ISBN : 978-602-17761-0-0
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© 2013 Published by Center for Pulp and Paper through REPTech2012
On-Site Production of New Bleaching Agent ”Peroxymonosulfuric Acid” and Application of It to Pulp Bleaching
Tetsuo Koshitsuka
a
, Hiroshi Kurata
b
, Shinjiro Sawamoto
c
a
Tokyo Research Laboratory, Mitsubishi Gas Chemical Company, Inc. 1-1, Niijuku 6-chome, Katsushika-ku, Tokyo, 125-8601, Japan, koshimgc.co.jp
Tel. : +81-3-3627-9674, Fax : +81-3-3627-9471.
b
Tokyo Research Laboratory, Mitsubishi Gas Chemical Company, Inc. 1-1, Niijuku 6-chome, Katsushika-ku, Tokyo, 125-8601, Japan, hamaguchimgc.co.jp
c
PT Peroksida Indonesia Pratama Graha Purna Bhakti Building, JI. Jend. A. Yani No. 39 PO. Box 53 Cikampek 41373, Indonesia, s_sawamotoptpip.co.id
ABSTRACT
In Japan, full-scale ECF bleaching started at the Niigata Mill of Hokuetsu Paper Company in 1998. After that, other companies also began to change from chlorine bleaching to ECF bleaching. The ECF bleaching methods
is a combination of chlorine dioxide, ozone, oxygen, and hydrogen peroxide. The problem of this ECF bleaching became clear that discoloration of product increased. In particular, we noticed discoloration of paper became
worse when three factors exist at the same time. Three factors are hexenuronic acid, aluminium sulfate, and acidic
papermaking. We researched chemicals that have the ability to remove hexenuronic acid eficiently andknew that peroxymonosulfuric acid can remove hexenuronic acid eficiently. Peroxymonosulfuric acid can be produced by
the reaction between conc. hydrogen peroxide and conc. sulfuric acid. But, continuous production method of peroxymonosulfuric acid was not popular because of the large amount of reaction heat that was produced by the
reaction and severe corrosion. We overcame many dificulties, and established industrial methods and equipment to produce peroxymonosulfuric acid in continuous ways. This method and equipment was irst adopted in the world
at the Tomioka Mill of Oji Paper Company. After that, a bleaching sequence that introduced peroxymonosulfuric acid revealed some performance like 1 resolution method for the discoloration problem, 2 cost performance, 3
high brightness, and 4 increase in production. This method is being used at four mills and one more mill will adopt this same method in the near future.
Keywords: ECF, discoloration, acidic papermaking, hexenuronic acid, peroxymonosulfuric acid, hydrogen peroxide, sulfuric acid
1. Introduction
In 1980s, dioxins were detected in the seawater of Baltic Sea in Northern Europe, which was
determined to have been caused by the chlorine bleaching of the pulp industry. This incident initiated
the change from chlorine bleaching to chlorine-free bleaching.
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Since then, this changes had spread to the North American countries; and, then in 1998,
irst full-scale chlorine free bleaching was started at the Niigate Mill of Hokuetsu Paper Company. After
that, many companies introduced the chlorine free bleaching and, at present, chlorine-free bleaching has
been implemented at almost all mills in Japan. As alternatives of chlorine bleaching, elemental chlorine
free shortened as ECF bleaching that mainly uses chlorine dioxide and totally chlorine free shortened
as TCF bleaching that uses no chlorine compounds at all were introduced. Globally, ECF bleaching is
the mainstream and TCF bleaching is employed only in about 5 - 10 . In ECF bleaching, main bleaching
agents are chlorine dioxide and oxygen bleaching agents like ozone, hydrogen peroxide, oxygen. In
TCF bleaching, peracetic acid is used other than these oxygen bleaching agents.These chlorine free
bleaching processes have problems like too high bleaching cost comparing to conventional chlorine
bleaching processes. As countermeasures to reduce the bleaching cost, methods to reduce use amount
of expensive chlorine dioxide by using hydrogen peroxide are generally employed. These include the
method Eop, Ep where hydrogen peroxide is used at the alkaline extraction stage, the method E
-P where it is used in the next stage of the alkaline extraction
stage, and the method where it is used in the last extraction stage P. As the result of the signiicant
cost down by the reduction of expensive chlorine dioxide usage, the problem of deterioration of pulp
discoloration has become apparent. Especially,
signiicant deterioration of discoloration was observed when the ECF bleached pulp is used for acid paper.
One of the causes of such deterioration has proved to be hexenuronic acid shortened as HexA that is
bonded to xylan in the pulp. As the countermeasures to such a problem, high-temperature acid treatment
shortened as A
treatment and high-temperature chlorine dioxide treatment shortened as D
treatment have been developed. Also, ozone is effective
to remove HexA. However these methods have problems like high energy cost and high equipment
cost. To solve these problems, we studied methods which require low energy and equipment costs.
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© 2013 Published by Center for Pulp and Paper through REPTech2012
As the study results of chemicals that effectively remove HexA, we have discovered that
“peroxymonosulfuric acid” can most effectively remove HexA. Peroxymonosulfuric acid shortened
as MPS is manufactured by the reaction between high-concentration hydrogen peroxide and high-
concentration sulfuric acid. Because this reaction is highly exothermic, it is necessary to control the reaction
temperature to manufacture peroxymonosulfuric acid at high yield. Various manufacturing methods
2, 3
that are suitable to manufacture small amount of it were proposed. However, they are not suitable
to manufacture a large amount that is applicable to pulp bleaching. We overcame these dificulties
and have completed the irst industrial-scale on-site production equipment
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of peroxymonosulfuric acid in the world. We also studied the pulp bleaching using
the peroxymonosulfuric acid and found out that 1 it is effective as a countermeasure to discoloration
and 2 it is possible to reduce the bleaching cost.
Accordingly, we applied this peroxymonosulfuric acid to the Tomioka Mill of Oji Paper Company, attained
the successes in discoloration countermeasure and cost reduction, and have put the irst bleaching process
using peroxymonosulfuric acid into practical use in the world
5, 6
. This process is being operated at four mills and is planned to be started operation further in
two mills near future. In this paper, we are introducing the on-site
production of peroxymonosulfuric acid and its application to pulp bleaching.
2. Discoloration Problems of ECF Pulp
