Arizona State University
One of the challenges currently faced by NASA is providing clean water from the limited supplies available in the isolated environment of a space shuttle or station. A viable option is recycling water from all available sources, namely urine and urine brine, through the use of membrane processes such as reverse osmosis (RO). We propose a membrane that consists of a thin polymer top layer containing molecular sieve nanoparticles that are highly selective for water, applied to a porous support layer that will allow for high water flux. Corrosion resistant materials will be chosen through systematic testing with synthetic urine solutions, and the fundamental factors controlling film formation will be investigated in detail to better control the quality of the final product. An appropriate polymer will be chosen to act as a total barrier to all substances, including small molecules such as urea, commonly found in urine. Such substances are very poorly rejected by commercial reverse osmosis membranes, leading to their complete inapplicability in such separations. By incorporating molecular sieve nanoparticles, water flux and separation factors will be drastically increased compared to pure polymer membranes that are tailored to allow for water permeation. While a nanoparticle-only membrane would provide very high water flux, such membranes are brittle, and require high temperatures to produce. Our membrane design will likely provide excellent separation, decreased cost of production over nanoparticle-only membranes, flexibility and long-term durability.