S-doped biomass catalyst triggered peroxydisulfate activation for methyl orange degradation

Abstract

Utilizing biomass as carbon precursor for peroxydisulfate (PDS) catalyst preparation could solve the problem of solid waste and water pollution treatment synergistically. However, the poor activity of pure biomass catalyst (BC) still needs further improvement. In this study, novel S-doped BC (S-BC) was prepared from chitosan (waste from agriculture and food industry) for PDS activation. With S doping, superior conductivity and defect (active sites) degree were achieved in S-BC. About 99.73% removal efficiency of methyl orange (MO) could also be achieved under the conditions of 3 mM PDS, 1.0 g L−1 S-BC, 10 mg L−1 MO, and initial pH of 3. This removal efficiency is higher than that of BC at 58.46%. Density functional theory calculation showed that the S2O82− ions were favorably adsorbed on the S-BC surface due to the negative adsorption energy of −3.048 eV. The O atoms in S–O bond (in S2O82−) could capture electrons from S atoms (in S-BC), leading the favorable breaking of this bond. Thus, resulting in the formation of surface attached radicals, O2·− and 1O2 for MO degradation, rather than SO4−· radicals in solution.