Study On Specificity Of Pulping And Bleaching Of AS-AQ Of Eucalyptuspellita From Families 123 And 200

E.ucalyptus is an important kind of raw material in papermaking industry,with an excellent performance of pulp and paper.This research discusses the the pulpability and bleaching ability of Eucalyptuspellita as a new resource in papermaking industry and also studies the biobleaching mechanism.Conclusions were as follows:(1) Through the comparison of the chemical components and fiber morphology of Eucalyptuspellita from 28 families,it can be found that families 123 and 200 are more suitable for pulping and papermaking.The specificity of family 123 is as follows:The content of ash contain is 0.14%;The content of alcohol benzene extractive is 1.33%;The content of lignin is 25.41%;The content of holcellulose is 76.31%;The content of polymeric pentoses is 15.94%;The length of fiber is 0.89mm;The width of fiber is 24.18μm and L/W is 36.97;The density is 0.65g/cm³.The specificity of family 200 is as follows:The content of ash contain is 0.16%;The content of alcohol benzene extractive is 1.78%;The content of lignin is 25.47%;The content of holcellulose is 76.40%;The content of polymeric pentoses is 13.90%;The length of fiber is 0.93mm;The width of fiber is 23.52μm and L/W is 39.63;The density is 0.59g/cm³.The best AS-AQ cooking condition is:Dosage of alkali(based on Na₂O) is 23～25%;Sulfitation(based on Na₂O) is 0.45～0.50;Dosage of NP-10 is 0.2%～0.5%;Dosage of AQ is 0.06%～0.08%;Heat preservation time is 140～160min;Maximum temperature is 170℃;Liquor to wood ratio is 4.5:1.(2) In General ECF bleaching,the result of D-Ep-D bleaching is the best.As the dosage of Cl is 2.4%,the result of family 123 pulp is:The brightness is 84.0%ISO;Viscosity is 868ml/g;Kappa Number is 8.34.The result of family 200 is:The brightness is 84.6%ISO;Viscosity is 938ml/g;Kappa Number is 8.15.Raising the temperature of the first ClO₂,the result of family 123 pulp is:The brightness is 85.0%ISO;Viscosity is 855ml/g;Kappa Number is 8.10.The result of family 200 is:The brightness is 86.2%ISO;Viscosity is 892ml/g;Kappa Number is 7.98.As the dosage of Cl is 1.2%,the brightness of family 123 is 85.9%ISO in O-D-Ep-D bleaching.As the dosage of Cl is 0.8%,the brightness of family 200 is 78.0%ISO in D-E-D bleaching.when the dosage of Cl is 2.4%,the brightness of family 200 is 84.1%ISO.(3) In the short O-P bleaching process of Eucalyptuspellita AS-AQ pulp,the brightness can be 80%ISO when using the KMnO₄ treatment before H₂O₂ bleaching.In H₂O₂ bleaching,sodium citrate can be used as a H₂O₂ bleaching stabilizer substituting for Na₂SiO₃.The result of adding 2%sodium citrate can be equal to adding 3%Na₂SiO₃.(4) The optimal condition of biobleaching treatment is:The dosage of xylanse is 25U/g;Treating temperature is 55℃;pH is 7.5;Treating time is 120min;Pulp consistency is 10%.As the AS-AQ pulp of Eucalyptuspellita is treated with the biobleaching,the brightness raised by 3%ISO;Viscosity raised by 31ml/g;Kappa Number reduced by 0.8.(5) According to the comparison of the change of chemical componens and the results of X-ray,SEM and IR,it is found that enzymes can degrade pentosan and dissolve out some lignin.The fiber will be porous and permeable.The enzymes improve the permeability of the pulp and the bleaching result.(6) In O-X-D-Ep-D bleaching process,the brightness of AS-AQ pulp can be increased up to 88%ISO as the dosage of Cl is 1.2%.At the same time,the viscosity is still at a high level.In O-X-A-D-Ep-D bleaching process,the brightness of AS-AQ pulp can be increased up to 88%ISO as the dosage of Cl is 1.0%.In O-X-Mn-P bleaching process the brightness of AS-AQ pulp can be increased up to 82%ISO.