Electrocatalytic deiodination of methyl iodide on a copper electrode

Methyl iodide (CH3I) was electrochemically degraded by using copper sheet as cathode and graphite sheet as anode in a two-compartment cell. The effects of key parameters on the degradation of CH3I, including tetraalkylammonium salts, current density, initial pH, and electrolyte concentration, were investigated. The results showed that 89% of CH3I can be removed under the optimized conditions of 0.05% tetrabutylammonium chloride (TBAC), current density of 3 mA cm−2, reaction temperature of 20 °C, initial pH of 4.5, and electrolyte of 0.5 M Na2SO4. Cyclic voltammetry was applied to investigate and preliminarily elucidate the electrochemical degradation mechanism. The major pathway for CH3I degradation is reductive deiodination. Dissociative electron transfer to CH3I led to carbon–iodine bond reductive cleavage, and the reactive hydrogen atom produced during electrolysis could promote the reductive process. CH4 and I− were the main products. This study suggests that electrochemical reduction may be a promising option for treatment of radioactive CH3I from nuclear power plants.