Bimetallic oxides with package structure for enhanced degradation of bisphenol a through peroxymonosulfate activation

Cobalt oxide (CoO) could activate peroxymonosulfate (PMS) to remove pollutants but the catalytic performance was restricted by limited active sites and it was with risk of harmful cobalt ion leaching. In order to solve these problems, bimetallic oxides with package structure were researched by dispersing CoO nanoparticles on a stable support (magnesium oxide, MgO) via simple one-step coprecipitation method. Co-Mg bimetallic oxides with minute quantities of CoO and highly dispersed structure could efficiently activate PMS for degradation of bisphenol A (BPA). The catalytic properties of catalysts with different molar ratios of Co and Mg were evaluated. The optimal molar ratio (0.075:15) of Co and Mg was found in the Co-Mg bimetallic oxides, which could maximize its catalytic performance for PMS in a wide pH range. Influences of different systems, catalyst dosages, PMS concentrations, temperatures, initial pH values and mineralization rates were researched for BPA degradation. And the oxidation capacities to remove BPA in the different aqueous matrices were evaluated for the catalyst/PMS system. The addition of anions and nature organic matter (NOM) showed that there existed positive (Cl- and H2PO4-) and negative (NO3-, HCO3-, HPO42- and NOM) effects for BPA degradation. Additionally, main reactive radicals were certified by quenching experiments. Four successive experiments and evaluation of concentration of cobalt ion leaching illustrated good stability of the catalyst, which was related with its package structure. Finally, activation mechanism of PMS, proposed degradation pathways of BPA and acute toxicity of degradation intermediates of BPA were analyzed.