Use of cation-coated filtration membranes for demineralization by electrodialysis

Abstract

Ion-exchange membranes (IEM) used in electrodialysis (ED) possess an intrinsic resistance that contributes to the energy consumption of ED treatments. In this work, the performance of cation-coated filtration membranes (CCFM), which are more conductive and less expensive than conventional IEMs, was investigated for the first time on food applications. Four CCFMs (FF50-B3X, FF50-WPR00, FF30-S11 and FF60-S11) were tested for NaCl solution demineralization and two of them (FF50-B3X and FF30-S11) were further tested for whey demineralization in comparison with an AMX anion-exchange membrane, commercially available and currently used in industrial stacks. During NaCl solution demineralization, no significant differences were observed between CCFMs and AMX membranes in terms of demineralization, global resistance and energy consumption. However, during whey demineralization, CCFMs were slightly less effective in terms of demineralization rate (15% less, FF30-S11 only) and energy consumption (both CCFMs): this was explained by the higher roughness and thickness of CCFMs. Furthermore, the overall resemblance in terms of electrochemical characteristics between CCFMs and AMX was in accordance with the results obtained for NaCl solution and whey demineralization. Considering the relatively low electrical energy needed by CCFMs in the overlimiting region, these membranes could also be of interest for ED treatments in overlimiting current conditions. Thus, CCFMs, which are low-cost membranes (40–60 €/m2), could be used for ED at an industrial scale.