ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 9, pp. 1446−1450. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © V. A. Brodskiy, A.M. Gaydukova, V.A. Kolesnikov, 2015, published in Zhurnal Prikladnoi Khimii, 2015, Vol. 88, No. 9, pp. 1300−1305.
AND CORROSION PROTECTION OF METALS
Inﬂ uence of pH of the Medium on the Physicochemical
Characteristics and Efﬁ ciency of Electroﬂ otation Recovery
of Poorly Soluble Cerium(III, IV) Compounds
from Aqueous Solutions
V. A. Brodskiy, A. M. Gaydukova, and V. A. Kolesnikov
Mendeleev University of Chemical Technology of Russia, Miusskaya pl. 9, Moscow, 125047 Russia
Received September 25, 2015
Abstract—The inﬂ uence of pH of solutions on the size, surface characteristics, and electroﬂ otation activity of
particles of poorly soluble cerium(III, IV) compounds was examined. The recovery completeness and efﬁ ciency
directly depend on the electrokinetic potential of poorly soluble cerium particles: the particles with the smallest
absolute value of the surface charge are recovered most completely and efﬁ ciently. The effect of Superﬂ oc series
ﬂ occulants of different nature on the efﬁ ciency of the electroﬂ otation process was demonstrated. Introduction of
a cationic ﬂ occulant leads to the process intensiﬁ cation, to a decrease in the treatment time to 2 min, and to an
increase in the degree of recovery of cerium compounds to 99%.
Rare earth metals play today the key role in the
production of materials for high-tech applications, such
as electronic and electrooptical devices, information
technologies, biomedicine, environment protection, and
power saving. In addition, rare earths are widely used
in traditional spheres, in particular, in metallurgy [1–4].
Cerium is the most widely abundant and used rare
earth element. It is used in many branches of industry,
in particular, in the production of luminophores,
industrial ceramics, catalysts for oil reﬁ ning industry,
superconductors, permanent magnets, high-quality glass,
batteries with long operation life, etc.
Wash waters from the above branches of industry
contain relatively large amount of cerium and are
valuable secondary raw material. Therefore, it becomes
necessary to develop new methods for efﬁ cient cerium
recovery. It should be noted that, in ore materials, cerium
is usually present in the form of Ce(III) compounds,
whereas industrial processes mainly use Ce(IV) com-
pounds [5, 6].
One of promising methods for recovery of metal
compounds from aqueous solutions is electroﬂ otation
. Therefore, a study of the electroﬂ otation recovery
of cerium(III, IV) from aqueous solutions with the aim
to enhance the process efﬁ ciency is a topical problem.
The decisive step in electroflotation recovery of
metal ions from aqueous solutions is the formation of
the dispersed phase. The most efﬁ cient procedure for
recovering metal ions involves formation of their poorly
soluble hydroxides or oxides by using acid–base reagents,
i.e., by controlling pH of the medium.
The main criteria for choosing pH of the medium
when performing electroﬂ otation treatment is minimal
solubility of the dispersed phase particles formed,
which apparently favors maximum complete recovery
of metal ions from wastewaters. On the other hand, pH
of the medium can inﬂ uence the surface characteristics
of particles of dispersed compounds, in particular, their
size and charge [8, 9]. It is known that these parameters
can inﬂ uence the electroﬂ otation process via two major