ORGANIC SYNTHESIS AND INDUSTRIAL
Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 12, pp. 2083−2087.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © V.I. Chursin, K.V. Obolenskaya, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 12, pp. 1999−1203.
Use of Glyoxal in Production of a Composite
Chromium Tanning Agent
V. I. Chursin and K. V. Obolenskaya
Moscow State University of Design and Technology, Moscow, Russia
Received December 30, 2010
Abstract—Conditions in which a composite chromium tanning agent can be obtained in the presence of glyoxal
were studied. It was found that the expenditure of the aldehyde and sulfuric acid affects the reduction kinetics of
hexavalent chromium. Spectrophotometry and conductometry were used to examine the composition of composite
tanning agents. It was shown that chromaldehyde tanning agents can be applied in manufacture of leather and fur.
Tanning is one of the most important processes in
manufacture of leather and fur. At present, more than
90% of world’s leather is manufactured using tanning
compounds of chromium(II). However, a shortage
of chromium compounds is felt in the world and
requirements to the ecological safety of industries
become increasingly stringent, which necessitates
improvement of the tanning process . The related
research is being conducted in two main areas. The
ﬁ rst, associated with the ecological safety of tanneries,
envisages that the expenditure of chromium tanning
compounds should be diminished and these compounds
should be fully recovered from processing solutions.
The second area consists in raising the efﬁ ciency
of the tanning process by combining chromium and
other, including organic, tanning agents. In this case,
the consumption of the chromium tanning agent can
be lowered, with the required strength and hygienic
properties of leather preserved. The most promising are
chromaluminum and chromaldehyde kinds of tanning.
The combined tanning with chromium compounds and
aldehydes provides the maximum heat resistance of
leather at the minimum expenditure of the chromium
tanning agent .
The goal of our study was to examine the possibility
of obtaining a composite chromaldehyde tanning agent
both by chemical reduction of potassium bichromate
with oxalic aldehyde (glyoxal) and by preparing
a blended formulation.
The following starting compounds were used:
powdered chromium tanning agent (PCT), basic Cr(III)
sulfate with 25% chromium oxide and basicity of
40%, OST (Industrial Standard) 6-18-219–75; sodium
of pure grade; and glyoxal
in the form of a 40% aqueous solution . Sodium
bichromate was reduced under permanent agitation with
a magnetic rabble. The process kinetics was monitored
by measuring the electrical conductivity with a HANNA
583 conductometer, and the refractive index with an IRF-
454 B refractometer. The basicity of the composite
tanning agents and their content of chromium oxide
were determined by standard methods . Solution
spectra were measured on an SF-46 spectrophotometer
in 10-mm cuvettes.
It is known that, in an acid medium, sodium
bichromate is a strong oxidizing agent and, in the
presence of a reducing agent, it is converted to
a compound with an oxidation state of 3 . Sodium
bichromate is reduced in the presence of sulfuric acid by
the following reaction (R is the reducing agent):
+ R = 2CrOHSO
As reducing agents can be used both organic and