Study On The Biological High Yield Pulp Of Mulberry Branch With Stronger Penetrative Thermostable And Alkaline Tolerant Xylanase Complex Pretreatment

Mulberry is an important lignocellulosic biomass. It has loose structure and can bedivided into bark and branch easily. Mulberry can relieve the pressure of short of wood inChina if we can use it sufficiently.The effects of xylanase pretreatment with different enzymedosage under different pH and temperature on the changes of chemical composition, pulp yieldand fiber morphology were investigated in this study. The effect of pretreatment was evaluatedquantitatively. Through comparing Mulberry branch of bio-mechanical pulp, bio-alkalineperoxide mechanical pulp, alkaline peroxide mechanical pulp and the alkaline peroxidemechanical pulp of Poplar, the advantages of mechanical pulp of Mulberry branch wereexplored, which laid the theoretical basis for the biorefinery of the mulberry branch. The mainresults are as follows:Mulberry branch have a certain potential in the preparation of chemical pulp. When thecooking tempereture from140℃to170℃after keeping for0.5h, the speed of delignificationis quickly. The suitable condition to Soda-AQ cooking process for mulberry were alkali (Na₂Ometer)19%, AQ amount0.05%, liquid ratio1:6, idling time0.5h, heating time2h and holdingtime0.5h. AQ has played a protective role of carbohydrates in the cooking process.The results indicated the self-made xylanase was a thermostable and alkaline tolerantcomplex enzymes with a small part of pectinase and cellulase, and could be applied in a widerange of pH and temperature, which can play a role effect in40-60℃and pH7.0-9.0.The cells swelled up and more coarse fiber surfaces were observed after enzymepretreatment, the fiber porosity and specific surface area increased as well, which couldimprove the chemicals penetration and reactivity in physical, chemical and biological masstransferring process, and was beneficial for improvement of bio-refinery efficiency.Integrated the conditions of enzyme dosage, temperature and pH on the pretreatment ofmulberry branch. The optimized enzyme pretreatment conditions were2.0IU/g of enzymedosage,50℃of reaction temperature and pH8.0, respectively.Considering the tend of crude pulp yield, fine pulp yield and whiteness, the suitablecondition to APMP process for mulberry branch were as follows: H₂O₂2.0%, NaOH3.0%,impregnation time60min in the first paragraph, and H₂O₂4.5%, NaOH3.0%, impregnationtime75min in the second paragraph.Comparative analysis of APMP of Mulberry and Poplar indicated that APMP of Mulberryhave better pulp performance, lower energy consumption, higher bulk and higher physicalstrength. The energy consumption was reduced by31.6%and the bulk was increased by 3%(compared with APMP of poplar).The results showed the potential advantages ofmechanical pulp by using mulberry.Compared Bio-MP, Bio-APMP and APMP of Mulberry, we can see that Xylanasepretreatment can save a certain amount of chemical drug consumption. It also has the potentialof reducing the energy consumption during the process of polishing. The brightness and bulkof biological mechanical pulp(Bio-MP and Bio-APMP) are higher than APMP. The brightneesand the bulk of Bio-MP were both increased by10%(compared with APMP). The energyconsumption of Bio-APMP was reduce by17%(compared with Bio-MP).The results reflect thepotential of biological mechanical pulp in mechanical pulp.