Cesium adsorption

Na -loess clay, where batch experiments were analyzed by X-ray diffraction and infrared and far-infrared measurements. The adsorption isotherm (Fig. 8.36) shows that loess clay is selective for cesium cations. The raw material contained a large amount of quartz, and the clay material was a mixture of kaolinite and an interstrati-fied iUite-smectite mineral as a result, equilibrium Cs" adsorption data are not consistent with a single site Langmuir model. Cesium adsorption on this particular soil clay occurs by cation exchange on sites with various cesium affinities. At low concentration, far-infrared spechoscopy shows the presence of very selective adsorption sites that correspond to internal collapsed layers. At high concentration, Cs MAS-NMR shows that cesium essentially is adsorbed to external sites that are not very selective. 

Fig. 8.36 Cs+ adsorption isotherm on Na+-loess clay. Reprinted from Bergaoui L, Lambert JF, Prost R (2005) Cesium adsorption on soil clay macroscopic and spectroscopic measurements. Applied Clay Science 29 23-29. Copyright 2005 with permission of Elsevier...

Bostick, B. C., Vairavamurthy, M. A., Karthikeyan, K. G., and Chorover, J. (2002). Cesium adsorption on clay minerals an EXAFS spectroscopic investigation. Environ. Sci. Technol. 36, 2670-2676. 

Development of collector electrode materials with lower work function ( 1.0 eV) is the most effective methods to improve energy conversion efficiency of a thermionic converter. At present refractory metals such as Mo, W, Nb with cesium adsorption are used as a collector with the work function values of about 1.7eV. It is suggested that metal oxide collectors can adsorb cesium more strongly and show lower values of work function. In the study, refractory metal oxides and AgO x were experimentally examined concerning the work function values and high temperature durability. A research thermionic converter of a W emitter and an AgO x collector was fabricated and power generation tested to examine the effectiveness of the AgO x collector. A new type of a FGM collector which integrates a... 

Example 15.3-3 Cesium adsorption Tests of a new selective ion exchanger for cesium adsorption use a bed 12 cm long with a 1 cm cross-section. These tests show a breakthrough time of 10 min and an exhaustion time of 14 min. We hope to scale up this process 10,000 times, (a) How much adsorbent is needed if the bed is kept 12 cm deep (b) How much is needed if the bed is 10 m long ... 

M. Ayyoob, and M.S. Hegde, An XPS study of the adsorption of oxygen on silver and platinum surfaces covered with potassium or cesium, Surf. Sci. 133, 516-532 (1983). 

M.V. Badani, and M.A. Vannice, Effects of cesium and chlorine on oxygen adsorption on promoted Ag/a AI203 catalysts, Appl. Catal. A 204, 129-142 (2000). 

Except for sensor applications, the intercalation of alkali metal ions in metal hexacyanoferrates was used for adsorption and separation of cesium ions from different aqueous solutions with Prussian blue [43,44] and cupric hexacyanoferrate [45,46],... 

L. Johansson, C. Samuelsson, and E. Holm, Adsorption of cesium in urine on copper hexacyanoferrate(II) -a contamination control kit for large scale in situ use. Radiat. Prot. Dosim. 81, 147-152 (1999). 

Comans, R. N. J. (1990), "Adsorption, Desorption and Isotopic Exchange of Cadmium on lllite Evidence for Complete Reversibility", in Sorption of Cadmium and Cesium at Mineral/Water Interfaces, Ph. D. Thesis, Rijksuniversiteit Utrecht, Netherlands. 

Another application for adsorption of metal impurities is in the nuclear power industry. Radioactive cesium is one of the compounds that is difficult to remove from radioactive waste. This is because ordinary resins and zeolites do not effectively adsorb radioactive cesium. In 1997, lONSlV lE-911 crystalline silicotitan-ate (CST) ion exchangers were developed and effectively used to clean up radioactive wastes in the Melton Valley tanks at Oak Ridge [268, 269], CST was discovered [270] by researchers at Sandia National Laboratories and Texas A M University, with commercial manufacture carried out by UOP. 

Barthomeuf, D.M. (1985) Process for separating ethylbenzene from xylenes by selective adsorption on a cesium substituted X zeolite. U.S. Patent 4,593,149. 

Figure 2. Adsorption of radionuclides on rock minerals, (a) (Topj Photomacrograph of a polished granite surface after exposure to a solution of radio-cesium Dark areas are exposed mica crystallites, (b) (Bottom) Autoradiograph of same surface showing uptake of cesium by mica.

III. The Adsorption of Cesium on Tungsten Using Thermionic Emission. 141... 

The study of the adsorption of cesium on tungsten is particularly fruitful because the rate of adsorption and the amount adsorbed can be measured easily and also because it is possible to measure the rate of evaporation of electrons, atoms, and positive ions from the same surface. From these data also can be deduced the nature of the adsorbed species and the forces between the adsorbed species and the tungsten atoms (3,4). 

Tamura and Jacobs (19) report adsorption on a montmorillonite sample from 6 M NaN03, from which we compute Dqq - 5, in the range of extrapolated values from Figure 8. Lewis and Thomas (2) report K/T of about 40 for low cesium loading and 0.04 M salt concentration, and Cast (10) about 35 for 0.001 M. These values are in the range implied by results in Figure 8 K/T 15 to 50). 

Physicochemical properties of L zeolites and of clinoptilolite were studied by adsorption, chromatographic, spectral, and ther-mogravimetric methods. The sodium form of L zeolite is characterized by better adsorption with respect to water and benzene vapor and by higher retention volumes of C C hydrocarbons and CO than potassium and cesium forms. The activation energy of dehydration determined by the thermogravimetric method decreases on going from the sodium to cesium form of L zeolite. When calcium is replaced by potassium ions in clinoptilolite, the latter shows a decreased adsorption with respect to water vapor. The infrared spectra of the L zeolite at different levels of hydration show the existence of several types of water with different bond characters and arrangements in the lattice. 

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