A novel cobalt doped MOF-based photocatalyst with great applicability as an efficient mediator of peroxydisulfate activation for enhanced degradation of organic pollutants

The issue of environmental pollution is currently more and more serious, and developing an effective method with universal applicability for removing various contaminants is pretty necessary. Herein, a novel photocatalyst denoted as Co-doped MIL-53-NH2(Fe : Co 4 : 1) was constructed via a feasible solvothermal method, which served as an efficient mediator to activate peroxydisulfate for degrading various organic pollutants. Results from the current work indicated that doping Co with an appropriate proportion could enhance the optical absorption intensity of MIL-53-NH2 and reduce the band gap. Furthermore, a Co ion acting as a mediator could facilitate the charge transfer through a Co3+/Co2+ redox pathway, and thereby suppress the recombination of photogenerated electron-hole pairs. More interestingly, the Co-doped MIL-53-NH2 exhibited excellent and extensive degradation abilities for various organic pollutants including bisphenol A (BPA), antibiotics and organic dyes in the presence of peroxydisulfate (PS) under visible light irradiation. It was also found that OH and SO4- were the major contributors to the catalytic process. Total organic carbon (TOC) analysis indicated that the majority of the contaminants were degraded into CO2 and H2O. Even in the real samples, the developed Co-doped MIL-53-NH2/PS/solar system still possessed excellent performance for the degradation of BPA. Possible photocatalytic mechanisms and the kinetics were also investigated. Besides, the Co-doped MIL-53-NH2 had good catalytic reusability and stability. To sum up, this study provides a promising approach for removing organic pollutants from wastewater.