(538h) VMD Desalination Using Nanocomposite Membranes Prepared By Hydrophilic Nano-Additives

Desalination has attracted many efforts over the past few decades. Lack of fresh water all over the world from south west of the United States to the Middle East and extended to Australia has drawn much attention toward the desalination as an alternative to compensate the water shortage. Among the processes that are used for this purpose, a larger portion of the market is occupied by the membrane-based technologies, i.e. 63.7%, and Reverse Osmosis (RO) has placed on top by managing approximately 60% of the market. In spite of its lower water production cost compared to the other desalination techniques, RO is considered to be a quite energy intensive process, which approximately 40% of the total water cost is spent for electrical energy consumption within the process. However, Membrane Distillation (MD) has demonstrated outstanding characteristics, which is potentially considered an appropriate alternative for RO in global market, although the process has not yet been commercialized, mainly due to the huge thermal energy consumption in MD besides lack of a champion in manufacturing the high performance durable MD membranes at industrial scale. To improve the performance of the MD membranes by enhancing their permeability, hydrophilic nanoparticles have shown a great potential via optimizing the membrane structure. Hydrophilic nanomaterials, such as CaCO₃, CuO, and amine modified SiO₂, were able to increase the pure water flux in a Vacuum Membrane Distillation (VMD) process by 102.3%, 153.4%, and 2456%, respectively, at an appropriate concentration, i.e. 2.0 wt.% for CaCO₃ and CuO and 7.0 wt.% for silica nanoparticles. Surface hydrophobicity of the MD membranes was not compromised as a result of the addition of the hydrophilic nanoparticles into the polymeric PVDF matrix and nanocomposite membranes possessed adequate Liquid Entry Pressure of water (LEP_w) to be used in seawater VMD desalination. Nanomaterials incorporated membranes demonstrated high selectivity by rejecting more than 99.9% of the sodium chloride when an artificial seawater with a NaCl concentration of 35 g/L was fed to the system.