Characteristics of ultrafiltration membranes fabricated from polysulfone and polymer-grafted silica nanoparticles: Effects of the particle size and grafted polymer on the membrane performance

Silica nanoparticles with a controlled size in the range of 10–100nm were synthesized and their surface was treated with various hydrophilic polymers to produce polysulfone (PSf)/silica nanoparticles composite membranes which exhibited enhanced performance in the ultrafiltration process. PSf composite membranes containing silica nanoparticles grafted with a hydrophilic polymer exhibited a much higher water flux than the PSf membrane. Among the PSf composite membranes containing silica nanoparticles grafted with poly(vinyl alcohol) (PVA-g-silica), poly(1-vinylpyrrolidone) (PVP-g-silica), and poly(1-vinylpyrrolidone-co-acrylonitrile) (P(VP-AN)-g-silica), the solute rejection of the PSf/P(VP-AN)-g-silica membrane was the same as that of the PSf membrane, while that of PSf/PVA-g-silica was significantly lower than that of the PSf membrane. The amount of grafted polymer on the particles decreased with increasing particle size. As a result, the water flux of the membranes increased with decreasing particle size, regardless of the type of grafted polymer. The PSf/P(VP-AN)-g-silica membrane showed the best performance among the membranes examined when the particle content and size were fixed. •Silica nanoparticles with a controlled size from 10 to 100nm were synthesized.•Ultrafiltration membranes were prepared from PSf and polymer grafted silica nanoparticle.•Fabricated membranes exhibited enhanced water flux.•Solute rejection depends on the miscibility between PSf and grafted polymer.