Fast degradation of florfenicol in SiC-Fe0 Fenton-like process: The overlooked role of atomic H* in peroxymonosulfate activation

Abstract

Herein, the SiC-Fe0 powders were mechanically synthesized and employed for activation of peroxymonosulfate (PMS) to remove florfenicol (FLO). Compared to Fe0/PMS system, up to a 3.97-fold increase in degradation rates of 20 mg/L FLO was observed by 25% (w/w) SiC-Fe0/PMS system in 5 mins, which could be attributed to the increased specific surface area and electron transfer rate of SiC-Fe0. Both the radical and non-radical processes were involved in the SiC-Fe0/PMS system, in which 1O2 and •O2− played the dominant role in the FLO degradation and SO4•− as well as •OH also participated in the system. ROSs investigation suggested that 1O2, •O2−, SO4•− were mainly generated from the decomposition of PMS and •OH was mainly derived from the ZVI (or Fe2+)-catalyzed activation of O2. Meanwhile, H* has a nonnegligible role in PMS activation or the transformation of iron species. Five intermediates of FLO in SiC-Fe0/PMS system were identified and a significant removal of the overall toxicity was observed. The degradation pathways of FLO were proposed to be hydrolysis, hydroxylation and dechlorination. Besides, this SiC-Fe0/PMS system shows effective removal rate for 2-chlorophenol, acetaminophen, tetrabromobisphenol A and carbamazepine, and the FLO-polluted surface water and artificial wastewater. Overall, this study demonstrated that SiC-Fe0 was promising in practical application and provided new insights into the generation mechanisms of ROSs in the ZVI/PMS system.