Fabrication of carbon nanotubes incorporated double-skinned thin film nanocomposite membranes for enhanced separation performance and antifouling capability in forward osmosis process

Abstract

Novel carbon nanotubes (CNTs) incorporated double-skinned thin film nanocomposite (TFN) membranes were fabricated by interfacial polymerization of polydopamine/CNTs and trimesoylchloride (TMC) on polysulfone (PSf) substrate. As controls, thin film composite (TFC) membrane without CNTs and FO membranes with single-skinned structures (top-skinned or bottom-skinned) was also fabricated. The prepared membranes were characterized and evaluated in terms of membrane morphology, structure, surface property, separation performance and antifouling capacity. The effect of membrane orientation, composition and concentration of draw solutions on FO performance was studied as well. It was found that CNTs had significant influence on the properties and the performances of the synthesized FO membranes. The double-skinned membranes owned excellent solute rejection without sacrificing water flux. By incorporation of CNTs, TFN membranes exhibited higher FO water flux than TFC membranes. The double-skinned TFN0.05 membrane, the optimal FO membrane, showed a 54% enhancement in water flux than double-skinned TFC membrane at TOP-FS orientation by using MgCl2 as draw solution and DI water as feed solution. Moreover, the double-skinned TFN0.05 membrane demonstrated remarkable antifouling capacity because of the prominent foulant resistance induced by CNT addition. This work paved a new way to fabricate high performance FO membrane by the utilization of double-skinned structure and incorporation of CNTs.