Sodium hypochlorite and Cu-O-Mn/ columnar activated carbon catalytic oxidation for treatment of ultra-high concentration polyvinyl alcohol wastewater.

Complete degradation of high concentration polyvinyl alcohol (PVA) is challenging. In this article, a two-stage process of NaClO pre-oxidation and columnar activated carbon (loaded with metal active components) catalytic oxidation was used to treat high concentration PVA wastewater. The degree of polymerization of PVA is 2400 and the water concentration is 15 wt %. In the first stage, NaClO efficiently broken long chain to short, the viscosity of PVA solution decreased from 45,100 mPaS to 4.65 mPaS. And in the second stage, the short chain was further oxidized to small molecules under HO with catalysts. The solution COD decreased from 206,240 mg/L to 38.38 mg/L. The composition of catalysts and the reaction conditions were optimized, the degradation mechanism was discussed. According to the experimental results, small pore size (8-10 mesh) activated carbon loaded copper and manganese catalyst (CMAC-S) was the best choice. The optimal conditions of CMAC-S were: molar ratio of copper to manganese was 2:1, the loading rate was 25 wt% and the dosage was 9.76 mg/100 ml. The whole process is mild (25 °C-40 °C) and reaction time is short (100 min). Moreover, free radical scavenging experiments shown that the catalytic oxidation stage follows the mechanism of hydroxyl radical reaction.