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Abstract: Electrically conductive composite of polyaniline–titanium(IV)phosphate (PANI–TiP) was synthesized by sol–gel method. The obtained composite was characterized by using Fourier transform infra red spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The composite showed good ion-exchange capacity and isothermal stability in terms of DC electrical conductivity retention at an ambient conditions below 100°C. The composite material was investigated as alcohol vapors sensor and compared with blank polyaniline. The results showed that the composite was more selective and sensitive towards methanol vapors. [ABSTRACT FROM AUTHOR]

Abstract: Polyaniline Sn(IV) phosphate, an ‘organic–inorganic’ composite material, was synthesized via sol–gel mixing of an electrically conducting organic polymer polyaniline into the matrices of inorganic precipitate of Sn(IV) phosphate. This material was used as a cation-exchanger. The physico-chemical properties of the material were determined using AAS, CHN elemental analysis, ICP-MS, UV–VIS spectrophotometry, FTIR, TGA–DTA, XRD, and SEM studies. Ion-exchange capacity, chemical stability, thermal stability and distribution behavior were also carried out to understand the cation-exchange behavior of the material. On the basis of distribution studies, the material was found to be highly selective for Pb(II). Its selectivity was examined by achieving some important binary separations like Pb(II)–Mg(II), Pb(II)–Sr(II), Pb(II)–Zn(II), and Pb(II)–Fe(III) on its column. This material possessed DC electrical conductivity in the semi-conducting range, i.e. 10−5–10−3 Scm−1. The stability in terms of DC electrical conductivity retention was also studied in an oxidative environment by two slightly different techniques viz. isothermal and cyclic techniques. The DC electrical conductivity of composite material was found stable upto 110°C under ambient conditions. [Copyright &y& Elsevier]

Abstract: The separation of Pb2+ from aqueous solutions was studied using a fibrous type polypyrrole thorium(IV) phosphate cation-exchanger column. This type of organic–inorganic composite material was prepared by incorporating polypyrrole into inorganic precipitate of Th(IV) phosphate, providing a new class of hybrid cation-exchangers with good ion-exchange capacity, higher stability, reproducibility and selectivity for heavy metals. The physico-chemical properties of this material were determined using some instrumental analyses. Ion-exchange capacity, pH-titrations, elution and distribution behavior etc. were also carried out to understand the ion-exchange behavior of the material. On the basis of distribution studies, the material was found to be highly selective for Pb(II) and its selectivity was examined by achieving some important binary separations like Pb(II)–Zn(II), Pb(II)–Al(III), Pb(II)–Mg(II), Zn(II)–Hg(II) etc. on its column that indicate its utility in environmental pollution control in one-way or other. For the determination of Pb(II) ions in solutions, a new heterogeneous precipitate based selective ion-sensitive membrane electrode was developed by means of this composite cation-exchanger as electroactive material. The membrane electrode is mechanically stable, with a quick response time, and can be operated over a wide pH range. The selectivity coefficients were determined by mixed solution method and revealed that the electrode is selective for Pb(II) in presence of interfering cations. The practical utility of this membrane electrode has been established by employing it as an indicator electrode in the potentiometric titration of Pb(II). [Copyright &y& Elsevier]

Composite materials formed by the combination of inorganic ion exchangers of multivalent metal acid salts and organic conducting polymers (polyaniline, polypyrrole, polythiophene, etc.), providing a new class of ‘organic–inorganic’ hybrid ion exchangers with better mechanical and granulometric properties, good ion-exchange capacity, higher stability, reproducibility and selectivity for heavy metals. Such a type of ion exchanger ‘polyaniline Sn(IV) tungstoarsenate’ was developed by mixing polyaniline into inorganic precipitate of Sn(IV) tungstoarsenate. This material was characterized using atomic absorption spectrometry, elemental analysis, Fourier transform infrared spectroscopy, simultaneous thermogravimetry–differential thermogravimetry, X-ray and scanning electron microscopy studies. Ion-exchange capacity, pH-titrations, elution and distribution behavior were also carried out to characterize the material. On the basis of distribution studies, the material was found to be highly selective for Cd(II) and its selectivity was tested by achieving some important binary separations like Cd(II)–Zn(II), Cd(II)–Pb(II), Cd(II)–Hg(II), Cd(II)–Cu(II), etc., on its column. Using this composite cation exchanger as electroactive material, a new heterogeneous precipitate based selective ion-sensitive membrane electrode was developed for the determination of Cd(II) ions in solutions. The membrane electrode is mechanically stable, with a quick response time, and can be operated within a wide pH range. The selectivity coefficients for different cations determined by mixed solution method were found to be less than unity. The electrode was also found to be satisfactory in electrometric titrations. [Copyright &y& Elsevier]