Potentiometric Determination of Mercury Ions by Sol-gel Synthesized Multi-walled Carbon Nanotubes Zr (IV) Phosphate Composite Fabricated Membrane Electrode

Abstract

Background: The nanocomposites are formed by introducing inorganic nano-clusters, fullerenes, clays, metals, oxides with numerous organic polymers. The assembly of these materials exhibits better properties such as catalytic, thermal stability and adsorption properties, etc. than the individual materials. Objective: The nanocomposite synthesized here by sol-gel method was primarily evaluated for cation exchange properties viz, elution concentration, elution behavior, effect of temperature on ion-exchange capacity. The synthesized composite was used as an electro-active component for fabrication of Hg2+ ion selective membrane electrode. Method : The sol-gel technique was used to synthesize multi-walled carbon nanotubes Zr(IV) phosphate composite cation exchanger. By the technique of solution casting the material as an electroactive part was used for the fabrication of mercury ion-selective membrane electrode. The potential response of the electrode was also investigated as a function of membrane composition and plasticizer. Results: The composite cation exchanger exhibited 1.8 meq g-1 ion-exchange capacity (IEC). It retained almost 65 % of its initial IEC upto a temperature of 400 °C. Distribution studies showed the selective nature of the composite for Hg(II) ions. The ion-selective membrane electrode exhibited typical Nernstian response towards Hg2+ ions in the concentration range 1×10-1 -1×10-7 M. Conclusion: The results discussed reveal that a new cation composite exchanger-multi-walled carbon nanotubes Zr (IV) phosphate exhibited excellent cation exchange properties and was found to be preferentially selective towards the Hg2+ ions. It was also used as an indicator electrode in the titration of Hg2+ using ethylenediaminetetraacetic acid as a titrant.