Incorporation of graphene oxide in the layer-by-layer self-assembly of polyacrylic acid and poly(diallyldimethylammonium chloride) to fabricate nanocomposite membrane for forward osmosis

In this study, polyacrylic acid (PAA) and poly (diallyldimethylammonium chloride) (PDDA) were self-assembly on the surface of hydrolyzed polyacrylonitrile membrane. Graphene oxide (GO) was embedded on the membrane through dispersing it on either PAA or PDDA solution. The presence of GO in the composite membrane made the surface morphology become rougher than that of the pristine membrane. In addition, the membrane maintained hydrophilic with improved surface electronegativity. During the performance evaluation (1 M Na2SO4 as draw solution, and pure water as feed), the membrane prepared with GO in PAA solution had the highest separation efficiency. Because GO facilitates the strong electrostatic interaction between PAA + GO with PDDA, resulting in a dense selective layer. At optimum concentration of GO in PAA with a bilayer, the composite membrane exhibited a water permeation flux of 16 LMH and a salt reverse diffusion of 22.3 gMH. Using different types of salts (Na2SO4, NaCl, MgSO4, MgCl as draw solution), the composite membrane confirmed that it was a nanofiltration-forward osmosis like type of membrane, giving a high separation efficiency for a draw solution of Na2SO4.