Preparation of monodispersed spherical mesoporous nanosilica–polyamide thin film composite reverse osmosis membranes via interfacial polymerization

Monodispersed spherical mesoporous nanosilicas were synthesized by the hydrothermal method using tetraethoxysilane as silica source, cetyltrimethylammonium bromide as template, ethanol as co-solvent, and sodium hydroxide as alkali source. The synthesized silica has an average particle diameter of 164 nm with a relative standard deviation of 4.87%, specific surface area of 1141 m2·g− 1, pore size of 2.47 nm, pore volume of 0.77 cm3·g− 1, and a pore structure radiating from the heart to the outer surface of the sphere. The spherical mesoporous nanosilica–polyamide thin film composite reverse osmosis (TFC RO) membranes were obtained by interfacial polymerization. The silica nanoparticles are visible in the TFC RO membranes based on the surface and cross-sectional SEM images. Correspondingly, energy dispersive X-ray spectroscopy analysis confirms that the silica has been successfully doped into the TFC RO membranes. The hydrophilicity of the TFC RO membranes is improved and water flux is increased from 19 L·h− 1·m− 2 (without nanosilica) to 53 L·h− 1·m− 2 (with 0.1% (w/v) mesoporous nanosilica loading), whereas all solute rejection rates are greater than 96%.

► We investigate spherical mesoporous nanosilica–polyamide TFC RO membrane. ► The synthesized membrane has dramatically improved permeability. ► The permeability–rejection tradeoff is not observed for the synthesized membrane.