Electrochemical activation of periodate with graphite electrodes for water decontamination: Excellent applicability and selective oxidation mechanism

• Published in: Water research (Oxford) 2023-07, Vol.240, p.120128-120128, Article 120128
• Main Authors: Luo, Mengfan, Zhang, Heng, Shi, Yang, Zhao, Jia, Feng, Can, Yin, Jialong, Liu, Yang, Zhou, Peng, Xiong, Zhaokun, Lai, Bo
• Format: Article
• Language: English
• Subjects: bisphenol A; Decontamination; disinfection; Electrochemical activation; electrochemistry; Electrodes; Environmental Pollutants; graphene; Graphite - chemistry; iodates; oxidation; Oxidation-Reduction; Periodate; Phenols; pollutants; QSAR; quantitative structure-activity relationships; Singlet oxygen; stoichiometry; Water; Water Pollutants, Chemical - chemistry
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2023.120128

•Electrochemical activation using graphite electrodes can successfulliy activate periodate (PI) for water decontamination.•1O2 as the primary reactive species is produced in the E-GP/PI system through the combination of O2•−.•A dual descriptor model is proposed to reveal the selective oxidation behavior of 1O2.•The E-GP/PI system shows strong pH tolerance, long-lasting performance, and high resistance to aqueous matrices.•BPA degradation mechanism is proposed based on experimental results and DFT calculations. Advanced oxidation technologies based on periodate (PI, IO4−) have garnered significant attention in water decontamination. In this work, we found that electrochemical activation using graphite electrodes (E-GP) can significantly accelerate the degradation of micropollutants by PI. The E-GP/PI system achieved almost complete removal of bisphenol A (BPA) within 15 min, exhibited unprecedented pH tolerance ranging from pH 3.0 to 9.0, and showed more than 90% BPA depletion after 20 h of continuous operation. Additionally, the E-GP/PI system can realize the stoichiometric transformation of PI into iodate, dramatically decreasing the formation of iodinated disinfection by-products. Mechanistic studies confirmed that singlet oxygen (1O2) is the primary reactive oxygen species in the E-GP/PI system. A comprehensive evaluation of the oxidation kinetics of 1O2 with 15 phenolic compounds revealed a dual descriptor model based on quantitative structure−activity relationship (QSAR) analysis. The model corroborates that pollutants exhibiting strong electron-donating capabilities and high pKa values are more susceptible to attack by 1O2 through a proton transfer mechanism. The unique selectivity induced by 1O2 in the E-GP/PI system allows it to exhibit strong resistance to aqueous matrices. Thus, this study demonstrates a green system for the sustainable and effective elimination of pollutants, while providing mechanistic insights into the selective oxidation behaviour of 1O2. [Display omitted]