Hydrogen Peroxide Bleaching
Highlights
State of the Art and
Research Direction
Art J. Ragauskas
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Hydrogen Peroxide Bleaching: Background, Mill Applications, and Research Directions, Exercises of Art
An in-depth analysis of hydrogen peroxide bleaching, including its background, mill applications, and research directions. the chemistry of peroxide bleaching, its role in mill applications, and the latest research findings in this field. It also discusses the role of metals and temperature in peroxide bleaching and future research directions.
Typology: Exercises
2021/2022
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Hydrogen Peroxide Bleaching
Highlights
State of the Art andResearch Direction
Art J. Ragauskas
Hydrogen Peroxide Bleaching • Background• Mill Applications• Research Directions
Peroxide Bleaching: BackgroundH
O 22
+^ M^
→^
HO
.^ + HO -^ + M
HO^2
- HO 2
-^
→^
HO
-^ + H 2
O 2
HO
-^ + M 2
+^
→^
HO
.^ + 2 M
HO
.^ + HO 2
-^
→^
-.O 2
- H
O 2
-.O 2 +^
M+
→^
O^2
- M
-.O 2
- HO
.^
→^
O^2
- HO
2O^2
.-^ + H
O^2
→^
O^2
- HO
-^ + HO 2
HO
.^ + HO
-^2
→^
HO + O^2
HO
.^ + M
→^
HO
-^ + M
HO
.^ + HO
.^
→^
HO^2
Peroxidechemistrystronglyinfluenced bymetals
Peroxide Bleaching: Background
O OCH^3 R -O^
HOO
- O OCH^3 R O -O^ HO
- O OCH^3 R O O
OCH^3 ROC O -O^
OCH^3 R O OH -O^
-^ O -^ HO
O^2
OCH^3 O O
O^ or^ OH^2 - O^2 OHC - (^) O OCH^3
OHC (^) O OCH^3
OHC (^) O OCH^3
OHC O
- O O (^) OCH^3
O
OCH^3 OC (^) O
- -HO
- O 2
z^ Dakin reaction^ z^
Dakin-like reaction
Lignin fragmentation reactions
Peroxide Bleaching: Background
O
XylanO
O
HO
O
HO
COH^2 OH
H^
H^2
O 2
/NaOH (^) Formed during pulping• 30 -50% of Southern HW Kappa #•10 - 20% of Southern SW Kappa #
NR
Peroxide:
Mill Applications
Eop
- Peroxide 0.1 - 0.5%– Temp.: 55 - 85
o^ C
- Time: 50 - 134 min– O
: 0.5 - 0.7% 2
consumed
- first extraction stage– P is largely brighteningchemistry -^ Ep
- Peroxide: 0.1 - 0.2%– Temp. 65- 85
o^ C
- Time: 45 - 120 min.– second extraction stage– Brightening chemistry -^ P -^ Peroxide: 0.5 - 1.5% –^ Temp. 65- 85
o^ C
-^ Time: 45 - 120 min.
Peroxide:
Mill Applications
- North America
- Primarily ECF
- D(Eop)DED• D(Eop)DEpD,• OD(Eop)D or OD(Eop)DEpD• D(Ep)DED• HD storage (0.1 - 0.2% P, pH approx. 9)
- Primarily ECF
P-Stage
Mill Applications
- Europe
- Greater bleaching sequence diversity in ECF & TCF
- OD(Eop)DED• O/OD(Eop)DP• OQ(Op)PaaQ(PO)• ODQ(PO)• OAZQ(Eop)(PO)• OQPZP
- Greater bleaching sequence diversity in ECF & TCF
Peroxide Bleaching: Role of Temperature 2.5% P Q HW Kraft Pulp •^ P* significantlyimproves peroxide •^ P* not just increasein rates •^ Capital intensive •^ Sensitive to M
-^ Q stage –^ yield
45403530252015105 0
30
70
110
130/C
% Delignification
P-Stage
Future Research Directions
- Peroxide Efficiency
•Improved Conditions•Catalysis•Modification of fibers
Peroxide Brightening Effects
8988 878685 848382 8180 0.
1
2
Peroxide Charge (%)
Tappi Brightness
DEDPDEPD
-^ D-stage generates active lignin structures for P-stage
Peroxide Activation - Catalyst
Peroxide Bleaching:
Research P-activators
O^ O O
AcN
N Ac
Ac^
N^
N^ Ac
Ac
Ac
OAcO
OAc
AcOAcO
OAc
OAc
OAc
OH
OAc OAc
OH
Pentacetyl Glucose
Diacetin
Diethyl Pyrocarbonate
DAED
TAED
- H-O-O -
RH^
-O-O-Ac+
RAc
All improve a P-stage by 15 - 40% >>stoichiometrically
Peroxide Bleaching:
Research P-catalyst
N
N V^
- O (^2) - O 2
- O 2
N FeN^
N N
O O
O O
HHO^
X X
Mn^
O^
Mn O N N^
N N
N^
N
O^
O