Liquid supported membrane of DGA used for rare earth elements separation. Tell me the background/introduction of this research, current state of the art, motivation, how these membrane are made , what is the appropriate characteristics of them, approaches that author followed, you can describe the problems of that approaches, why rare earth is challenging to separate, why current state of the art do not address that need, include two or 3 results and describe it. take those information from few journal papers and mention the correct citation.