Dissolution of zinc oxide using choline chloride-based deep eutectic solvents with various hydrogen bond donors

Zinc oxide dissolution was evaluated using three eco-friendly deep eutectic solvents made of choline chloride combined with ascorbic acid, maleic acid, or urea. Characterization methods including spectroscopy and thermal analysis confirmed the structure and stability of these deep eutectic mixtures. Among the solvents tested, the choline chloride and ascorbic acid combination achieved the highest dissolution efficiency at over eighty percent for five milligrams of zinc oxide, outperforming both the maleic acid and urea options. The superior performance of the ascorbic acid system stems from its reducing properties and ability to form stable zinc complexes. Optimal dissolution occurred under distinct temperature and duration conditions for each solvent, demonstrating the strong potential of acid based deep eutectic solvents for sustainable metal oxide processing.