(383bb) Functional Polymer-Based Membrane for Separation and Enrichment of Li+

Lithium (Li) is a highly-desired element used for a variety of applications--lithium-ion batteries, medicine, glass appliances, further production of polymers, and much more. Salt lake brine is the most common source for extracting lithium, worldwide. However, current methods of extracting lithium are costly, energy-intensive, polluting, and difficult to operate. Nanofiltration (NF) membranes present an exciting alternative method for collecting lithium, being cost-effective, low-energy intensive, low-waste generating, and environmentally friendly. NF270, a popular commercial membrane, may be coated with polydopamine (PDA) for some stability and separation enhancements, but still imposes issues. Chelating agent polymers, such as DTPA (Diethylenetriaminepentaacetic acid) or EDTA (Ethylenediaminetetraacetic acid) form complexes with multi-valent metal ions, such as Mg²⁺, as opposed to monovalent metal ions, such as Li⁺. This presents a fascinating and unique opportunity to incorporate cheating agents into a membrane to encourage the complex-formation of Mg²⁺ ions, while simultaneously allowing Li⁺ ions to pass through. Typically, there is a tradeoff between permeance and selectivity. Chelating agents, such as EDTA, can enhance Li⁺ selectivity up to 360% (compared to ~77% for NF270 and ~133% for NF270-PDA), with similar permeance as NF270 and NF270-PDA.