Solvent extraction of chromium(VI) into 1-octanol as an ion-pair with the tetrabutylammonium ion

The solvent extraction of chromium(VI) in 0.1 mol dm(-3) sodium nitrate solutions with tetrabutylammonium ions (tba(+)) into 1-octanol was studied. From the dependence of extraction on the concentration of hydrogen ion, tba(+), and chromium(VI), it was concluded that chromium(VT) was extracted in the form tba(+)HCrO(4)(-). The first and second acid dissociation constants for chromic acid and the extraction constant for the ion-pairs were determined. Although there was not much difference in the extraction of tba(+) with coexisting NO3- in the aqueous phase into 1-octanol and into chloroform, the extraction of HCrO4- with tba(+) into 1-octanol was much improved compared with chloroform.