Mohsin Qureshi

Synthesis of Tin(IV) antimonate of high thermal and chemical stability : Separation of Mg2+ from Sr2+, Cd2+, Al3+ and La3+

Abstract Seven samples of antimonates of tin(IV), iron(III) and thorium(IV) have been synthesized under various conditions. The chemical stabilities of these antimonates were determined in dilute solutions of mineral acids. The distribution coefficients of metal ions were determined at different pH values on tin(IV) antimonate. The analytical importance of this exchanger was demonstrated by achieving the separations of some important pairs of metal ions.

Preparation and properties of stannic tungstate

Abstract Stannic tungstate gel (Sn:W ratio 3:1) has been prepared by mixing 0·02 MM aqueous solutions of stannic chloride and sodium tungstate in the volume ratio 2:1. Its ion exchange capacity is 0·57 meq/g. Its chemical stability, K d values and pH titration curves are also described.

Synthesis and ion-exchange properties of thermally stable stannic selenite.

Stannic selenites have been synthesized under a variety of conditions. The most stable sample is prepared by mixing 0-0.5M solutions of stannic chloride and sodium selenite in the ratio of 1:1 at pH 1. It is a bifunctional amorphous material. A tentative structure has been proposed on the basis of chemical composition, pH titrations, infrared and thermogravimetric analyses. Its ion-exchange capacity is 0.75 and 0.73 meq g after drying at 50 degrees and 500 degrees respectively. Its analytical importance has been established by the following quantitative separations: Cu(2+) from Ni(2+), Co(2+), Fe(3+), Ga(3+) and In(3+), Fe(3+) from Pb(2+) and Sc(3+), and Sc(3+) from VO(2+).

Cation exchange in formic acid-dimethyl sulphoxide media: Separation of thorium from uranium, yttrium, lanthanum and cerium

Cation-exchange studies for 26 metal ions in dimethyl sulphoxide, acetone, and formic acid-DMSO-water systems on Dowex 50W-X8 arc reported. Thorium can be separated from uranium, yttrium, lanthanum and cerium by elution first with DMSO and then with 2 M nitric acid.

Comparative study of titanium(IV)-based exchangers in aqueous and mixed solvent systems

The antimonate, arsenate, tungstate, molybdate and selenite of titanium have been synthesized. Their composition and chemical and thermal stability have been determined. Effects of pH and temperature on ion-exchange capacity have been studied. Titanium antimonate was found to be the most stable. The utility of these ion-exchangers for analytical separations was examined by determining the distribution coefficients for 26 metal ions in some aqueous, non-aqueous and mixed solvent systems. Quantitative separations of HgCd, PbCu and PbZn have been achieved on titanium tungstate columns, and LaBa mixtures have been separated on a titanium arsenate column.

Studies on chromium(III) hydroxide, arsenate, antimonate, molybdate and tungstate.

Five water-insoluble compounds of chromium(III) have been synthesized by mixing 0.10M solutions of chromic chloride and the appropriate sodium salts in the volume ratio of 1:2, at pH 6-7. Their ion-exchange characteristics have been compared. The tungstate has the highest chemical stability and the arsenate has the highest ion-exchange capacity. Chromium(III) molybdate columns have been used to separate Pb(2+) from numerous metal ions.

Synthesis and IR, X-ray and ion-exchange studies of some amorphous and semicrystalline phases of titanium antimonate : Separation of VO2+ from various metal ions

Amorphous and semicrystalline samples of titanium antimonate have been synthesized by mixing solutions of titanium (IV) chloride and antimony pentachloride of different concentrations in various volume ratios at a constant pH of zero. The selectivities for twenty-seven metal ions of four chemically different samples have been compared. IR spectra and d values for titanium antimonates have been compared with those reported for antimonic acid and sodium antimonate.

Chromatographic behaviour of 47 metal ions on titanium(IV) arsenate papers

Titanium arsenate papers with As/Ti ratios 0.2-2.2 have been prepared and 47 metal ions chromatographed on these papers in 10(-5)-4M nitric acid. The effect of pH and of the Ti/As ratio on the R(f) values has been studied. A new quantity R(i) (R(i) = R(f) on untreated papers minus R(f) on treated papers) has been defined. The effect of the concentration of the loading reagents on the Ti/As ratio of the ion-exchanger precipitated on the papers has been determined Contrary to Alberti, it is shown that Lederers equation is obeyed by titanium arsenate papers in the sodium form if the activity of Na(+) ions is considered instead of their concentration. It has also been demonstrated that the selectivity sequence for cations on titanium arsenate papers is not the same as that on titanium arsenate columns.

Synthesis, ion-exchange behaviour and composition of tin(IV) hexacyanoferrate(II)☆

Abstract Tin(IV) hexacyanoferrate(II) as an inorganic ion exchanger has been prepared in thirteen different ways by varying the pH, the mole ratios mixed and the concentration. Exhaustive analytical studies of a sample having a Sn/Fe mole ratio of 3:1 and an ion-exchange capacity of 2.02 mequiv./g dry weight have been made. These include investigation of its stability in different solvents and its composition, pH-tritrations, ion distribution studies, thermogravimetry, and X-ray diffractional measurements. On the basis of all these experimental data a tentative approach to the formula of the compound was made. The potentiality of its use as an ion exchanger has been demonstrated by the achievement of some important and difficult separations.

Preparation and properties of titanium arsenates

Abstract Amorphous titanium arsenates have been prepared by mixing solutions of titanic chloride and sodium arsenate of different concentrations and in varying volume ratios. The material prepared by mixing 0·05M titanic chloride and 0·05M sodium arsenate in the ratio 1 : 1 was studied in detail for its ion exchange capacity, stability, thermogravimetry, pH-titration curve and K d values. The structures of one sample was established tentatively and its utility demonstrated by separating Pb(II) from Cu(II), Zn(II), Mg(II) and Ga(III).