly within 30 s while maintaining high stability and wide pH adaptability. Under optimal conditions, the degradation rate of BPA reached 99 % within 18 min, and the total organic carbon (TOC) removal rate was 86.8 %. The quenching experiment and electron spin resonance (ESR) analysis confirmed that sulfate ions (SO4-·) and singlet oxygen (1O2) play a dominant role in the degradation process, and hydroxyl radicals (·OH) are the key active species for PMS activation. High performance liquid chromatography mass spectrometry (HPLC-MS) analysis identified the main degradation pathways of BPA, while toxicological evaluations using mung bean experiments and TEST indicated that the ecological toxicity of the degradation intermediates was significantly reduced. This study provides an effective strategy for the degradation of organic pollutants via hydroxyl radical-mediated photocatalytic PMS activation in heterojunction systems.