Advanced Electrochemical Oxidation of 1,4-Dioxane via Dark Catalysis by Novel Titanium Dioxide (TiO_2) Pellets

摘要

1,4-dioxane is an emerging groundwater contaminant with significant regulatory implications. Because it is resistant to traditional groundwater treatments, remediation of 1,4-dioxane is often limited to costly ex situ UV-based advanced oxidation. By varying applied voltage, electrical conductivity, seepage velocity, and influent contaminant concentration in flow-through reactors, we show that electrochemical oxidation is a viable technology for in situ and ex situ treatment of 1,4-dioxane under a wide range of environmental conditions. Using novel titanium dioxide (TiO_2) pellets, we demonstrate for the first time that this prominent catalyst can be activated in the dark even when electrically insulated from the electrodes. TiO_2-catalyzed reactors achieved efficiencies of greater than 97% degradation of 1,4-dioxane, up to 4.6 times higher than noncatalyzed electrolytic reactors. However, the greatest catalytic enhancement (70% degradation versus no degradation without catalysis) was observed in low-ionic-strength water, where conventional electrochemical approaches notoriously fail. The TiO_2 pellet's dark-catalytic oxidation activity was confirmed on the pharmaceutical lamotrigine and the industrial solvent chlorobenzene, signifying that electrocatalytic treatment has tremendous potential as a transformative remediation technology for persistent organic pollutants in groundwater and other aqueous environments.