Cobalt(VI)-oxo species-mediated selective oxidation of electron-rich organic contaminants by Co-loaded hydroxylated g-C3N4 with high resistance to an inhibitory effect of background constituents

• Published in: Applied surface science 2024-10, Vol.669, p.160545, Article 160545
• Main Authors: Lee, Youn-Jun, Son, Chae-Young, Jeong, Yoo Jae, Cho, In Sun, Park, Seong-Jik, Lee, Chang-Gu
• Format: Article
• Language: English
• Subjects: Anti-interference; Cobalt-oxo species; Ionization potential; Persulfate activation
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2024.160545

[Display omitted] •Co-loaded hydroxylated g-C3N4 was prepared by the facile impregnation method.•Co(IV)O exhibits notably higher steady-state concentration than ROS.•Co(IV)O showed high reactivity toward electron-rich pollutants.•Co(IV)O was highly resistant to the inhibitory effect of the complex water matrix. Understanding of the selectivity of high-valent cobalt-oxo species (Co(IV)O) toward diverse organic pollutants with different characteristics in the presence of background constituents remains limited. Here, we prepared Co-loaded hydroxyl group-grafted graphitic carbon nitride (Co-OHCN) using a facile method for the effective formation of Co(IV)O. The role of the hydroxyl group in anchoring Co ions was investigated using several characterization methods (TEM, XRD, FT-IR, and XPS). Co-OHCN exhibited superior efficiency in degrading 4-chlorophenol (4-CP) (98.0 % ± 0.3 %) within 15 min of peroxymonosulfate (PMS) activation reaction. In the Co-OHCN/PMS system, Co(IV)O had the highest steady-state concentration ([Co(IV)O] = 1.40 × 10−10 M), significantly exceeding that of other reactive oxygen species (ROS) ([SO4−] = 9.22 × 10−13 M, [OH] = 1.82 × 10−13 M). The dominant role of Co(IV)O in 4-CP degradation was further revealed through scavenger tests, probe methods, and electrochemical analysis. Additionally, the anti-interference of Co(IV)O in the degradation of electron-rich organic substrates to background constituents (NOM and halide ions) was systemically validated using three organic pollutants with different ionization potential values (diclofenac, 4-CP, and benzoic acid). This study provides insight into an efficient strategy for Co(IV)O -mediated pollutant elimination and organic substrate-dependent selectivity of Co(IV)O during water decontamination.