US EPA

7326068 

Journal Article 

Formation and degradation mechanisms of CX3R-type oxidation by-products during cobalt catalyzed peroxymonosulfate oxidation: The roles of Co3+ and SO4· 

Chen, T; Yu, Z; Xu, T; Xiao, R; Chu, W; Yin, D 

2021 

Yes 

Journal of Hazardous Materials
ISSN: 0304-3894
EISSN: 1873-3336 

Elsevier 

AMSTERDAM 

405 

124243 

English 

33109408 

10.1016/j.jhazmat.2020.124243 

WOS:000616143200003 

Sulfate radical (SO4·-)-based advanced oxidation processes (AOPs) attract increasing attention in the control of micropollutants. However, SO4·- can react with other chemicals present in water and result in undesired oxidation by-products (OBPs) generation. The formation and degradation mechanisms of CX3R-type OBPs during cobalt catalyzed peroxymonosulfate (Co2+/PMS) oxidation were investigated. In the formation of CX3R-type OBPs, both Co3+ and SO4·- could convert chloride to free chlorine that then reacted with natural organic matter, leading to the formation of CX3R-type OBPs. The concentrations of trichloromethane, chloral hydrate, dichloroacetonitrile, dichloroacetamide and trichloroacetamide after 15 min reaction were 9.8, 3.9, 1.2, 5.9 and 22.3 nM, respectively. Compared to SO4·-, Co3+ played a more significant role in the CX3R-type OBP formation and calculated toxicity values of CX3R-type OBPs. CX3R-type OBPs could not only be formed but also be degraded at the same time during Co2+/PMS oxidation. As for the degradation of CX3R-type OBPs, both Co3+ and SO4·- could transform CX3R-type OBPs to chloride. Compared to Co3+, SO4·- played a more important role in the degradation of CX3R-type OBPs and the conversion from chloride to final by-product chlorate. The adverse effects that results from Co3+ need more attention in SO4·--based AOPs application. 

SO4 center dot--based advanced oxidation processes; Free radical; CX3R-type oxidation by-products; Toxicity 

JOURNAL OF HAZARDOUS MATERIALS