The influence of tetraethylorthosilicate and polyethyleneimine on the performance of polyethersulfone membranes

The effect of inorganic and organic additives in polyethersulfone (PES) membranes was investigated for the possible enhancement in ultrafiltration performances. Tetraethylorthosilicate (TEOS) and polyethyleneimine (PEI) were chosen as inorganic respective silica precursor and organic additive based on their potential to promote hydrophilicity in PES membranes. With the addition of TEOS and PEI in PES casting solution, the viscosity and hydrophilicity were increased.In addition of TEOS in PES, the SiO2 particles were homogeneously dispersed in PES matrix, a large amount of OH groups on the SiO2 particles generated, and led to an improvement in the hydrophilic property. Characterizations of membranes by FTIR and X-ray Diffraction (XRD) confirmed that the PES suffered a transform from various functional groups due to the addition of TEOS. The 40% of water permeability was found by 5% addition ion of TEOS and PEI repressively. The top surface and cross-section morphology of PES membranes changed from dense-like structure to finger-like macrovoids structure with increasing TEOS and PEI content. Protein solution separation was investigated using lysozyme and bovine serum albumin (BSA) with the concentration of 1000 ppm. The observed sieving coefficient of protein decreased exponentially with increasing contents of TEOS and PEI in PES membranes.

► With the addition of TEOS and PEI in PES, the viscosity and hydrophilicity were increased.
► Hydroxyl group in PEI and silica network might have changed the dense top surface of PES membrane.
► 40% of water permeability was found by 5% addition ion of TEOS and PEI.
► Observed sieving coefficient of protein decreased with increasing contents of TEOS and PEI.
► Observed permeate flux for lysozyme is low as compared to BSA solution.