The Development of Electrochemical Systems for the Oxidation of Organic Contaminants for Water Treatment

Abstract

1,4 dioxane, also known as dioxane, is a contaminant of emerging concern, with no natural methods of degradation and no established treatment methods. This study investigates the use of both direct and indirect electrochemical advanced oxidation processes to generate radicals for dioxane oxidation, and how adjusting electrochemical parameters may be used to tune dioxane oxidation towards target compounds, thus offering a pathway to combine wastewater treatment with the synthesis of valuable compounds. Ion chromatography and nuclear magnetic resonance were used to identify and quantify the liquid products. The electro-Fenton process was used to indirectly oxidize dioxane via the activation of H2O2 generated in situ. H2O2 was quantified using TiOSO4 in an acidic solution. It was found that perfluorinated sulfonic acid binders can tailor carbon materials towards H2O2 production in acidic media, with as little as 5 wt% of PFSA binder dramatically improving both current density and H2O2 selectivity. Fe2+ concentration was shown to shift product selectivity of the Electro-Fenton process, with higher concentration resulting in greater selectivity towards C1 products. Early analysis of anodic oxidation of dioxane on ZnO reveals that carbonate radicals- formed from the oxidation of the bicarbonate electrolyte- are also part of the oxidation pathway, resulting in a different range of products than previously documented in the literature.