Selective oxidation of organic pollutants over a new Co-based MOF via peroxymonosulfate activation under UV light: Performance and mechanism

Abstract

The oxidation processes dominated by nonradical singlet oxygen (1O2) could accomplish highly selective oxidation, which attracted increasing attentions in recent years. However, the 1O2 generation path still remains ambiguous. In this study, a new 3D Co-based metal–organic framework (MOF) namely BUC-100 was solvothermally synthesized from CoCl2·6H2O, 1,3,5-tris(1-imidazolyl) benzene (TIB) and terephthalic acid (H2BDC). The as-prepared BUC-100 was used to selectively degrade various organic contaminants including both electron-donating and electron-withdrawing contaminants. The results revealed that the organic contaminants with electron-donating functional groups like –OH, –NH2 and alkyl groups rather than electron-withdrawing functional groups like –NO2 were easier to be degraded without significant interference of co-existing anions. Furthermore, Rhodamine B (RhB) was adopted as a pollutant model to optimize the reaction conditions and explore the possible oxidative degradation mechanism. The RhB degradation efficiency was up to 100% within 40 min in the presence of 0.3 g/L BUC-100, 0.4 mM peroxymonosulfate (PMS) and LED UV light irradiation. According to the results of trapping experiments, electron spin resonance (ESR) characterization, and quantitative/qualitative experiments, it was found that 1O2 played the dominant role in organic pollutants decontamination, in which the self-reaction of SO5•− was the main source of 1O2.