Vanadium permeability

The structure of quaternised poly (tetramethydiphenyl ether sulphone). (Z.S. Mai et al., Ardonconductive membranes with ultralow vanadium permeability and excellent performance in vanadium flow batteries, ChemSusChem, 2013, 6, 328-335. Copyright Wiley-VCH Verlag GmbH Co. KGaA. Reprinted with permission.)... 

Iodide ion-selective electrode The iodide electrode has broad application both in the direct determination of iodide ions present in various media as well as for the determination of iodide in various compounds. It is, for example, important in the determination of iodide in milk [44,64,218, 382, 442], This electrode responds to Hg ions [150, 306, 439] and can be used for the indirect determination of oxidizing agents that react with iodide, such as 10 [305], lOi [158], Pd(II) [117, 347,405] and for the determination of the overall oxidant content, for example in the atmosphere [393], It can also be used to monitor the iodide concentration formed during the reactions of iodide with hydrogen peroxide or perborate, catalyzed by molybdenum, tungsten or vanadium ions, permitting determination of traces of these metals [12,192,193, 194, 195]. The permeability of bilayer lipid membranes for iodide can be measured using an I"... 

Research related to the use of vanadium phosphates or V2O5 as oxidants of gases such as CO and SO2 in commercial processes shows that solid vanadyl sulfate can serve as a gas-permeable solid-phase electrolyte [102]. Two reversible redox features are observable at slow scan rates (20-150 mV s ) by CV in a gas-tight two-electrode cell packed with powdered VOSO4 3H2O between a 10-mm carbon disk and a 3-mm glassy carbon electrode. The V(IV/V) couple was observed at 0.55 V versus C, and the V(IV/III) couple was observed at —0.97 V. Unlike in aqueous solution where vanadyl sulfate is reduced to [V(H20)6] ", the V=0 bond in the solid remains intact. The oxidation of CO(g) can be observed when it is introduced into this cell. 

Van Deventer and co-workers (23) recently investigated the thickness of vanadium oxide on as-received metal and heated specimens. Oxide thicknesses of up to 10 pm were observed, depending on the treatment. Hydrogen pretreatment seemed to increase the hydrogen permeability through the specimens. Similar effects of hydrogen pretreatment frequently have been seen. 

For the vanadophore region, the sulfate concentration has been estimated to be of the order of 1.3 M and pH 2.349 With no evidence for a stable complex within the vanadocyte, Figure 14 depicts an interesting mechanism proposed for vanadium and sulfate accumulation.350 Anionic vanadium(V) (as HVO ") and sulfate ions enter the cell. Provided that within the vanadophore there is a strong reducing agent, vanadium can be reduced to vanadium(IV) and vanadium(III), cationic at the low pH in the vanadophore. If the vanadophore membrane is permeable to anions but not cations, the reduced vanadium remains trapped. 

Figure 14 Mechanism of vanadium accumulation in the vanadophore assuming a membrane permeable only to anions...

Morrison S. J., Carpenter C. E., Metzler D. R., Bartlett T. R., and Morris S. A. (2002) Design and performance of a permeable reactive barrier for containment of uranium, arsenic, selenium, vanadium, molybdenum, and nitrate at Monticello, Utah. In Handbook of Groundwater Remediation Using Permeable Reactive Barriers—Applications to Radionuclides, Trace Metals, and Nutrients (eds. D. L. Naftz, S. J. Morrison, J. A. Davis, and C. C. Fuller). Academic Press, San Diego, CA, pp. 371-399. 

Siemon H, Schneider H, Fuhrmann GF. 1982. Vanadium increases selective K+-permeability in human erythrocytes. Toxicology 22 271-278. 

The vanadium pentoxide cataKtic membrane reactor was prepared by coating its sol inside the Vycor tube membrane. After heat treatment of the prepared membrane, the [010] planes of vanadium pentoxide layer were grown largely which contributes to partial oxidation reaction of 1-butene to maleic anhydride. The partial oxidation of 1-butene to maleic anhydride was carried out in the catalytic membrane reactor. The maximum selectivity of 95% was obtained at 350 °C when the surface velocity was 500cm/h. And at this condition, oxygen permeability was almost four times higher than the reaction had not occured. 

Fuhrmann GF, Huttermann J and Knaue PA (1984) The mechanism of vanadium action on selective KT-permeability in human erythrocytes. 

It is also becoming increasingly apparent that the specific chemical form of a metal is a factor in its toxicity. Water-lipid partitioning, cell-wall permeability, and metabolic transport are just a few of the factors influenced by chemical form which, in turn, influence toxicity. Hexavalent chromium, pentavalent vanadium, divalent manganese, arsine, and methylmercury are more toxic than other forms of the corresponding metal. ... 

If Vegard s Law is obeyed, the lattice parameters as summarized in Table 8.2 imply that W, Nb, Ta and U also expand the lattice of vanadium. The non-hydride forming element W may reduce solubility and permeability as in the case of Mo [43], The elements Nb, Ta and U that form strong hydrides, and which increase lattice parameters as well, should increase solubility. 

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