1070-4272/01/7407-1079$25.00C2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 7, 2001, pp. 1079!1081. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 7,
2001, pp. 1051!1053.
Original Russian Text Copyright + 2001 by Khlopochkina, Gaivoronskii, Gavrishchuk, Elliev, Yashina.
AND INDUSTRIAL INORGANIC CHEMISTRY
Oxidation of Polycrystalline Zinc Selenide
with Atmospheric Oxygen
E. L. Khlopochkina, P. E. Gaivoronskii, E. M. Gavrishchuk,
Yu. E. Elliev, and E. V. Yashina
Lobachevskii State University, Nizhni Novgorod, Russia
Institute of Chemistry of High-Purity Substances, Russian of Academy of Sciences, Nizhni Novgorod, Russia
Received June 16, 2000; in final form, February 2001
Abstract-Oxidation of granulated polycrystalline zinc selenide (grain size 0.236.5 mm) with atmospheric
oxygen at 4303700oC was studied. The optimal conditions for the oxidation were found. An installation
for the oxidation of kilogram amounts of zinc selenide was designed and fabricated.
Published data on the oxidation of zinc selenide as
single crystals, polished plates, and powders include
estimates of the oxidation rate at 3003950oC, com-
position of the reaction products, and suggested equa-
tions for the oxidation . However, there are a
number of contradictions in the determination of com-
position of the nonvolatile oxidation products. For
instance, according to , zinc oxide is the only
nonvolatile product, but in  significant amounts
(up to 18%) of zinc selenite were found in the range
4903560oC along with zinc oxide. According to ,
zinc selenite is the main product of the oxidation
at 300oC; as the temperature increases, its fraction
appreciably decreases as compared to zinc oxide.
Volatile oxidation products either were not inves-
tigated at all [1, 2, 5] or only their qualitative com-
position as a mixture of selenium and selenium di-
oxide [3, 4] was established. The effect of the grain
size of the initial zinc selenide on the rate of its oxida-
tion is still obscure, and probable oxidation mech-
anisms were not discussed.
In this work the study was concerned with waste
polycrystalline zinc selenide of various grain size,
formed from production of optical parts for IR tech-
nique . One of the ways of processing waste prod-
ucts is their oxidizing calcination. In this connection,
the aims of this work were to study the oxidation
kinetics of granulometric zinc selenide samples of
various grain size, to identify the products of the oxi-
dation at 4303700oC, and also to study the mech-
anism of the oxidation with atmospheric oxygen.
First we carried out a thermodynamic analysis of
the system zinc selenide3air. Though the oxidation
conditions were far from equilibrium, the thermo-
dynamic analysis is important for the estimation of
the relative contents of products both in gas and con-
densed phases. The calculation was carried out at
various stoichiometric ratios of the initial reactants.
The calculated equilibrium concentrations of com-
ponents (in moles per total number of moles of atoms
in the initial substances) for the system zinc selenide3
air in excess oxidant (molar ratio zinc selenide3
oxygen in the experiments was 1 : 4.5) are given in
Fig. 1. Apparently, within the whole temperature
Fig. 1. Temperature dependence of the equilibrium com-
position of the system zinc selenide3oxygen. (C) Equilibri-
um concentration [mol (mol of atoms)
]. Phase: (a) gas
and (b) condensed.