Development of Novel Desalination Membranes
Although the vast majority of the Earth's surface is dominated by oceans, seas, lakes, and glaciers, geological surveys indicate a mere 0.8% of this supply is freshwater that is adequate for human consumption. Additionally, industrial production of food and chemicals, mining operations, and other human activities can produce significant amounts of waste water that must be treated before it can be reused. Thus, efficient water desalination is vital to sustaining the quality of life for human populations living without sufficient access to freshwater resources. The flexibility of the layer-by-layer (LbL) assembly process enables the creation of composite polyelectrolyte/clay multilayer films on porous substrates to develop novel RO membranes. Assembly of multilayer films via the spray-LbL technique is particularly suited for the creation of active layers because asymmetric films can be deposited one to two orders of magnitude more quickly than possible with traditional dip-LbL assembly. The composition of the deposited films can be controlled via manipulation of the process conditions such as spray times, concentration of the solutions, and ionic strength. Composite films constructed of polymers and nanosilicate clays have been shown to have favorable properties for application in RO water desalination membranes.