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© 2013 Published by Center for Pulp and Paper through REPTech2012
On the other hand, Oxone showed effective HexA removal ability on a par with ozone. However, Oxone
is expensive and contains low percentage of oxygen in the molecule. Therefore, it is dificult to make it into
practical use as it is. Accordingly, we have decided to use peroxymonosulfuric acid synthesized from
sulfuric acid and hydrogen peroxide.
Fig. 3 Relationship between Peroxymonosulfuric Acid Addition Rate and Hexenuronic Removal
Quantity Figure 3 shows the relations between
peroxymonosulfuric acid addition rate and HexA removal quantity. The peroxymonosulfuric acid addition
rate and HexA removal quantity showed an almost linear relationship; where 0.5 of peroxymonosulfuric
acid could have removed about 10 μmolg-pulp of HexA and 1.0 could have removed about 16 μmolg-pulp
respectively. Also, although peroxymonosulfuric acid can be effective not only in HexA removal but also in
lignin removal, it was more effective in HexA removal.
4. On-site Production of Peroxymonosulfuric Acid
4.1 Properties
Peroxymonosulfuric acid H
2
SO
5
, alias Caro’s acid is transparent syrupy liquid with strongly
acidic and oxidative properties. Fig. 4 shows its structural formula and Table 3 shows its properties.
Peroxymonosulfuric acid can be synthesized from high-concentration hydrogen peroxide and high-
concentration sulfuric acid by the following reaction;
however, because it is an equilibrium reaction, it exists in the aqueous solution, co-existing with hydrogen
peroxide and sulfuric acid.
H
2
O
2
+ H
2
SO
4
← →
H
2
SO
5
+ H
2
O
In the case of reacting 45 hydrogen peroxide with 98 sulfuric acid, the heat of reaction is about 78 KJ
mol. Because high-concentration peroxymonosulfuric acid is unstable and dangerous, it is desirable to
immediately dilute it just after the synthesis before use.
Fig.4 Chemical Structural Formula of Peroxymonosulfuric Acid
Table 2 Comparison with HexA Removal Ability
Effect Reactive
Species Chemicals
Conditions Dosage
Initial HexA µmolg
Decrease of HexA
µmolg Eficiency
ΔHexAe wt
mol
H
2
SO
4
90
O
C, 90 min, pH3 1.17
0.01194 37.43
9.4 O
Radical ClO
2
irst stage 60
O
C, 60 min, pH3.5 0.5
0.007407 34.43
15.4 416.4
O Anion
NaClO 70
O
C, 90 min, pH9.327.56
0.2 0.005634
24.0 after Eo 5.6
497.0 Δ
Cation H
2
O
2
acid 70
O
C, 90 min, pH1.7 0.2
0.00588 24.0 after Eo
1.5 127.6
O Cation
H
2
O
2
+Mo50ppm 70
O
C, 180 min, pH3 0.2
0.00588 35.98
7.3 619.0
O Radical
H
2
O
2
+Fe30ppm 70
O
C, 180 min, pH3 0.2
0.00588 35.98
7.9 670.1
O Cation
Peracetic acid 70
O
C, 90 min, pH4.94.5 0.5
0.00658 24.0 after Eo
10.1 767.5
X Anion
Sodium persulfate 70
O
C, 90 min, pH12.2 0.5
0.002101 24.0 after Eo
0.1 23.8
Δ Radical
Persulfuric acid 70
O
C, 180 min, pH3 1
0.0042 34.8
2.0 238.1
Δ Cation
Nitrous acid 70
O
C, 180 min, pH3 1
0.01449 35.98
7.0 240.9
Cation
Ozone pH3, normal temp, 3 min
0.5 0.01042
35.98 26.8
1287.4
Cation Oxison 2KHSO
5
. KHSO
4
.K
2
SO
4
70
O
C, 90 min, pH3 0.5
0.0016268 24.0 after Eo
5.8 1782.6
Cation
H
2
SO
5
70
O
C, 90 min, pH3 0.5
0.004386 35.98
10.0 1140.0
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Table 3 Property of Peroxymonosulfuric
Chemical Name Peroxymonosulfuric Acid
Form Liquid of Clear and Colorless
mixture of H
2
O
2
, H
2
SO
4
,H
2
O Formula
H
2
SO
5
Molecular Weight 114.09
Active Oxygen 14.00
pH 1 2 Solution, 25
o
C, Synthesis with 45 H
2
O
2
= 95 H
2
SO
4
= 1 :3 mol
Density 1.04 gcm
3
2 Solution ORP
-1.44 V
4.2 The Effects of The “Sulfuric Acid and Hydrogen Peroxide Ratio” and The “Concentration of
