Cation exchange, experimental methods

The kinetics of the hydration reaction of cyclopentene with a strongly acidic cation-exchange resin as catalyst have been studied. Parameters of the intrinsic kinetics model were solved by the Gauss-Newton method based on the experimental data, after excluding the influence factors of internal and external diffusion 34... 

The experimental data presented in this paper demonstrates the potential of CuCl/HCl electrolysis for nuclear hydrogen production. The CuCl/HCl electrolysis reaction requires a cation exchange membrane in order to produce hydrogen at a current density that exceeds 0.1 A-cm-2. In order to carry out the hydrogen production reaction a platinum electro-catalyst is required. The copper(I) oxidation reaction, on the other hand, does not require a Pt catalyst. This reaction proceeds quite readily on Pt-free graphite electrodes. Methods to mitigate the passage of the copper ion species across the membrane need to be developed to maintain the performance of the cell at the desired level. 

Cation exchanged zeolites are successfully applied as catalysts or selective sorbents in separation technologies. " For both catalytic and sorption processes a concerted action of polarizing cations and basic oxygen atoms is important. In addition, transition metal cation embedded in zeolites exhibit peculiar redox properties because of the lower coordination in zeolite cavities compared to other supports." " Therefore, it is important to establish the strength and properties of active centers and their positions in the zeolite structure. Various experimental methods and simulation techniques have been applied to study the positions of cations in the zeolite framework and the interaction of the cations with guest molecules.Here, some of the most recent theoretical studies of cation exchanged zeolites are summarized. 

Typical experimental curves obtained with this new chromatographic method are presented in Fig. 17. In these experiments the solution of cesium and rubidium (X( = 0.1), salt mixture (0.45M), and alkali (0.3M) was passed through a fixed-bed column filled with sulfophenolic cation exchanger KU-I (the bed height was 28 cm., its diameter was 8 mm) previously equilibrated with 0.45 M solution of cesium and rubidium nitrate (1 9). 

The effective diffusion coefficients were calculated from the experimentally observed data (time, amount of cation exchanged, temperature), using Paterson s solution of Fick s second law, or published approximate solutions (8, 16). Taking into consideration particle shape and particle size distribution, the differential coefficients of internal diffusion in ion exchange can be ascertained by a method previously described (9). 

Studies (1, 2, 3, 4) on the separation of americium-curium from lanthanide elements indicate that both cation exchange chromatography (8, 9) and the Talspeak solvent extraction process (U), 11) are promising methods. Only the most recent work at Oak Ridge National Laboratory is reported in this paper. Potential chemical processes for americium-curium removal and evaluations of their feasibility have been reported previously (U 2, 3, 4). The most recent experimental work carried out includes the following ... 

Bruggenwert, M.G.M., Kamphorst, A., 1982. Survey of experimental information on cation exchange in soil systems. In Bolt, G.H. (Ed.), Soil Chemistry B. Physico-Chemical Methods. Elsevier, pp. 141-203. 

Dendroanalysis (dendrochemistry) is the retrospective biomonitoring of trace metal pollution using the distributions of metals in tree rings. The value of the method is questioned, since trace metal distributions in wood are unstable. The distributions are affected by physiological processes in the life wood tissue. The transition from sapwood to heartwood affects the element distributions. Furthermore, the element patterns depend on the cation exchange capacity of the wood tissue. Currently it seems not possible to decipher the information which may be stored in the distribution patterns of trace metals in. stems of trees. Experimental approaches are described that may help to extract information from trace metals in tree rings. 

The principle of the leaching/cation exchange method is to derive an experimental data set describing the solid phases present (their mineralogy, CECs, in situ cation occupancies and... 

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