Effect of a novel hydrophilic double-skinned support layer on improving anti-fouling performance of thin-film composite forward osmosis membrane

A thin-film composite (TFC) membrane with hydrophilic double-skinned support layer was developed to improve anti-fouling performance. The double-skinned separate casting technology was applied to obtain the double-skinned support layer and the polyacrylonitrile (PAN) concentration in the bottom casting solution was adjusted. Then, the support layer was carboxylated by immersing in a 1.5 M NaOH solution for 2 h. Finally, TFC membrane with hydrophilic double-skinned support layer was obtained by the interfacial polymerization. When the PAN concentration in the bottom casting solution was 10 wt%. TFC membrane with hydrophilic double-skinned support layer (TFC-10 %) showed the best performance. The water flux of TFC-10 % reached 17.6 LMH and the reverse salt flux was 5.6 gMH. Under the double interception effect of the double-skinned structure and the steric hindrance of the hydration layer on the support layer, good anti-fouling property of TFC-10 % was observed under bovine serum albumin (BSA) foulant. Compared to the traditional TFC membrane, the normalized flux of TFC-10 % increased by 80 %. The anti-fouling performance was also analyzed by microaction mechanisms using AFM and QCM-D. It was found that the adhesion force between TFC-10 % and BSA was small, therefore fewer pollutants were adsorbed on TFC-10 %, and its adsorption layer was loose and easy-cleaning.