High efficient manganese-nitrogen co-doped lignin-based carbon catalysts to activate peroxymonosulfate for the degradation of bisphenol A

Mn-based catalysts have attracted widespread attention because of their low price, sufficient source and effective activation of peroxymonosulfate (PMS) to generate free radicals for rapid degradation of organic pollutants. In most pulp and paper industries, lignin sulfonates are usually the waste streams or serve as low-value fuels. However, lignin sulfonates due to its abundant aromatic structure and sulfur functional groups, is regarded as an excellent carbon resource. The stability of supported Mn-based catalyst can be improved by doping nitrogen atoms through the formation of covalent bonds. In this work, Mn, N co-doped carbon composites were prepared by one-step carbonization, and the catalysts were characterized by TEM, XRD, XPS, etc. and the results show that the catalysts with low Mn content mainly contain highly dispersed Mn species such as MnNx species, while high Mn loading catalyst includes some MnOx species. The catalytic performances of the catalysts were evaluated by the degradation of bisphenol A (BPA) by activating PMS, which can reach >95 % in 8 min. Catalyst recyclability experiments demonstrate that carbon-based materials have good stability without the remarkable leaching of metal ions during the degradation reaction. The results of radical capture experiments and radical-assisted ESR show that the active species of the reaction is non-free radical singlet oxygen (1O2), which can effectively degrade BPA. This study provides a facile and efficient method to prepare high-efficient Mn-N-C catalysts in the catalytic decomposition of BPA.