Speciation vanadium

Vanadium speciation for concentrations below 4%V is not easily ascertained. In general, for V-containing compounds, terminal V=0 band frequencies have values greater than 900 cm 1 these bands appear only when the presence of V20g is observed, Figs. 4E-4F. 

Much of the analytical chemistry of vanadium is concerned with its use in ferrous and nonferrous metallurgy. Vanadium also finds application in catalysis and in the paint and ceramic industries. Environmental concerns about vanadium arise primarily from air-pollution problems. Vanadium can be released from fly ash and oil-combustion products. There are only a few references on vanadium speciation. One reference reported the simultaneous determination of V(IV) and V(V) [25]. Postcolumn reaction with PAR resulted in detection limits of about 10 ppb, even in the presence of high concentration of phosphate. Unfortunately, the studies were not carried out in samples. Urasa et al. [2] used DCPAE detection to speciate V02 and another vanadium species thought to be VOCU ". 

NMR spectra. No changes in vanadium speciation were observed after 20 hours for these media samples. After adding yeast cells to the medium and exposing them for 15 hours to the presence of 5.0 mM vanadate, the spectra of the medium and the cells show evidence of several forms of vanadium(V) at both pH values. Interestingly, Vio was found in both media of samples grown at pH 4.0 and 6.5. Since no V,o was found in media at pH 6.5 after 15 hours unless the yeast had been grown in the media, the formation of Vio is apparently due to the yeast cells. 

IN VITRO STUDIES OF VANADIUM SPECIATION AND REDOX CHEMISTRY... 

There are several reasons for performing speciation. Of course there are the academic studies of various types of trace metals and their conversion and equilibria of various forms. Industrial speciation is important. The effectiveness of chromium plating baths depends on the amounts of Cr(III) and Cr(VI) that are present. Gold plating processes involve the use of Au(I) and Au(III) cyanide complexes. Vanadium speciation is important in the recovery of sulfur from geothermal water. 

In this work ion-exchange and gel-permeation chromatography coupled with membrane filtration, photochemical oxidation of organic metal complexes and CL detection were applied to the study of the speciation of cobalt, copper, iron and vanadium in water from the Dnieper reservoirs and some rivers of Ukraine. The role of various groups of organic matters in the complexation of metals is established. 

Geochemical Controls The speciation of uranium and vanadium has been determined for groundwaters from the calcrete-hosted carnotite deposits. These were completed in Geochemists Workbench v.7 using in-... 

Tomlinson, Wang and Caruso [96] used an Alltech Adsorbosphere cation-exchange column for the speciation of vanadium (IV) and (V) with ICP-MS detection. Single ion monitoring at m/z 51 was used and the mobile phase consisted of 7 mM 2,6-pyridine... 

Other groups have also examined vanadium(V) catalyzed oxidation of bromide by dihydrogen peroxide in acidic aqueous or aqueous/organic mixtures, although without examining the detailed speciation of the vanadium peroxo compounds in solution [77-82], These reports have focused more on the nature of the substrate brominated and the product distribution under different conditions. 

XRD, XPS, and Raman characterization of V supported on pseudoboehmite alumina or on amorphous aluminosilicate gels (metal loaded with a solution of V0+z Naphthenate in benzene) have indicated the presence of tetrahedrally and octahedrally coordinated vanadium (31) having speciation and dispersion that depends on vanadium concentration (and surface area) present on the steamed (760°C/5h) samples. 

Andersson, I., S J. Angus-Dunne, O.W. Howarth, and L. Pettersson. 2000. Speciation in vanadium bioinorganic systems 6. Speciation study of aqueous peroxovanadates, including complexes with imidazole. J. Inorg. Biochem. 80 51-58. 

Elvingson, K., A.G. Baro, and L. Pettersson. 1996. Speciation in vanadium bioinorganic systems. 2. An NMR, ESR, and potentiometric study of the aqueous H+-vanadate-maltol system. Inorg. Chem. 35 3388-3393. 

Elvingson, K., M. Fritzsche, D. Rehder, and L. Pettersson. 1994. Speciation in vanadium bioinorganic systems. 1. A potentiometric and 51V NMR study of aqueous equilibria in the H+-vanadate(V)-L-a-alanyl-L-histidine system. Angew. Chem., Int. Ed. Engl. 48 878-885. 

Kaliva, M., T. Giannadaki, A. Salifoglou, C.P. Raptopoulou, and A. Terzis. 2002. A new dinuclear vanadium(V)-citrate complex from aqueous solutions. Synthetic, structural, spectroscopic and pH-dependent studies in relevance to aqueous vanadium(V)-citrate speciation. Inorg. Chem. 41 3850-3858. 

The active sites of these enzymes can have a nitrogen ligand, usually as histidine (acid phosphatases and some protein phosphatases), a nucleophilic serine residue (alkaline phosphatases), a cysteine residue in which the thiol group can form a covalent species with the phosphate ester (protein phosphatases), or an aspartate-linked phosphate (plasma membrane ion pumps). The inhibitory form of vanadium is usually anionic vanadate V(V), but cationic vanadyl V(IV) has also shown strong inhibition of some types of phosphorylase reactions. Above neutral pH, speciation of vanadyl ions produces anionic V(IV) species capable of inhibition of enzymes in the traditional transition-state analogue manner [5],... 

Osinska-Krolicka, I., H. Podsiadly, K. Bukietynska, M. Zemanek-Zboch, D. Nowak, K. Suchoszek-Lukaniuk, and M. Malicka-Blaszkiewicz. 2004. Vanadium(III) complexes with L-cysteine-stability, speciation and the effect on actin in hepatoma Morris 5123 cells. J. Inorg. Biochem. 98 2087-2098. 

Primary sources documented after each chapter minimize the need to search the literature, 80 illustrations provide structural information, reaction schemes, spectra, speciation diagrams, and biochemical schemes, and 22 tables present detailed information with references to primary sources. Packed with current and authoritative information, the book covers chemistry and bioinorganic vanadium chemistry in a broad and systematic manner that engenders comprehensive understanding. 

Explores the chemistry, environmental influences, pharmacological applications, and technological uses of vanadium Compiles the results from research on the aqueous coordination reactions characterizing the vanadium(V) oxidation state Details the application of NMR spectroscopy to the speciation of vanadium compounds... 

Tian, H., Ross, E.I. and Wachs, I.E. (2005) Quantitative determination of the speciation of surface vanadium oxides and their catalytic activity. Journal of Physical Chemistry B, 110 (19), 9593-500. 

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