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

Advanced oxidation technologies based on periodate (PI, O-I(4)-) 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 (O-1(2)) is the primary reactive oxygen species in the E-GP/PI system. A comprehensive evaluation of the oxidation kinetics of O-1(2) 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 pK(a) values are more susceptible to attack by O-1(2) through a proton transfer mechanism. The unique selectivity induced by O-1(2) 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 O-1(2).

Automated summary

In this study, electrochemical activation using graphite electrodes was found to significantly enhance the degradation of micropollutants by periodate. The system showed high efficiency in removing bisphenol A, wide pH tolerance, and long-term stability. It also reduced the formation of iodinated disinfection by-products by transforming periodate into iodate.