Hydrophilic porous asymmetric ultrafiltration membranes of aramid-g-PEO copolymers

A series of experimental aramid-g-PEO copolymers was employed to fabricate ultrafiltration (UF) membranes by the conventional method of phase inversion, using N,N-dimethylformamide as the solvent and water as the coagulating medium. By adjusting the dope concentration for each polymer, porous membranes were attained which were suitable for UF operations and were tested using a laboratory-scale cross-flow test unit. The water flux of the membranes showed a strong dependency on the chemical composition, with water permeability increasing with increasing PEO content in the copolymer. Their separation potentials were investigated using standard solutions of poly(ethylene oxide) (PEO) as the feed, and the performance of the membranes in UF operations was systematically compared. A relationship between the dope concentration and the molecular weight cut-off (MWCO) could be observed, with higher concentrations resulting in a lower MWCO. In contrast, it was observed that the higher the content of PEO in the copolymer the greater the MWCO. In fouling tests performed using a bovine serum albumin (BSA) solution, aramid-g-PEO UF membranes exhibited very good antifouling properties compared to a commercially sourced polysulfone membrane and to polyamide UF membranes. The results of this work indicate that aramid-g-PEO copolymers are promising materials for the fabrication of fouling resistant membranes for biomacromoleculesʹ separations.