ABSTRACT
Sy n t h e t i c , water-soluble polyelectrolytes can be used to recover and concentrate dilute metal ions and other inorganic and organic solutes from aqueous solutions for analytical and process applications. Using commercially available polymeric backbones and a wide va riety of synthetic methods, new polyelectrolytes with selective receptors for metal ion and other inorganic species have been prepared [1,2]. When these polymeric polyelectrolytes are used in concert with ultrafiltration (UF) membranes, the polymer-metal complex, or guest-host polymer complex, can be readily retained, recovered, purified and concentrated [3], Water and small, unbound solutes pass freely through the UF membrane, becoming per meate, while bound solutes remain as the retentate. The permeate stream, which is reduced in or “free” of the solutes bound to the polymer, can be used in further processing steps or dis charged. The sequestered or bound solute is released from the receptor sites by adjusting the chemical and sometimes physical conditions of the retentate solution. A second UF step (diafiltration) recovers the sequestered solute in a concentrated form for recycle or disposal and retains the soluble polymer for additional process cycles.
