1070-4272/05/7802-0324 C 2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 2, 2005, pp. 324!328. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005,
Original Russian Text Copyright + 2005 by Zemnukhova, Shkorina, Fedorishcheva.
AND POLYMERIC MATERIALS
Composition of Inorganic Components of Buckwheat
Husk and Straw
L. A. Zemnukhova, E. D. Shkorina, and G. A. Fedorishcheva
Institute of Chemistry, Far Eastern Division, Russian Academy of Sciences, Vladivostok, Russia
Received June 3, 2004
Abstract-The composition of inorganic components and content of soluble substances in wastes from pro-
cessing of seed (ordinary) buckwheat were studied in relation to the plant strain, type of a raw material (straw
or husk), and processing conditions.
The interest in renewable agricultural wastes as
promising raw materials for production of a variety
of chemicals has increased recently. Here we studied
some characteristics of large-tonnage wastes from pro-
cessing of buckwheat: straw and husk (fruit shells,
shucks). Much less data on these wastes are available
as compared to the related products of rice processing
. In comparison with rice wastes, buckwheat
wastes contain more organic matter and significantly
less inorganic matter. Among organic substances are
compounds of the flavoid group, including rutin and
quercetin , lipids, and biologically active polysac-
charides . There are data on recovery of polysac-
charides , cellulose , dyes and food addi-
tives [13, 14], furfural , medicinals , antioxi-
dants , and sorbents  from buckwheat wastes.
However, until now, the main part of buckwheat
wastes has not been used in chemical industry and is
burnt in fields or used as a fuel for boilers, fillers for
pillows, packing of fruits and fragile goods, and feed.
In this study, we examined inorganic components
in ash and extracts of wastes from production of seed
buckwheat in relation to the plant strain, type of raw
materials (straw or husk), and processing conditions.
We studied samples of buckwheat husk (BH) and
straw (BS) taken in 199432002 in the Primorskii
(BH-2, 3, 639, and BS-137) and Krasnodar (BH-10)
krais, Amurskaya (BH-1) and Nobosibirsk (BH-9)
oblasts, and China (BH-4).
The numbering of raw material samples is given according
to the collection of the Institute of Chemistry, Far Eastern
Division, Russian Academy of Sciences.
Husk was sifted through a sieve, and a fraction
with a particle size of no less than 2 mm was selected
for experiments. Straw was cut into fragments ap-
proximately 10 mm long. The initial raw material was
washed with water and dried in air.
All the samples of raw materials were analyzed for
the content of ash residue and soluble (extractable)
substances. For this purpose, a weighed portion of
a raw material (60 g) was carbonized in a quartz cup
in air at approximately 300oC to remove volatiles and
then burnt in a muffle at 650oC to constant weight
to obtain an ash residue. Another weighed portion of
the raw material was extracted at 80390oC for 1 h
with water or acid (HCl, H
) or NaOH so-
lutions (concentration of acids and alkali 0.1 and 1 N),
or a mixture (1 : 3) of chloroform with ethanol. In all
runs, the solid : liquid ratio was 1 : 10.
The resulting products (ash, extracts, and insoluble
residue of raw materials) were subjected to chemical,
spectral (a PGS-2 spectrometer), flame atomic absorp-
tion (an AA-780 Nippon Jharrell Ash device, Japan),
IR spectroscopic (a Perkin3Elmer spectrophotometer,
), and X-ray phase (a DRON-2.0 dif-
radiation) analyses by the standard
procedures. The content of silicon was determined gra-
vimetrically [18, 19], and that of phosphorus in the ex-
tracts, photocolometrically .
The results obtained in studying the ash obtained
from buckwheat husk and straw are listed in Tables 1
According to the X-ray diffraction analysis, the ash
obtained from buckwheat husk and straw is, in con-
trast to that from rice husk and straw , in the crys-
talline state (Fig. 1). The yield of ash from buckwheat