Ionomer-coated filtration membranes as an alternative to ion-exchange membranes for demineralization by electrodialysis

Industrial application of ion-exchange membranes, the key component of many electro-membrane processes, is often hindered due to their high cost-result of complex fabrication methods and use of highly engineered precursors. As an alternative to conventional anion-exchange membrane (AMX), this study focuses on the fabrication of cation-coated filtration membranes (CCFM-Type 1 and CCFM-Type 2) by depositing a thin layer of crosslinked branched polyethyleneimine (PEI)-based ionomer on top of the porous substrate. The use of commodity precursors (PEI) in combination with energy efficient fabrication processes ensures a low end-cost for CCFMs. The properties and the performances of these membranes are evaluated and compared with AMX. Though ionic conductance of both CCFMs is found to be lower than AMX, similar electrochemical behavior is observed for all three membranes. In terms of performance, the highest NaCl demineralization rate is given by CCFM-Type 2, while whey demineralization rate for all three membranes is similar. Energy consumption during both processes is increased for CCFMs probably due to noticeably higher global resistance which the ED system reaches during the process. These promising results suggest the possible application of these cost-effective CCFMs in electrodialysis demineralization processes as an alternative to commercial AMX at an industrial level.