Solvent Extraction Of Vanadium Research Articles

Solvent extraction of vanadium(IV) from hydrochloric acid solutions by neutral organophosphorus compounds

The extraction of vanadium(IV) from hydrochloric acid solutions by tri-n-octylphosphine oxide (TOPO) or tri-n-butylphosphate (TBP) in benzene has been investigated under different conditions. The organic phases have been analysed stoichiometrically and spectrophotometrically. As a result, it has been found that the extraction equilibrium can be expressed as VOCl 2(aq) + nTOPO(org) ⇌ VOCl 2 · nTOPO(org) or VOCl 2(aq) + nTBP(org) ⇌ VOCl 2 · nTBP(org), in which n = 1 or 2. The structure for the complexes formed in the organic phase is proposed on the basis of the results obtained.

Solvent extraction of vanadium(V) by di-(2-ethylhexyl)-phosphoric acid from nitric acid solutions

Abstract Extractions of vanadium(V) from diluted and concentrated nitric acid solutions by di(2-ethylhexyl)phosphoric acid (HDE-HP) in various solvents have been studied. From diluted nitric solutions, V(V) is extracted by dimeric (HDE-HP) 2 in non polar solvents such as kerosene and by monomeric HDE-HP in polar solvents such as n -butanol. From concentrated nitric acid solutions, the extracted complex of vanadium involves nitrates group participation.

Synergistic Effect in the Extraction of Vanadium (V, IV)-Thenoyltrifluoroacetonate

The synergistic effect of 1-butanol(BuOH) on the solvent extraction of vanadium(V) with 2thenoyltrifluoroacetone(TTA Htta) was investigated and the extraction reaction was explained in terms of the esterification: VO2' 2Htta. BuOH, =VO(tta)2(BuO), H20 The extraction constant of the above reaction was obtained to be K..=1.7 10S. ln contrast, in the case in which tri-n-octylphosphine oxide(TOPO) was used as an additive, the synergistic effect is attributable to the reaction: VO2' Httaor, TOPO, VO2(tta)(TOPO)er, H, The synergistic extraction of vanadium(N)was found to be explained by the formation of an adduct: VO2 2 Htta.. g=VO(tta)2, 2 H and VO(tta)2, g Sg=VO(tta)2S, g, where S denotes an additive. The stability of the resulting adducts decreases in the order: TOPO isoquinoline quinoline 1-butanol.

Separation and solvent extraction of vanadium and uranium with n-propyl 2,3,4-trihydroxybenzoate

A spectrophotometric method is described for the separation and determination of trace quantities of vanadium(IV) and (V) from uranium(VI). Vanadium is selectively separated from uranium by extraction at pH 6.5 into n-propyi 2,3,4-trihydroxybenzoate (PTB) dissolved in t-pentanol. Up to 120 μg of vanadium can be determined by measuring the absorbance of the blue complex in the organic phase at 585 nm. Uranium(VI) remains in the aqueous layer and can be determined spectrophotometrically by its reaction with PTB in aqueous acetone to produce a brown-red colour at pH 7.6–8.8. Solutions containing 25–275 μg of uranium absorb at 370–380 nm according to Beer's law. By modification, this procedure can be used for the determination of the two metals in native phosphate rocks. The effects of diverse ions on the determination of vanadium and uranium have also been examined.

Solvent extraction of vanadium from chloride solutions using di-(2-ethylhexyl)-phosphoric acid

Extraction of vanadium (IV) from chloride solutions by di-(2-ethylhexyl)phosphoric acid (HDPA) in kerosene has been found to take place principally through the formation of neutral mononuclear vanadyl complexes with mono-ionized dimers of HDPA. No evidence has been obtained of chloro- or hydroxy-group participation in the extracted complex. At very high solvent loadings it appears that the extracted complex involves HDPA monomer rather than the dimer. Most effective extraction is obtained when the diluent has little or no propensity for forming hydrogen bonds with the HDPA.