Tailoring the surface properties of PES ultrafiltration membranes to reduce the fouling resistance using synthesized hydrophilic copolymer

A novel polyethersulfone (PES)/sulfonated poly (arylene ether sulfide sulfoxide sulfone) (SPAESSS) blend ultrafiltration (UF) membranes with excellent antifouling properties were prepared using phase inversion induced by immersion precipitation method. A new hydrophilic copolymer (SPAESSS) with 40 mol% disulfonation was successfully synthesized via aromatic nucleophilic substitution copolymerization. Different concentrations of the copolymer (0–15 wt.%) were used in the PES casting solution. The physicochemical properties and wettability of the membrane surface were characterized using attenuated total reflection-Fourier transform infrared spectra (ATR-FTIR) and contact angle, respectively. They were also characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), filtration performance and fouling analysis. The hydrophilicity of PES membranes was significantly enhanced by addition of the SPAESSS in the casting solution. The presence of the sulfonic acid groups and sulfoxide linkages on the ATR-FTIR spectra of modified membranes confirmed the existence of SPAESSS in the PES membrane structure. The morphological studies showed that the membranes with smaller surface pore size, uniform pore size distribution and lower thickness of skin layer were formed by addition of SPAESSS in the casting solution. The surface roughness of the blend membranes was decreased with increase in SPAESSS content. The obtained results of the membrane performance tested by dead-end filtration of bovine serum albumin (BSA) solution indicated that BSA protein rejection of the blended membrane was improved. However, the pure water and BSA permeability of the blend membrane were slightly decreased with increasing SPAESSS concentration in the casting solution. Furthermore, it was found that the flux recovery, total flux loss and irreversible fouling of PES membrane were considerably improved when SPAESSS added in the casting solution. It means that the blended membranes posse the antifouling properties.

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► Synthesis of SPAESSS as a hydrophilic copolymer via aromatic nucleophilic substitution copolymerization.
► Fabrications of PES/SPAESSS blend membranes using phase inversion technique.
► Higher hydrophilicity and antifouling properties of blend membranes than PES membrane.
► Reduction of the surface pore size and surface roughness by increasing in SPAESSS contents.