Anodic dissolution of refractory metals in choline chloride based binary mixtures.

摘要

Choline chloride (CC) based binary mixtures have physicochemical properties that are comparable to the ionic liquids, that is why they are put in deep eutectic solvents (DESs) category of ionic liquids. Refractory metals like molybdenum (Mo) and tungsten (W) are studied for anodic dissolution in these DESs and faradaic current efficiency of dissolution was calculated for these metals. Anodic dissolution depends on the ability of hydrogen bond donors (HBDs) to engage and solvate the free chloride ions. Urea, ethylene glycol (EG) and glycerin (Gly) were used as HBDs with choline chloride for making deep eutectic solvents (DESs). Cyclic voltammeteric measurements show the large electrochemical window that these binary mixtures exhibit. Both the metals show almost no passivation in these media. Weight loss measurements show faradaic current efficiencies for both the metals up to 80% for choline chloride and glycerol, 30% for choline chloride and ethylene glycol, 17% for choline chloride and urea. Tt was also found that decreasing the current density increases dissolution efficiency.