(58e) Separation Challenges in Membrane-Based Water Applications

Various separation processes are used extensively in dilute aqueous applications ranging from valuable chemical/pharmaceutical recovery to high value metals recovery from mining effluents to water purification and detoxification. Technologies include adsorption, affinity separations, ion exchange, solvent extraction, membrane separations, etc. Membrane separation technologies (such as, RO, NF, MF, UF, ED, CDI, etc,) are expanding at a rapid rate with applications ranging from complete desalination to selective protein and low MW organics recovery to water reuse and water detoxification. In addition, by integrating life sciences and nanotechnology one can overcome a variety of separation challenges through bioinspired and responsive nanostructured membranes. Integrating the principles of other separation technologies, such as, adsorption/ion exchange/chromatography to membranes, one can reduce the effect of diffusional mass transfer issues and high level sorption site utilization issues. Various membranes and module designs also suffer from use in elevated temperature (even 90 ^oC) and corrosive condition applications. Selective separations are often needed where one needs very low (may be less than 5%) NaCl separation while rejection divalent or trivalent ions to eliminate osmotic pressure issues and allowing water reuse. The presentation will include: research needs, challenging selective separation examples, hybrid systems, responsive and bioinspired membranes for selectivity, need for surface functionalization, and discussions on flux vs. selectivity.