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

Abstract

• S-doped Cu-Mn bimetallic oxides (S-CuMnO) were successfully prepared. • 100% of 2,4,6-TCP (20 mg/L) was decomposed and 60% of TOC was removed by PMS activated with S-CuMnO. • SO 4 − , OH, O 2 − and 1 O 2 were responsible for the rapid degradation of 2,4,6-TCP. • Sulfur doping improved not only the catalytic activity of the catalyst but also its stability. In this study, the sulfur-doped copper-manganese bimetallic oxides (labelled as S-CuMnO) were successfully fabricated via a calcination under N 2 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 SO 4 − , OH, O 2 − radicals and singlet oxygen ( 1 O 2 ), 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 N 2 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.