Study of the process of dissolution of lanthanum hydroxide in deep eutectic solvents

Deep eutectic solvents are potentially promising media for metals from various materials, including rocks. Of particular interest is the possibility of extracting rare earth elements, the demand for which is growing due to the expansion of their consumption. However, there are little data on the solubility of rare earth element compounds in deep eutectic. The purpose of this work is to study the process of dissolution of compounds of rare earth elements, in particular lanthanum hydroxide, in deep eutectic solvents. The dynamics of the dissolution of lanthanum hydroxide in deep eutectic solvents based on choline chloride and malonic, malic, tartaric and citric acids, was investigated. It was found that the concentration of lanthanum when using a deep eutectic solvent with tartaric acid almost immediately reaches a plateau, with malonic and malic acid it gradually decreases, and with citric acid it increases. The highest concentration of lanthanum is achieved by using a mixture of choline chloride with citric acid — 10.9 g / l.