Ion exchangers as adsorbents for removing metals from aquatic media.

A polyaniline-based composite cation-exchange material was synthesized by way of sol-gel method and studied to explore its analytical and environmental applications. It was characterized by using instrumental analyses [Fourier transform infrared (spectrometer), X-ray, thermogravimetric analysis/differential thermal analysis, standard electron microscopy, and transmission electron microscopy]. Physicochemical studies, such as ion-exchange capacity, pH titrations, and chemical stability, along with effect of eluent concentration and elution, were also performed to exploit the ion-exchange capabilities. pH titration studies showed that the material presents monofunctional strong cation-exchange behavior. This nanocomposite material is semicrystalline in nature and exhibits improved thermal and chemical stability. The partition coefficient studies of different metal ions in the material were performed in demineralised water and different surfactant media, and it was found to be selective for Pb(II) and Hg(II) ions. To exploit the usefulness of the material as an adsorbent, some important quantitative binary separations of metal ions were performed on polyaniline Zr(IV) molybdophosphate columns. This composite cation exchanger can be applied for the treatment of polluted water to remove heavy metals.

Synthesis and characterization of a new cation exchanger-zirconium(IV)iodotungstate: separation and determination of metal ion contents of synthetic mixtures, pharmaceutical preparations and standard reference material.

Samples of zirconium(IV)iodotungstate have been synthesized under varying mixing order and ratios of aqueous solution of potassium iodate, sodium tungstate and zirconium oxychloride at pH 1. A tentative formula was proposed on the basis of chemical composition, FTIR and thermogravimetric studies. The material shows a capacity of 0.68 meq g(-1) (for K+) which can be retained up to 200 degrees C. pH titration data reveal its monofunctional behavior. The distribution coefficient values of metal ions have been determined in various solvent systems. A number of important and analytically difficult quantitative separations of metal ions have been achieved using columns packed with this exchanger. In order to demonstrate practical utility of this material, Hg2+ and Pb2+ have been selectively separated and determined in the synthetic mixtures. Assay of Al3+ and Mg2+ in commercial tablets and analysis of lead in the standard reference material have also been attempted.

Synthesis, characterization and analytical application of hybrid; acrylamide zirconium (IV) arsenate a cation exchanger, effect of dielectric constant on distribution coefficient of metal ions.

A new hybrid inorganic-organic cation exchanger acrylamide zirconium (IV) arsenate has been synthesized, characterized and its analytical application explored. The effect of experimental parameters such as mixing ratio of reagents, temperature, and pH on the properties of material has been studied. FTIR, TGA, X-ray, UV-vis spectrophotometry, SEM and elemental analysis were used to determine the physiochemical properties of this hybrid ion exchanger. The material behaves as a monofunctional acid with ion-exchange capacity of 1.65 meq/g for Na(+) ions. The chemical stability data reveals that the exchanger is quite stable in mineral acids, bases and fairly stable in organic solvents, while as thermal analysis shows that the material retain 84% of its ion-exchange capacity up to 600 degrees C. Adsorption behavior of metal ions in solvents with increasing dielectric constant has also been explored. The sorption studies reveal that the material is selective for Pb(2+) ions. The analytical utility of the material has been explored by achieving some binary separations of metal ions on its column. Pb(2+) has been selectively removed from synthetic mixtures containing Mg(2+), Ca(2+), Sr(2+), Zn(2+) and Cu(2+), Al(3+), Ni(2+), Fe(3+). In order to demonstrate practical utility of the material quantitative separation of the Cu(2+) and Zn(2+) in brass sample has been achieved on its columns.