Polysulfone with glycopolymer for development of antifouling ultrafiltration membranes

Ultrafiltration (UF) composite and blend membranes from poly(2,3,4,6-tetra-O-acetyl-D-glucopyranoside methacrylate) (GP)-grafted MCNTs (GP-graft-CNTs) and GP homopolymer with different weight ratios of PSF and PVP were fabricated for antifouling application. Some portions of each fabricated nanocomposite and blend membranes were chemically treated to deacetylate the pendant acetyl glucopyranoside moieties of macromolecular chains to obtain hydrophilic pendant D-glucopyranoside units of macromolecular chain grafts of MCNTs and GP homopolymer in UF membranes. Fouling features of the membranes at 2 bar functioning pressure were evaluated by permeating BSA solutions and oil–water emulsion. The tri-polymer blend UF membranes exhibited 96% BSA rejection (GP3-T membrane) and 93% oil rejection (GP1 membrane) whereas composite membranes showed 89% BSA (g-GPC2) and 83% oil (g-GPC3) rejections from their respective feeds. The deacetylated nanocomposite membrane, g-GPC1-T (GP-graft-CNTs/PSF/PVP at 0.33/86.67/13 weight ratio) exhibited superior flux for BSA solution (135 LMH) than the fabricated membranes (nanocomposite membranes: 88–132 LMH; GP/PSF/PVP = 46–88 LMH) at 2 bar operating pressure. Composite membranes exhibited flux for oil–water feeds even after 8 h whereas the blend membranes showed no flux after 1 h. The modified nanocomposite membrane for oil–water emulsion feeds, g-GPC1 exhibited a maximum 230 LMH flux having oil rejection of 75%. Treated composite membranes demonstrated a higher flux recovery ratio (FRR = 87–94%) than the untreated nanocomposite membranes (FRR = 17–37%) and blend membranes of GP/PSF/PVP (FRR = 51–81% for as-cast membranes and FRR = 13–22% for treated membranes) for oil–water emulsion feeds.