Sulfamethoxazole degradation by regulating active sites on distilled spirits lees-derived biochar in a continuous flow fixed bed peroxymonosulfate reactor

Defect type and interactions among active sites are critical in heterogeneous peroxymonosulfate (PMS) system. Herein, a continuous flow fixed bed PMS reactor with distilled spirits lees derived biochar (DSLBs)/quartz wool was designed to explore the synergistic roles of active sites. Satisfyingly, with high graphite N, CO content and defect degree, DSLB-800 exhibited superior catalytic activity, durability and applicability for sulfamethoxazole (SMX) removal. The dominant contribution of 1O2, and minor roles of SO4•− and •OH were confirmed. Single graphite N, CO and C-O, combined interactions between graphite N and pyridine N, graphite N and pyrrole N, pyridine N and pyrrole N, CO and OC-O, OC-O and C-O, as well as interactions among graphite N, pyridine N and pyrrole N contributed to 1O2 generation. Notably, the double vacancy defect was also a preferential site for 1O2 production. This study advances mechanistic understanding of collaborative contribution of active sites to PMS activation.