Carbon Nanotube Composite Coated Stainless Steel Disk Electrode with Polypyrrole film as Ion-to-electron Transducer for the Determination of Hg(II)

An ion-selective electrode for mercury (II) ion is fabricated based on primarily electrodeposition of polypyrrole on the surface of stainless steel electrode, followed by coating with multiwall carbon nanotubes (MWCNTs), poly (vinyl chloride) (PVC) composite membrane which is modified with a new enamine ionophore. Polypyrrole film because of its good stability and conductivity was prepared as an intermediate layer of solid contact electrode. The combination of conducting polymers with those of MWCNTs leads to an improved performance of the resulting sensing devices. The electrode showed a Nernstian slope of 29.34±0.25 mV decade-1 over a wide concentration range of 5.0×10-7 to 1.0×10-2 M with the detection limit of 1.4×10-7 M of Hg(NO3)2. The proposed electrode exhibited a very good selectivity toward Hg (II) ion over a variety of metal ions. The response of this nanocomposite membrane electrode remains stable for at least two months without observing any considerable deviation. The practical applicability of this sensor as an indicator electrode in potentiometric titration of Hg (II) ions with EDTA and in titration of mixed halides are demonstrated. This electrode was also successfully applied for the determination of mercury ions in river water samples.