Pulsed Electrochemical Degradation of Micropollutants via <i>In Situ</i> Generated Sulfate Radical: Rapid Reaction Kinetics and Low Energy Requirement
Zijun Zhou, Wentian Zheng, Mengjiao Xie, Yifan Ren, Meng Liu, Shijie You, Nadeeshani Nanayakkara, Yanbiao Liu
Abstract
The electrochemical oxidation technology shows considerable promise for decentralized water purification. However, conventional direct current (DC)-based electrochemical approaches encountered significant challenges in micropollutant degradation and energy efficiency due to inherent mass transfer limitation and high energy requirements. Herein, we introduced a pulse-induced strategy to strengthen the electrochemical oxidation process and enhance the decontamination of micropollutants. The proposed pulsed current (PC)-based electrochemical system leveraged the ubiquitous SO 4 2– in water to achieve the sequential electro-generation of S 2 O 8 2– and SO 4 •–, thereby improving efficiency and sustainability. Periodic fluctuations in anode potential induced by square-wave currents dynamically reconfigure the composition of the electric double layer (EDL) on the anode surface, resulting in an increase in the local concentration of reactants and facilitating the release of nonreactive ions. This mechanism established favorable alternating conditions for efficient purification of micropollutants. Under optimal conditions, the PC mode ( k obs = 0.028 min –1 ) exhibited a superior degradation rate constant for bisphenol A (BPA) compared to the DC mode ( k obs = 0.016 min –1 ) while simultaneously reducing energy consumption by 65.9%. Finite element simulations based on Fick’s second law revealed the release of S 2 O 8 2– and the replenishment of BPA at the anode surface under PC conditions. This study presents an efficient and economically viable strategy for environmental remediation that not only demonstrates exceptional treatment efficiency but also exhibits immense potential for widespread implementation across various environmental scenarios.