| With the energy crisis and the growing problems of environmental pollution, to eliminate pollution from fountainhead, to use resources efficiently, to improve the competitiveness of the industry and to realize the sustainable development of industries is the mere way to build green economy. Pulp and paper industry-has the characteristic of huge consumption of plant resources, so how to achieve the comprehensive utilization of plant resources has attracted much attention.In the precondition of keeping the property and pulp yield of traditional kraft process with simao pine, the paper took the "biomass refinery" concept as a starting point and studied the influence to the property and pulp performance in pulp industry when hemicellulose was separated. Besides, the system of Hemicellulose Extraction Prior to Pulping also had been established.The hemicellulose which is from preextraction was reused as the additive for the pre-treatment of beating. The paper studied the property respectively when the hemicellulose was added to simao pine conventional kraft pulp, simao pine bleaching kraft pulp, bagasse caustic soda anthraquinone pulp and eucalyptus bleaching pulp. Moreover, the paper also improved fiber quality and beating energy'consumption through the analyse of pulp performance.The result of the study of hemicellulose pre-extraction in traditional simao pine kraft process indicates that alkali charge and temperature in pre-extraction are the two major factors in affecting the hemicellulose dissolution and second pulping. If alkali charge or temperature is raised reasonably, pulp yield will increase, the Kappa number of the pulp of the second pulping will be reduced and the physical property of pulp will be improved. In the system of hemicellulose pre-extraction of the kraft pulping, At the base of total alkali charge 25%(pre-extraction+Sec.pulp), when the pre-extraction NaOH charge is 8%, the hemicellulose yield is more than 10%.At the same time, the pulp yield is 46.52%, pulp Kappa number is 26.03, and pulp viscosity is 1041mL/g.In the beating degree of 45°SR, physical properties of paper are as follows:tensile index 86.35N-m/g, tear index 8.84mN·m2/g, burst index 5.39kPa·m2/g, folding times 2891.Among them, the fine pulp yield and pulp viscosity index are also higher than that of conventional kraft pulp strength. However, the pre-extraction has a heavy impact on the tear strength.The study of the function of hemicellulose-added beating system in simao pine kraft process shows that if hemicellulose is used as addictive in wood pulp beating system, amount of water-containing and strength property will be raised effectively. The add of hemicellulose does great help to raise the ratio of fine fiber and to protect fiber length. When the function time of hemicellulose is extended and hemicellulose content is raised, pulp strength also will be improved effectively.But in the grass pulp system such as bagasse, the add of hemicellulose does little help to reduce the energy comsumption of beating.The results of alkaline hemicellulose pre-extraction mechanism show that, n the conditions of pre-extraction alkali charge 8%, liquid ratio 1:4, extraction temperature 130℃and the pre-extraction time 150min, molecular weight of hemicellulose ranges from 3493 to 3505.The structure of hemicellulose is studied by means of IC, FT-IR, GPC,1H-NMR and 13C-NMR.The results show that: different pre-extraction hemicellulose contains rhamnose, arabinose, galactose, glucose, xylose, mannose, glucuronic acid, galacturonic acid component, of which xylose account is higher, mannose content is lower.Because the mannose is difficult to dissolve out, so its content is lower. Besides, pre-extraction hemicellulose contains large amounts sugar hydroxyl peak, and major inβhexose. |
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