Water vapor transport properties of interfacially polymerized thin film nanocomposite membranes modified with graphene oxide and GO-TiO2 nanofillers

Graphene oxide (GO) and its composite with TiO2 (GT) were utilized as nano-filler materials to prepare highly permeable and water vapor selective nanocomposite membranes. The nano-fillers were characterized using different analytical tools to determine their physicochemical properties. Nanocomposite membranes were prepared by dispersing the nano-fillers in aqueous phase monomer solution for interfacial polymerization reaction on the inner surface of Polysulfone hollow fiber membrane. Surface morphology and bonding chemistry of the nanocomposite membrane was analyzed using various analytical tools. The two types of nano-fillers were compared for their compatibility with the polyamide matrix, and consequently, the water vapor separation performance of the resulting membrane. Results revealed that both the nano-fillers are firmly attached to the polyamide layer via hydrogen and covalent bonds. GT based membranes have higher surface roughness and better hydrophilicity as compared to GO. In addition, GT membranes have more carboxyl groups and lesser degree of cross-linking due to the interference with interfacial polymerization reaction. This leads to a higher permeance (2820 GPU) and a water vapor/nitrogen selectivity when compared to other TFN membranes reported in literature. The nano-fillers act as active sites for preferential transport of water vapor molecules through the membrane thereby, significantly improving water vapor permeance.