Solvent extraction of the ion-pairs of chromium(VI) and molybdenum(VI) with trioctylmethylammonium chloride and benzyldimethylcetylammonium chloride.
The number of capriquat molecules per chromium(VI) atom in the chromate-capriquat ion-association complex has been found to be between one and two. The distribution ratio in the extraction of chromium(VI) with capriquat is dependent on the dielectric constant of the organic solvent, with a minimum at a dielectric constant of about 8. The absorption spectra of the ion-pair extracted into cyclohexane, carbon tetrachloride, benzene and n-butanol are very similar to that of chromate in aqueous solution. The absorption spectra of the chromium(VI)-capriquat extracts in these organic solvents gradually change to an absorption spectrum similar to that of HCrO(4)(-) in aqueous solution. Chromium(VI)-capriquat extracted into chloroform and 1,2-dichloroethane gives absorption spectra similar to that of HCrO(4)(-)in aqueous medium. The chromium(VI)-capriquat species extracted into 1,2-dichloroethane may be (Q(+))(2).CrO(4)(2-)(H(2)O)(n). In contrast, chromium(VI) is extracted with capriquat into the other organic solvents from ammoniacal medium as a mixture of (Q(+))(2).CrO(4)(2-)(H(2)O)(n) and Q(+).NH(4)(+).CrO(4)(2-)(H(2)O)(n). The spectral change is ascribed to the change of the extracted species from (Q(+))(2).CrO(4)(2-)(H(2)O)(n) and Q(+)NH(4)(+).CrO(4)(-)(H(2)O)(n) to Q(+).HCrO(4)(2-)(H(2)O)(n-1). The chromium(VI)-zephiramine species extracted is formulated as (Q(+), NH(4)(+))(2)CrO(4)(2-)(H(2)O)(n).(Q(+).Cl(-))(m). Molybdenum(VI) is extracted with capriquat into the same organic solvents as a mixture of (Q(+))(2).MoO(4)(2-)(H(2)O)(n) and Q(+).NH(4)(+).MoO(4)(2-).(H(2)O)(n).
Ohashi
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Department of Chemistry, Faculty of Science, Ibaraki University, Mito 310, Ibaraki, Japan.
Shikina
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Nagatsu
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Ito
I
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Yamamoto
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