Eco-friendly and low-cost homogeneous cation exchange membranes functionalized by sodium dodecyl sulfate and applied in fine desalination

Abstract

BackgroundThe complex preparation process of traditional sulfonated polymers highlights their shortcomings as membrane matrix materials and leads to the high cost and environment unfriendly nature of cation exchange membranes (CEMs). MethodIn this study, a one-pot technology was adopted to prepare novel CEMs, with the cost of these membranes at only one fifth that of a commercial CEM. The complex synthetic process of traditional polymers was directly bypassed and polyethersulfone (PES) with rigid framework and sodium dodecyl sulfate (SDS) for permselectivity were directly blended to prepare CEMs. Significant findingsPES and SDS cannot dissolve in N-methylpyrrolidone (NMP) solvent to form a homogeneous solution. However, polyvinylpyrrolidone (PVP) was found to change this heterogeneous solution into a homogeneous solution as an accidental remedy, which was the key to success for this one-pot technology. The compatibility of CEM materials was good and the internal structures of these CEMs regular. For prepared and commercial CEMs, when ED desalination rates reached 90.4 and 90%, energy consumptions were 11.7 and 11.3 kW·h/m3, respectively. Long-term CEM desalting stability was investigated using 50 ED cycles. This study developed a novel CEM preparation route and demonstrated good prospects for these low cost CEMs in ED applications.