@article {doi:10.1021/acs.est.2c04903,
	title = {Revealing the Generation of High-Valent Cobalt Species and Chlorine Dioxide in the Co3O4-Activated Chlorite Process: Insight into the Proton Enhancement Effect},
	journal = {Environmental Science \&amp; Technology},
	volume = {57},
	number = {5},
	year = {2023},
	note = {PMID: 36607701},
	pages = {1882-1893},
	abstract = {A Co3O4-activated chlorite (Co3O4/chlorite) process was developed to enable the simultaneous generation of high-valent cobalt species [Co(IV)] and ClO2 for efficient oxidation of organic contaminants. The formation of Co(IV) in the Co3O4/chlorite process was demonstrated through phenylmethyl sulfoxide (PMSO) probe and 18O-isotope-labeling tests. Both experiments and theoretical calculations revealed that chlorite activation involved oxygen atom transfer (OAT) during Co(IV) formation and proton-coupled electron transfer (PCET) in the Co(IV)-mediated ClO2 generation. Protons not only promoted the generation of Co(IV) and ClO2 by lowering the energy barrier but also strengthened the resistance of the Co3O4/chlorite process to coexisting anions, which we termed a proton enhancement effect. Although both Co(IV) and ClO2 exhibited direct oxidation of contaminants, their contributions varied with pH changes. When pH increased from 3 to 5, the deprotonation of contaminants facilitated the electrophilic attack of ClO2, while as pH increased from 5 to 8, Co(IV) gradually became the main contributor to contaminant degradation owing to its higher stability than ClO2. Moreover, ClO2{\textendash} was transformed into nontoxic Cl{\textendash} rather than ClO3{\textendash} after the reaction, thus greatly reducing possible environmental risks. This work described a Co(IV)-involved chlorite activation process for efficient removal of organic contaminants, and a proton enhancement mechanism was revealed.},
	doi = {10.1021/acs.est.2c04903},
	url = {https://doi.org/10.1021/acs.est.2c04903},
	author = {Su, Ruidian and Li, Nan and Liu, Zhen and Song, Xiaoyang and Liu, Wen and Gao, Baoyu and Zhou, Weizhi and Yue, Qinyan and Qian Li}
}
