Sustainable Generation of Sulfate Radicals and Decontamination of Micropollutants via Sequential Electrochemistry

Abstract

The removal of emerging micropollutants in the aquatic environment remains a global challenge. Conventional routes are often chemically, energetically, and operationally intensive, which decreases their sustainability during applications. Herein, we develop an advanced chemical-free strategy for micropollutants decontamination that is solely based on sequential electrochemistry involving ubiquitous sulfate anions in natural and engineered waters. This can be achieved via a chain reaction initiated by electrocatalytic anodic sulfate (SO42−) oxidation to produce persulfate (S2O82−) and followed by a cathodic persulfate reduction to produce sulfate radicals (SO4̇−). These SO4̇− are powerful reactive species that enable the unselective degradation of micropollutants and yield SO42− again in the treated water. The proposed flow-through electrochemical system achieves the efficient degradation (100.0%) and total organic carbon removal (65.0%) of aniline under optimized conditions with a single-pass mode. We also reveal the effectiveness of the proposed system for the degradation of a wide array of emerging micropollutants over a broad pH range and in complex matrices. This work provides the first proof-of-concept demonstration using ubiquitous sulfate for micropollutants decontamination, making water purification more sustainable and more economical.

Keywords

• Advanced oxidation
• Chain reaction
• Sulfate radical
• Micropollutants
• Sequential electrochemistry