1070-4272/01/7404-0592 $25.00 C 2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 4, 2001, pp. 592!595. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 4, 2001,
Original Russian Text Copyright + 2001 by Stavitskaya, Mironyuk, Kartel’, Strelko.
AND ION-EXCHANGE PROCESSES
Sorption Characteristics of [Food Fibers] in Secondary
Products of Processing of Vegetable Raw Materials
S. S. Stavitskaya, T. I. Mironyuk, N. T. Kartel’, and V. V. Strelko
Institute of Sorption and Endoecological Problems, National Academy of Sciences, Kiev, Ukraine
Received May 30, 2000; in final form, November 2000
Abstract-Some structural-sorption characteristics of a series of secondary products (wastes) obtained in
processing of vegetable raw materials, such as wheat straw, buckwheat peel, sunflower husk, and beet pulp,
containing fibrous cellulose skeleton ([food fibers]), were determined. The effect of chemical and mechano-
chemical modification of these products on the characteristics of their pore structure and sorption activity
with respect to organic substances, heavy metal ions, and
Sr radionuclides was studied.
Previuos studies [1, 2] have shown that linear reg-
ular homopolysaccharides (cellulose, mannans, and
chitin), contained in products of vegetable origin
(grasses, legumes, vegetables, fruits, berries, algae,
mushrooms, etc.) and also called [food fibers] (FFs),
which are insoluble in water owing to strong intra-
molecular association, have noticeable binding ability
with respect to a number of heavy metals and radio-
nuclides, among them transuranium elements. It has
been found experimentally that, in human and animal
gastrointestial tracts, FFs are able to sorb calcium,
copper, zinc, and iron ions, and also cholic acids,
nitrous slags, phenols, and other toxic substances and
to detoxicate the organism . Medical and bio-
logical studies indicate that FFs used as sorbing food
additives facilitate removal of various toxicants from
the organism in curing many diseases, which appreci-
ably increases the efficiency of therapeutic procedures
and reduces their duration.
Because of the need for widening the assortment
of sorbents (enterosorbents and food additives), it is
an urgent task to study sorption, ion-exchange, and
complexing characteristics of a number of vegetable
products, which appear most often as nonutilizable
wastes of agricultural industry.
The aim of this work was to study comprehensive-
ly the sorption characteristics of some FF-containing
products, such as wheat straw, buckwheat peel, sun-
flower husk, and beet pulp. These products were sub-
jected to chemical or mechanochemical modification:
(1) lyophilic drying of the product after treatment with
buffer solutions of varied acidity and (2) thermal ex-
trusion of a moistened product.
Lyophilic drying (cold vacuum dehydration) of
the products was carried out on a laboratory setup at
temperatures ranging from 310 to 315oC after swell-
ing of these products during boiling in buffer solu-
tions with pH 3.56 (KC
), 7.05 (KH
), and 9.18 (K
) for 1 h and keeping
the resulting suspensions at room temperature for 7
days, washing of the solid phase with distilled water
to neutral wash water pH, and filtration.
The mechanochemical treatment of the samples
was carried out on a pilot two-worm extruder.
technical characteristics were as follows: length 1.5 m,
outlet diameter 63 mm, rotation speed of the worms
30345 rpm, and temperature in the area of maximum
compression 1603180oC. The initial product fed in-
to the extruder had moisture content of 25%.
The main goal of the modification of these prod-
ucts was to raise their internal adsorption surface area
and facilitate the access to active centers of FF-con-
taining materials. Therefore, it was of interest to es-
timate the sorption characteristics of the modified
products with respect to organic substances, toxic
metals, and radionuclides.
The features of the pore structure of the products
and their capacity for molecular and ion-exchange
sorption were studied by common procedures [6, 7].
The specific surface area S
was measured gas-
chromatographically from the thermal desorption of
argon. The volume of sorption pores, W
, was de-
Ukrainian Research Institute of Machines for Plastic Produc-