ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2009, Vol. 54, No. 11, pp. 1816–1819. © Pleiades Publishing, Inc., 2009.
Original Russian Text © T.B. Kuvshinova, V.M. Skorikov, V.D. Volodin, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 11, pp. 1896–1899.
PHYSICOCHEMICAL ANALYSIS
OF INORGANIC SYSTEMS
Reaction of Bismuth Nitrate with Sodium Citrate
in Water−Glycerol Solutions
T. B. Kuvshinova, V. M. Skorikov, and V. D. Volodin
Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991
Russia
Received February 17, 2009
Abstract—The reaction in a Bi(NO3)3–Na3Hcit–(H2O + glycerol)1 system was studied in a wide range of com-
ponent ratios by the solubility method and pH-metry in combination with chemical analysis of solid phases.
Poorly soluble phases of Bi(Hcit)x(OH)3(1 – x) · mH2O (x < 1) and sodium bismuth citrate NaBiCit · 3H2O were
obtained. The compounds synthesized were characterized, and their compositions were refined by X-ray dif-
fraction, DTG, and IR spectroscopy.
DOI: 10.1134/S0036023609110199
1
Bismuth compounds find wide use, particularly, as a mixture of water with glycerol in the volume ratio of
pharmaceticals [1]. Therefore, bismuth salts with car- 2 : 1. with a constant content of Bi(NO3)3 · 5H2O in
boxylic acids are of interest.
each sample (0.0049 mol), the amount of the precipitat-
ing agent was gradually increased over a wide interval:
the initial molar ratios n = [Cit] : [Bi] ranged from 0.25
to 8.0. The total volume of a sample was 100 mL. The
precipitates formed were separated by filtration and
washed with an H2O –glycerol (2 : 1) mixture and then
with 50% ethanol. The solid phases washed were dried
in air at room temperature until a constant weight was
achieved.
In this work, we studied the interactions, composi-
tion, and formation conditions of compounds in the
Bi(NO3)3–Na3Hcit–(H2O + glycerol) system. It is
known that the dissolution of bismuth nitrate in water is
accompanied by its hydrolysis to poorly soluble bis-
muth oxy- and hydroxynitrates [2]. Bismuth nitrate is
readily soluble in nitric acid, but at low concentrations
of the latter (0.1–0.2 N) these solutions are also rather
unstable. Stable in time highly concentrated solutions
(up to ~1 g/mL Bi(NO3)3 · 5H2O) are formed when mix-
tures of water with polyhydric alcohols (glycerol, man-
nitol, and others) are used as solvents. It can be
assumed that the bismuth ion with polyatomic alcohol
forms associates that are sufficiently stable to retain
bismuth in the solution and simultaneously make it pos-
sible to completely precipitate bismuth as a poorly sol-
uble compound.
For chemical analysis, samples were dissolved in
HNO3. Bismuth was precipitated in the form of BiPO4.
To determine the citrate ion, an sample of the substance
was burnt in an oxygen flow and examined on a Carlo
Erba 1108 analyzer. This method also made it possible
to monitor the nitrate ion content in the compound.
The precipitation of sodium zink uranyl acetate,
after bismuth was preliminarily separated as BiOCl,
and potentiometric titration with the OP-Na-0711-P
Na-selective electrode (Radelkis, Hungary) were used
for sodium determination.
EXPERIMENTAL
Neutral bismuth citrate was used both as a sample
synthesized by us and as a commercial high-purity
grade reagent. The compounds synthesized in the sys-
tem were characterized by X-ray diffraction (DRON-3
diffractometer, CuKα radiation), DTA (Netzsch STA-
409), and IR spectroscopy (Carl Zeiss UR-20, KBr pel-
lets).
RESULTS AND DISCUSSION
According to visual observation data (Fig. 1a), the
amount of the poorly soluble bismuth compound pre-
cipitated (phase I) upon the addition of the precipitating
agent increases up to n ~ 1; then, beginning with
n ~ 1.2–1.3, the precipitate gradually goes to the solu-
tion again and is dissolved completely at n ~ 1.5–1.6.
The corresponding noticeable break is observed in the
pH curve. The solution formed is metastable (its stabil-
ity ranges within 10–15 min, depending on the precipi-
tation conditions) and with time again precipitates solid
The starting solutions (0.195 mol/L Bi(NO3)3 · 5H2O
and 0.5 mol/L Na3Hcit · 5.5H2O) were prepared using
3–
7
1
Hereafter, according to foreign publications, Hcit = C H O
,
6
5
and Cit = C H O4–
.
6
4
7
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