Pervaporation dehydration of ethanol by using polyelectrolyte complex membranes based on poly (N-ethyl-4-vinylpyridinium bromide) and sodium carboxymethyl cellulose

Poly (N-ethyl-4-vinylpyridiniumbromide) (PEVP) was synthesized by the reaction between poly (4-vinylpyridine) (P4VP) and ethyl bromide, and polyelectrolyte complexes (PECs) based on PEVP and sodium carboxymethyl cellulose (CMCNa) were prepared in HCl aqueous solutions. The ionic complexation degrees (ICD) of PECs can be effectively controlled by tuning either quaternization degree (QD) of PEVP polycation or carboxylate group (–COO–) content on CMCNa polyanion, which was characterized by elemental analysis (EA) and Fourier transform infrared (FT-IR). The dilute solution viscosity behavior of PECs was investigated by Ubbelohde viscometer. The hydrophilicity and surface morphologies of polyelectrolyte complex membranes (PECMs) were examined by contact angle meter and field emission scanning electron microscopy (FESEM), respectively. The PECMs were subjected to dehydration of ethanol and showed very high separation performance. Interestingly, the permeation flux of PECMs increased while water content in permeate decreased with increasing ICD. The performance was discussed in terms of the unique structural characteristics of PEVP, PECs and PECMs.