No abstract

Functionalized membranes represent a field with multiple applications. Examination of specific metal−macromolecule interactions on these surfaces presents an excellent method for characterization of these materials. These interactions may also be exploited for heavy metal sorption from drinking and industrial water sources. Various low-capacity, silica-based ion-exchange and chelating sorbents (about 0.5 mmol of metal/g of resin) are available for treatment of such waters. Cellulosic membrane-based sorbents, functionalized with polyamino acids, present an excellent approach for high-capacity (3−14 mmol of metal/g of sorbent) metal sorption. Silica-based membrane sorbents possess metal sorption capacities approaching those of cellulosic-based membranes, with the added benefits of excellent acid and solvent resistance. Metal sorption capacities of silica-based membrane sorbents with various polyamino acids range from 0.6 mmol to 1.4 mmol of metal/g of sorbent. Ion exchange, chelation, and electrostatic interactions form the basis of metal sorption. Electrostatic interactions are greatly magnified in membrane-based sorbents, and are partly responsible for their high capacities. Regeneration of these sorbents has also been shown, including the possibility for selective desorption of metals.

This report is one component of a work unit encompassing identification and bench-scale testing of low-cost sorbents for treatment of metalscontaminated water and waste streams. The report was prepared by Ms. Susan