(725d) Broader Wastewater Reclamation with Mixed Matrix Membranes

The global water crisis demands new technologies to support reuse of impaired water sources. However, wastewater reclamation remains limited by the poor ability of even the most selective technologies to sequester certain small neutral solutes. We hypothesize that the development of a membrane with more rigid void spaces will enhance selectivity toward emerging contaminants. Carbon molecular sieves (CMS) were incorporated in reverse osmosis (RO) thin film composite membranes. Carbon derived from polyamide powders was made by emulsifying aqueous and organic solutions traditionally used in interfacial polymerization and subsequent pyrolysis with up to 50 ppm of oxygen. Porosity measurements of char indicate a minimum pore size of 3 Å that increases to 10 Å as soak temperature ranges from 500 °C to 900 °C. Permeation testing in a bench-scale RO system under cross-flow conditions at 400 PSI show control membranes, without CMS, had a water permeability of 0.76 ± 0.12 L m^-2 h^-1 bar^-1 and NaCl rejection of 99.03 ± 0.32 %. Mixed matrix membranes had a water permeability of 0.78 ± 0.11 L m^-2 h^-1 bar^-1 and NaCl rejection of 90.39 ± 5.78 %, due to defects introduced from sieves. Although initial results are modest, they suggest defect-free incorporation of CMS from highly cross-linked polymers could increase selectivity toward contaminants in aqueous separations.