Russian Journal of Applied Chemistry, Vol. 75, No. 8, 2002, pp. 1354 1356. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 8, 2002,
pp. 1381 1383.
Original Russian Text Copyright
2002 by Ostanova, Chubarov, Drozdov, Patrushev.
BRIEF
COMMUNICATIONS
Oxidation of Zinc Sulfide
in the System HNO Fe(NO ) H O
3
3 3
2
S. V. Ostanova, A. V. Chubarov, S. V. Drozdov, and V. V. Patrushev
Institute of Chemistry and Chemical Technology, Siberian Division,
Russian Academy of Sciences, Krasnoyarsk, Russia
Received October 10, 2001; in final form, February 2002
Abstract The behavior of zinc sulfide in the system HNO Fe(NO ) H O at 25, 55, and 80 C was studied
3
3 3
2
using the simplex-lattice design method.
Data on reactions of certain metal sulfides with mi-
neral acids are well known; however, the range of sys-
tems under study is rather narrow. The system HNO3
Fe(NO ) H O has been studied insufficiently [1].
X , H O (55.56 M); X , Fe(NO ) (1.8 M); and X ,
1 2 2 3 3 3
HNO (3.2 M). As functions served the extents to
3
2
+
which Zn passes from ZnS into solution.
3
3
2
A simplex-lattice design for the incomplete cubic
model used to describe the system under study is pres-
ented in the table. These data were used to calculate
the regression equations for 25, 55, and 80 C:
This system was studied to analyze reactions of
zinc sulfide in the ternary system HNO Fe(NO3)3
3
H O at various HNO and Fe(NO ) concentrations
2
3
3 3
and to obtain data on the composition of precipitates
formed in redox reactions at 25, 55, and 80 C.
Y25 = 0.05X1 + 21.79X2 = 49.44X3 + 30.95X1X2
+
24.16X1X + 96.34X2X + 113.09X X X ,
3 3 1 2 3
EXPERIMENTAL
Zinc sulfide was synthesized by the technique de-
scribed in [2] and identified by X-ray phase analysis;
Y55 = 0.08X1 + 12.46X2 + 37.31X3 + 74.42X1X2
+ 37.16X1X3 + 49.70X2X3 176.91X X X ,
2
1
1
2 3
its specific surface area Ssp = 4.1 m g was deter-
mined by BET. Chemically pure iron(III) nitrate and
nitric acid, and also distilled water, were used in the
study. The experiments were carried out in a temper-
ature-controlled system (the accuracy of temperature
measurements was 0.1 C) in the course of 2 h (pre-
liminary experiments showed that the concentration
of Zn2+ ions in solution remains unchanged after 2-h
contact of zinc sulfide with the solution) with per-
manent stirring and initial s : l ratio of 1 : 5.
The concentration of Zn2+ ions in the liquid phase
was determined by titrimetry and atomic-absorption
spectrophotometry [3, 4], and that of nitric acid, by
titrimetry [4]. After filtration, the solid phase was
washed with water and ethanol to remove the solution,
dried, and subjected to X-ray phase analysis.
Y80 = 0.07X1 + 50.00X2 + 55.22X3 + 22.53X1X
2
9
8.05X1X3
19.40X2X3 + 237.98X X X .
1 2 3
The root-mean-square error was 3%. It was found
that these equations describe adequately the data ob-
tained in control experiments nos. 8 10, with 97%
probability. The equations were used to construct
phase diagrams for the temperatures under study
(Figs. 1a 1c).
The increase in the degree of Zn2+ leaching is
directed toward the HNO Fe(NO ) system in all the
3
3 3
diagrams, with the most complete extraction of about
2% achieved at 25 C. The same behavior is observed
at 55 and 80%, but the degree of leaching of zinc ions
is lower (40 and 55%, respectively). Addition of nitric
acid to the solution promotes the oxidation reaction,
with an increase in acidity favoring sulfide break-
6
The results obtained were processed by means of
the simplex-lattice design [5]. The following compo-
nents were the vertices of the concentration triangle:
1
070-4272/02/7508-1354 $27.00 2002 MAIK Nauka/Interperiodica