Sodium dodecyl sulfate/C-UIO-66 regulation of nanofiltration membrane with pleated and thin polyamide layer structure

Abstract

Nanofiltration membranes based on polyamide (PA) are widely used in fields such as brackish water desalination and drinking water purification due to their excellent retention of multivalent salts. However, uncontrolled and extremely fast polymerization easily produces thicker PA layers, which reduces permeability. Moreover, smooth support layer usually leads to PA layers with low roughness, which is not benefit for improving of flux. Based on these aspects, an innovative method of co-regulating interfacial polymerization based on anionic surfactant sodium dodecyl sulfate (SDS) and carbonized-UIO-66 (C-UIO-66) nanoparticles has been reported. The adsorption of anionic surfactant on the surface of C-UIO-66 slows down the diffusion rate of aqueous monomer and helps to form thin PA layer (<33 nm) which is thinner than the original thin film composite (TFC) membrane (144.29 ± 17.62 nm). Besides, C-UIO-66 nanoparticles with different sizes are deposited on the surface of the support layer, providing rougher surface for interfacial polymerization. Due to the irregular surface of SDS/C-UIO-66 intermediate layer, the prepared PA layer has folded structure. Compared with original TFC membrane, the preferred thin film nanocomposite (TFN) nanofiltration membrane possesses permeation flux of 58.59 L·m−2·h−1, which increased by 114.3 % together with the maintaining the rejection rate of Na2SO4 above 96 %.