Nitrogen-doped carbocatalyst activated persulfate (PS) for oxidation polymerization of bisphenol A (BPA): importance of nonradical activation of PS

Abstract

Using metal-free catalysts is widely recognized as a promising approach toward wastewater remediation because of the absence of metal leaching. However, the oxidation products involved in the oxidation process and the corresponding mechanisms are still not clear. In this work, N-doped carbocatalysts (CN) were fabricated using as-prepared g-C₃N₄ and glucose solution, and the reactivity of the as-prepared catalysts was optimized by controlling calcination temperature. Correspondingly, increasing the calcination temperature promotes the catalytic oxidation of BPA. The positive correlations between the contents of pyridinic-N and graphitic-N and the k_obs values of BPA oxidation, as well as XPS analysis indicate the important roles of pyridinic-N and graphitic-N in BPA oxidation. According to the series of characterizations of the oxidation products and Raman analysis of the reaction process, the moderately activated persulfate (PS) on the CN catalyst is the predominant species in BPA oxidation and BPA can be oxidized to BPA polymers with high selectivity by H-abstraction under alkaline conditions. This work highlights the important role of the moderate activation of PS in the polymerization of phenolic contaminants under alkaline conditions, which enriches our understanding of the oxidation of aromatic contaminants by PS under alkaline conditions.