Enhanced degradation of 2,4,6-trichlorophenol by activated peroxymonosulfate with sulfur doped copper manganese bimetallic oxides

In this study, the sulfur-doped copper-manganese bimetallic oxides (labelled as S-CuMnO) were successfully fabricated via a calcination under N2 protection and used as a catalyst to activate peroxymonosulfate (PMS) for the degradation of 2,4,6-trichlorophenol (2,4,6-TCP). For comparison, sulfur-doped monometallic oxides including S-CuO and S-MnO and non-doped copper-manganese bimetallic oxides (CuMnO) were also synthesized through the same processes. Complete decomposition of 2,4,6-TCP (20 mg/L) and a high removal of total organic carbon (60%) were achieved within 30 min at 0.8 mM PMS, 0.07 g/L S-CuMnO and pH 7. S-CuMnO exhibited the highest catalytic activity among the tested catalysts, which may be attributed to the abundant Cu(I), increased specific surface area and superior electrical conductivity of S-CuMnO. The results of electron paramagnetic resonance (EPR) and radical scavenger tests testified that the reactive oxygen species (ROS) included SO4−, OH, O2− radicals and singlet oxygen (1O2), which were mainly responsible for the efficient removal of 2,4,6-TCP. In addition, it was found that the catalytic activity of the used S-CuMnO could be greatly enhanced by calcination again under N2 protection. Furthermore, the intermediates involved in the degradation of 2,4,6-TCP were identified and the possible degradation pathways were further proposed. This work opens up new perspectives for designing highly efficient catalysts to decompose organic pollutants in aqueous solution.