Synthesis and characterization of polyamide/polyester thin-film nanocomposite membranes achieved by functionalized TiO₂ nanoparticles for water vapor separation

In this study, we report the synthesis of thin film nanocomposite (TFN) membranes by interfacial polymerization (IP) on porous polysulfone (PSf) hollow fiber membrane supports. We also investigate the synthesis of carboxylated TiO₂ (C-TiO₂) and hydroxylated TiO₂ (H-TiO₂) nanoparticles using a simple technique and evaluate the performance of the TFN membranes incorporated with these nanoparticles for water vapor separation. Comparative studies were carried out on membranes with and without the incorporation of nanoparticles (TFN and TFC) for water vapor separation. Aqueous 3,5-diaminobenzoic acid (DABA)/nanoparticles mixture solutions and organic trimesoyl chloride (TMC) were used in the IP process. The reaction between these two monomer solutions at the interfaces of PSf hollow fiber substrates resulted in the formation of the TFN membranes. Functionalized TiO₂ nanoparticles (TiO₂NPs) with a size of about 60 nm were used for the fabrication of the TFN hollow fiber membranes. These TFN membranes were characterized using different modern techniques and evaluated in comparison with the tidy TFC membranes. Their performances were evaluated based on the water vapor permeability and selectivity. Experimental results indicate that the carboxylated TiO₂ nanoparticle (C-TiO₂NPs) incorporated membrane shows improved performance compared to other membranes. By changing the nanoparticles, better hydrophilicity was obtained; the contact angle was decreased from 90° (PSf) to 46° (TFN) and the water vapor permeance was increased from 780 GPU (TFC) to 1131 GPU (TFN) with high selectivity being maintained (from 115 to 548) when the C-TiO₂NPs content was 0.05 (wt%).