Development of carboxylated TiO₂ incorporated thin film nanocomposite hollow fiber membranes for flue gas dehydration

In this work, thin film nanocomposite (TFN) membranes for water vapor removal have been fabricated by incorporation of carboxylated TiO₂ nanoparticles in the polyamide membrane matrix. Surface of pure TiO₂ was modified to introduce functional groups on the TiO₂ surface and increase the hydrophilicity of the nanoparticles. Modified nanoparticles were then homogeneously dispersed in the aqueous phase monomer (3, 5-diaminobenzoic acid) and reacted with trimesoyl chloride (TMC) to form a thin film nanocomposite membrane (TFN) on top of the polysulfone hollow fiber membrane (HFM) substrate. The carboxylation of TiO₂ was confirmed by FTIR spectra. Intrinsic properties of the TFN were analyzed by ATR-FTIR, scanning electron microscopy (SEM), atomic force microscopy (AFM) and water contact angle. Introduction of carboxylated TiO₂ caused a more dense and cross-linked polyamide layer due to its high binding affinity with the polyamide layer, which was also confirmed by SEM analysis. Furthermore, the addition of modified nanoparticles also increased the hydrophilicity of the TFN membrane due to excess carboxylic groups. Water vapor permeance and selectivity drastically improved due to the increased water vapor permeation paths provided by the modified nanoparticles. A maximum water vapor permeance and selectivity of 1340 GPU and 486 respectively, were obtained at optimum conditions. In addition, effect of reaction time and monomer concentration have also been studied and correlated.