Low-Cost Manufacturing of High-Performance Ion Exchange Membranes for Electrodialysis using Initiated Chemical Vapor Deposition

Electrodialysis and other membrane-based, electro-driven desalination methods offer advantages over current methods for desalination including low costs, reduced energy consumption, low plant footprints and minimal feed pretreatment. However, the high cost and poor selectivity of ion exchange membranes, as well as their susceptibility to scaling, still prevent electro-driven desalination technologies from being applied to their fullest potential across all salinity regimes. In the proposed work, GVD Corporation has applied its method for polymer thin film deposition, called iCVD, to develop roll-to-roll-compatible manufacturing process for ion exchange membranes with a sale price of less than $20/m2 – a factor of 4- 15x less than conventional methods. GVD has also shown that it can use iCVD to make membranes more selective by applying a thin modifying layer to the membrane surface. Selective membranes will have better scaling resistance and greater utility in recovery of valuable minerals, such as magnesium and calcium fertilizers, manganese and lithium for rechargeable batteries and heavy metals for industrial processes, helping to offset the operating costs of desalination. Lower-cost production of membranes with high selectivity will allow a dramatic reduction in levelized cost of water for electrodialysis of both low- and high-salinity feed waters. The consequent widespread adoption of electrodialysis (and other related technologies) for the treatment of natural feeds and wastewater streams will help to combat water scarcity, reduce energy consumption for water treatment, and create novel sources of critical minerals and more efficient reuse of industrial chemicals. In Phase I, GVD developed processes for the deposition of four target ion conductive polymers. GVD showed that applying a 1-micron-thick layer of these polymers to porous supports resulted in an ion exchange membrane with excellent selectivity, conductivity and stability. Applying a very thin layer of GVD’s materials to surface of a membrane results in a dramatic enhancement of selectivity – useful for multiple applications. In Phase II, GVD will focus on refining the materials and supports used to achieve the best performing membranes at the lowest cost. GVD will carry out extensive characterization of the performance of the membranes in desalination by electrodialysis and in two selected commercial applications with the help of supporting commercial partners. Finally, GVD will design a full-scale deposition tool for the fabrication of membranes at the target cost. In this work, GVD is partnering with Prof. Chinmayee Subban and the University of Washington (UW) to perform measurements of membrane selectivity and conductivity and real measurements of electrodialysis efficiency using iCVD membranes.