Spectrophotometric determination of vanadium(IV) and vanadium(V) in each other's presence. Review

Taylor, M. Joan; Staden, Jacobus Frederick van

doi:10.1039/an9941901263

Cited by 134 publications

(69 citation statements)

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“…Numerous spectrophotometric methods are summarized in a review document (21). The reagents listed in Table 6-3 were screened for suitability using acidic aqueous solutions.…”

Section: Resultsmentioning

confidence: 99%

Reducing Power Production Costs by Utilizing Petroleum Coke

Galbreath¹,

Toman²,

Zygarlicke³

1999

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EXECUTIVE SUMMARYThe effects of blending petroleum shot cokes with Powder River Basin (PRB) subbituminous coals on grindability, combustion reactivity, fouling/slagging, and electrostatic precipitator (ESP) fly ash collection efficiency were investigated over a 2-year period. Testing was conducted using three different laboratory-scale downfired combustion systems. Fly ash and deposit samples were analyzed using a variety of techniques, including inductively coupled plasma-atomic emission spectroscopy, x-ray diffraction, x-ray absorption fine-structure spectroscopy, wavelengthdispersive x-ray fluorescence spectrometry, scanning electron microscopy, electron probe microanalysis, and digital image analysis.A PRB subbituminous coal with a Hardgrove grindability index (HGI) of about 56 at 26 wt% moisture and a petroleum shot coke with an average HGI of 38 were used for testing the effects of parent fuel hardness on PRB coal-petroleum coke blend grindability. Samples of the PRB coal, petroleum shot coke, and coal-coke blends of 95:5 and 85:15 (on a weight basis) were pulverized under identical conditions. Ni and V analyses of three size fractions (<45 µm, $45 µm but <75 µm, and $75 µm) for each pulverized fuel indicate that the finest particle-size fraction of the petroleum coke is significantly enriched in V and Ni, whereas V and Ni are uniformly distributed among the three particle-size fractions of the pulverized PRB coal. The finest particle-size fractions of the coal-coke blends are not enriched in V and Ni relative to their coarser size fractions, suggesting that the softer Ni-and V-depleted coal particles are preferentially fractioned into the finest size fractions during pulverization.Combustion kinetic testing in a drop-tube furnace of a PRB coal, petroleum coke, and an 80 wt% PRB coal-20 wt% petroleum coke blend indicates that the parent fuels essentially burn independently of each other. It was demonstrated that the combustion kinetics of a given coalpetroleum coke blend in the drop-tube furnace can be predicted from those of the parent fuels because of the two-stage combustion process.Measurements of deposits (i.e., initial slagging temperatures, crushing strengths, and ash fouling deposition rates) produced from burning PRB coal-petroleum coke blends (coke blends of 0%, 10%, and 20% on a weight basis) in a drop-tube furnace under slagging and high-temperature fouling conditions indicate that petroleum coke blending with PRB coal impedes the rate of fouling deposit growth but promotes slagging and slag deposit strength. Although petroleum coke blending slows the rate of ash fouling deposition, it promotes ash sulfation and the formation of an anhydrite-rich base layer on tube surfaces.Testing of a PRB coal and two (95:5 and 85:15) coal-coke blends in a 42-MJ/hr (40,000 Btu/hr) downfired combustion system indicates that the primary effect of petroleum coke blending on flue gas composition is a significant increase in sulfur concentration. Sulfur speciation analyses using U.S. Environmental Protection Agenc...

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“…Numerous spectrophotometric methods are summarized in a review document (21). The reagents listed in Table 6-3 were screened for suitability using acidic aqueous solutions.…”

Section: Resultsmentioning

confidence: 99%

Reducing Power Production Costs by Utilizing Petroleum Coke

Galbreath¹,

Toman²,

Zygarlicke³

1999

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“…Searching for systems which allow a sensitive, selective, fast and inexpensive determination of vanadium are attracting special interest, due to great industrial, biological, ecological, and pharmacological importance of this element [14][15][16][17]. Vanadium can exist in many oxidation states (from II to V), but most methods have concentrated on its determination in the pentavalent and tetravalent states, as these are the most common forms encountered in inorganic and biological systems [15,16].…”

Section: Fig 1 Structure Of Mono-and Ditetrazolium Salts Deriving Frmentioning

confidence: 99%

“…Vanadium can exist in many oxidation states (from II to V), but most methods have concentrated on its determination in the pentavalent and tetravalent states, as these are the most common forms encountered in inorganic and biological systems [15,16]. Among the important color reactions of V(V) are those with heterocyclyc azo dyes [14][15][16]18].…”

Section: Fig 1 Structure Of Mono-and Ditetrazolium Salts Deriving Frmentioning

confidence: 99%

The solvent extraction and spectrophotometric determination of vanadium (V) with 4-(2-thiazolylazo)resorcinol and tetrazolium salts

et al. 2007

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Abstract:The formation and extraction of ion-associate complexes between the vanadium(V) -4-(2-thiazolylazo)resorcinol (TAR) anionic chelate and the cations of some mono-and ditetrazolium salts {3- (4,5-dimethyl-2-thiazol-tetrazolium] chloride (Tetrazolium blue chloride) and 3,3'-(3,3'-dimetoxy-4,4'-biphenylene)bis[2-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride] (Nitro blue tetrazolium chloride)} have been studied. The optimum extraction conditions have been found. The composition of the V-TARmonotetrazolium and V-TAR-ditetrazolium complexes extracted into chloroform has been determined to be 1:2:3 and 2:4:3 respectively. The extraction, distribution and association constants, and the recovery factors have been calculated. The relationship between the molecular weight of tetrazolium cations, and the association constants of their complexes has been discussed. The special behavior of the tetrazolium cations, containing -NO 2 groups has been noticed. The effects of foreign ions and reagents on the extraction of vanadium with TAR and the best tetrazolium salt -MTT have been studied. A sensitive, selective, simple and fast method for the determination of vanadium has been developed.

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“…These experimental results give us ground to represent the complex with the general formula mentioned above. Taking into account the state of V(V) 27 and TAR 28 in aqueous solutions at the optimum pH we suggest the following scheme of complex formation: …”

Section: Vanadium(v)-tar-mbt-water-chloroform Systemsmentioning

confidence: 99%

Some Ternary Phenylmethoxybis(tetrazolium) Complexes of Vanadium(IV,V) and Their Constants of Association

Gavazov¹,

Racheva²,

Lekova³

et al. 2012

Croat. Chem. Acta

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Abstract. Several liquid-liquid extraction systems containing vanadium {vanadium(IV) or vanadium(V)}, azoderivative of resorcinol {ADR: 4-(2-pyridylazo)-resorcinol (PAR) or 4-(2-thiazolylazo)-resorcinol (TAR)} and (phenylmethoxibis)tetrazolium salts {MBT: 3,3'-(3,3'-dimetoxy-4,4'-biphenylene)-bis(2,5-diphenyl-2H-tetrazolium) chloride (Blue Tetrazolium, BT) or 3,3'-(3,3'-dimetoxy-4,4'-biphenylene)-bis[2,5-di(4-nitrophenyl)-2H-tetrazolium] chloride (Tetranitroblue Tetrazolium, TNBT)} were studied. The optimum operating conditions and compositions of the extracted species were found. The constants of association (β) between MBT 2+ and the anionic V-ADR chelates (Chel n-) were calculated. Previously reported negative linear relationship between log β and the number of nitro groups included in tetrazolium cation (N nitro ) was discussed taking into account the obtained results and literature data for V-ADR-MBT complexes of the same class, in which MBT is BT or 3,3'-(3,3'-dimetoxy-4,4'-biphenylene)bis[2-(4-nitrophenyl)-5-phenyl-2H-tetrazolium] chloride (Nitroblue Tetrazolium, NBT). (doi: 10.5562/cca1885)

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Spectrophotometric determination of vanadium(IV) and vanadium(V) in each other's presence. Review

Cited by 134 publications

References 83 publications

Reducing Power Production Costs by Utilizing Petroleum Coke

Reducing Power Production Costs by Utilizing Petroleum Coke

The solvent extraction and spectrophotometric determination of vanadium (V) with 4-(2-thiazolylazo)resorcinol and tetrazolium salts

Some Ternary Phenylmethoxybis(tetrazolium) Complexes of Vanadium(IV,V) and Their Constants of Association

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