TAPPSA 2010 Influence of enzymes on refining of eucalyptus pulps Crystal Steel Francois Wolfaardt.

TAPPSA 2010

Influence of enzymes on refining of eucalyptus pulps

Crystal SteelFrancois Wolfaardt

Technology Centre

Aim

Improve the refining of Eucalyptus grandis and E. nitens

pulps using cellulases & hemicellulases

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Why Eucalyptus grandis and E. nitens?

Slide 4Slide 4

Eucalyptus grandisTraditional wood timer sourceExpansion of pulp & paper industry increased need for more land, which were at higher altitudes

E. nitens was grown due to cold tolerance

Eucalyptus nitens Grows fast & adaptableGood quality fibreSmaller fibres & thinner cell wallsHigh tensile, bulk density, opacity and brightness

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Introduction: Refining of wood pulp fibres

Refining pulp fibres

Fibrillation & fines

Fibre swelling De-curling

Cutting

Reduced fibre lengthIncreased effective length & sheet formation

Increased bonding & strength of fibres

Improved bonding & reduced pulp freeness

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Introduction: Enzymes

Hemicellulase Xylanase (X) (HW)

CellulasesEndoglucanase (EG)

Cellobiohydrolase (CBH)

Crystallinecellulose

Amorphouscellulose

No

n-red

ucin

g en

d

Red

uci

ng

en

d

CBHII CBHI

EG

Hemicellulose

X

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Refining with enzymes

1µm1µm

Hardwood pulp samples treated with endoglucanase on commercial scale with refining.

Untreated Treated

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Introduction: Refining with enzymes

Enzyme refining of pulp fibres

Fibrillation & fines ?

Fibre swelling ? De-curling ?

Cutting ?

Technology CentreSlide 9

Method: Pilot scale refining

3% pulp consistency Enzymes: 0.02g protein/ kg pulp

Endoglucanase, Cellobiohydrolase & Xylanase

Sample before incubation, at 20 min & at each refining energy:

E. grandis 24.9, 49.2, 73.1, 96.5 & 119.4 kWh/t

E. nitens 21.5, 42.3, 62.6, 82.2 & 101.3 kWh/t

Technology CentreSlide 10

Method: Sample analysis

PulpFreeness (CSF)Water retention value (WRV)

PaperTensile strengthTear strengthBulk densityPorosity

20 cm

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Results : E. grandis & E. nitens refining curves

0

100

200

300

400

500

600

0 20 40 60 80 100 120

Energy (kWh/t)

Fre

enes

s (m

l CS

F)

Control CBH Xylanase EG

0 20 40 60 80 100

Energy (kWh/t)

E. grandis E. nitens

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Results and Discussion

-100

-50

0

50

100

150

Energy CSF WRV Tear Tensile Bulk Porosity

Re

lative

ch

an

ge

(%

)

Control @ 450 ml

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Results: Xylanase

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Results: Xylanase

-100

-50

0

50

100

150

Energy CSF WRV Tear Tensile Bulk Porosity

Re

lative

ch

an

ge

(%

)

E. grandis E. nitens

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Results: Endoglucanase

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Results: Endoglucanase

-100

-50

0

50

100

150

Energy CSF WRV Tear Tensile Bulk Porosity

Re

lative

ch

an

ge

(%

)

E. grandis E. nitens

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Results: Cellobiohydrolase

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Results: Cellobiohydrolase

-100

-50

0

50

100

150

Energy CSF WRV Tear Tensile Bulk Porosity

Re

lative

ch

an

ge

(%

)

E. grandis E. nitens

?

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Conclusions

Enzymes affected properties in a similar way on the two HW species

Most noted change with enzymes were:

Xylanase on E. nitens with a 75% reduction in porosity

EG on E. grandis with a 50% improvement in tensile

CBH on E. grandis with 12% increase in tear and 20% increase in tensile

The enzymes have better improvements on E. grandis than E. nitens

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General Conclusion

Enzymes do improve pulp propertiesHOWEVER

Enzymes are specific in their activity on different pulps Specific properties need to be targeted possibly at the

expense of others

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Acknowledgements

Sappi Manufacturing UKZN – EM Unit Genencor, Novozymes and AB Enzymes