TAPPSA 2010 Influence of enzymes on refining of eucalyptus pulps Crystal Steel Francois Wolfaardt
Technology Centre Aim Improve the refining of Eucalyptus grandis and E. nitens pulps using cellulases & hemicellulases
Technology Centre Why Eucalyptus grandis and E. nitens? Slide 4 Eucalyptus grandis Traditional wood timer source Expansion 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 & adaptable Good quality fibre Smaller fibres & thinner cell walls High tensile, bulk density, opacity and brightness
Technology Centre Introduction: Refining of wood pulp fibres Refining pulp fibres Fibrillation & fines Fibre swelling De-curling Cutting Reduced fibre length Increased effective length & sheet formation Increased bonding & strength of fibres Improved bonding & reduced pulp freeness
Technology Centre Introduction: Enzymes Hemicellulase Xylanase (X) (HW) Cellulases Endoglucanase (EG) Cellobiohydrolase (CBH) Crystalline cellulose Amorphous cellulose Non-reducing end Reducing end CBH II CBH I EG Hemicellulose X
Technology Centre Refining with enzymes 1µm Hardwood pulp samples treated with endoglucanase on commercial scale with refining. Untreated Treated
Technology Centre Introduction: Refining with enzymes Enzyme refining of pulp fibres Fibrillation & fines ? Fibre swelling ? De-curling ? Cutting ?
Technology Centre Slide 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 & kWh/t E. nitens 21.5, 42.3, 62.6, 82.2 & kWh/t
Technology Centre Slide 10 Method: Sample analysis Pulp Freeness (CSF) Water retention value (WRV) Paper Tensile strength Tear strength Bulk density Porosity 20 cm
Technology Centre Results : E. grandis & E. nitens refining curves E. grandis E. nitens
Technology Centre Results and Discussion 450 ml
Technology Centre Results: Xylanase
Technology Centre Results: Xylanase
Technology Centre Results: Endoglucanase
Technology Centre Results: Endoglucanase
Technology Centre Results: Cellobiohydrolase
Technology Centre Results: Cellobiohydrolase ?
Technology Centre 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
Technology Centre General Conclusion Enzymes do improve pulp properties HOWEVER Enzymes are specific in their activity on different pulps Specific properties need to be targeted possibly at the expense of others
Technology Centre Acknowledgements Sappi Manufacturing UKZN – EM Unit Genencor, Novozymes and AB Enzymes