Tackling Challenges of Long-Term Electrode Stability in Electrochemical Treatment of 1,4-Dioxane in Groundwater.

Abstract

Electrochemical advanced oxidation is an appealing point-of-use groundwater treatment option for removing pollutants such as 1,4-dioxane, which is difficult to remove by using conventional separation-based techniques. This study addresses a critical challenge in employing electrochemical cells in practical groundwater treatment─electrode stability over long-term operation. This study aims to simulate realistic environmental scenarios by significantly extending the experimental time scale, testing a flow-through cell in addition to a batch reactor, and employing an electrolyte with a conductivity equivalent to that of groundwater. We first constructed a robust titanium suboxide nanotube mesh electrode that is utilized as both anode and cathode. We then implemented a pulsed electrolysis strategy in which reactive oxygen species are generated during the anodic cycle, and the electrode is regenerated during the cathodic cycle. Under optimized conditions, single-pass treatment through the cell (effective area: 2 cm2) achieved a remarkable 65-70% removal efficiency for 1,4-dioxane in the synthetic groundwater for over 100 h continuous operation at a low current density of 5 mA cm-2 and a water flux of 6 L m-2 h-1. The electrochemical cell and pulse treatment scheme developed in this study presents a critical advancement toward practical groundwater treatment technology.