Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 5, pp. 792−797.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © L.B. Naumova, T.S. Minakova, E.B. Chernov, N.P. Gorlenko, I.A. Ekimova, 2011, published in Zhurnal Prikladnoi Khimii, 2011,
Vol. 84, No. 5, pp. 762−767.
OF SYSTEMS AND PROCESSES
Adsorption–Desorption of Water Vapor
on Initial and Modiﬁ ed Peat Samples
L. B. Naumova
, T. S. Minakova
, E. B. Chernov
, N. P. Gorlenko
, and I. A. Ekimova
Tomsk State University, Tomsk, Russia
Surgut State University, Surgut, Khanty-Mansi autonomous okrug, Russia
Received December 6, 2010
Abstract—Speciﬁ c features of adsorption–desorption of water vapor on the initial samples of valley-bog and
raised-bog peat and on the samples modiﬁ ed with iron and aluminum salts were studied and interpreted in terms
of the model of a process with two types of sorption sites.
Studies in the ﬁ eld of chemistry of peat, which is
a kind of strategic stock of natural resources, are of
doubtless interest from the viewpoint of its rational
use. The number of studies in this ﬁ eld intensely
grows [1–3]. This is due to the presence of various
reactive components in the peat structure, creating
prerequisites for multifunctional use of peat. It is of
particular importance to study the moisture absorption
characteristics of peat by the adsorption method
allowing evaluation of processes that occur on the
surface and determination of thermodynamic functions
and giving better insight into the mechanism of the
effect of modifying additives.
In this study we examined adsorption–desorption
of water vapor on the initial and modiﬁ ed peat samples
with the aim to evaluate the possibility of separating
aluminum and iron ions on peat.
The investigation objects were samples of raised-
bog and valley-bog peat samples, initial and modiﬁ ed
with iron(III) and aluminum chloride solutions, with the
following characteristics: (1) peat from Orlovo deposit,
Tomsk oblast, raised-bog, degree of degradation 5–10%
(initial); (2) peat from Orlovo deposit, Tomsk oblast,
raised-bog, degree of degradation 5–10% (modiﬁ ed with
, с = 0.05 M); (3) peat from Tagan deposit, Tomsk
oblast, valley-bog, degree of degradation 23% (initial);
(4) peat from Tagan deposit, Tomsk oblast, valley-bog,
degree of degradation 23% (modiﬁ ed with FeCl
, с =
0.05 M); (5) peat from Tagan deposit, Tomsk oblast,
valley-bog, degree of degradation 23% (modiﬁ ed with
, с = 0.05 M).
Experiments on water vapor adsorption were
performed by the gravimetric static method (McBain–
Bakr spring balance) with a vacuum installation allowing
evacuation to the residual pressure of 5 × 10
The pressure was measured with a McLeod manometer
and a U-shaped manometer. Extension of the spiral of
the McBain–Bakr balance was recorded with a V-630
cathetometer. The spiral sensitivity was 2.2 × 10
. As adsorbate we used double-distilled water.
Water was puriﬁ ed by repeated freezing–pumping–
thawing. The total error of the adsorption measurements
was within 4–16% of the adsorption (desorption)
value. Prior to measurements, the samples were kept in
a vacuum (10
mm Hg) at 298 K for 24 h. The weight
of peat samples was 40 mg.
Figure 1 shows the isotherms of adsorption–
desorption of water vapor on various peat samples. The
adsorption and desorption values were calculated per
gram of dry peat. Analysis of the adsorption isotherms
allows them to be assigned to two types according to