Insights into the Electrochemical Degradation Mechanisms of Imidazolium-Based Ionic Liquids in the Aqueous Solution

Abstract

With the widespread application of ionic liquids (ILs), their non-biodegradability and toxicity have increasingly impacted the environment. This study focused on the electrocatalytic oxidation of imidazolium-based ILs in the aqueous solutions using boron-doped diamond (BDD) electrodes, and the mechanisms were also fully elucidated. The effect of main parameters, i.e. current density, pH value, supporting electrolyte concentration and initial IL concentration, on the degradation efficiency of ILs were systematically investigated. The results indicated that the highest degradation efficiency occurred under acidic conditions, while variations in the supporting electrolyte concentration had a minimal impact on the electrocatalytic oxidation process. Additionally, the presence of phosphates and glucose was found to inhibit the degradation of ILs. The extension of the alkyl chain in IL cation was detrimental to the degradation ability of ILs. Finally, the intermediate products identified by GC-MS suggested the possible degradation pathways and mechanisms for the IL interested in this work. This study might provide some insights into developing the effective strategies to mitigate the environmental impact of ILs.

Keywords: Ionic liquids, electrochemical oxidation, Boron-doped diamond electrode, Intermediates