1070-4272/01/7407-1112$25.00C2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 7, 2001, pp. 1112!1117. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 7,
2001, pp. 1084!1090.
Original Russian Text Copyright + 2001 by Samonin, Grigor’eva, Dalidovich.
AND ION-EXCHANGE PROCESSES
Composite Sorbents Based on Inorganic Adsorbents
V. V. Samonin, L. V. Grigor’eva, and V. V. Dalidovich
St. Petersburg State Technological Institute, St. Petersburg, Russia
Received October 9, 2000; in final form, March 2001
Abstract-The routes of fabricating and the main properties of composite sorbents based on mineral ad-
sorbents as fillers and inorganic binders are considered.
The possibilities and methods of fabricating and
the properties of composite sorbents (CSs) based on
mineral adsorbents as fillers and organic polymers as
binders were considered in . In many cases, such
CSs were unsuitable for repeated exploitation, because
the temperatures for regeneration of sorbents incor-
porated into CSs exceed the range of stability of or-
ganic polymeric matrices.
Synthesis of such CSs and their possible structure
have been reported previously . The polymeric
nature of some inorganic compounds of silicon and
aluminum [6, 7] suggests that interaction of the initial
sorbent with the inorganic polymer should occur
similarly as with organic binder.
In this work we prepared and stuided CSs based on
inorganic sorbents and polymeric binders of various
origins and structures.
Inorganic sorbents were silica gel (KSMG grade),
NaX zeolite, AOA-1 grade active aluminum oxide
(AAO), and coarse-pore water-resistant silica gel
(OSG grade) impregnated with lithium and calcium
Silicic acid sol (SAS), aqueous sodium silicate
solution (water glass, WG), and potassium tetrasilicate
(PTS) based cement were inorganic binders. They are
readily available and have the enhanced thermal
stability as compared to organic materials, which
is essential in view of necessity of recovering inor-
ganic sorbents at high temperatures (from 1803200oC
for silica gel to 3503400oC for zeolite). Moreover,
the different structure of these polymeric systems
allows the mechanism of the formation of CSs based
on inorganic polymers to be analyzed in more detail.
The CS as consolidated mixture was prepared in
the shell of the adsorber, which is the main part of
The filler used with a WG binder was NaX zeolite
mixed with active aluminum oxide (AOA-1 grade)
in the 1 : 1 ratio. The mixture of this composition is
optimal for synthesizing, for example, mineral filters
intended for complex purification of freons to remove
moisture and degradation products of freon oils. After
vibration packing of granules, the aqueous binder
solution was poured through the mixture and then the
fabricated CS was dried for 43 6hat2003350oC
depending on the initial sorbent. The WG had the
ratio m = 2.2 of the number of SiO
in sodium silicate and contained 40 wt % sodium
silicate. The coagulants (aqueous solutions containing
5325 wt % H
OH, or CaCl
) were added to
it preliminarily. The coagulant fraction was varied
within 10365 wt % of WG, the latter amounting to
20 wt % of CS.
CS as consolidated mixture with SAS binder was
prepared similarly. SAS with a density of 2.5 g cm
containing 20 wt % substance, with micelle size of
25 nm and pH 10.5, was used in the experiments.
The initial SAS was diluted by a factor of 2 or 3, if
necessary. The SAS aqueous solution in an amount of
50% of the volume of the initial sorbent was poured
through the mixture.
CS with PTS binder in the form of consolidated
mixture was also prepared in the shell of the adsorber.
The binder used in this work was the calcination prod-
uct of the K
(30 mol % K
O) system ensur-
ing the best strength characteristics of cement stone
upon tempering and solidification . According
to X-ray phase analysis, PTS is a mixture of potassi-
um tetrasilicate (monoclinic crystal system, density