Preparation and characterization of novel pegylated hydrophilic pH responsive polysulfone ultrafiltration membrane

In this work, novel cross linked pegylated functional copolymer poly (acrylic acid-co-polyethylene glycol methyl ether methacrylate) was prepared from AA and PEGMA, via precipitation polymerization using toluene as solvent. The copolymer was directly blended with polysulfone (PSF) using N-methylpyrrolidone (NMP) as solvent to prepare flat sheet polymeric membrane by the phase inversion method. Presence of copolymer in blended membrane was confirmed by Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. Blended membranes showed enhanced pore density, pure water flux and hydrophilicity. Cross sectional morphology of the membranes was changed significantly with higher wt% of the copolymer. Contact angle and hydraulic permeability of modified membrane with 7 wt% of copolymer were 48.7° and 0.794 L/m2 h kPa compared to 63.2° and 0.353 L/m2 h kPa respectively, for unmodified membrane. The blended membranes also showed evidence of pH sensitivity compared to unmodified membrane. For membrane modified with 7 wt% of the copolymer, hydraulic permeability was increased from 0.355 to 0.794 L/m2 h kPa when pH was changed from 11 to 2. Finally, fouling resistance behavior of modified membrane was studied by bovine serum albumin protein separation study. Modified membrane achieved a maximum of around 90% flux recovery ratio after bovine serum albumin (BSA) separation, which is remarkably higher compared to 37% flux recovery ratio of unmodified membrane. Effect of pH for BSA rejection on different membranes was also studied at pH 2, pH 7 and pH 11. It was found that modified membranes had almost same rejection at pH 7 and pH 11, but rejection was much lower at pH 2.