Custom-made PEI/exfoliated-MoS nanocomposite ultrafiltration membranes for separation of bovine serum albumin and humic acid.

Herein, we report the effect of the exfoliated molybdenum disulfide (eMoS) nanosheets in improving the permeability and anti-fouling properties of the PEI ultra-filtration (UF) membrane using bovine serum albumin (BSA) and humic acid (HA) as model fouling agents. The PEI/eMoS nanocomposite membranes were prepared via phase inversion method using three different eMoS concentrations (0.5, 1 and 2wt%) designated as PEI-0.5, PEI-1 and PEI-2, respectively. Fourier transform infra-red spectroscopy employed to probe the surface functionalities on the membranes. Contact angle measurement, pure water flux, swelling rate and solute rejection studies confirmed the improved hydrophilicity of the PEI/eMoS nanocomposite membranes than the individual entities. Flux recovery ratio (FRR), reversible and irreversible fouling results evidenced the improved fouling resistance of PEI/eMoS modified membranes than the individual counterparts. SEM results evidenced that the nanoscale eMoS significantly altered the membrane morphology by causing increased porosity and larger macrovoids formation on the surface as well as in the bulk of the membrane. PEI-1 membrane showed an increased pure water flux (52.54Lmh) and water content (74.8%) whereas lesser contact angle (69.2°) and hydraulic resistance (1.85kPa/Lmh). Resistance to fouling performance of PEI-1 membrane was evident from the FRR values of 95.3 and 90.2% and rejection values of 94.5 and 92.4% for BSA and HA respectively. PEI-2 membrane agglomerates with eMoS and hindered the membrane permeability by blocking the macrovoids in the bulk which restricted the permeation and fouling resistance of the membrane. Amongst various nanocomposite membranes investigated, the PEI-1 membrane exhibited better hydrophilicity and fouling resistance properties due to the availability of the favorable surface and bulk characteristics.