Catalytic activation of persulfate by nanoscale zero-valent iron-derived supported boron-doped porous carbon for bisphenol A degradation.

In this study, boron-doped porous carbon materials (BCs) with high surface areas were synthesized employing coffee grounds as carbon source and sodium bicarbonate and boric acid as precursors; afterward, nanoscale zero-valent iron (nZVI) and BCs composites (denoted as nZVI@BCs) were further prepared through reduction of FeSO4 by NaBH4 along with stirring. The performance of the nZVI@BCs for activating persulfate (PS) was evaluated for the degradation of bisphenol A (BPA). In comparison with nZVI@Cs/PS, nZVI@BCs/PS could greatly promote the degradation and mineralization of BPA via both radical and non-radical pathways. On the one hand, electron spin resonance and radical quenching studies represented that •OH, SO4•-, and O2•- were mainly produced in the nZVI@BCs/PS system for BPA degradation. On the other hand, the open circuit voltages of nZVI@BCs and nZVI@Cs in different systems indicated that non-radical pathway still existed in our system. PS could grab the unstable unpaired electron on nZVI@BCs to form a carbon material surface-confined complex ([nZVI@BCs]*) with a high redox potential, then accelerate BPA removal efficiency via direct electron transfer. Furthermore, the performances and mechanisms for BPA degradation were examined by PS activation with nZVI@BC composites at various conditions including dosages of nZVI@BCs, BPA and PS, initially pH value, temperature, common anions, and humid acid. Therefore, this study provides a novel insight for development of high-performance carbon catalysts toward environmental remediation.