Hybrid vinyl silane and P123 template sol-gel derived carbon silica membrane for desalination

Mesoporous, interlayer-free, hybrid carbon-silica membranes based on organosilica of triethoxyvinylsilane (TEVS) and pluronic triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (P123) were successfully prepared by modified acid-base catalysed sol-gel method. Xerogels and membranes were pyrolyzed under inert conditions in vacuum and nitrogen to form the hybrid carbon silica structures. FTIR analyses showed the presence of Si-C groups in addition to silanol and siloxane groups for samples pyrolysed at 450 A degrees C. Vacuum pyrolyzed xerogels produced slightly higher pore volumes than that of the nitrogen pyrolyzed samples. As a result, the vacuum pyrolyzed membranes produced highest water fluxes compared to the nitrogen pyrolyzed membranes. Best water fluxes were measured at 6.26 (1 wt%, 60 A degrees C) and 2.92 (15 wt%, 60 A degrees C) L m(-2) h(-1) with salt rejections of 99.7% and 99.9%, respectively. This study demonstrates that the combined strategy of a sol-gel synthesis containing vinyl organosilica and polymeric template followed by vacuum pyrolysis conferred the carbonized silica membranes with excellent selectivity of water from the hydrated salt ions and reasonable water fluxes for water desalination applications. [GRAPHICS] .