Ion exchangers, inorganic

Considerable work has been carried out over the years to develop inorganic ion exchange materials. Apart from clays and zeolites, which were in fact the 

Inorganic ion exchangers fall roughly into two groups crystalline, such as the ammonium salts of the 12-heteropolyacids, and amorphous, such as zirconium phosphate. One example from each group will be described. 

Zirconium phosphate, which is easily prepared by the addition of a solution of zirconyl nitrate or chloride to a phosphate solution is extremely insoluble and will not dissolve in solutions of high or low pH. It is an inorganic polymer of composition Zr(H2P04)2-H20 and a relative 

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Ion Exchange. Crystalline molecular sieve ion exchangers do not foUow the typical rules and patterns exhibited by organic and other inorganic ion exchangers. Many provide combinations of selectivity, capacity, and stability superior to the more common cation exchangers. Their commercial utilization has been based on these unique properties (59). 

A. Clearfield, Inorganic Ion Exchange Materials, CRC Press, Boca Raton, Fla., 1982. 

The incorporation of minute amounts of certain ions into lattice type inorganic ion exchanging films can induce changes in the polymer morphology that can be... 

In Chapter 14, one of the least-used applications of TLC and PLC is described, namely inorganics and organometallics. These separations in the analytical mode often require quite unusual stationary phases (e.g., inorganic ion exchangers and impregnated and mixed layers) combined with a variety of diverse mobile phases. This means that the use of the analogous systems in the preparative mode represents an unusually difficult challenge. 

Catalysis of supported metal ions is an area of interest. There are a number of advantages in depositing catalytically active metal ions on a support. The ion exchange method of catalyst immobilization is simple and the attractiveness of this method is further increased by providing stable inorganic ion exchangers of known structures as supports. 

A process that employs a powdered inorganic ion exchanger in a slurry has also been proposed [7]. This process appears rather cumbersome and messy since the ion-exchange materials must be repeatedly filtered and re-pulped over each cycle This process will also be expensive to operate, since the ion exchanger must be regenerated with NaOH. 

Preparation and studies of nonsiliceous inorganic ion exchangers—insoluble salts, heteropolyacids 1956... 

Natural inorganic ion exchangers have the following disadvantages ... 

Synthetic inorganic ion exchangers Zeolites Synthetic zeolites (Figure 4.7) are available as powder, pellet, or bead. The greatest advantage of synthetic zeolites against natural zeolites is that they can be manufactured with a wide variety of physicochemical properties. The main disadvantages of synthetic zeolites are... 

In Tables 4.9 and 4.10, a comparison of organic and inorganic ion exchangers is presented. 

The following models have been mainly used in liquid-phase adsorption and biosorption and, in some cases, for ion-exchange systems with inorganic ion exchangers (Rengaraj et al., 2004 Bektas and Kara, 2004). 

Beaven, G.W., Cross, J.E., Hooper, E.W., Study of the Behaviour of Inorganic Ion Exchangers in the Treatment of Medium Active Effluents. Part V. The Encapsulation of Inorganic Ion Exchangers in Cement, Rep. AERE-G-4421, United Kingdom Atomic Energy Authority, Harwell (1988) Beeckman, J.W., Froment, G.F., Chemical Engineering Science, 35, 805 (1980)... 

Ultra short lived radionuclides, with a half-life of a few seconds to a few minutes are readily available from long-lived parent radionuclides adsorbed to an organic or inorganic ion exchange support matrix (1-3). These radionuclide generator systems are an inexpensive alternative to an on-site cyclotron, especially for positron emitters used for positron emission tomography (PET). 

The preparation, composition, structure and leaching characteristics of a crystalline, ceramic radioactive waste form have been discussed, and where applicable, compared with vitrified waste forms. The inorganic ion exchange materials used such as sodium titanate were prepared from the corresponding metal alkoxide. The alkoxides were reacted in methanol with a base containing the desired exchangeable cation and the final powder form was produced by hydrolysis in an acetone-water mixture followed by vacuum drying the precipitate at ambient temperature. 

The use of inorganic ion exchangers to solidify liquid radioactive waste followed by pressure sintering to produce a ceramic waste form appears to be a viable alternative to calcina-tion/vitrification processes. Both the process and waste form are relatively insensitive to changes in the composition of the waste feed. The stability of the ceramic waste form has been shown to be superior to vitrified wastes in leaching studies at elevated temperatures. Further studies on the effects of radiation and associated transmutation and the influence of temperature regimes associated with potential geologic repositories are needed for a more definitive comparison of crystalline and amorphous waste forms. 

C. B. Amphlett, Inorganic Ion Exchange Materials , Elsevier, Amsterdam, 1964. 

The sensor construction is shown in Figure 16. As a proton conductor, Nafion (DU PONT, Nafion 117 H-type) membrane or disks of several inorganic ion exchangers were used. With sample gas and reference air passing over the respective electrodes, the electric... 

Palmer, D. A. Meyer, R. E., "Adsorption of Technetium on Selected Inorganic Ion-Exchange Materials and on a Range of Naturally Occurring Minerals under Oxic Conditions," J. Inorg. Nucl, Chem. 1981, 43, 2979. 

Zeolites and inorganic ion-exchange catalysts have been treated in reactive milling to alter their properties. For example, the amorphization of Zeolite A has been described by Kosanovic et al. [93] these authors observed a loss of crystallinity, a decrease of cation-exchange capacity, and an increase of solubility of A and Y zeolites which was caused by breaking of Si-O-Si and Si-O-Al bonds in the zeolite. 

Clearfield A. In Inorganic Ion-Exchange Materials Clearfield, A., Ed. CRC Press Boca Raton, FL 1982. 

We discuss crystalline inorganic ion exchangers, such as [97,98,104,134-146] zeolites, hydrotal-cites, alkali metal titanates, titanium silicates, and zirconium phosphates, and also organic ionic exchangers such as the ion-exchange resins. However, details are given only in the case of the archetypal crystalline ionic exchangers, that is, aluminosilicate zeolites [97,98,104,134]. 

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