1070-4272/03/7608-1337 $25.00 C 2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 8, 2003, pp. 1337!1343. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 8, 2003,
Original Russian Text Copyright + 2003 by Gert, Matyul’ko, Shishonok, Zubets, Kaputskii.
AND POLYMERIC MATERIALS
Nitric Acid Procedure for Production of Powdered Cellulose II
Forms with Various Morphologies and Comparison
of Their Structural and Sorption Characteristics
E. V. Gert, A. V. Matyul’ko, M. V. Shishonok, O. V. Zubets, and F. N. Kaputskii
Research Institute of Physicochemical Problems, Belarussian State University, Minsk, Belarus
Received April 14, 2003
Abstract-A two-stage procedure for production of powdered cellulose II, based on polymorphous transforma-
tion of native cellulose I and hydrolytic dispersion of the fiber with a single reagent, nitric acid, was proposed.
A search for new procedures for production of pow-
dered cellulose (PC) forms with improved characteris-
tics is an urgent task. The most commonly used mod-
ification of PC is microcrystalline cellulose (MCC)
produced by partial acid hydrolysis of cellulose fi-
ber to the so-called limiting degree of polymerization
(DP). The vast majority of studies in this field are
aimed to improve the conditions of hydrolytic cleav-
age of native fiber (cellulose I), characterize the re-
covered MCC-I, and determine the fields of its appli-
At the same time, some publications [4, 5] reported
similar data on cellulose II produced in the form of
powder from the native fiber, using hydrolytic dis-
persion. According to , the polymorphous transition
from cellulose I to cellulose II results in increased
dispersity and whiteness of the final products, which
is important, e.g., for pharmaceutical applications.
The polymorphous transformation is usually effected
by mercerization of native cellulose with 15320%
aqueous sodium hydroxide. Thus, to produce pow-
dered cellulose II from native fiber, both alkaline and
acidic reagents are used, which is inconvenient for
Here, we discuss the possibility of polymorphous
transformation and hydrolytic dispersion of cellulose
with a single reagent, nitric acid. The structural and
sorption characteristics of powdered samples of vari-
ous morphologies, prepared by the acidic process, are
presented in comparison with the similar characteris-
tics of the samples produced by the traditional pro-
cedure and also of MCC-I.
Purified wood sulfite cellulose of the Raikord brand
(96% a-cellulose, DP = 1500) was used as the starting
material for production of powdered forms.
The working 68.5% HNO
solution was prepared
from commercial 72% HNO
of ultrapure grade.
The acid concentration was checked by the solution
density at 20oC. Along with the acid, 18% NaOH was
used. Production of all powdered forms of cellulose
was completed by repeated washing of the final prod-
ucts to neutral reaction of the wash waters, removal of
water with acetone, and drying at room temperature.
After drying, the samples were additionally milled
in a mortar to a dispersity allowing sifting through
a 100-mm sieve.
Variations of physical and chemical characteristics
of cellulose in polymorphous transformation by the
nitric acid procedure were judged from the IR spec-
tra recorded on a Specord 75-IR spectrophotometer.
Samples were prepared as described in . The con-
tent of bound nitrogen in the samples was deter-
mined by the Kjeldahl procedure .
The degree of polymerization of powdered cellu-
lose forms was estimated from the viscosity of nitrate
ester solutions according to the procedure  tested
on the samples of cellulose with known DP.
X-ray diffraction patterns were recorded on an
HZG-4a diffractometer (Cu
radiation, Ni filter).
The samples in the form of flat discs were prepared by
cold pressing. The crystallinity index of the samples