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

James O. Ojo, David A. Oyegoke


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, ?H, 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 VO2Cl·nROH and (VO2Cl)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.

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International Journal of Chemistry   ISSN 1916-9698 (Print)   ISSN 1916-9701 (Online)

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