Oxidative degradation of acid red 73 in aqueous solution over a three-dimensional OMS-2 nanomaterial

Abstract

Manganese oxide octahedral molecular sieve (OMS-2) and doped derivatives were synthesized via a one-pot reflux method and used in heterogeneous oxidative degradation of acid red 73 in aqueous solution. Doping metals and dopant loading influenced morphology and oxidation ability of the OMS-2-based materials significantly. Ce and Bi co-doped OMS-2 (Ce-Bi-OMS-2) demonstrated enhanced oxidation reactivity and recyclability for the degradation of acid red 73 because of the unique three-dimensional morphology, the enhanced surface area and the rich surface oxygen vacancies. About 96% of acid red 73 at a concentration of 200 mg/L was degraded under neutral conditions over Ce-Bi-OMS-2 doped by 8 wt% metals. COD and TOC removal efficiencies were 33% and 25% respectively, and the toxicity of the wastewater to Escherichia coli was reduced by Ce-Bi-OMS-2 mediated degradation. The degradation pathway was carefully investigated and kinetic study indicated that the co-doping substantially lowered the apparent activation energy from 31.22 kJ/mol (original OMS-2) to 18.48 kJ/mol.