Facile synthesis of oxygen vacancies enriched ZnFe2O4 for effective photocatalytic peroxodisulfate activation

Water pollution is a global environmental problem that needs to be solved urgently. Among them, visible light-assisted catalytic peroxodisulfate (PDS) activation, as an efficient advanced oxidation technology, has great potential in organic wastewater treatment. Therefore, it is crucial to develop efficient photocatalysts based on PDS activation. Here, introducing defects in ZnFe2O4 to construct abundant oxygen vacancies (ZFOV) could not only promote the photocatalytic degradation of TCH, but also enhance magnetic nanoparticles-activated PDS. It was shown that the ZFOV/PDS/vis system could degrade TCH by ∼ 65 % within 30 min, about 1.23 times greater than that of ZFO/PDS/vis system. More importantly, the degradation rate was still over 58 % after three reuse cycles and extremely low leaching of Zn and Fe were observed. The effects of pH, PDS concentration, humic acid, anions and cations on TCH degradation in the presence of ZFOV/PDS/vis systems were also investigated in detail. Combining experimental results revealed that oxygen vacancies acted as catalytically centers which supplied abundant local electrons for the adsorbed S2O82− reaction to produce OH and SO4− via a single electron transfer process. Additionally, oxygen vacancies could also boost electron transfer and take part in the Fe2+/Fe3+ redox cycle. Our study might open up new avenues for designing high efficiency photocatalyst by means of surface engineering and PDS activation.