Preparation, characterization and analytical applications of a new and novel electrically conducting fibrous type polymeric–inorganic composite material: polypyrrole Th(IV) phosphate used as a cation-exchanger and Pb(II) ion-selective membrane electrode

Abstract

‘Polymeric–inorganic’ composite type of cation-exchanger ‘polypyrrole Th(IV) phosphate’ was prepared by mixing polypyrrole into fibrous inorganic precipitate of Th(IV) phosphate. This type of composite possesses a new class of hybrid ion-exchangers with good ion-exchange capacity (I.E.C.), higher stability, reproducibility and selectivity for heavy metals. The physicochemical properties of the material were determined using AAS, CHN elemental analysis, ICP-MS, UV-VIS spectrophotometry, FTIR, thermogravimetric analyses-differential thermal analysis (TGA-DTA), XRD and SEM studies. Ion-exchange capacity, pH-titrations, elution and distribution behavior etc. were also carried out to characterize the material. On the basis of distribution studies, the material was found to be highly selective for Pb(II), a heavy metal pollutant in the environment. Its selectivity was examined by achieving some important binary separations like Pb(II)–Zn(II), Pb(II)–Ni(II), Pb(II)–Cu(II) and Pb(II)–Cd(II) on its column that indicate its utility in environmental pollution control in one-way or other. This electroactive material also showed the DC electrical conductivity in the range of 10 −6 to 10 −4 S cm −1. A new heterogeneous precipitate based selective ion-sensitive membrane electrode was developed by using this composite cation-exchanger for the determination of Pb(II) ions in solutions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations.