Kanak Varshney

Synthesis, Ion-Exchange Behavior, and Analytical Applications of a New, Crystalline, and Stable Zirconium(IV) Arsenosilicate Cation-Exchanger: Analysis of Some Silicate Rocks

Abstract A new crystalline inorganic ion-exchanger, Zr(IV) arsenosilicate, has been synthesized and shows high chemical and thermal stability. It is also stable under γ-radiations of moderately high strength. The utility of this material has been demonstrated by achieving quantitative separation of Hg(II) from such other metal ions as Cd(II), Pb(II), Ni(II), Co(II), Zn(II), Al(III), and Fe(III) on its columns. Some silicate rocks have also been analyzed using this material.

Synthesis, Composition, and Ion-Exchange Behavior of Thermally Stable Zr(IV) and Ti(IV) Arsenophosphates: Separation of Metal Ions

Abstract Two new inorganic ion-exchange materials, Zr(IV) and Ti(IV) arsenophosphates, have been synthesized. They are reproducible in behavior and possess excellent thermal stability. Their tentative structures have been proposed based on pH titrations, thermogravimetry, chemical analysis, IR studies, and other ion-exchange properties. Distribution studies of some metal ions have also been made on the basis of which several useful binary separations have been achieved such as Fe(III) from VO(II), Cu(II), and Zn(II); Pb(II) from Cu(II), Hg(II), and Zn(II); Ti(IV) from UO2(II) and Ce(IV); and Mg(II) from Sr(II) and Ba(II).

Synthesis, ion-exchange behaviour and analytical applications of stannous ferrocyanide : Separation of Mg-Ca, Mg-Ba, Mn-Co, Mn-Ni and Y-Th

Abstract Stannous ferrocyanide has been synthesized as an inorganic ion exchanger having an Sn:Fe ratio of 1:1 and a cation-exchange capacity of 2.03 mequiv./g (dry-weight). It is fairly stable in water and dilute solutions of acids, sodium and ammonium salts and reducing agents such as hydrazine sulphate, ascorbic acid and tartaric acid. Ion distribution studies of twenty-eight metals have been made on this ion exchanger, and on the basis of these studies five binary separations (Mg—Ba, Mg—Ca, Mn—Co, Mn—Ni and Y—Th) have been achieved on its column. Papers impregnated with stannous ferrocyanide have also been used for eighteen other separations. A tentative structure of this compound is proposed on the basis of chemical analysis, pH titrations, thermogravimetry, IR spectrophotometry and the aqueous chemistry of tin and the ferrocyanide ion.

Radiation stability of some thermally stable inorganic ion exchangers

Effect of various doses of gamma radiation on the ion-exchange capacity, distribution coefficient values, elution behaviour, pH titration and infrared spectra of some thermally stable inorganic ion exchangers has been studied systematically. No change has been observed in the ion-exchange capacity, elution behaviour and the infrared spectra of the materials irradiated up to a total dose of 3·108 rad, while, a change has been observed in their pH-titration and distribution behaviour.

Unusual Selectivities of Stannic Arsenate Layers in DMSO-HCI Systems: Separation of Zirconium from Numerous Metal Ions

Abstract The adsorption behavior of 52 metal ions has been studied in DMSO-HCI systems using stannic arsenate layers. A remarkable feature of this study is a dramatic decrease in adsorption of many ions when compared to the corresponding water-HCI systems. This specific DMSO effect has been explained and used for important binary and ternary separations. In DMSO-5 M HCI (1:1), Zr4 + and Mo6 + have been separated from each other and from a mixture of Th4 +, Ca2 +, Y3 +, Nb5 +, Ta5 +, In3 +, Ti4 +, and the rare earths.

Ion-exchange kinetics of some metal pollutants and their separation on zirconium (IV) phospho- and silico-arsenate cation exchangers

Abstract Exchange kinetics of some polluting metal ions such as Mn(II), Fe(II), Co(II), Ni(II), Zn(II) and Cd(II) has been studied on zirconium(IV) phospho- and silico-arsenates, apply ing an approach based on the Nernst-Planck equations. As a result, some kinetic and thermodynamic parameters like diffusion coefficients, activation energies, and entropies of activation have been evaluated under the conditions favouring a particle diffusion-controlled mechanism. The theoretical predictions derived from these studies have been correlated with the practically achieved separations of cadmium(II) from some metals mentioned above.

Evaluation of the dimensionless time parameter for some particle diffusion controlled forward and reverse H(I)—metal(II) exchanges

Abstract The dimensionless time parameter (τ) has been evaluated as a function of fractional exchange of H(I) for some bivalent ions and of the bivalent ions for H(I) using the explicit approximation given by Helfferich et al., applicable to a particle diffusion-controlled ion-exchange process. The calculations have been made using a computer.

A KINETIC APPROACH TO EVALUATE THE ENERGY AND ENTROPY OF ACTIVATION FOR THE EXCHANGE OF ALKALINE EARTH METAL IONS ON TIN(IV) TUNGSTATE CATION EXCHANGER

Abstract A new approach based on the Nernst-Planck equations has been applied to study the reaction kinetics on the surface of tin(IV) tungstate for the Mg(II)-H(I), Ca(II)-H(I), Sr(II)-H(I) and Ba(IT)-H(I) exchanges under the conditions favouring a particle diffusion phenomenon. On the basis of these studies the various physical parameters such as the effective diffusion coefficients, activation energies and entropies of activation have been evaluated which give some informations regarding the mechanism of ion-exchange on the surface of inorganic materials.

Ion-Exchange and Selectivity Behavior of Thermally Treated and γ-lrradiated Phases of Zirconium(IV) Arsenophosphate Cation Exchanger: Separation of Al(III) from Some Metal Ions and Removal of Cations from Water

Abstract Ion-exchange and selectivity behavior of zirconium(IV) arsenophosphate (ZAP) has been studied systematically after thermal and irradiation treatments. As a result, an increase in the ion-exchange capacity and a complete reversal in the selectivity sequence for some common metal ions has been observed on heating. The modified phase of ZAP has been utilized successfully for the quantitative separation of aluminum from numerous metal ions and for the removal of cations from water.

A Novel Quantitative Separation of Cr(III) from Numerous Metal Ions on β-Stannic Arsenate Thin Layers in DMSO—HCI Systems

Abstract This paper deals with the thin-layer chromatography of metal ions on β-stannic arsenate using dimethylsulfoxide solvent system. A novel quantitative separation of Cr(III) has been developed on these thin layers. The method is precise and accurate and can be applied for the quantitative separation of Cr(III) from mixtures containing Cu, Nb, Ta, Ce, Ni, Co, Al, Zn, Mn, Th, La, Cd, and Pt. A mechanism dealing with this separation is also been presented based on the kinetic inertness of Cr(III), the properties of DMSO, and the selectivity of β-stannic arsenate.