Degradation of benzene derivatives in the CuMgFe-LDO/persulfate system: The role of the interaction between the catalyst and target pollutants

A novel insight on the role of interactions between target pollutants and the catalyst in the copper-containing layered double oxide (LDO)-catalyzed persulfate (PS) system was elucidated in the present study. 4-Chlorophenol (4-CP), as a representative benzene derivative with a hydroxyl group, was completely removed within 5 min, which was much faster than the reaction of monochlorobenzene (MCB) without a hydroxyl group, with the degradation efficiency of 31.7% in 240 min. Through the use of radical quenching and surface inhibition experiments, it could be concluded that the interaction between 4-CP and CuMgFe-LDO, rather than free radicals, played a key role in the decomposition of 4-CP, while only the free radicals participated in the MCB degradation process. According to electron paramagnetic resonance and X-ray photoelectron spectroscopy data, the formation of a Cu(II)-complex between phenolic hydroxyl groups and surface Cu(II) was primarily responsible for the degradation of phenolic compounds, in which PS accepted one electron from the complex and generated sulfate radicals and chelated radical cations. The chelated radical cations transferred one electron to Cu(II) followed by Cu(I) generation and pollutant degradation successively. (C) 2019 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.