The effect of nanoscale zero-valent iron-loaded N-doped biochar on the generation of free radicals and nonradicals by peroxydisulfate activation

Abstract

To gain a deeper understanding of the roles of N-doping in nanoscale zero-valent iron (nZVI)-based catalysts for persulfate-based advanced oxidation processes (AOPs), five catalysts, biochar (BC), N-doped biochar (NBC), nZVI, nZVI-loaded pristine biochar (nZVI@BC) and nZVI-loaded N-doped biochar (nZVI@NBC), were prepared for peroxydisulfate (PDS) activation to degrade bisphenol A (BPA). Because of the synergy between nZVI and NBC, nZVI@NBC exhibited a better catalytic ability and possessed more active species in PDS activation. Mechanisms were proposed including radical pathways (HO• and SO4•−) and nonradical pathways (1O2). PDS activation by Fe0 generated radicals while graphitic N, pyridinic N and CO in nZVI@NBC were employed for 1O2 generation. In addition, nZVI@NBC showed a high anti-interference capacity and stability. The analysis of the intermediates produced by the degradation of BPA confirmed that HO•, SO4•− and 1O2 are involved in the reaction of the nZVI@NBC system. Our research provides a new perspective on the synergistic effect of nZVI and N-doped materials in AOPs for endocrine disrupter degradation.