Alkanols for the Extraction of Vanadium (V) From Hydrochloric Acid Solutions

Abstract

Extractive recovery of vanadium (V) from hydrochloric acid solutions using alkanols (1-butanol and 1-octanol) dissolved in n-heptane has been investigated by liquid-liquid extraction, propelled by the need to proffering alternatives to the scarce and relatively costly organophosphorous extractants. At the studied pH range (1.0-4.0), with 1-butanol as extractant, the percentage V(V) extraction (extraction efficiency, E%) reached optimum (E% = 63.3) at pH of 0.5, and for 1-octanol, optimum E% was 73.3 at pH 1.0.Increasing concentration of HCl at the studied range (1.0-6.0 mol L -1 ) was found to have an appreciable effect on percentage V(V) extraction. With both extractants, E% peaked at 6.0 mol L -1 HCl with values 86.7 and 70.0% for 1-butanol and 1-octanol, respectively. With increase in the concentration of extractants, both extractants produced a trend of increase/decrease in E% for V(V), suggesting the extraction of two different species. The optimal percentage extraction values were 76.7 and 96.7% observed at log[1-butanol] = 0.81 mol L -1 and log[1-octanol] = 0.49 mol L -1 , in that order. The determined enthalpy change, ΔH, for 1-butanol and 1-octanol systems were -19.9kJ mol -1 and -37.1 kJ mol -1 , respectively, indicating exothermic extraction processes. On the number of required extraction stages, 1-octanol gave a higher extraction efficiency after three consecutive extractions (E% = 99.3) than 1-butanol (E% = 88.6). Recycling experiment showed 1-octanol as more recyclable than 1-butanol (Recycling coefficient R.C. = 1.0 for 1-octanol while R.C. < 1.0 for 1-butanol). All extractants mixed with 1-butanol were found antagonistic. All added foreign ions decreased E% for V(V). From slope analysis, analytical and spectra data, the extracted complexes have been formulated as VO 2 Cl·nROH and (VO 2 Cl) m ·nROH (where m >> n) at low and high concentrations of extractant, respectively. On the whole, 1-octanol could be adjudged a better extractant for vanadium (V) under the prevailing experimental conditions.

On the Extraction of Vanadium (V) by Alkanols: A comparative Study of 1-pentanol and 3-methyl-1-butanol Isomers as Extractants for Vanadium (V) Extraction from Hydrochloric Acid Solutions

“…The effect of concentration of HCl investigated at the range 1.0-7.0 mol L -1 on V (V) extraction with 1-pentanol and 3-methyl-1-butanol is presented in Figure 4 The observed general increase in E% at increased concentration of HCl for both extractants could be explained on the basis of increased desolvation of coordinated water from the V (V) hydration sphere, making the pervanadyl specie (VO 2 +) available for binding to the alkanolic oxygen, as similarly reported by the current authors on V (V) extraction by 1-butanol and 1-octanol and other workers (Ojo & Adeeyinwo, 2011;Thomas & Reddy, 2003;Ojo & Oyegoke, 2013).…”

“…Extraction, separation and analysis (vanadium -phosphotungstate method) were carried out as previously reported except that pentanol and 3-methyl-1-butanol were used as extractants (Ojo & Oyegoke, 2013).…”

“…Vanadium applications in various fields of human endeavours particularly modern technology, as well as its extraction in form of cationic vanadium (V) have been reported in recent work (Ojo and Oyegoke, 2013). The use of alkanols to extract valuable metals such as niobium (V) and tantalum (V), aluminium (III), gallium (III) and indium (III) was reviewed as well (Yamada, Hayashi & Yasui, 2006).…”

“…In the previous work reported by the current authors, vanadium (V) was extracted from HCl solutions by 1-butanol and 1-octanol with remarkable efficiencies, (Ojo & Oyegoke, 2013). It is a common knowledge that several alkanols such as 1-pentanol ( Figure 1) and 3-methyl-1-butanol ( Figure 2) share similar electronic and solvating properties with those previously investigated, and at least superficially, are expected to have the potentiality for V (V) extraction.…”

Mechanism of the extraction of Molybdenum(VI) from diluted HCl and HNO₃ solutions with di(2-ethylhexyl)phosphoric acid

“…The determined slope was 1.7 (≈ 2), hence n = 1, which suggests that two molecules of D2EHPA dimers are associated with MoO 2 2+ which is in agreement with that observed in V (IV)-D2EHPA-H 2 SO 4 (Biswas et al, 2004) and Zn (II)-D2EHPA-H 3 PO 4 (Mellah and Benachour, 2006) systems. The log K ex equals -0.5 suggesting a low spontaneous extractive reaction which again warranted the rigorous and prolonged shaking during equilibration similar to what we reported in vanadiumHCl-d2EHPA sytem (Ojo et al, 2012).…”