University of Kentucky,
Keywords: water remediation, metal capture, water technologies
Summary:Abstract: Providing access to safe drinking water has been identified as one, and possibly the most important, of the grand challenges facing scientists in the 21st century. The contamination of aquifers by toxic metals and organic compounds is a widespread problem that prevents these potentially potable sources from being used for drinking water. For toxic metals one can use precipitation technique or ion exchange. Conventional ion exchange materials have low capacity, on the other hand metal capture at high capacity can be obtained by the use of bound polyelectrolytes (multiple binding sites) on macroporous polymeric membrane media. Helixcoil transitions of polyeletrolytes also allow ease of regeneration. The metal sorption results indicated not only high capacity but also rapid uptake rate. Metal sorption with polypeptide functionalized membranes is extremely high (for example, >1g metal/g for Pb) compared to conventional ion exchange (50 to 100 mg/g). Regarding toxic chloro-organics (such as, TCE, TCP, PCBs, etc.) in water, oxidative techniques utilizing free radicals (hydroxyl radicals, sulfate radicals) have proven effective for dechlorination and degradation. Many free radical generating processes rely on the reaction of Fenton-like processes using ferrous iron and hydrogen peroxide to form hydroxyl radicals and require lower pH. Our approach with chelate modified solution-phase reaction or iron ion/iron oxide bound to polymer chains in membranes allow near neutral pH operation and reduced rate of hydrogen peroxide consumption. The presentation will include: (1) multi-site polyelectrolyte functionalized system for high capacity toxic metal capture, (2) chelate (such as, citrate) modified Fenton type reaction for organic degradation, (3) membrane bound Fe(II)/Fe(III) to iron oxide particles from chloroorganic degradation to toxic Se/As removals. The speaker acknowledges his students Minghui Gui, Noah Meeks, Scott Lewis, Steve Ritchie, Y.C. Li, and also Dr. S. Sikdar of US EPA. In addition to various industrial collaborations and fundings, NIH-NIEHS-SRC, NSF-IGERT, US EPA–STAR program and NSFEPSCoR program provided considerable financial support.