Precipitate Formation of Nickel 8-Quinolinol Complexes from Solutions Containing Perchlorate and Sulfate Ions

Abstract

Based on the fact that several kinds of anions take part in the solvent extraction of nickel with 8-quinolinol(Hql), the precipitate formation of nickel 8-quinolinol complexes was examined using aqueous nickel(II) solutions containing perchlorate and sulfate anions. The precipitate formed at pH 4.0 from the perchlorate solution contains a large amount of perchlorate ions; its mole ratio of nickel, 8-quinolinol and perchlorate ion is close to 1:3:0.5, which is that of the dimeric ion-pair complex, [Ni2ql3(Hql)3]ClO4. The precipitate formed at pH 9.0 contains no perchlorate ion; it seems to be the mixture of Niql22Hql and Niql22H2O. On the other hand, the precipitate formed from the sulfate solution contains no sulfate ions, regardless of pH. The precipitates formed in the range of pH 4-8 seem to be a mixture of Ni2ql42Hql, Niql22Hql or Niql22H2O according to pH, but the precipitate for pH 9.0 is Niql22H2O. The composition of these precipitates was ascertained and is discussed on the basis of the results of their TG-DTA and IR spectra.