Development of robust and high-performance polysilsesquioxane reverse osmosis membranes modified by SiO2 nanoparticles for water desalination

Robust and highly water permeable organically bridged polysilsesquioxane (PSQ) reverse osmosis (RO) membranes were prepared by introducing SiO2 nanoparticles into bis[3-(triethoxysilyl)propyl]amine (BTESPA)-based RO membrane by the sol–gel process. Nitrogen adsorption/desorption isotherm measurements revealed that BET surface areas are significantly increased by introduction of SiO2 nanoparticles. RO experiments using a 2000 ppm NaCl aqueous solution indicate that the addition of SiO2 nanoparticles improves membrane RO performance; water permeability was 1.2 × 10-12 m3/m2sPa and salt rejection was approximately 98%. It was also found that these membranes exhibited high thermal stability, i.e., after heat treatment at 95 ℃ for 180 min, the membranes showed a salt rejection decrease of less than 2.5%. In addition, the membranes manifested favorable resistance to chlorine exposure, namely, salt rejection decrease was less than 2% after 10,000 ppm⋅h NaOCl exposure.