Mineralization of organics in hazardous waste sulfuric acid by natural manganese oxide ore and a combined MnO2/activated carbon treatment to produce qualified manganese sulfate.

To effectively dispose and utilize the hazardous waste H2SO4 generated from alkylation, an environmentally friendly and feasible technology for the simultaneous oxidative degradation of organics and consumption of H2SO4 was developed. Pyrolusite, a natural manganese oxide ore, was used for the oxidative degradation and mineralization of the organics, and reduction leaching of Mn from the pyrolusite occurred simultaneously. The total organic carbon (TOC) removal and Mn leaching efficiency were 46% and 16.44%, respectively. In addition, pyrites was applied as a reductant to extract Mn from the pyrolusite, and an Mn leaching efficiency of 98.31% was obtained under the optimized conditions of 4/1 liquid/solid ratio, 350 rpm stirring speed, 1.5 mol L-1 H2SO4 concentration, and 95 °C for 1 h in the first oxidative degradation stage and a molar ratio of FeS2/MnO2 of 0.55/1 for 4 h in the reduction leaching stage. Subsequently, a combined treatment of MnO2/activated carbon was developed for further oxidation and adsorption of the organics in the solution, with the TOC removal of 84.11%. The resulting purified MnSO4 solution was concentrated to produce qualified MnSO4∙H2O, which met the requirements of an industrial product. This technology showed application potential in highly-efficient removal of hazardous organic contaminates.

PMID 30562658  /  Cai X, Shen F, Zhang Y, Hu H, Huang Z, Yin Y, Liang X, Qin Y, Liang J