Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 1, pp. 1−8.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © M.V. Maslova, L.G. Gerasimova, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 1, pp. 3−9.
INORGANIC SYNTHESIS AND INDUSTRIAL
The Inﬂ uence of Chemical Modiﬁ cation on Structure
and Sorption Properties of Titanium Phosphates
M. V. Maslova and L. G. Gerasimova
Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Resources, Kola Scientiﬁ c Center,
Russian Academy of Sciences, Apatity, Murmansk oblast, Russia
Received February 18, 2010
Abstract—Physical and chemical methods of analysis were used to study the effect of chemical modiﬁ cation
of titanium phosphates on their sorption properties, depending on the chemical composition of a composite and
nature of a modiﬁ er. The dependence of exchange capacity of the materials on the degree of their crystallinity
Ion-exchange technologies are widely used for the
puriﬁ cation of industrial wastewaters, in water prepara-
tion, hydrometallurgy, catalysis, medicine, and biochem-
istry . Inorganic ionites have certain advantages over
organic resins due to chemical and thermal stability and
selectivity with respect to certain ions [2–4]. Among
the broad class of inorganic materials, phosphates of
tetravalent elements play the important role.
Titanium phosphates are obtained as amorphous gels
with a P : Ti ratio of nearly 1. Heating of amorphous
product in a solution of phosphoric acid leads to slow
crystallization of titanium phosphate. The products with
varied degree of crystallinity suitable for speciﬁ c appli-
cation may be obtained by varying the concentration of
reagents and reaction temperature .
Because titanium phosphates are weakly acid ionites,
they exhibit the ion-sieve effect in acid solutions,
whereas ions larger than K
are exchanged solely in
neutral and alkaline solutions. In this region, the proton
of a layer is neutralized, which causes layers to swell
(extend) and thus facilitates exchange of larger cations.
The exchange proceeds via diffusion of ions from the
outer surface inside the ionite grain to form boundary
phases . The modiﬁ cation of titanium phosphates
by transferring them into an alkali form increases their
exchange capacity. For example, the ionites in Na form
work as selective ion exchangers in the acid pH range,
because the Na phase formed at the grain edges of the
ionite causes interplanar spacing to swell, thus assisting
diffusion of exchange cations toward the solid phase
The structure and degree of crystallinity are the
important characteristics of ion exchangers based on
titanium phosphates. Crystalline materials in H form
possess regular structure with an interplanar spacing of
7.6 Å. Transferring them into a salt form causes interpla-
nar spacing to extend to 11 Å, thus greatly facilitating
incorporation of exchange ions into the ionite lattice
. Amorphous materials are agglomerated particles
with badly formed layers . The structural defects af-
fect ion-exchange properties of a material. The layers
may also be extended by the transformation of gels into
a salt form, therewith exchange of large cations can be
impeded due to irregular structure of tunnel channels.
In the study, the effect of chemical modiﬁ cation of tita-
nium phosphates on their structure and sorption properties
was determined, depending on the chemical composition
of a composite and nature of a modiﬁ er. The data obtained
may be important in practice for the synthesis of titanium
phosphates with prescribed properties.