Competitive anion exchange

4 Mobilization of arsenic in water 6.4.1 Competitive anion exchange 

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However, particularly for the unsaturated acids, the epoxidation catalysis was not heterogeneous. Competitive anion exchange between the (peroxo)-tungstate and the carboxylate possibly causes leakage of W. 

The chemical phenomena in this case are more complicated than in competitive cation exchange on NH4Y zeolite. HC1 acts not only as a competitor but also as a stabilizing agent for the coordination sphere of platinum. It has been shown [113, 114] that the [PtCl6]2- anion can lose two to four chloride ligands after a few hours in the absence of hydrochloric acid. 

The future for electrodialysis-based wastewater treatment processes appears bright. The dilute concentrations of metals in the waste streams do not degrade or foul the cation or anion exchange membranes. The concentrate streams are recirculated to build up their metal content to a level that is useful for further recovery or direct return to the process stream. Ongoing research in the development of cheaper cation exchange membranes, and stable anion exchange and bipolar membranes will allow electrodialysis-based applications to become more competitive with other treatments. 

The competition between ions in the mobile phase and adsorbed counter ions on the stationary phase is given by equations (3.32) and (3.33) for anion exchangers and cation exchangers, respectively ... 

Kirmse and Rinkler pointed out that these results exclude free competition of the anions for intermediate carbonium ions because in this case the isobutyl ion would be expected to show the lowest selectivity. The simplest explanation of the data is that a diazonium-methoxide ion pair is formed and undergoes anion exchange prior to loss of nitrogen. The large amount of isobutyl azide can be ascribed either to the fact that a fraction of the methyl ethers is formed from dissociated ions which have had more time to undergo rearrangement, or (and) that a fraction of the isobutyl azide is formed from nucleophilic displacement on the diazonium ion. Either way it is difficult to avoid the conclusion that... 

Murphy BEP. The determination of thyroxine by competitive protein-binding analysis, employing an anion-exchange resin and radiothyroxine. J Lab Clin Med 1965 66 161-7. 

The present paper considers equilibria of adsorption on surface beginning from a simple case of uncompeting sorption on a monobasic site, sorption in the presence of competition, adsorption on dibasic sites, adsorption of polybasic organic molecules on monobasic cation and anion exchanger or dibasic ampholyte. 

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