Nanostructured Membranes for Water Purification

Application of nanotechnology to water purification is currently faced with the issue of how to design nanomaterials that are capable of collecting and preconcentrating a large number of contaminants per unit volume. Specifically, it is not clear how to interface nanoparticles with contaminants because direct addition of nanoparticles into drinking water may require extra separation steps to recover the expensive nanomaterials. Due to their large pore sizes, conventional membrane filters cannot be used for removing submicron particles, engineered nanoparticles, or biological particles within the range of 100. nm or below. To overcome these challenges, we present transformative membrane technologies that are based on the use of nanostructured conducting phase-inverted poly(amic acid) membranes to isolate and remove silver nanoparticles, quantum dots, and titanium dioxide particles in environmental samples. nPAA membranes have also been utilized to remove pathogenic bacteria in drinking water. Filtration efficiency of over 99.98% was recorded for most contaminants. The membrane pore sizes were experimentally controlled from 4 to 35. nm, and the optimized membranes were tested against three of the most common drinking water contaminants, namely Escherichia coli, Citrobacter freundii, and Staphylococcus epidermidis. Hundred percent removal of these microbial species were recorded and the results were validated with conventional plating techniques.