Abstract
Conducting polymeric-inorganic composite ion-exchange materials are now considered as an advanced class of materials due to their excellent ion-exchange behavior as well as their analytical and electroanalytical applications. In this study, electrically conductive nanocomposite of polyaniline Sn(IV) tungstomolybdate (PSTM) was synthesized by sol–gel method via the blend of inorganic precipitate of Sn(IV)tungstomolybdate into the matrix of polyaniline gel having good ion-exchange capacity and electrical conductivity behavior. The so obtained composite was characterized by using several sophisticated instrumental analyses; such as FTIR, TGA-DTA, XRD, SEM and TEM. Electrical conductivity behavior of this composite material was investigated by using 4-probe-in-line DC electrical conductivity measuring technique and the electrical conductivity was found in semiconductor region; i.e., 10−2 S cm−1, which followed Arrhenius equation for its temperature dependence. The thermal stability of the PSTM composite material in terms of dc electrical conductivity retention was studied under isothermal and cyclic techniques and electrical conductivity of the composite was found to be sufficiently stable under ambient temperature conditions. The dependence of the electrical conductivity on the concentration of conducting phases i.e., polyaniline exhibited that the increase in electrical conductivity followed the percolation threshold. Using this electroactive composite cation-exchanger, a novel heterogeneous precipitate based ion-selective membrane electrode was developed for the determination of Pb(II) ions in solutions. The membrane electrode has a quick response time with mechanically stable and can be used within a varied pH range. The selectivity coefficients for various cations evaluated by mixed solution method were found to be less than unity. The electrode was also found to be suitable in electrometric titrations.