A study on Neodymium recovery from aqueous solutions for designing a new generation of sandwich liquid membrane

Liquid Membrane (LM) based processes, as Supported Liquid Membranes (SLMs), have been proposed, for over 30 years, as effective methods for the selective separation of inorganic/organic species from different water streams. The industrial use of SLMs has been limited mainly by their poor stability. To investigate on the main cause of system destabilization and the optimal conditions for mass transport, a good reference system is the traditional SLM. To this aim the recovery of neodymium (Nd) from acidic media by a traditional SLM has been studied, giving particular attention to permeation and stability. The results clearly evidenced that system stability was strongly influenced by the solubilization of the carrier in the aqueous phases. The consideration and the experimental results reported in this work give useful information to shift the next research step versus the development of a 2nd generation of SwLM able to give satisfactory system performance in view of industrial application, such as Nd as well as rare earth elements or salt recovery from aqueous media.