Desalination, Vol.451, 59-71, 2019
Water vapor selective thin film nanocomposite membranes prepared by functionalized Silicon nanoparticles
In this work, we have reported a facile method to improve the water vapor permeation performance of thin film nanocomposite membranes by tailoring the surface properties of Silicon nanoparticles. Inductively coupled plasma technique was utilized to synthesize amorphous Silicon nanoparticles (similar to 10 nm) which were immediately dispersed in alcohol solvents to functionalize the hydrogenated surface. The major aim was to increase the loading capacity of nanoparticles in the polyamide membrane without sacrificing the membrane performance. The nanoparticles were then added to the aqueous phase monomer for interfacial polymerization reaction to form a polyamide nanocomposite membrane. The physicochemical properties of the nanocomposite membranes were investigated using electron microscopy, surface roughness profiling, water contact angle, and X-ray photoelectron spectroscopy. The isopropyl alcohol (IPA) dispersed nanoparticles showed better hydrophilicity and higher surface roughness than ethanol counterparts. Mixed gas permeation tests indicated that the addition of nanoparticles in the polyamide membrane increases the water vapor permeation due to the excess sorption sites provided by the nanoparticles. The degree of polyamide cross-linking decreased in modified membranes as compared to the pristine polyamide membrane. Nonetheless, the increase in hydrophilicity compensated for the membrane selectivity. Furthermore, isopropyl alcohol dispersed nanoparticles showed higher permeance, flux, and selectivity even at higher concentrations indicating a uniform dispersion in the polyamide membrane. A maximum water vapor permeance of 2125 GPU with vapor/gas selectivity of 581 was observed for nanocomposite membranes containing 1.0 wt% IPA dispersed Silicon nanoparticles.