The University of Texas System

Chang Wei

Krishnan Rajeshwar

Sanjay Basak

The treatment of solutions of metal ions with redox polymers under conditions to reduce the ions to a lower valence. The resulting solutions of the lower valence ions are separated from the polymers, and the polymers are regenerated for further use in such treatment. The method of the invention is employed to convert high valence, toxic metal ions to lower valence ions of reduced toxicity. Preferably, the electronically conductive polymer is mounted on a suitable support, and a solution of the toxic metal ion is brought into contact with the polymer. A variety of redox polymers, in particular, electronically conductive polymers, may be used in the practice of the invention, and individual such polymers may be structurally altered to suit particular metal ions. Polymers especially contemplated for use in the invention are polypyrroles, polyanilines and polythiophenes. All of these polymers are characterized as redox polymers with a positive charge on their backbones. In general, suitable polymers are redox polymers bearing a positive charge on their backbones with an E.sub.o of the (surface) redox couple sufficiently negative to react with a metal ion of interest. Thus, for example, an E.sub.o more negative than 1.16V is preferred for the recovery of Cr(VI).

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Arlington, TX, United States of America

Chang Wei