Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 1, pp. 145−150.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
I.M. Lipatova, L.I. Makarova, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 1, pp. 148−153.
AND POLYMERIC MATERIALS
Mechanical Activation of Chitin in Aqueous
and Alcoholic Suspensions
I. M. Lipatova and L. I. Makarova
Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, Russia
Received July 6, 2009
Abstract—The effect of hydroacoustic treatment performed in a rotary-pulsatory apparatus on the state of aqueous
and alcoholic suspensions of crab chitin was examined.
Chitin is a polyaminosaccharide widely occurring
in the nature. After cellulose, it is the second renewable
product of the biosphere. The application area of this
natural biopolymer can be expanded by preparing
its derivatives via chemical modification. Chemical
modification of chitin, which is extremely poorly
soluble in available solvents, is traditionally performed
under heterogeneous conditions. This polysaccharide
is characterized by highly crystalline supramolecular
organization and developed system of intermolecular
hydrogen bonds, which is responsible for its low reactivity
in processes occurring under heterogeneous conditions.
Therefore, preparation of highly substituted derivatives
of chitin requires its preliminary activation.
The known methods of chitin activation, based on
reprecipitation from concentrated phosphoric acid  or
swelling in active organic media , can be implemented
only in laboratory practice because of long process
time and large consumption of expensive chemicals.
Mechanical procedures of activation of natural polymers
are more promising for commercial implementation.
A very efﬁ cient procedure of chitin activation is extrusion
grinding, which combines the effects of shear strains and
high pressure on the polymer . However, the drawbacks
of this method are structural nonuniformity of the polymer
obtained by activation and considerable decrease in its
molecular weight. Procedures of chitin activation in
the form of an aqueous suspension are known, such as,
e.g., ultrasonic treatment . With common ultrasonic
equipment, the process is performed in the batch mode
and takes much time, and high uniformity of the product
cannot be attained. Hydroacoustic devices are free of
these drawbacks. In a hydroacoustic apparatus, a ﬂ uid
material is subjected to a complex effect of ultrasonic
cavitation and hydrodynamic forces in the course of high-
speed passing through narrow gaps between elements of
the rotor and stator of the apparatus .
The goal of this study was to examine the possibility
and efficiency of using hydroacoustic treatment for
mechanical activation of chitin in aqueous and alcoholic
Experiments were performed with suspensions
of chitin isolated from crab shells by the traditional
acid–alkaline procedure. As dispersion media we used
distilled water and ethanol. The solid phase content of
the suspensions was 1 and 2 wt %.
Chitin suspensions were treated in a laboratory rotary-
pulsatory apparatus (RPA) in the recycle mode. The
temperature-controlled working chamber of the apparatus
is formed by a rotor and a stator whose cylindrical rings
have rectangular channels. The mean gap between the
rotating and stationary elements of the working chamber
is 0.3 mm. The rotor rotation rate is 5000 rpm, which
corresponds to a shear rate gradient of 17.4 × 10
treatment time was varied in the range 4–30 s.
The average particle size d
in the mechanically
treated suspensions was measured with an ANALYSETTE