Authors:J. Stejskal, J. Soukup, J. Doležal, and V. Kouřím
The use of organic polymers as binding agents for inorganic ion-exchangers has been studied. Poly-vinyl acetate and polystyrene
polymers were applied to ammonium phosphomolybdate and zinc ferrocyanide. The method of preparation and hydromechanical properties
of the resulting materials in ion-exchange columns are described. The materials were used for caesium removal from simulated
Purex high-level radioactive waste solutions. The break-though capacities and results of repeated sorption-elution cycles
Authors:J. Doležal, J. Stejskal, M. Tympl, and V. Kouřím
The possibility of using the sol-gel method for preparation of inorganic ion-exchangers with a silica gel matrix has been
demonstrated on the ammonium molybdophosphate-silica gel (AMP-SG) system. For the preparation of the ion-exchanger a sodium
silicate solution, containing AMP and components to cause gelling to silica gel after increase of the temperature of the solution,
is poured into a hot stirred silicone oil. The solution forms droplets, which are filtered off after their gelling, washed
and dried. Beads containing 65 wt.% of AMP per gram of dry material have been prepared by this method and tested in ion-exchange
columns for caesium removal from nitric acid solutions. Caesium may easily be desorbed with ammonium chloride or nitrate solutions.
The ion-exchanger is suitable for long-time reversible column operation, having not only good chemical, thermal and radiation
stabilities but also good mechanical and hydrodynamic properties and resistance to abrasion. It combines the advantage of
the good kinetics of ion-exchange obtained with microparticles of precipitated inorganic ion-exchanger, with the low flow
resistance of large particles.
Authors:S. D. Sharma, K. G. Varshney, and S. C. Mojumdar
Inorganicionexchangers have been of great interest for the last six decades, zirconium(IV) phosphate being the most extensively studied material [ 1 , 2 ]. Next to this are the tin(IV)-based materials, due to
Ferrocyanides of zirconium(IV) and tin(IV), antimonates of cerium(IV) and titanium(IV), and cerium(IV) tungstate, has been
shown to be useful materials as inorganic ion exchangers in radio- and analytical chemistry. These materials are sufficiently
stable towards high dose of γ-radiations. Attempt is made to study some structural aspects and possible exchange sites of
these materials using different techniques like thermal, Mössbauer and infrared spectroscopy.
Methods of preparation of granules of inorganic ion exchangers as well as methods for improvement of granular strength of these materials are reviewed. The resulting ion exchangers are classified in three groups—intrinsic, supported and composite ion exchangers. Their properties are compared and possibilities of their technological application are evaluated. A new method of preparation of inorganic-organic composite sorbents of inorganic ion-exchangers and polyacrylonitrile binding matrix is described, advantages and disadvantages of such sorbents are discussed. Proposed fields of application include tratment of liquid radioactive and/or hazardous wastes, decontamination of natural water as well as analytical applications.
Microcrystalline zirconium phosphate (-ZrP), hydrous manganese dioxide (HMnO), ammonium molybdophosphate (AMP) and silica gel supported forms of these materials as well as silica gel (SG) itself were investigated by thermoanalytical, electron microscopic, X-ray diffraction and infrared spectrometric methods. Chemical composition, structure and some related properties of the inorganic ion exchangers mentioned above are reported.
The effect of -irradiation on the ion-exchange capacity, distribution coefficient and the efficiency for binary separations of some thermally stable inorganic ion exchangers have been studied. Irradiation upto 100 Mrad, has no effect on these substances, except thorium tungstate which showed changes in ion-exchange capacity, distribution behaviour and in binary separations.
Authors:K. Varshney, S. Agrawal, K. Varshney, U. Sharma, and S. Rani
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.
The radiochemical method has been used for investigation of the adsorption of radium on eighteen inorganic ion exchangers. The distribution coefficient of radium obtained are as follows: barite 2955, celestite 2420, BaSO4 4350, BaCrO4 5245, Ba3(PO4)2 5775, MnO2·nH2O 1681, La2O3·nH2O 4150, Zerolit S/F 2920, etc.