Methyl silicate promotes the oxidative degradation of bisphenol A by permanganate: Efficiency enhancement mechanism and solid-liquid separation characteristics

Abstract

Permanganate (Mn (VII)) is an environmentally-friendly mild oxidant in the field of advanced oxidation treatment, however, manganese colloids are produced as byproducts, which is difficult to separate from water, resulting in secondary pollution. This study used potassium methyl silicates (PMS) as surface modifiers to improve the aggregation of colloidal particles by increasing the hydrophobicity of the colloidal surface, and then explored the oxidation of bisphenol A (BPA) by Mn (VII) under the influence of potassium methyl silicate and the solid-liquid separation performance of the reaction system. The results showed that PMS and sodium silicate (SS) substantially enhanced the degradation of BPA by Mn (VII), and the promotion effect of potassium methyl silicate was greater than that of sodium silicate. PMS provided not only enough adsorption sites for MnO2 colloidal particles formed in the reaction process, but also reaction space for Mn (VII) to catalyze the oxidation of BPA. PMS combined with the hydroxyl group of MnO2 through hydrogen bonds and forms hydrophobic PMS-MnO2 complexes which accelerated sedimentation by polycondensation. The strong adsorption ability of in situ formed MnO2 colloids also accelerated the deposition of PMS-MnO2 complex. This study solved the low efficiency problem of Mn (VII) oxidation degradation of organic pollutants and difficult separation of manganese containing colloids and provided a new strategy for the efficient utilization of Mn (VII).