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Journal of Thermal Analysis and Calorimetry
Authors: K. Varshney, V. Jain, A. Agrawal, and S. Mojumdar

Abstract  

Pyridine based zirconium(IV) phosphate (PyZrP) and tin(IV) phosphate (PySnP) have been synthesized as new and novel intercalated ion exchangers. These materials have been characterized using X-ray, IR spectra, TG, DTG and DTA studies in addition to their ion exchange capacity, elution, pH titration, concentration and distribution behaviour. The distribution studies towards several metal ions in different media/concentrations have suggested that PyZrP and PySnP are selective for Hg(II) and Pb(II), respectively. As a consequence some binary separations of metal ions involving Hg(II) and Pb(II) ions have been performed on a column of these materials, demonstrating their analytical and environmental potential.

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A new tin dithiocarbamate containing sulphur bridges, di-μ-sulphidobis [bis(N,N-diethyldithiocarbamato)tin(IV)], has been isolated from the thermal decomposition of tetrakis(N,N-diethyldithiocarbamato)tin(IV). A dimeric structure is proposed on the basis of results from mass spectrometry, infrared spectroscopy, thermal analysis and vapour pressure osmometry.

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Abstract  

Tin(IV) antimonate with different Sb/Sn molar ratios has been prepared. The characterization of the product materials was carried out using X-ray diffraction pattern, themal analysis and infrared spectra. The saturation capacities of sodium and cesium were found to increase with Sb/Sn molar ratios. TheK d values on thermal treatment of tin(IV) antimonate, as a cation exchanger, have been measured for some heavy metal ions in the temperature range of 50–400 °C. The maximum adsorption of 10–4M of the metal ions studied was obtained at 400 °C. The selectivity sequence was Eu3+>Co2+>Sr2+>Cs+ for the sample heated up to 400 °C. No adsorption was observed on the sample heated at 700 °C because of the formation of SnO2 and Sb6O13.

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Abstract  

Column chromatographic technique has been utilized to study the column performance of uranyl ion separation on tin(IV) antimonite hydrous oxide matrix. Different flow rates were applied, at 0.6 ionic strength and pH 3, to evaluate the effect of different flow rate on column breakthrough behaviour. Van Demeeter equation was used to emphasize the optimum column conditions. High equivalent to theoretical plate, breakthrough capacity (Q 0.5) were also calculated.

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Abstract  

This paper is concerned with the study of isotope exchange reaction between Sn(II) and Sn(IV) in hydrochloric acid solutions. The kinetics of the exchange reaction of tin in these solutions were studied by extraction of Sn(IV)-hydroxyquinolate into chloroform.113Sn tracer, initially in the Sn(IV) state, was used. The rate of exchange reaction was determined at 22°C in a wide range of hydrochloric acid concentrations (2.8–12M). The dependence of the exchange rate on the concentration of chloride and hydrogen ions in these solutions (ionic strength: I∼8 and I∼12) are given. The activation energy dependence on chloride ion concentration at I∼12 was determined. The possible mechanism of the exchange reaction between tin(II) and tin(IV) is discussed on the basis of these data.

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Abstract  

Kinetics of the exchange reaction of cadmium(II)-ammine complex ion using radio-active isotope115Cd in the same chemical form in hydrous oxides of zirconium(IV), silicon(IV) and tin(IV) has been studied. It has been found that the major contribution in the overall exchange process is from the surface of the exchanger particles. It has also been found that the rate of exchange follows the order: hydrous ZrO2>hydrous SnO2>hydrous SiO2

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1,10-phenanthroline (phen), 2,2′-bipyridyl (bipy), pyridine (py) and 4-picoline (4-pic) complexes of dibutyltindichloride (Bu2SnCl2) and dimethyltindichloride (Me2SnCl2) were synthesized. The complexes were characterized with the help of elemental analyses, IR spectra and thermal analyses. The complexes were found to have the compositions [Bu2SnCl2·phen], [Bu2SnCl2·bipy], [Me2SnCl2·phen], [Me2SnCl2·bipy], [Me2SnCl2·2py] and [Me2SnCl2·2(4-pic)]·H2O. All these complex compounds appeared to posses octahedral structures. Thermodynamic parameters, such as activation energyE a * enthalpy change ΔH and entropy change ΔS, for the dehydration and sublimation of the complexes were evaluated using some standard methods.

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Abstract  

A novel type of tin oxide and its cation exchange properties are described. The preparation of the oxide is rather unusual and consists in the precipitation of SnO·xH2O in the presence of sodium nitroprusside and its digestion in the presence of sodium nitrite. The final product is a partially reduced tin dioxide (PRTD) with one out of eight atoms of metal in the lower oxidation state of +2 and a great part of the bound water hydrogen replaced by sodium. Usual applications of commercially available tin dioxide exchangers can be extended to PRTD with remarkable advantages.

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Abstract  

The complexes of the type SnCl4(HL)·EtOH and SnCl2L2 (HL 1 : the Schiff base resulted in 1:1 condensation of isatin and aniline; HL 2 : the Schiff base resulted in 1:1 condensation of isatin and p-toluidine) have been synthesized and characterized. The thermal analysis of the new ligands and complexes has evidenced the thermal intervals of stability and also the thermal effects that accompany them. The Schiff bases thermal transformations consist in phase transitions, Carom–N bond cleavage and thermolysis processes. The different nature of the complexes generates their different thermal behaviour. The complexes lead in three steps to SnO2 and in all cases the Schiff bases degradation generates a pyrrolidone-coordinated derivative. As for the SnCl4(HL)·EtOH complexes, the SnCl4 formed during the last step is involved in two competitive processes, one consists in their volatilisation while the other one leads to SnO2. As result the SnO2 residue is smaller than the theoretically expected.

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