Preparation of Bridged Polysilsesquioxane Membranes from Bis[3-(triethoxysilyl)propyl]amine for Water Desalination

Bridged polysilsesquioxane membranes containing amine units were prepared from bis[3-(triethoxysilyl)propyl]amine (BTESPA) by a sol-gel process, which consisted of sol formation by hydrolysis/condensation polymerization of BTESPA under neutral conditions and calcination of cast films of the sols on sulfonated polyethersulfone support membrane. A similar treatment of BTESPA, including sol formation under acidic conditions, afforded membrane with ammonium units. Thus-obtained porous BTESPA-based membrane was subjected to reverse osmosis (RO) experiments using 2000 ppm aqueous NaCl solution to examine its water desalination properties. Maximal liquid permeance (1.2 × 10−13 m3/m2·Pa·s) and NaCl rejection (97%) were achieved using the ammonium-containing membrane.