High performance ultrafiltration composite membranes based on poly(vinyl alcohol) hydrogel coating on crosslinked nanofibrous poly(vinyl alcohol) scaffold

A new kind of high flux ultrafiltration (UF) membrane based on poly(vinyl alcohol) (PVA) electrospun nanofibrous scaffold support and PVA hydrogel coating has been demonstrated. The long-term performance of such membranes was optimized by a variation of degree of hydrolysis (i.e. 88-99%) and molecular weight (e.g. 13,000-124,000 g/mol) in the electrospun PVA scaffold in conjunction with chemical crosslinking of PVA hydrogel coating. It was found that the electrospun scaffold fabricated by 96% hydrolyzed PVA with relatively high molecular weight (e.g. 85,000-124,000 g/mol) exhibited very good overall mechanical performance before and after crosslinking. A PVA hydrogel coating, fabricated from the same material composition as the electrospun scaffold but different crosslinking conditions, was used as the anti-fouling layer for high-throughput water ultrafiltration. Results indicated that such unique hydrophilic nanofibrous composite membranes exhibited a flux rate (>130 L/m2 h) significantly higher than commercial UF membranes but with similar filtration efficiency (rejection rate >99.5%).