1070-4272/01/7411-1786$25.00C2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 11, 2001, pp. 1786!1788. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 11,
2001, pp. 1734 !1736.
Original Russian Text Copyright + 2001 by Gerasimova, Maslova, Zhdanova, Okhrimenko.
AND INDUSTRIAL INORGANIC CHEMISTRY
Composition of Solid Phases Isolated from Sulfuric Acid
Solutions of Titanium(IV) by the Action of Phosphoric Acid
L. G. Gerasimova, M. V. Maslova, N. M. Zhdanova, and R. F. Okhrimenko
Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials,
Kola Scientific Center, Russian Academy of Sciences, Apatity, Murmansk oblast, Russia
Received January 30, 2001
Abstract-The composition of titanium phosphates precipitated in the course of the hydrothermal sulfuric
acid decomposition of sphene concentrate in the presence of phosphoric acid was studied.
Titanium phosphate compounds, or, more exactly,
titanium(IV) hydrophosphates, are known as effective
inorganic ion exchangers (sorbents) removing from
wastewater the ions of cobalt, nickel, cadmium, and
radioactive elements [1, 2]. Production of such sor-
bents from solutions of titanium intermediate products
and the influence of solution acidity [3, 4], tempera-
ture , and conditions of washing and heat treatment
of hydrated synthesis products  on their properties
were actively studied in Russia.
Titanium(IV) phosphates are also used as fillers of
paper and rubber and in compositions of weatherproof
paint-and-varnish materials . In this case the
requirements to titanium phosphate products are dif-
ferent from those for the sorbents. In particular, they
should have pigmentary properties, and also high
weather resistance .
The aim of this work was to synthesize such com-
pounds and to study their composition and properties.
Titanium(IV) solutions obtained upon the sulfuric
acid decomposition of sphene CaSiTiO
were used as
titanium intermediate products. Such solutions contain
4003500, and also
impurities of iron, silicon, and calcium compounds.
The filtrate obtained from the apatite decomposition
with sulfuric acid (P
content 30%) was used as
a phosphorus-containing component.
Experimental technique consists in the following.
Phosphoric acid was added into titanium(IV) sulfuric
acid solution in the ratio TiO
The process was carried out with stirring under hy-
drothermal conditions (~100oC) for 1.532 h, and
the resulting suspension was kept without stirring
for 10 h. Then the precipitate was separated from
the liquid phase and washed with water at the
solid : liquid ratio of 1 : 10. The precipitation condi-
tions and precipitate compositions are given in
The degree of titanium(IV) precipitation from solu-
tions increases with increasing consumption of phos-
phoric acid; the filtration rate of the resulting suspen-
sion also increases, which is indicative of the forma-
tion of agglomerates with the surface low-active to-
ward the liquid phase.
The freshly precipitated substances are X-ray
amorphous. Their thermal treatment (~750oC) yields
products consisting mainly of a single phase (TiO)
. The endothermic effects at 1703350oC are
due to dehydration and to the loss of adsorbed water
and water of crystallization. The exothermic effect at
7303750oC is not accompanied by a change in weight
and is due to crystallization of the amorphous sub-
stance (Fig. 1).
We have studied in more detail the production of
titanium phosphate precipitates from titanium(IV)
sulfuric acid solutions, when phosphoric acid was
taken not in excess but in the amount corresponding
to the weight ratio TiO
= 1 : 0.5. The acid
was added not before heating the initial titanium(IV)
solution, but after boiling it for 2, 7, and 14 h. The
initial sulfuric acid solution of titanium(IV) contained
110 g l
and 500 g l
. Such [ti-
tanic] system is very stable, and without external
actions (dilution with water and addition of seeds) the
titanic phase is not formed, though the speciation of
the dissolved titanium(IV) changes. Thus, whereas in