Simultaneous oxidative degradation of toxic acid wastewater from production of nitrocellulose and release of Mn 2+ from low‐grade MnO 2 ore as oxidant

BACKGROUND The development of a low cost and simple treatment process is necessary for toxic organic effluents. This work investigated the feasibility of the oxidative degradation of toxic nitrocellulose acid wastewater ( NAW ) using low‐grade MnO 2 ore as a cheap oxidant and the simultaneous release of Mn 2+ for preparation of electrolytic manganese metal ( EMM ). RESULTS Under optimal conditions of 100 g L −1 MnO 2 ore, 200‐mesh ore particles, concentrated H 2 SO 4 to NAW ratio of 0.12:1, contact time 120 min, stirring speed 160 rpm and temperature 90 °C, the total organic carbon ( TOC ) removal of the NAW and Mn release efficiency reached 98% and 97%, respectively. The TOC removal was significantly correlated with the release of Mn. The inert layer model best described the extraction behavior of Mn and apparent activation energy was 54.1 kJ mol −1 . Concomitant with TOC removal, the degradation of polysaccharide, phenol, protein and nitrocellulose occurred; meanwhile, the MnO 2 totally dissolved owing to reductive extraction of Mn. CONCLUSION A highly significant correlation occurred between TOC removal and Mn 2+ release, suggesting a reciprocal causation. The present process was competent to simultaneously realize oxidation degradation of NAW and reductive dissolution of Mn 2+ for EMM production, displaying a promising application prospect. © 2016 Society of Chemical Industry