Synthetic inorganic ion exchangers. XI. Preparation,properties and ion-exchange behaviour of zirconium tungstate

Summary Samples of zirconium tungstate have been prepared under different conditions and their physico-chemical properties, composition, IR spectra and cation-exchange behaviour are reported. Separations of a number of metal ions from Bi³⁺ and from Pb²⁺ have been worked out.Part X. Ref. [1].     

Comparison of nonporous silica-based ion exchangers and monolithic ion exchangers in separations of inorganic anions

Low capacity anion exchangers for IC have been prepared by modification of nonporous uniformed silica MICRA microbeads and by modification of the organic polymeric monolithic matrixes prepared in situ in quarz capillary. Due to the small particle size (1.5 microm) high-performance adsorbents were prepared allowing to obtain up to 190,000 tp/m. However, the column possesses a very high back-pressure and can be used in a short length up to 50 mm only to meet the requirements of conventional chromatographic equipment. An analysis of a test mixture of seven anions was completed within 3 min with a back column pressure of about 350 bar (HETP of about 5.5 microm, where HETP is the height equivalent to the theoretical plate). Monolithic capillary columns provide lower efficiency per column unit length than MICRA columns; however, they can be used at a longer length because of their low flow resistance. Monolithic column of ca. 40 cm length has workable pressure below 10 bar and allows separation of a five anions test mixture within less than 10 min. A better efficiency of monolithic column (HETP approximately 75 microm) can be achieved at reduced flow rates when the analysis time is not a critical parameter.     

Investigation of the resistance of some naturally occurring and synthetic inorganic ion exchangers against gamma radiation

The effect of various doses of gamma radiation on the ion-exchange capacity, distribution coefficient values, elution behaviour, physical effect, pH titration and infrared spectra of some synthetic inorganic ion exchangers, namely the cerium substituted phosphates; and naturally occurring inorganic ion exchangers, zeolites from different parts of Iran, have been studied systematically.No significant change has been observed in the ion-exchange capacity (with the exception of CeP(Na), CeP(Di·Na) and zeolite 5 (deposits of arababad talas)), elution behaviour, physical effect, chemical stability and the infrared spectra of the synthetic ion exchangers irradiated upto a total dose of 200 kGy, while a change has been observed in the pH-titration and distribution behaviour. The increase in pH is sharper for irradiated samples with divalent cations than for the normal samples. Furthermore, the K_d values, and hence the selectivity towards certain cations increase with the total dose absorbed, reaching its optimum selectivity with the dose of 50–100 kGy. The natural zeolites chosen for these studies, show, similar pattern to those of synthetic ion exchangers, and in some cases an extremely high selectivity toward certain cations, like Be^II. These make, zeolites, which are naturally occurring ion exchangers more viable economically, and extremely useful alternative in this industry.     

Investigation of silica gel supported inorganic ion exchangers

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.     

Radiation stability of some thermally stable inorganic ion exchangers

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.     

Recent uses of liquid ion exchangers in inorganic analysis

A review of recent uses of liquid ion exchangers in inorganic analysis is presented.     

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.     

The adsorption behaviour of microamounts of radium on inorganic ion exchangers

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.Presented at the International Conference on Nuclear and Radiochemistry, Beijing, Sept. 1–5, 1986.     

The effects of ionizing radiations on synthetic organic ion exchangers

Effects of ionizing radiations on organic ion exchangers are recognized as a vexing problem in the processing of special nuclear materials and high specific activity radioactive waste forms. An extensive literature survey, started in 1976 and updated periodically, indicates that radiation decomposition of ion exchange materials has the potential for a variety of undesirable consequences. It is also apparent from this survey that systematic efforts to identify and resolve these problems and to develop radiation resistant ion exchangers are extremely limited. There is, however, widely scattered information in the literature that is useful in designing and operating ion-exchange-based process systems with reasonable assurance of safety. The compilation of experimental data presented in this paper can contribute to better design and safer operations of synthetic organic ion exchange systems at nuclear material processing facilities.     

Distribution of heteroatoms of synthetic ion exchangers in pyrolysis products

Distribution of sulfur and nitrogen atoms in products of pyrolysis of spent synthetic ion exchangers AV-17 and KU-2 in the temperature range 50–550°C was studied. The compounds containing heteroatoms were identified, and their amounts were determined.     

Synthesis and thermal stability of some inorganic ion exchangers based on silicon and tin

A number of silicon-based inorganic ion exchangers were synthesized under different conditions of preparation. The original and regenerated ion exchange capacities (IECs) were determined. Thermal stability of these materials was investigated in the temperature range of 40?C800?°C. The gain/loss of IEC was studied as a function of temperature. These exchangers show a higher IEC and its retention to a considerable extent at elevated temperatures when compared to that of corresponding ion exchangers which do not contain silica. The thermogravimetric curve shows greater percent mass loss in H⁺ form of the exchanger than in K⁺ form. Dehydration studies seem to throw some light on the state of water molecules present in various samples. The empirical formula and the tentative structure for stannic arseno silicate have also been proposed.     

Synthetic inorganic ion exchanger. IX. Thorium antimonate. Synthesis,properties and ion exchange separations

Summary Thorium antimonate has been synthesised by mixing 0.1 M Th(NO₃)₄ solution in 0.1 N HNO₃ and 0.05 M potassium pyroantimonate and by mixing 0.1 M Th(NO₃)₄ solution in 0.1 N HNO₃ with 0.1 M SbCl₅ in 4N HCl at controlled pH. The preparative procedure, composition, I.R. spectra, chemical and thermal stability, physico-chemical properties and distribution coefficients of metal ions on thorium antimonate have been determined at pH 5.5–6.5. On the basis of distribution co-efficient values separations of Cu(II) from Mg(II), Ni(II), Mn(II), Mg(II), from Zn(II) and Cd(II) and Zn(II) from Cd(II) have been achieved. Part VIII: Reference [1]     

Fr and Ra fixation on some inorganic sorbents or mixed composite ion exchangers

Zinc and nickel hexacyanoferrates (II) present a high affinity for²²³Fr and no retention for²²³Ra in hydrochloric acid solutions with concentrations greater than 0.5N. Hydrated antimony pentoxide is the best sorbent for²²³Ra. Incorporated in a composite exchanger, it could be used for decontamination purposes.     

Studies on sorption of plutonium on inorganic ion exchangers from sodium carbonate medium

Sorption of Pu(IV) from sodium carbonate medium has been investigated by using three inorganic ion exchangers, viz. alumina, silica gel and hydrous titanium oxide (HTO). Distribution ratios (D) of Pu(IV) for its sorption on these ion exchangers have been determined. The values are 700, 10³ and 10⁴ for alumina, silica gel and hydrous titanium oxide, respectively, from 0.1M sodium carbonate medium. The high distribution ratios indicate their suitability for the removal of Pu(IV) from sodium carbonate waste streams. Pu(IV) breakthrough capacities have been determined with 5 ml bed at a flow rate of 30 ml per hour. The 10% Pu(IV) breakthough capacities for alumina and silica gel are 3 g l^–1 and 14 g l^–1, respectively. The capacity of HTO is 60 g of Pu(IV) per liter of exchanger at 4% Pu(IV) breakthrough.     

Selective preconcentration of uranyl ion by silica gel phases modified with chelating compounds as inorganic polymeric ion exchangers.

Four chemically modified chelating silica gel phases (I - IV) with ion exchange groups were tested for their potential capability to selectively bind, extract and preconcentrate uranyl ions (UO(2)(2+)) from different aqueous solutions as well as ore samples. Factors affecting such determination processes were studied and optimized. These included the pH of the contact solution, the mass of the silica gel phase extractant, the stirring time during the application of a static technique and the eluent concentration for desorption of the surface-bound uranyl ion and interfering anions and cations. All these factors were evaluated on the basis of determinations of the distribution coefficient value (K(d)) and the percent recovery (R%). Percent recovery values of 91% for silica phase (II) and 93% for silica phase (IV) were identified in the optimum conditions. The proposed preconcentration method was further applied to uranium ore samples as well as granite samples. The determined percentage and ppm values are in good agreement with the standard assigned ones. The structure of the synthesized silica gel phases (I - IV) and their uranyl bound complexes were identified and characterized by means of infrared analysis, thermal analysis (TGA) and potentiometric titration.     

Titanium(IV) tungstosilicate and titanium(IV) tungstophosphate: two new inorganic ion exchangers

Crystalline phases of Ti(IV) tungstosilicate and Ti(IV) tungstophosphate have been synthesised. The ion-exchange capacities of Ti(IV) tungstosilicate and Ti(IV) tungstophosphate have been reported as 0.44 and 0.80 mequiv./g, respectively. Both materials show monofunctional ion-exchange characteristic and are stable in 0.1 M solutions of HNO3, HCl, H2SO4 and acetone and benzene. Ti(IV) tungstosilicate is found to be more stable thermally than Ti(IV) tungstophosphate (loss in ion-exchange capacity was found as 58 and 80%, respectively for samples heated at 200 degrees C). The Kd values for heavy metals such as Pb, Hg, Cd, Sb, Co, Zn, Ni, Fe, Cr etc. have been reported in demineralised water and two surfactant media by batch processes. Cr3+, Fe3+ and Sn4+ are totally adsorbed on both the materials in demineralised water while a decrease in Kd value with increase in concentration of two surfactants is reported. On the basis of Kd values for metal ions, thirteen binary separations and five ternary separations on Ti(IV) tungstosilicate and thirteen different binary separations and four different ternary separations on Ti(IV) tungstophosphate have been achieved. Separation of methylamine from ethylamine has been done by GC on a column packed with Ti(IV) tungstophosphate.     

Selective adsorption and stable solidification of radioactive cesium ions by porous silica gels loaded with insoluble ferrocyanides

Development of highly functional cesium selective adsorbents for the decontamination of high-activity-level water(HALW) from the Fukushima NPP-1 accident is very urgent. In order to selectively adsorb the radioactive cesium, three kinds of novel porous silica gels loaded with insoluble ferrocyanides(SLFC) were prepared using a successive impregnation/precipitation method. Based on the results of previous research, the SLFC composites have relatively large uptake ratio above 95%, distribution coefficients(Kd) above 103 cm3/g, and excellent adsorption kinetics even in seawater. The solidification results also indicate that zeolites have an excellent Cs immobilization characteristic, gas-trapping and self-sintering abilities, and low leachability. We chose three kinds of SLFC composites to achieve the optimization of solidification by mixing with nine kinds of additives at high temperatures(up to 1200 °C). The Cs contents in the three composites were estimated to be below 30% of the initial contents and decreased with the three stages at calcination temperatures ranging from 25 to 1200 °C. By contrast, the Cs immobilization ratio was markedly lowered by mixing with additives: of those, allophane had the best immobilization result. By increasing the additive ratio to 50 wt%, the Cs immobilization ratio became almost 100% and no volatilization of Cs was detected even after calcination at 1200 °C. This result indicates that calcination of the mixture of SLFC composites after adsorbing Cs+ ions and specific additives under appropriate ratio is effective for stable solidification.     

Studies on synthetic inorganic ion exchangers-V: preparation, properties and ion-exchange behaviour of amorphous and crystalline thorium tungstate

Amorphous and crystalline thorium tungstate have been prepared by mixing 0.1M thorium nitrate and 0.1M sodium tungstate under different conditions. The physico-chemical properties, chemical stability, composition, TGA, DTA, X-ray, infrared absorption and ion-exchange behaviour of thorium-tungstate are reported and discussed. Distribution coefficients of metal ions on thorium tungstate have been determined at pH 2-3 and 5.5-6.5. Selective ion-exchange separations of bismuth and mercury from other metal ions have been achieved on a column of thorium tungstate.     

Isolation and separation of transplutonium and rare-earth elements in unusual oxidation states on ion exchangers in inorganic acid solutions

The behaviour of transplutonium and rare-earth elements on anion and cation exchangers in solutions of H₃PO₄ and H₂SO₄ in the presence of oxidants (KBrO₃, PbO₂, (NH₄)₂S₂O₈) and in HCl solutions in the presence of reducing agents [Zn(Hg), Eu²⁺] depending on acid concentration as well as on oxidant content and nature in solution or in resin and other factors has been studied. Effective methods of Bk(IV), Ce(IV), Am(VI), Eu(II) and Md(II) separation from trivalent TPE and REE, as well as continuous methods of isolation of isotopically pure radionuclides²⁵⁰Bk,¹⁴⁴Pr by using ion exchangers and inorganic acid solutions have been developed.     

Synthesis and properties of new N,S-containing fibrous ion exchangers

New N,S-containing fibrous ion exchangers were prepared by polymer-analogous transformations of Nitron fiber, involving amination with polyethylenepolyamines (ethylenediamine and diethylenetriamine), followed by the reaction of the aminated fiber with carbon disulfide. The materials obtained efficiently take up silver ions from multicomponent aqueous solutions of metal ions and from dilute solutions containing calcium ions.