ISSN 1070-4272, Russian Journal of Applied Chemistry, 2014, Vol. 87, No. 9, pp. 1319−1325. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © F.K. Khakimova, K.A. Sinyaev, 2014, published in Zhurnal Prikladnoi Khimii, 2014, Vol. 87, No. 9, pp. 1329−1335.
AND POLYMERIC MATERIALS
Environmentally Safe Bleaching of Bisulﬁ te Pulp
F. K. Khakimova and K. A. Sinyaev
Perm National Research Polytechnic University, Komsomol’skii pr. 29, Perm, 614990 Russia
Received May 27, 2014
Abstract—Bleaching of bisulﬁ te pulp with high fraction of residual lignin was studied. Bleaching was performed
using two oxidants: hydrogen peroxide in acid medium in the deligniﬁ cation stage and sodium chlorite in the ﬁ nal
bleaching. Oxidative degradation of the pulp and chemical loss of the ﬁ ber are quite moderate in the process,
and changes in the ﬁ ber size and mechanical properties of the pulp are insigniﬁ cant. This technology ensures
high degree of deresiniﬁ cation with respect to total and “harmful” resins, i.e., it eliminates “resin problems” in
production of paper and cardboard.
Pulp bleaching using elemental chlorine free (ECF)
and total chlorine free (TCF) technology meets the
modern environmental requirements to the production
of bleached pulp. Today the ECF bleaching technology
is preferred. Owing to the capability for easy bleaching
and to speciﬁ c properties of sulﬁ te pulp, its production
is the best suited for the introduction of chlorine-free
The modern technologies of pulp bleaching involve
two stages: deligniﬁ cation, which can be considered as
continuation of cooking, and bleaching proper (ﬁ nal
Bleaching by the ECF process most frequently
involves the use of oxygen–alkali extraction (EO) in
the deligniﬁ cation stage and of treatment with chlorine
dioxide (D) in the ﬁ nal bleaching. However, EO, along
with such an important advantage as formation of
no toxic chlorinated organic compounds, has certain
drawbacks: need for using sophisticated and expensive
equipment, because the process is performed at elevated
pressure, and low process selectivity; some authors
[1, 2] note the appearance of toxic substances in off-
gases from EO.
Furthermore, the use of chlorine dioxide in the
traditional pulp bleaching technology makes it necessary
to arrange a special shop on for the production of
chlorine dioxide from explosive sodium chlorate on the
Therefore, when developing new bleaching technolo-
gies, it is necessary to pay attention to simpliﬁ cation of the
equipment used and to proper choice of bleaching agents.
An alternative to EO is its replacement by hydrogen
peroxide under the conditions when it exhibits delignifying
properties, namely, in strongly alkaline and acid media.
Using the ﬁ rst deligniﬁ cation alternative, it is possible
to bleach medium-hardness sulﬁ te pulp with hydrogen
peroxide only, using the scheme EP–Pd–AA–P–A ,
where EP is oxidative alkali treatment in the presence of
hydrogen peroxide, Pd is alkaline peroxide deligniﬁ cation,
AA is the pulp treatment with an acetic acid solution, P
is peroxide bleaching, and A is the pulp treatment with a
sulfurous acid solution.
Recently there has been a trend at pulp plants, caused
by economical factors, toward production of very hard
pulp with a high fraction of residual lignin. In bleaching
such sulﬁ te pulp by the ECF process, the deligniﬁ cation
can be performed by the oxygen–alkali extraction, and the
ﬁ nal bleaching, by the classical procedure with chlorine
dioxide: D–E–D. Bleaching by such technology should
ensure 88–90% pulp brightness .
This study deals with bleaching of commercial
spruce bisulﬁ te pulp by an economically advantageous