USE OF ELECTROCHEMICAL QUARTZ-CRYSTAL MICROBALANCE TECHNIQUE TO TRACKELECTROCHEMICALLY ASSISTED REMOVAL OF HEAVY-METALS FROM AQUEOUS-SOLUTIONS BY CATION-EXCHANGE COMPOSITE POLYPYRROLE-MODIFIED ELECTRODES

The removal of heavy metals from aqueous solutions is of great importa nce. A new method of electrochemically assisted removal of heavy metal ions from aqueous solutions is presented. Composite polypyrrole films with cation-exchange properties were synthesized on the electrode sur face. The uptake of cations by the polymer film is based on the counte rion effect and occurs without any change in their oxidation state. Th e incorporation of cations and their preconcentration inside the polym er matrix take place during the negative potential step. The regenerat ion of the membrane and the release of accumulated cations occur upon the potential reversal step. No chemicals for the regeneration of the membrane are required. The use of the electrochemical quartz crystal m icrobalance (EQCM) technique allowed us to characterize the ion dynami cs in composite polymer films and to track in situ the incorporation a nd release of heavy metal cations such as Pb+2, Cd+2, and Ni+2. (C) 19 97 Academic Press.