Simultaneous Preconcentration Flotation-Separation
and Spectrophotometric Determination of Thorium, Lanthanum and Yttrium
in Some Geological and Environmental Samples
A.M. Abdallah, M.A. Kabil, M.A. Akl*, D.S. Ismael
Department of Analytical Chemistry,
Faculty of Science, Mansoura University 35566, P.O. Box 70, Mansoura,
Egypt
The extraction and
preconcentration of a metal complex via surfactant-mediated phase
separation was studied. A sensitive, selective and low-cost methodology
for the determination of micro amounts of thorium, lanthanum and yttrium
ions, using Eriochrome Cyanine R (ECR) with a flotation step prior to
spectrophotometric determination was developed. The precipitate in the
scum layer was quantitatively collected, stripped with 4 ml of 3% HCl
and measured spectrophotometrically at 540 nm for Th(IV) and at 650 nm
for both La(III) and Y(III). The stripping of Th(IV), La(III) and Y(III)
from the scum layer was carried out in one step with different mineral
acids. The stripping efficiency was found to be quantitative in the case
of HCl. An excess amount of ECR was used to eliminate the interfering
effects of various foreign species. The proposed procedure was applied
to the determination of Th(IV), La(III) and Y(III) spiked in natural
water samples and in some ore samples. Additionally, the mechanism of
flotation of the metal chelate was proposed to be due to a physical
interaction between the metal chelate and the oleic acid surfactant
through the Van der Waals force.
Keywords: Thorium, Lanthanum,
Yttrium, Flotation, ECR, Oleic acid, Spectrophotometry, Ores |