Dissertation > Industrial Technology > Light industry,handicrafts > Paper Industry > Pulping process

Study on Enzyme Treatment before and after Oxygen Delignification of Acacia Kraft Pulp

Author WangYuXiu
Tutor TongGuoLin
School Nanjing Forestry University
Course Pulp and Paper Engineering
Keywords Oxygen delignification Laccase / xylanase system Xylanase Pre-processing and post-processing
Type Master's thesis
Year 2010
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This issue through biological enzyme treatment with oxygen delignification combined application of different combinations of different kinds of biological enzymes to explore the delignification rate of oxygen delignification and carbohydrate degradation enzyme treatment, the results of their research on improve the effects of oxygen delignification and enzyme industrial application significance. Paper laccase / xylanase (LXS) system with conventional xylanase X Acacia KP pulp pretreatment, and after the oxygen delignification treatment optimum conditions are preferably; LXS and X Acacia wood KP pulp pretreatment comparison of enzyme treatment on the the homemade of kraft cooking high kappa the Acacia wood pulp, and EMCC depth delignification to low kappa pulp oxygen delignification impact on oxygen off the influence of the process conditions of the lignin; pretreatment methods and post-processing on the effect of the oxygen delignification and four enzyme system - LXS X Laccase / Mediator System (LMS) and thermostable xylanase XHT oxygen off effect of lignin hexenuronic acid; by analyzing the oxygen delignification and the influence of the enzyme treatment, the microstructure of the fiber is observed by SEM, and the HPLC analysis of the degradation of components of the enzymatic hydrolyzate analysis of the influence of the enzyme treatment on the oxygen delignification role mechanism. The results show that: 1, LXS pretreatment the low kappa Acacia EMCC kraft pulp suitable amount of enzyme for 7IU · g -1 ; LXS pretreatment slurry oxygen delignification suitable reaction time, the highest reaction temperature and the amount of base used for 60min, 100 ° C and 2.5%; use LXS suitable reaction time and amount of enzyme after the oxygen delignification treatment were 2h and 5IU · g -1 . X pretreatment low kappa Acacia EMCC kraft pulp suitable for the role of time and the amount of enzyme were of 1.5h and 4IU · g -1 ; X-pretreated slurry oxygen delignification appropriate amount of alkali 2.5%; the oxygen delignification X processing suitable for the role of time and the amount of enzyme were of 1h and 4IU · g -1 . 3 low kappa Acacia EMCC kraft pulp oxygen delignification the LXS and X processing effect are superior pretreatment; x compared with LXS X treatment improving oxygen delignification rate and protection carbohydrate less LXS, but more help to improve the whiteness of the slurry. 4, the the homemade acacia kraft pulp (high kappa) LXS pre-processing and post-processing of the appropriate amount of enzyme for 7IU · g -1 , and 5IU · g -1 ; X preprocessing and post-processing of the appropriate amount of enzyme, respectively, for 6 IU g -1 , and 4IU g -1 . 5 enzyme treatment of the homemade acacia kraft pulp oxygen delignification more obvious than the EMCC depth delignified kraft pulp; After LXS after treatment, slurry oxygen delignification rate increased by 11 percentage points, viscosity compared to the single segment oxygen delignification compared to almost no significantly decreased, the brightness increase of about 4 units; x post-processing slurry whiteness can be increased by approximately 7 units. 6, from the effect and economic viability for the oxygen delignification of view, four enzyme system XHT with oxygen off lignin in conjunction after-treatment is the most appropriate. 7, Hex.A after removal of the enzyme treatment, for improving the oxygen delignification rate, the protection of the viscosity of the slurry and to improve the whiteness of the role of significantly decreased; SEM observation after enzyme treatment, the surface of the fiber and the cross section of a large number of cracks and porosity, wherein the enzyme after-treatment is the most obvious, the dissolution of the degradation product for the penetration and bleaching chemicals in the subsequent bleaching create conditions. 8, oxygen delignification lignin enzymatic hydrolyzate before and after results of HPLC analysis, X-treatment liquid than LXS treatment liquid having a high xylose content, X treatment on xylan in the slurry has a certain degradation.

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