Fabrication of porous polymeric nanocomposite membranes with enhanced anti-fouling properties: Effect of casting composition

A mixed matrix porous polymeric membranes with anti-fouling properties were prepared by phase-inversion method from a quaternary system of polysulfone/N,N-dimethylformamide/polyvinilpyrrolidone (PVP)/nanosilver (nAg). The effect of casting mixture composition on the membrane morphology, performance, and anti-fouling (including anti-biofouling) properties was evaluated by microscopic, spectroscopic and surface characterization techniques. The results showed a substantial effect of casting mixture composition on the morphology and selectivity of membranes. The incorporation of nAg to a casting mixture containing 5 wt% PVP induced morphological changes in membrane structure including increase in pore sizes, suppression of macrovoids and thinning of the skin layer. These changes were further resembled in the separation and anti-fouling properties of membranes. The permeate flux of membranes increased regardless of PVP concentration, while the separation properties of membranes formed from a casting mixture containing 5 wt% PVP were significantly compromised as compared to those formed with 1 wt% PVP. Under the same nAg loading, the membrane casted from a mixture contained 1 wt% PVP had better anti-fouling properties with respect to bovine serum albumin. The bioassays with Pseudomonas aeruginosa revealed that anti-biofouling properties of membranes (including antibacterial and anti-adhesive properties) were significantly induced upon addition of nAg. The findings of this study highlight the importance of casting mixture composition and interactions between its components for the optimization of membrane anti-fouling behavior while maintaining high separation properties.