Endo-Beta 1,4 Xylanase
Enzyme Applications in Pulp and Paper: An Introduction to Applications
Dr. Richard VendittiAssociate Professor - Director of Graduate ProgramsDepartment of Wood and Paper Science Biltmore Hall Room 1204Raleigh NC 27695-8005Tel. (919) 515-6185 Fax. (919) 515-6302Email: [email protected]
Slides courtesy of Phil Hoekstra.
Endo-Beta 1,4 Xylanase
Enzymes
• Are proteins that catalyze chemical reactions
• Biological cells need enzymes to perform needed functions
• The starting molecules that enzymes process are called substrates and these are converted to products
Endo-Beta 1,4 Xylanase
Cellulase enzyme which acts on cellulose substrate to make product of glucose.
Endo-Beta 1,4 Xylanase
Enzymes
• Are extremely selective for specific substrates
• Activity affected by inhibitors, pH, temperature, concentration of substrate
• Commercial enzyme products are typically mixtures of different enzymes, the enzymes often complement the activity of one another
Endo-Beta 1,4 Xylanase
Types of Enzymes in Pulp and Paper and Respective Substrates
• Amylase --- starch• Cellulase --- cellulose fibers• Protease --- proteins• Hemicellulases(Xylanase) ---hemicellulose• Lipase --- glycerol backbone, pitch• Esterase --- esters, stickies• Pectinase --- pectins
Endo-Beta 1,4 Xylanase
Enzyme Applicationsin Pulp and Paper
• Treat starches for paper applications• Enhanced bleaching• Treatment for pitch• Enhanced deinking • Treatment for stickies in paper recycling• Removal of fines• Reduce refining energy• Cleans white water systems• Improve softness in tissue• Clean outs
Endo-Beta 1,4 Xylanase
Starch Conversion for Surface Coatings
• Amylases are used to cleave starch molecules to reduce the viscosity
• Used for surface sizing and for starch in coatings
• Not used for dry strength agent additive
Endo-Beta 1,4 Xylanase
Bleaching
• Hemicellulases (xylanases) are used to cleave hemicelluloses in fiber, making the bleaching process more effective
• May be able to reduce bleaching chemicals by up to 30%
• Can improve brightness
Endo-Beta 1,4 Xylanase
Pitch treatment
• Lipases used to control pitch in pulping processes
• Converts tri-glycerides to fatty acids which are more stable in water, won’t deposit as much
Endo-Beta 1,4 Xylanase
CH2 –--------- CH –---------CH2 Triglycerides
Ester-Bonds
│OH OH
│C=O│(CH2)15 CH3
glycerolFatty acids
OH OH
O OO
C=O
(CH2)15 CH3
C=OC=O
(CH2)15 CH3 (CH2)15 CH3
CH2 –--------- CH –---------CH2
Endo-Beta 1,4 Xylanase
Deinking
• Paper recycling inks and stickies attach to fibers at the surface of the fibers, stuck to microfibrils
• Cellulase and hemicellulase enzymes hydrolyze these microfibrils, releasing the adhesives
• Esterases help breakdown ink particles • Enzyme assisted DI reported to remove 30-60%
more toners• Enzyme assisted DI reported to improve
brightness by 4-5 points
Endo-Beta 1,4 Xylanase
Control and Removal Methods for Stickies
– Use of environmentally benign adhesive (recyclable adhesive)
– Avoidance: Control of recovered paper quality– Mechanical removal: screening and water clarification– Chemical control: polymers surfactants, others– Passivation with inorganics– Enzyme hydrolysis– Physical adsorption to paper fibers: retention– Dispersion– Protection: treatment of equipment to limit deposits– Mill shut down for clean-up
Endo-Beta 1,4 Xylanase
CLASSIFICATION OF STICKIES
PRIMARY SECONDARY(Formed in
pulper)(Change in environment, pH, temp., etc.)
Endo-Beta 1,4 Xylanase
MACRO VS MICRO STICKIES
Macrostickies
Microstickies
Retained on 6-cut (0.15 mm) slotted screen*
Accepted by 6-cut (0.15 mm) slotted screen*
* Trend is towards 0.10 mm or 0.075 mm slotted screen
Endo-Beta 1,4 Xylanase
Stickies Control
• Microstickies in dilution water recirculateback into the systems
• Microstickies agglomerate under shear and pH changes and contribute to macrostickies, secondary stickies
• Reducing microstickies will make a significant impact on macrostickies
• Ability to measure both micro and macro is important
Endo-Beta 1,4 Xylanase
Endo-Beta 1,4 Xylanase
Without Proper Water Clarification (<20% reduction):“ re-introduction of stickies”
Endo-Beta 1,4 Xylanase
Enzymes as stickies treatment
• Esterases used to break ester bonds in polymers used in toners and adhesives
• Improved paper cleanliness• Less deposits, less clean up on PM• Can be used as substitute for talc or
solvent based dispersants
Endo-Beta 1,4 Xylanase
- (CH2 – CH - CH2 – CH - CH2 – CH )n -
PVAcEster-Bonds
- (CH2 – CH )- CH2 – CH - CH2 – CH )n -│OH OH
│C=O│CH3
PVAlcoholAcetic acid
OH OH
O OO
C=O
CH3
C=OC=O
CH3 CH3
Endo-Beta 1,4 Xylanase
polyvinyl acetate -(-CH2CH-)n-
OCOCH3
HydrophobicSurface
without Esterase
Agglomerates of PVAc
Polyvinyl alcohol
OH
OHHO
OHOH
OH
OHHO
OHOH
OH
OHHO
OHOH
OH
OHHO
OHOH
OH
OHHO
OHOH
OH
OHHO
OHOH
OH
OHHO
OHOH
OH
OHHO
OHOH
OH
OHHO
OHOH
with Esterase
OH
Hydrophilic
OH
OHOH
OH
OH
OH
OHOH
OHOH
OH
OH
polyvinyl alcohol + acetic acid-(-CH2CH-)n-
OH + CH3COOH
Endo-Beta 1,4 Xylanase
Impact on stickies chemistry
• Optimyze has two impacts on stickies– Cleaves ester bonds to reduce size of stickies– Surfaces on smaller stickies are converted to
alcohol groups• Alcohol groups are less tacky• Alcohol groups are polar, which allow DAF
polymers to grab onto them for removal
Endo-Beta 1,4 Xylanase
Electron micrographsUntreated Treated
Endo-Beta 1,4 Xylanase
Optimyze Plus 735 trial data
stickies transfer on reel samplesduring Optimyze Plus 735 evaluation
0
20
40
60
80
100
120
140
160
2/12 3/4 3/24 4/13 5/3 5/23
stic
kies
0
0.2
0.4
0.6
0.8
1
1.2
BLX
130
64 d
osag
e (lb
/t)
count
PPM
BLX dosage
Endo-Beta 1,4 Xylanase
Caustic replacement: neutral deinking for newsprint deinking
• Caustic is used in pulping recycled fibers to swell fibers, improving paper making potential
• Cellulase enzymes can be used in conjunction with or as a substitute for the caustic to swell fibers
• Neutral deinking has some advantages including less COD in the white water, lower costs
Endo-Beta 1,4 Xylanase
Decrease energy in refining
• Cellulase enzymes cause partial depolymerization of cellulose and swelling of fibers, more flexible fibers
• Reduction of fines• Improves efficiency of refining, can
decrease energy consumption or obtain improved strength at higher freeness
• Often better runnability or less dryer energy required
Endo-Beta 1,4 Xylanase3/3/2010
Fibrillation
Endo-Beta 1,4 Xylanase
Fiber Modification
• Enzymes can assist this de-lamination process
• Conditions fiber for refining• Reduces refining energy• Changes the refining curve• Old rules do not apply• Laboratory Testing
Endo-Beta 1,4 Xylanase
Case History
• MILL: Quebec• FIBER: Recycled/Softwood Kraft• GRADE: Napkin• GOAL: Increase tensile strength to
middle of specification, reduce kraft fiber usage
• METHODS: Treated MOW stock at the pulperwith 0.5 to 1.0 kg/tonne BZM 2545, about 3 hours of contact time
Endo-Beta 1,4 Xylanase
Machine Trial of Buzyme 2545in Napkin grade
0
5
10
15
20
25
30
35
40
45
Pre-trial Trial
Kraf
t Usa
ge (%
)
245
250
255
260
265
270
275
Tens
ile S
tren
gth
SWK UsageTensile
Endo-Beta 1,4 Xylanase
Machine Trial of Buzyme 2545in Napkin grade
0
5
10
15
20
25
Pre-trial Trial
Kraf
t Usa
ge (%
)
0
50
100
150
200
250
300
Tens
ile S
tren
gth
SWK UsageTensile
Refining energy reduced
Endo-Beta 1,4 Xylanase
Results: Machine Trial of Buzyme 2545in Napkin grade
• Reduced kraft from 40% to 0% of furnish• Increased tensile to a “comfortable” range• Refining energy reduced 14% • Drainage is better, but cannot take
advantage of it, due to drive limitations
Endo-Beta 1,4 Xylanase
Hydrolysis of fines
• Fines build up in water loop in PM and cause drainage, formation and paper properties problems
• Cellulase enzymes hydrolyze these fines, making them soluble, improving PM ops
• Can run PM faster (up to 10% faster in some cases?)
Endo-Beta 1,4 Xylanase
Softness in tissue
• Cellulase enzymes improve softness by hydrolyzing cellulose in fibers, creating weak spots in fibers, making fibers flexible
• Softness increases of up to 25%• P&G has several patents, some donated
to NCSU
Endo-Beta 1,4 Xylanase
Case History
• MILL: Quebec• FIBER: 95% SWD/5% Recycled Fiber• GRADE: Premium Bath• GOAL: Reduce refining energy, increase
softness and bulk, maintain tensile
• METHODS: Treated stock at the pulper with0.5 to 1.0 kg/tonne BZM 2545, about 3 hours of contact time
Endo-Beta 1,4 Xylanase
Bulk vs. TensileBuzyme 2535 vs. Glyoxylated Polyacrylamide
7
8
9
10
11
12 14 16 18 20 22GMT/BW
B/B
W
Buzyme 2535 Gloxylated PAM
Linear (Buzyme 2535) Linear (Gloxylated PAM)
Average Bulk to Tensile Increase of 3.5%
Endo-Beta 1,4 Xylanase
Results
• Shut down refiners• Maintained tensile• Bulk/basis weight increased by avg. of 3.5%• Able to reduce BWT due to increase in tensile• Machine speed increase of 100 FPM, due to
better drainage
Endo-Beta 1,4 Xylanase
ROI for Fiber Modification• Reduction in refiner energy• Less fines generation
– Better drainage– Softer feel– Less dusting– Cleaner white water
• Reduction in starch or CMC• Fiber substitution
– Could use more MOW, less virgin
Endo-Beta 1,4 Xylanase
Improved biodegradability of pulp mill waste water
• Cellulases and Hemicellulases used to degrade cellulose and other high molecular weight polymers
• COD/BOD ratio of domestic sewage 2:1• COD/BOD ratio of paper mill waste water
up to 5:1• Hydrolysis of cellulose fines by enzymes
to lower molecular weight sugars that are more biodegradable
Endo-Beta 1,4 Xylanase
Clean Ups / Boil Outs
• Amylase to treat starch deposits in clean ups of starch preparation/application equipment
• Protease used as biodispersants or enzyme boil-outs, cleave protein molecules in deposits and solubilize deposits
Endo-Beta 1,4 Xylanase
Summary• Enzymes are green chemicals that can
improve operations in pulp and paper• Wide variety of enzymes, must be
applied with understanding of how they work
• Several widely accepted applications, starch, bleaching, clean ups
• Future: high valued functionalized fibers, improved pulping, specialized paper properties, conversion of wastes to fermentable sugars.
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