CN103343472B - Biochemical-method ECF (Extracellular Fluid) bleaching process for KP (Kraft Pulp) of fast growing poplars - Google Patents

Biochemical-method ECF (Extracellular Fluid) bleaching process for KP (Kraft Pulp) of fast growing poplars Download PDF

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CN103343472B
CN103343472B CN201310300563.8A CN201310300563A CN103343472B CN 103343472 B CN103343472 B CN 103343472B CN 201310300563 A CN201310300563 A CN 201310300563A CN 103343472 B CN103343472 B CN 103343472B
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陈嘉川
吉兴香
杨桂花
田中建
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Qilu University of Technology
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Abstract

The invention discloses a biochemical-method ECF (Extracellular Fluid) bleaching process for KP (Kraft Pulp) of fast growing poplars. The process is characterized by comprising the following steps of: (1) cooking: putting fast growing poplar wood chips into a cooking pot for cooking so as to obtain primary pulp, then, washing and screening so as to obtain paper pulp; (2) carrying out pretreatment by using xylanase; and (3) bleaching ECF: the bleaching of the paper pulp subjected to enzyme treatment comprises the steps of: firstly, carrying out oxygen delignification or intensified oxygen delignification on the paper pulp subjected to enzyme treatment; washing the paper pulp after the oxygen delignification is ended, and then, carrying out D-section chlorine dioxide bleaching; washing the paper pulp after the D-section chlorine dioxide bleaching is ended, and then, carrying out E-section treatment; and washing the paper pulp after the E-section treatment is ended, and then, carrying out second D-section treatment. According to the process, an ODED bleaching sequence is adopted to carry out bleaching, the paper pulp with higher whiteness and viscosity is obtained, and the whiteness of the bleached pulp reaches 88.1% ISO to the maximum and reaches 87.6% ISO to the minimum in the case that the total consumption of ClO2 is 1%; and the whiteness of the ODED-bleached pulp is 85.1% ISO.

Description

The bleaching process of the KP slurry biochemical process ECF of a kind of fast-growing poplar
Technical field
The bleaching process that the present invention relates to the KP slurry biochemical process ECF of a kind of fast-growing poplar, belongs to pulp technology for making paper.
Background technology
Fast-growing poplar is the chief species that the northern area of China woods paper My Perspective On The Co-building adopts, belong to fast-growing leaf wood, they have fast growth, strong adaptability, nature whiteness is high, material loose, the absorbability of liquid is good, and lignin content is lower, and the content of cellulose and hemicellulose is higher, can be used for producing chemical pulp, semi-chemical pulp and mechanical pulp etc., is one of main high-quality paper making raw material of northern China.Fast-growing poplar in Northern Europe, the northern area of North America and China is widely cultivated, it has comprised multiple kinds, representational have black poplar, Triploid of Populus Tomentosa, a middle forest poplar etc., growth characteristic, the constituent of these fast-growing poplars are all very approaching.
In recent years, high yield pulp development is swift and violent, but high yield pulp exists shortcomings such as refining energy consumption is large, pulping intensity is lower and retention of whiteness is poor, easy brightness reversion cause high yield pulp to be difficult to the paper that some paper strengths are high, be difficult for brightness reversion, Heat stability is good of manufacturing paper with pulp.Therefore within the quite a long time from now on, the manufacture paper with pulp superiority of high-grade paper of chemical pulp can not become.Fast-growing poplar is as a kind of good paper making raw material, its yield of producing chemical pulp is higher, generally in 51% left and right, and the own whiteness of fast-growing poplar is high, and the former pulp brightness after chemical pulping is generally in 30%ISO left and right, exceed 3-5%ISO left and right compared with the former pulp brightness of other leaf woods, and fast-growing poplar is as a kind of broad-leaved wood paper making raw material of high-quality, the black liquor producing in its digestion process, there is ripe treatment technology, can be to environment.
Fast-growing poplar chemical pulp is to adopt chemical agent, under specific conditions of cooking, and by the most of lignin stripping in plant fiber material, retain cellulose as much as possible, and the paper pulp of reservation hemicellulose in various degree.The yield of chemical pulp is relatively low, and generally between 40-55%, but content of cellulose in chemical pulp is high, paper strength greatly, easily bleach, be difficult for brightness reversion, good endurance.Therefore adopt biological enzyme formulation bio-bleaching to bleach with chemical method the Bleaching Technology that combines, the low oligosaprobic chemical pulp production technology of the easy beating energy consumption of high-whiteness high-strength of preparation fast-growing poplar, is one of important channel of China's pulping and paper-making development.
Summary of the invention
For above-mentioned prior art, the object of the invention is to change the technique of traditional pure chemistry method association with pulp bleaching, the technique that adopts bio-bleaching to combine with chemical bleaching, in the time reaching identical pulp brightness, further reduce the pollution of bleaching waste liquor to environment thereby consume chemical bleaching liquor still less, or while consuming identical chemical bleaching liquor, make the more Gao Gengyi making beating of whiteness of paper pulp, further reduce the beating energy consumption of paper pulp, realize the low consumption high efficiency bleaching of fast-growing poplar sulfate pulp.
The present invention is achieved by the following technical solutions: the concentration of following related slurry if no special instructions, is mass percent; Related reagent, the consumption of medicine, if no special instructions, be all for oven dry stock.
A bleaching process of the KP slurry biochemical process ECF of fast-growing poplar, step is as follows:
(1) boiling: get quick growth poplar wood sheet, put into digester boiling, obtain magma, then wash fully, screen, obtain paper pulp, the Kappa number of paper pulp is 16～21;
(2) xylanase pretr eatment;
(3) ECF bleaching: the above-mentioned paper pulp through enzyme processing is bleached, and bleaching process is that ODED floats order, and the step of bleaching is: first, to carry out deoxidation lignin or strengthening deoxidation lignin through the paper pulp of enzyme processing; After oxygen delignification finishes, paper pulp is washed, then carry out D section ClO 2 bleaching; After D section ClO 2 bleaching finishes, paper pulp is washed, then carry out the processing of E section; After the processing of E section finishes, paper pulp is washed, then carry out the processing of second D section, complete.
Further, the concrete mode of described boiling is: the quick growth poplar wood sheet of getting length 15～25mm, width 10～20mm, thickness 3～5mm, after natural air drying, in 15L electric heating rotating autoclave, carry out boiling, make fast-growing poplar sulfate magma, the condition of boiling is: alkali charge 20%(is to over dry raw material, Na 2o meter), sulphidity 24%, liquor ratio 1:4,165 DEG C of boiling maximum temperatures are carried out little venting 15min, heating-up time 120min, temperature retention time 90min in the time of 105 DEG C; After boiling, fully wash, screen, obtain paper pulp, the Kappa number of paper pulp is 16～21.
Further, the concrete mode of described xylanase pretr eatment is: adjusting pulp density is 10%, then uses zytase X 1, X 2or X 3process, in processing procedure, rub once at interval of 10～15min, to ensure that enzyme mixes with the even of paper pulp; After processing, take out, put into boiling water bath 10min, make zytase inactivation cessation reaction, with entering next step bleaching process after running water cleaning paper pulp.
Described zytase X 1provide (the letter zytase Pulpzyme HC of trade name Novi, article number CKN00117 and CDN00429) by Novozymes Company, liquid state, cellulose-less enzyme is lived; Zytase X 2, X 3by Shenzhen, the biological Co., Ltd of green micro-health provides (trade name zytase, article number LV-1 and LV-2), is white powder solid, and all cellulase is not lived.
Described zytase X 1, X 2or X 3the concrete technology condition of processing is as follows: X 1the process conditions of processing: enzyme dosage 8IU/L(is for the cumulative volume of paper pulp), 50～55 DEG C of temperature, pH8, time 120min; X 2the process conditions of processing: enzyme dosage 6IU/g(is for the quality of exhausted paper pulp), 55～60 DEG C of temperature, pH8～9, time 120min; X 3the process conditions of processing: enzyme dosage 8IU/g(is for the quality of exhausted paper pulp), temperature 50 C, pH8～9, time 120min.
Further, the concrete mode of described ODED bleaching process is: Oxygen Delignification of Fast-Growing is: starch dense 10%, NaOH consumption 2.5%, oxygen is pressed 0.6MPa, 100 DEG C of temperature, time 80min, MgSO 4consumption 0.5%; D section: ClO 2consumption is 0.5%, original ph 5, temperature 70 C, starch dense 10%, time 120min; E section: NaOH consumption 2%, starch dense 10%, temperature 70 C; Second D section: ClO 2consumption is 0.5%, original ph 5, temperature 70 C, starch dense 10%, time 120min.
The present invention adopts zytase to carry out preliminary treatment to paper pulp, then floats order by ODED and bleaches, and has obtained the paper pulp that whiteness and viscosity are higher, (X refers to xylanase pretr eatment) specific as follows:
XODED floats order at ClO 2in the situation of total consumption 1%, the whiteness of bleached pulp is up to 88.1%ISO, minimum 87.6%ISO; The whiteness of ODED bleached pulp is 85.1%ISO, processes than not exceeding 2.5-3.0%ISO by the whiteness of slurry after the floating of enzyme processing, and kept higher pulp viscosity and lower Kappa number through enzyme.
With respect to not using xylanase pretr eatment, directly bleaching for the paper pulp obtaining, still less, folding strength on average exceeds 40 times making beating loss of whiteness value of the present invention, and burst index on average exceeds 0.45Nmg -1, fracture length on average exceeds 0.35KM, and it is very little that tear index differs.The present invention has also compared the correspondence of three kinds of xylanase treatment paper pulp and has floated the bleaching effect of order, finds: the effect of the pulp treatment of three kinds of enzymes difference to some extent, from the initial effect that affects oxygen delignification, has influence on ODED always and float the bleaching results of order.Wherein help float effect best be X 2, be secondly X 1, be finally X 3.But on the whole, these three kinds of enzymes help that to float effect all obvious.In the time reaching identical or close beating degree, the former required making beating revolution still less, can be saved beating energy consumption 20% left and right.
Brief description of the drawings
Fig. 1: KP magma fiber properties schematic diagram.
Fig. 2: through zytase X 1the paper pulp fiber characteristic schematic diagram of processing.
Fig. 3: through zytase X 2the paper pulp fiber characteristic schematic diagram of processing.
Fig. 4: through zytase X 3the paper pulp fiber characteristic schematic diagram of processing.
Fig. 5: through the paper pulp fiber characteristic schematic diagram of ODED bleaching.
Fig. 6: through X 1the paper pulp fiber characteristic schematic diagram of ODED bleaching.
Fig. 7: through X 2the paper pulp fiber characteristic schematic diagram of ODED bleaching.
Fig. 8: through X 3the paper pulp fiber characteristic schematic diagram of ODED bleaching.
Fig. 9: the AFM two dimensional image of fast-growing poplar KP slurry.
The AFM two dimensional image of Figure 10: ODED slurry.
Figure 11: fast-growing poplar X 2the AFM two dimensional image of ODED slurry.
Figure 12: fast-growing poplar X 3the AFM two dimensional image of ODED slurry.
Figure 13: the AFM 3-D view of fast-growing poplar KP slurry.
Figure 14: the AFM 3-D view of fast-growing poplar ODED slurry.
Figure 15: fast-growing poplar X 2the AFM 3-D view of ODED slurry.
Figure 16: fast-growing poplar X 3the AFM 3-D view of ODED slurry.
Detailed description of the invention
Below in conjunction with embodiment, the present invention is further illustrated.In embodiment not the method for detailed description be under the conventional method in field, raw materials used, reagent etc. is existing product in prior art.
The process optimization of embodiment 1 xylanase treatment fast-growing poplar sulfate pulp
Zytase is a kind of protein with single-minded catalytic, and it is stricter to the requirement of environment, that is to say that each enzyme has its specific optimal environmental condition.Zytase is all being obtained obvious effect aspect chemical pulping and bleaching preliminary treatment.According to pertinent literature, the factor that affects xylanase pretr eatment mainly contains enzyme dosage, temperature, pH value and time etc., and these factors have impact in various degree to oxygen delignification effect and follow-up bleaching.In these influence factors, temperature is relevant with the characteristic of zytase itself with pH value, and relatively less on the character impact of slurry.This experiment, by conversion experiment condition, is inquired into the most suitable preliminary treatment fast-growing of different xylanase preparations poplar sulfate pulp process conditions.
In the time that different xylanase preparation is discussed in consumption, temperature, pH value, the optimum value of time, adopt identical Oxygen Delignification of Fast-Growing condition below, this is with reference to oxygen delignification condition preferably in the past: starch dense 10%, NaOH consumption 2.5%, oxygen is pressed 0.6MPa, 100 DEG C of temperature, time 80min, MgSO 4the all drug dosages of consumption 0.5%(are all for oven dry stock, as follows).
This tests raw material sources used:
Experiment is to mix quick growth poplar wood sheet with quick growth poplar wood sheet, takes from Shandong sun Paper Co., Ltd.Chip dimensions length 15-25mm, width 10-20mm, thickness 3-5mm, the qualification rate of wood chip is more than 90%, and wood chip is from fetch in stock ground, for subsequent use after natural air drying equilibrium water conten.
Zytase X 1provided by Novozymes Company, liquid state, cellulose-less enzyme is lived; Zytase X 2, X 3all have Shenzhen biological Co., Ltd of green micro-health to provide, be white powder solid, all cellulase is not lived.
When experiment, fast-growing poplar is carried out to boiling, obtain after paper pulp, then carry out xylanase pretr eatment.Digestion process is: in 15L electric heating rotating autoclave, carry out boiling, make fast-growing poplar sulfate magma.The condition of boiling is: alkali charge 20%(is to over dry raw material, Na 2o meter), sulphidity 24%, liquor ratio 1:4,165 DEG C of boiling maximum temperatures are carried out little venting 15min, heating-up time 120min, temperature retention time 90min in the time of 105 DEG C.Boiling disposed slurry is through fully washing, screening.Paper pulp yield 49.3%, the Kappa number 18.5 of paper pulp, viscosity 842.7mL/g, whiteness 36.5%ISO.
After xylanase pretr eatment, carry out oxygen delignification, oxygen delignification experiment is carried out in JF-DSTE polymerization reaction kettle (have and stir and automatic constant-temperature function).Its Oxygen Delignification of Fast-Growing is: starch dense 10%, NaOH consumption 2.5%, oxygen is pressed 0.6MPa, 100 DEG C of temperature, time 80min, MgSO 4consumption 0.5%.
The impact of the consumption of 1.1 zytases on fast-growing poplar sulfate pulp oxygen delignification
In order to obtain best enzyme treatment effect, the consumption of zytase must carry out optimization selection.This is because the content difference of different paper pulp kind xylans, the xylan content of hardwood pulp is higher than the content of softwood pulp, such as the xylan content of Eucalyptus Kraft Pulp is higher than masson s pine pulp, and xylan more easily can and, so the consumption of enzyme is less, in the suitable situation of pH value and temperature, the consumption of zytase with greater activity is just few than common zytase consumption.Starch dense too low required enzyme dosage and also want corresponding increase.Therefore, zytase consumption number affect enzyme and process the effect of fast-growing poplar sulfate pulp oxygen delignification, affect whiteness and the Kappa number of oxygen delignification paper pulp, also the following bleaching effect and the production cost that affect paper pulp after oxygen delignification, the consumption of therefore inquiring into three kinds of different zytases has important practical significance.Three kinds of Novel xylanase X 1, X 2, X 3consumption experimental studies results in table 1,2,3.
Table 1 zytase X 1the impact of the oxygen delignification performance of consumption on pretreating paper pulp
Note: zytase X 1other conditions of processing: 55 DEG C of temperature, time 120min, starch dense 10%, pH value 8-9.
As can be seen from Table 1, along with zytase X 1the increase of consumption, the whiteness of the paper pulp after oxygen delignification tends towards stability after progressively increasing, and the Kappa number of paper pulp reduces amplitude and no longer changes from large to small, and the viscosity of paper pulp declines after first rising to some extent slightly, as zytase X 1when consumption is 8IU/L, the better effects if of oxygen delignification is a little.Can find out from the experimental data of table 1, compare than untreated paper pulp through the paper pulp of xylanase treatment, the whiteness of paper pulp raises and viscosity also slightly raises, and the pulp property after oxygen delignification increases.
Table 2 zytase X 2the impact of the oxygen delignification performance of consumption on pretreating paper pulp
Note: zytase X 2other conditions of processing: temperature 50 C, time 120min, starch dense 10%, pH value 8-9.
As can be seen from Table 2, along with zytase X 2the increasing of consumption, after oxygen delignification, the whiteness of paper pulp progressively increases, and while waiting zytase to be increased to 10IU/g, pulp brightness no longer changes; The viscosity of paper pulp first increase tend towards stability afterwards and slightly reduce; The Kappa number of paper pulp first strengthens and is tending towards afterwards constant with the increase reduction amplitude of zytase consumption.As can also be seen from Table 2, as zytase X 2when consumption is 6IU/g, after oxygen delignification, the performance of paper pulp is best.
Table 3 zytase X 3the impact of the oxygen delignification performance of consumption on pretreating paper pulp
Note: zytase X 3other conditions of processing: temperature 50 C, time 120min, starch dense 10%, pH value 8-9.
As can be seen from Table 3, along with zytase X 3the increase of consumption, after oxygen delignification, the whiteness of paper pulp first raises and is tending towards afterwards constant; The Kappa number of paper pulp first declines to tending towards stability afterwards and no longer changes; After the viscosity of paper pulp first increases to some extent, increasing degree slows down and tends towards stability.As can also be seen from Table 3, work as X 3when consumption is 8IU/g, the performance improvement effect of the paper pulp after oxygen delignification is best.
Can find out from table 1,2,3, three kinds of zytases that cellulase is not lived are in the time improving pulp oxygen delignification performance, show some common features: along with the increase of enzyme dosage, the whiteness of paper pulp progressively improves, finally can improve pulp brightness 1.3-1.5%ISO; The Kappa number of paper pulp reduces amplitude at 1-1.2; The viscosity rise amplitude of paper pulp is in 30mL/g left and right.After xylanase treatment, the improvement of oxygen delignification pulp property provides good precondition to the improvement of follow-up bleached pulp performance.Meanwhile, due to the production unit of three kinds of zytases and the difference of technique, while having caused three kinds of enzyme pulp treatment, the effect of generation is also incomplete same, is mainly manifested in: in the time reaching same treatment effect, the consumption of enzyme is different.
The impact of 1.2 reaction temperatures on fast-growing poplar sulfate pulp oxygen delignification
Zytase is a kind of biocatalyst, and within the scope of certain active temperature, the reaction speed of enzyme and paper pulp is accelerated along with the rising of temperature, if temperature reduces, its reaction speed declines.But in the time that temperature exceedes a certain boundary, even inactivation of the activity decreased of enzyme.Generally, the effect of zytase and paper pulp mainly contains two aspects: the one, and in the time that temperature raises, the speed of reaction is accelerated, and the 2nd, along with the rising enzyme of temperature loses activity gradually, the reaction speed of enzyme and the functioning efficiency of enzyme are reduced.Therefore select suitable reaction temperature, the usefulness of giving full play to zytase is significant.Temperature is to three kinds of Novel xylanase X 1, X 2, X 3fast-growing poplar NaOH anthraquinone slurry oxygen delignification effect affected to result of study in table 4,5,6.
Table 4 temperature is to zytase X 1the impact of the oxygen delignification performance of pretreating paper pulp
Note: enzyme dosage is 8IU/L, time 120min, starch dense 10%, pH value 8-9.
As can be seen from Table 4, along with the rising of temperature, zytase X 1the usefulness of performance first increases afterwards and weakens, and when temperature is during at 55 DEG C, the whiteness of paper pulp reaches 60.1%ISO, reaches maximum, and the Kappa number of paper pulp is down to minimum, and viscosity remains on best level; In the time that temperature exceedes 60 DEG C, pulp brightness starts to reduce, and the viscosity of paper pulp declines obviously.This shows zytase X 1enzyme activity in the time of 55 DEG C, be more satisfactory.But consider zytase X from actual production 1select treatment temperature be 50-55 DEG C relatively good, be conducive to the practical operation of producing and reduce the adjusting difficulty of temperature, be conducive to reduce production costs and increase economic efficiency.
As can be seen from Table 5, along with temperature raises, zytase X 2the effect of performance first increases afterwards and weakens.As can be seen from Table 5, along with the rising of pretreatment temperature, the pulp brightness after oxygen delignification starts to improve, but in the time that temperature exceedes 55 DEG C, after oxygen delignification, the whiteness of paper pulp starts to reduce; When temperature is during lower than 55 DEG C, the Kappa number of paper pulp reduces along with the rising of temperature, but in the time that temperature exceedes 55 DEG C, Kappa number starts no longer to reduce the rising with temperature on the contrary and raises; When temperature is during at 55 DEG C-60 DEG C, the viscosity of paper pulp becomes along with the rising of temperature greatly, but in the time that temperature exceedes 60 DEG C, viscosity decrease speed is obvious.These experimental results show zytase X 2the usefulness maximum of preliminary treatment fast-growing poplar sulfate pulp performance in the time that temperature is 55-60 DEG C.
Table 5 temperature is to zytase X 2the impact of the oxygen delignification performance of pretreating paper pulp
Note: enzyme dosage is 6IU/g, time 120min, starch dense 10%, pH value 8-9.
As can be seen from Table 6, as zytase X 3while being 50 DEG C with the temperature of paper pulp effect, the pulp brightness after oxygen delignification is the highest, reaches 60%ISO, and it is minimum 7.2 that the Kappa number of paper pulp reaches, and the viscosity of paper pulp reaches maximum 731mL/g.As can also be seen from Table 6, along with the further rising of temperature, after oxygen delignification, the whiteness of paper pulp starts to reduce, and Kappa number starts to raise, and the viscosity of paper pulp declines.This shows, zytase X 3in the time that temperature is 50 DEG C, performance helps that to float effect best.
Table 6 temperature is to zytase X 3the impact of the oxygen delignification performance of pretreating paper pulp
Note: enzyme dosage is 8IU/g, time 120min, starch dense 10%, pH value 8-9.
Can find out from table 4,5,6, after the oxygen delignification of the temperature of three kinds of zytases preliminary treatment fast-growing poplar sulfate pulp in the time of 50-60 DEG C of scope, the character of paper pulp is better.Zytase X 1in the time that temperature is 50-55 DEG C, the usefulness of enzyme is better, zytase X 2in the time that temperature is 55-60 DEG C, the efficiency of enzyme is comparatively desirable, zytase X 3in the time that temperature is 50 DEG C, enzyme is most effective.In the time respectively three kinds of zytases being carried out to zymologic property research, using pure xylan as substrate, the optimum temperature of three kinds of zytases is 55-60 DEG C, but in actual experiment, zytase X 1and X 3when pretreating paper pulp, in the time reaching optimum efficiency, decrease than ideal temperature, this may with paper pulp in xylan and the structure of pure xylan or character there are differences and cause.But zytase X 2the optimal temperature of pretreating paper pulp is consistent with the temperature of zymologic property research, and this may be relevant with the characteristic of enzyme self.
The impact of 1.3pH value on fast-growing poplar sulfate pulp oxygen delignification
The scope of application difference of different zytase pH is also very large, and their applicable pH values can be divided into acidity, neutrality and alkaline.The activity of most of zytase need to competence exertion effect within the scope of applicable pH value, and the too high too low conformation that all can affect zymoprotein of pH value, even makes zytase lose activity, thereby directly has influence on the effect of xylanase treatment paper pulp.The zytase of the paper pulp after the most applicable processing boiling is alkaline enzyme, the present invention first three kinds of enzymes that Novel xylanase is all meta-alkalescence of use.Different pH values to the experimental data of these three kinds of xylanase treatment fast-growing poplar sulfate pulp oxygen delignification effects in table 7,8,9.
Table 7pH value is to zytase X 1the impact of pretreating paper pulp on oxygen delignification effect
Note: enzyme dosage is 8IU/L, temperature 50 C, time 120min, starches dense 10%.
As can be seen from Table 7, zytase X 1after preliminary treatment fast-growing poplar sulfate pulp oxygen delignification, the whiteness of paper pulp is along with the increase of pH value first increases rear reduction, and in the time of pH value 8, the whiteness of paper pulp is up to 60.1%ISO; The Kappa number of paper pulp is along with the increase of pH value first reduces rear increase, in the time of pH value 8, and Kappa number minimum 7.1; The viscosity of paper pulp is along with the increase of pH value first increases rear reduction, and in the time of pH value 8, the viscosity of paper pulp reaches maximum 740mL/g.As can be seen from Table 7, pH value in the time of 9-10, zytase X 1usefulness also good, kept higher whiteness, lower Kappa number and higher viscosity.Consider from the angle of actual production, using zytase X 1time pH value the best be modulated to 8, if but be modulated at the scope of 8-10, also can bring into play better and more stable effect and usefulness.
As can be seen from Table 8, zytase X 2after preliminary treatment fast-growing poplar sulfate pulp oxygen delignification, the whiteness of paper pulp is along with the increase of pH value first increases rear reduction, and in the time of pH value 8, the whiteness of paper pulp is up to 60.2%ISO; The Kappa number of paper pulp is along with the increase of pH value first reduces rear increase, in the time of pH value 9, and Kappa number minimum 7.2; The viscosity of paper pulp is along with the increase of pH value first increases rear reduction, and in the time of pH value 9, the viscosity of paper pulp reaches maximum 740mL/g.This shows zytase X 2effect in the time that pH value is 8-9 is best, has kept the whiteness that paper pulp is the highest, minimum Kappa number and maximum viscosity.PH value be 7 and the pretreating effect of 10 o'clock while being 8-9 compared with pH value effect slightly poor, but from the angle of actual production, zytase X 2applicable pH value be that alkalescent or neutrality are fine, but preferably pH value in the scope of 8-9.
Table 8pH value is to zytase X 2the impact of pretreating paper pulp on oxygen delignification effect
Note: enzyme dosage is 6IU/g, 55 DEG C of temperature, time 120min, starches dense 10%.
As can be seen from Table 9, zytase X 3after preliminary treatment fast-growing poplar sulfate pulp oxygen delignification, the whiteness of paper pulp is along with the increase of pH value first increases rear reduction, and in the time of pH value 8, the whiteness of paper pulp is up to 60.2%ISO; The Kappa number of paper pulp is along with the increase of pH value first reduces rear increase, in the time of pH value 8, and Kappa number minimum 7.1; The viscosity of paper pulp is along with the increase of pH value first increases rear reduction, and in the time of pH value 8, the viscosity of paper pulp reaches maximum 734mL/g.In the time of pH value 9, the whiteness 60%ISO of paper pulp, Kappa number 7.2, the viscosity 731 of paper pulp, a little gap of effect during with pH value 8, but gap is very little, can draw thus, zytase X 1pretreating paper pulp preferably pH value is 8-9.
Table 9pH value is to zytase X 3the impact of pretreating paper pulp on oxygen delignification effect
Note: enzyme dosage is 8IU/g, temperature 50 C, time 120min, starches dense 10%.
Can find out from table 7,8,9, the pH value of three kinds of zytases is all more satisfactory to the treatment effect of paper pulp within the scope of 8-10.Zytase X 1best pH value is 8, zytase X 2optimal pH be 8-9, zytase X 3optimal pH be 8.In the time respectively three kinds of zytases being carried out to zymologic property research, using pure xylan as substrate, the optimum pH value of three kinds of zytases is all 8, zytase X when for the treatment of paper pulp 1and X 3most suitable pH value is all 8, and the zymologic property of this and they matches.And zytase X 2the optimum value of pulp treatment is 8 and 9, not quite identical with its zymologic property, and in the time of pulp treatment, alkali resistance increases, and can reduce like this number of times of pulp washing after boiling, and saving water resource and reduce energy consumption is conducive to the application of actual production.
The impact of 1.4 times on fast-growing poplar sulfate pulp oxygen delignification effect
There is certain influence time to xylanase treatment fast-growing poplar sulfate pulp, if the time is too short, the performance of enzyme cannot be performed to ultimate attainment, if overlong time is unfavorable for enhancing productivity.Based on this, in immobilized enzyme consumption, temperature, pH value with starch and studied the impact of time on pretreatment effect under dense condition.Experimental result is in table 10,11,12.
Table 10 time is to zytase X 1the impact of pretreating paper pulp on oxygen delignification effect
Note: enzyme dosage is 8IU/L, temperature 50 C, pH value 8-9, starches dense 10%.
As can be seen from Table 10, along with the prolongation of time, zytase X 1fast-growing poplar sulfate pulp after treatment is after oxygen delignification, and the whiteness of paper pulp starts after progressively improving to reduce, and in the time that the time is 120min, the whiteness of paper pulp reaches peak 60.1%ISO; The Kappa number of paper pulp starts to raise after first progressively reducing, when the time is during at 120min, and Kappa number near minimum 7.1; The viscosity of paper pulp starts after progressively raising to reduce, and in the time that the time is 120min, the viscosity of paper pulp reaches maximum 740mL/g.Also can find out from the experimental data of table 10, along with the prolongation of time, the action effect of enzyme starts to decline, and this may be because zytase and paper pulp be long action time, and enzymolysis product has produced certain inhibitory action to enzyme with reacting of paper pulp.Therefore zytase X 1the time 120min of pulp treatment is advisable.
As can be seen from Table 11, along with the prolongation of time, zytase X 2fast-growing poplar sulfate pulp after treatment is after oxygen delignification, and the whiteness of paper pulp is also first to raise and reduce afterwards, and in the time that the time is 120min, the whiteness of paper pulp is up to 60.2%ISO; The Kappa number of paper pulp first declines and starts afterwards to uprise, and in the time that the time reaches 120min, the Kappa number of paper pulp is minimum to 7.2; The viscosity of paper pulp starts to reduce after first becoming greatly, and in the time that the time is 120min, the viscosity of paper pulp is up to 745mL/g.The experimental data of consolidated statement 11 can draw, zytase X 2the time of pulp treatment is not that the longer the better, exceedes after 120min when the time, and the action effect of enzyme starts to weaken, therefore zytase X 3the time 120min of pulp treatment is advisable.
Table 11 time is to zytase X 2the impact of pretreating paper pulp on oxygen delignification effect
Note: enzyme dosage is 6IU/g, 55 DEG C of temperature, pH value 8-9, starches dense 10%.
As can be seen from Table 12, along with the prolongation of time, zytase X 3fast-growing poplar sulfate pulp after treatment is after oxygen delignification, and the viscosity of paper pulp first raises and reduces afterwards, and in the time that the processing time is 120min, the viscosity of paper pulp reaches maximum 731mL/g; The whiteness of paper pulp is also first to raise and reduce afterwards, and in the time that the processing time is 120min, the whiteness of paper pulp is also first to improve rear reduction, and in the time that the processing time is 120min, the whiteness of paper pulp reaches maximum 60%ISO; It is large that the Kappa number of paper pulp first reduces rear change, and in the time that the processing time is 120min, the Kappa number of paper pulp is down to minimum 7.2.Also can find out from table 12, in the time reaching the highest whiteness, minimum Kappa number and the highest viscosity, zytase X 3the pulp treatment time is 120min, exceedes this time treatment effect and just starts to weaken, and this may be because zytase and paper pulp be long action time, and enzymolysis product has produced certain inhibitory action to enzyme with reacting of paper pulp.
Table 12 time is to zytase X 3the impact of pretreating paper pulp on oxygen delignification effect
Note: enzyme dosage is 8IU/g, temperature 50 C, pH value 8-9, starches dense 10%.
Can find out that from table 10,11,12 these three kinds of zytases are basically identical to the treatment effect of paper pulp: the one, along with the prolongation of time, the whiteness of paper pulp first raises and reduces afterwards, and the Kappa number of paper pulp first reduces rear rising, and the viscosity of paper pulp first increases afterwards and diminishes; The 2nd, the time of continuing these three kinds of xylanase treatment paper pulp of prolongation, the whiteness of paper pulp starts to reduce, Kappa number starts to raise, pulp viscosity starts to decline.Therefore when the optimization process time is all controlled at 120min, be advisable.Table 10,11,12 experimental result also show, be not that the longer the better action time for zytase and paper pulp, but there is time preferably, if overlong time, may affect the activity of enzyme, also may make the part lignin of stripping start again to deposit on fiber, reduce the usefulness of zytase, overlong time is also unfavorable for enhancing productivity simultaneously.Therefore the time of selecting suitable xylanase treatment paper pulp is very important.
Comprehensive above-mentioned experimental technique analysis result, can show that three kinds of zytases preferably process the process conditions of fast-growing poplar sulfate pulp: zytase X 1preferred process condition be: enzyme dosage 8IU/L, temperature 50 C, pH8, time 120min; Zytase X 2preferred process condition be: enzyme dosage 6IU/g, 55 DEG C of temperature, pH8-9, time 120min; Zytase X 3preferred process condition be: enzyme dosage 8IU/g, temperature 50 C, pH8-9, time 120min.
The optimization of embodiment 2 bleaching conditions
2.1.1 raw material
Experiment is to mix quick growth poplar wood sheet with quick growth poplar wood sheet, takes from Shandong sun Paper Co., Ltd.Chip dimensions length 15-25mm, width 10-20mm, thickness 3-5mm, the qualification rate of wood chip is more than 90%, and wood chip is from fetch in stock ground, for subsequent use after natural air drying equilibrium water conten.
Zytase X 1provided by Novozymes Company, liquid, cellulose-less enzyme is lived; Zytase X 2, X 3all have Shenzhen biological Co., Ltd of green micro-health to provide, be white powder solid, all cellulase is not lived.
2.1.2 boiling experiment
In 15L electric heating rotating autoclave, carry out boiling, make fast-growing poplar sulfate magma.The condition of boiling is: alkali charge 20%(is to over dry raw material, Na 2o meter), sulphidity 24%, liquor ratio 1:4,165 DEG C of boiling maximum temperatures are carried out little venting 15min, heating-up time 120min, temperature retention time 90min in the time of 105 DEG C.Boiling disposed slurry is through fully washing, screening.Paper pulp yield 49.6%, the Kappa number 18.9 of paper pulp, viscosity 950ml/g, whiteness 36.5%ISO.
2.1.3 xylanase pretr eatment
Three kinds of xylanase pretr eatment experiments all complete in polyethylene plastic bag.The poplar sulfate pulp of having washed after boiling is mixed in plastic bag with enzyme, enzyme treatment process condition and the experimental procedure optimized according to embodiment 1, after regulating pH value and starch zytase liquid that dense rear handle modulates and putting into bag and evenly mix, put into the water-bath that sets temperature and carry out constant temperature processing.In processing procedure, rub once with hand at interval of 10-15min, to ensure that enzyme mixes with the even of paper pulp.Slurry takes out after processing the stipulated time, then puts into boiling water bath 10min, makes zytase inactivation cessation reaction, with entering following bleaching operation after running water cleaning paper pulp.
2.1.4 oxygen delignification and the experiment of strengthening oxygen delignification
The experiment of fast-growing poplar sulfate pulp oxygen delignification is carried out in JF-DSTE polymerization reaction kettle (have and stir and automatic constant-temperature function).Its Oxygen Delignification of Fast-Growing is: starch dense 10%, NaOH consumption 2.5%, oxygen is pressed 0.6MPa, 100 DEG C of temperature, time 80min, MgSO 4the all drug dosages of consumption 0.5%(are all for oven dry stock, as follows).
The process conditions of two sections of oxygen delignifications: first paragraph O1: starch dense 10%, NaOH consumption 2.5%, oxygen is pressed 0.6MPa, 100 DEG C of temperature, time 20min, MgSO 4consumption 0.5%; Second segment O 2: supplement 0.5% NaOH, oxygen is pressed 0.5MPa, time 60min.
The process conditions of fast-growing poplar sulfate pulp strengthening oxygen delignification Op are: starch dense 10%, NaOH consumption 2.5%, oxygen is pressed 0.6MPa, 100 DEG C of temperature, MgSO 4consumption 0.5%, Na 2siO 3consumption 0.7%, H 2o 2consumption 3%, time 80min.
The process conditions of first paragraph oxygen delignification and second segment strengthening oxygen delignification: first paragraph O 1: starch dense 10%, NaOH consumption 2.5%, oxygen is pressed 0.6MPa, 100 DEG C of temperature, time 20min, MgSO 4consumption 0.5%; Second segment O 2P: supplement 0.5% NaOH, add 3% H 2o 2, Na 2siO 3consumption 0.7%, oxygen is pressed 0.5MPa, time 60min.
The process conditions of two sections of strengthening oxygen delignifications: first paragraph O 1P: starch dense 10%, NaOH consumption 2.5%, H 2o 2consumption 1%, oxygen is pressed 0.6MPa, 100 DEG C of temperature, time 20min, Na 2siO 3consumption 0.7%, MgSO 4consumption 0.5%; Second segment O 2P: supplement 0.5% NaOH, add 2.5% H 2o 2, oxygen is pressed 0.5MPa, time 60min.
2.1.5 the bleaching experiment of paper pulp
The bleachings such as D, E, Q, P or processing section carry out respectively in polyethylene plastic bag.Get 30g oven dry stock at every turn, according to the experimental procedure of drafting, after required liquid is evenly mixed, pour in plastic bag, after slurry and liquid are mixed, put into thermostat water bath and bleach or process.In the process of bleaching or processing, take out with hand and rub even mixing once at interval of 15min, ensure paper pulp and the even mixing of floating agent.
2.1.6 analytical method
The mensuration of viscosity: the method according to standard GB/T 1548-1989 regulations is carried out.
The mensuration of Kappa number: according to GB1546-1989 standard test.
The mensuration of whiteness: paper pulp is discongested after device discongests through fiber, copies into the scraps of paper on Buchner funnel, air-dry rear with YQ-Z-48B
Whiteness instrument is measured.
Folding number: in using, domestic MIT folding strength tester is measured.
Burst index: with swedish company L & W produce bursting strength tester measure.
Fracture length: with swedish company L & W produce anti-tensile tester measure.
Tear index: with the TMI of u s company produce tearability tester measure.
2.1.7 the mensuration of making beating and beating energy consumption
Slurry after defibrination adopts KRK company to produce PFI mill and pulls an oar, and beating consistency is 10%, and beater roll(er) and beater chamber gap are 0.2mm, and beating pressure is 3.4Nmm -1.The beating degree of making beating disposed slurry is measured and is adopted Xiao Baier-Rui Gele YQ-Z-13 beating degree analyzer to measure.
The revolution of making beating specific energy consumption: PFI mill is linear with beating energy consumption within the specific limits, and this experiment required making beating revolution when reaching identical beating degree calculates energy loss-rate.Beating energy consumption reduction rate in this experiment=(enzyme is processed the bleached pulp making beating revolution of the enzyme processing of after bleaching slurry making beating revolution-not)/is not with bleached pulp making beating revolution × 100% of enzyme processing.
2.1.8 ESEM
By carrying out respectively oxygen-delignified pulp through the paper pulp of different enzyme processing from magma under the identical experiment condition of embodiment 1 " oxygen delignification experiment ", carry out the different orders of floating subsequently and bleach gained paper pulp etc., after running water washing, utilizing the quick handshcet former of triumphant match to copy formulation amount is 60g/m 2l Water Paper page, then by l Water Paper page in vacuum drier dry 48 hours, after metal spraying is processed, is observe and take pictures on the ESEM of QUANTA200 in model, and accelerating potential is 10kV.
2.1.9 atomic force microscope observation
Getting slurry sample 0.1g to be measured is distributed in the distilled water of 200mL, break up with dispersing device, fiber is evenly distributed in water, then getting a droplet with pipette is put on mica sheet, single fiber is distributed on mica sheet, air-dry 24h under room temperature, then uses MultiMode SPM model AFM (AFM) produced in USA to carry out scanning and photograph, and the model of probe is NP-20.
2.1.10 xylanase activity is measured
Adopt DNS method to measure (being conventional determining method of the prior art).
2.1.11 enzyme preparation characteristic is determined
Zytase X 1, X 2, X 3enzyme activity determination measure according to DNS method, it the results are shown in Table 13 and table 14.
The characteristic of table 13 liquid xylanase preparation
The characteristic of table 14 solid xylanase preparation
2.2 results and discussion
2.2.1 the effect of xylanase treatment to fast-growing poplar sulfate pulp ECF bleaching
Zytase, for the preliminary treatment before association with pulp bleaching, has the consumption that reduces chlorine-containing bleaching, further alleviates the pollution to environment, improve filterability and the fragility of paper pulp, increase fiber separating degree, improve the whiteness of floating rear paper pulp, reduce beating energy consumption, the advantage such as save production cost.Fast-growing poplar is the important paper making raw material of northern China, and it has higher whiteness, longer fibre length and material density is moderate, and easily the easily feature of bleaching of boiling, is applicable to the high whiteness of preparation and high-intensity chemical pulp.For this reason, the present invention carries out bleaching research three kinds of Novel wooden glycan for the fast-growing poplar sulfate pulp of different bleaching process, inquire into the whiteness of Xylanase-aided Bleaching paper pulp, the fibre morphology variation etc. that becomes the physical strength index of paper and float rear slurry, for novel commercial xylanase provides theoretical foundation in fast-growing poplar kraft bleaching industrial applications and popularization.
All bleaching process that the present embodiment contains the bleaching of oxygen delignification section all carry out when xylanase treatment paper pulp before oxygen delignification, and its process conditions are the xylanase treatment process conditions of optimizing in embodiment 1.
The impact on fast-growing poplar sulfate pulp ODED bleaching results of three kinds of xylanase pretr eatments
Adopt zytase X 1, X 2and X 3before fast-growing poplar sulfate pulp ODED floats order bleaching, carry out preliminary treatment, inquire into the impact of xylanase treatment on fast-growing poplar kraft bleaching performance.
The process conditions of three kinds of xylanase treatment fast-growing poplar sulfate pulp oxygen delignification best results optimizing according to embodiment 1, carry out this experiments in conjunction with ODED bleaching conditions.Concrete process conditions are as follows: X 1the process conditions of processing: enzyme dosage 8IU/L, temperature 50-55 DEG C, pH8, time 120min; X 2the process conditions of processing: enzyme dosage 6IU/g, temperature 55-60 DEG C, pH8-9, time 120min; X 3the process conditions of processing: enzyme dosage 8IU/g, temperature 50 C, pH8-9, time 120min.
ODED floats the process conditions of order bleaching: the process conditions of oxygen delignification section are shown in 2.1.4.D section: ClO 2consumption is 0.5%, original ph 5, temperature 70 C, starch dense 10%, time 120min; E section: NaOH consumption 2%, starch dense 10%, temperature 70 C; Second D section: ClO 2consumption is 0.5%, original ph 5, temperature 70 C, starch dense 10%, time 120min.
Through and do not carry out ODED bleaching through the poplar sulfate pulp of xylanase treatment simultaneously, to ensure the comparativity of bleaching results, xylanase pretr eatment to fast-growing poplar sulfate pulp ODED bleaching results in table 15.Paper pulp after bleaching is pulled an oar with PFI mill, and the making beating revolution of controlling various slurries makes its beating degree be controlled at 42 ° of SR left and right, then copies and makes quantitative 60g/m 2paper, then the physical properties such as its folding strength, bursting strength, tear index, fracture length are detected, its result is as table 16.
The impact of table 15 xylanase pretr eatment on fast-growing poplar sulfate pulp ODED bleaching results
As can be seen from Table 15, float according to ODED and XODED the association with pulp bleaching result that order completes different, wherein X 2the final bleaching whiteness that ODED floats order is the highest, reaches 88.1%, and the final whiteness of floating order compared with ODED exceeds 3.0%ISO, and has kept the highest pulp viscosity 785mLg in these four kinds are floated order -1; Next is X 1oDED floats the comparatively ideal of bleaching results of order, and the final whiteness of paper pulp reaches 87.8%ISO, and the final whiteness of floating order compared with ODED exceeds 2.7%ISO, and has kept higher pulp viscosity 780mLg -1; That enzyme action effect is relatively weak is X 3oDED floats order, but the final whiteness of floating rear slurry has also reached 87.6%ISO, does not exceed 2.5%ISO, the viscosity 776mLg of paper pulp by the final whiteness that the ODED of enzyme processing floats order -1, than the high 11mLg of viscosity with the paper pulp of enzyme processing not -1.
As can be seen from Table 15, through paper pulp xylanase treatment and that do not pass through xylanase treatment, floating after order bleaching the also difference of Kappa number that paper pulp is final, X through ODED 2it is minimum 1.6 that ODED floats the Kappa number of order, floats low 0.5 unit of Kappa number of order compared with ODED, is secondly X 1oDED and X 3the Kappa number that ODED floats order is all 1.7, floats the Kappa number Dou Di0.4Ge unit of order compared with ODED.This shows that three kinds of common features of zytase are: through the paper pulp of enzyme processing, float in order bleaching process at ODED, be conducive to removing of lignin, further reduce the Kappa number of paper pulp, but the more conventional order of floating has kept higher pulp viscosity, this may be that cellulase is not alive because of three kinds of zytases, the effect of zytase makes paper pulp fiber show the degraded of part hemicellulose, liquid soaks into better, thereby has removed more lignin, has improved the whiteness of floating rear paper pulp.
It can also be seen that from table 15, float rear slurry after beating and papermaking, the whiteness of paper pulp has decline in various degree.Wherein, it is at most 2.1%ISO that the whiteness of not floating order through the ODED of xylanase treatment reduces, through the X of enzyme processing 2the whiteness reduction minimum that ODED floats order is 1.7%ISO, through X 1oDED and X 3the loss of whiteness that ODED floats order is 1.8%ISO, this shows through the loss of whiteness of the paper pulp of enzyme processing paper pulp after making beating still less, this may be because through enzyme is after treatment float after slurry Kappa number lower, float rear slurry lignin content still less, the more ageing-resistant brightness reversion that is difficult for of paper pulp.
The comparison of table 16ODED/XODED bleached pulp physical properties of paper
Can find out from 16, the paper pulp of the paper pulp after XODED bleaching after than ODED bleaching is more easily pulled an oar.In the time reaching close 42 ° of SR of beating degree, required making beating revolution still less, beating energy consumption reduction rate is greatly about 20% left and right, this may be due to the processing through zytase, hemicellulose small part degraded in paper pulp, bleaching liquid makes fiber softening while more deeply soaking into, and more easily making beating is more energy-conservation.
The physical property of as can be seen from Table 16, floating rear paper pulp makes moderate progress.Through xylanase treatment with untreated floating after slurry all copy that to make be quantitatively 60g/m 2paper, the former bursting strength, fracture length and folding strength all to some extent raise, wherein pass through X 2the physical property of floating rear paper pulp of processing is best, and folding strength ratio is not with exceed 60 times of enzyme processing, and fracture length has improved 0.38Km, and burst index exceeds 0.6Nmg -1, tear index increases a little, but is also that this severally floats rear slurry and copy the peak of making paper.Through X 1and X 2that processes floats rear slurry, show equally good physical property: these two kinds of bleached pulps are copied the paper folding strength of making and improved more than 40 time, fracture length raising is greater than 0.3Km, tear index declines slightly, may be because bleaching liquid soaks into when fully removing more lignins fiber also damage to some extent.
But in general, after XODED floats order bleaching, (X) totally applied chlorine of ODED is 1.0%, float more than rear pulp brightness reaches 85%ISO, can improve the final whiteness 2.5-3%ISO of paper pulp, and float rear slurry and kept higher viscosity, kept better bleaching selectivity, improved more significantly the physical property of floating rear slurry.
The effect of three kinds of xylanase treatment paper pulp difference to some extent, from the initial effect that affects oxygen delignification, has influence on ECF always and respectively floats the bleaching results of order.Wherein help float effect best be X 2, be secondly X 1, be finally X 3.But totally compare, it is all comparatively desirable that the helping of this three kinds of enzymes floated effect.Due to the market price difference of three kinds of enzymes, applicable environment is also different, can be as required in actual production, and the enzyme that alternative costs are suitable, process conditions and production adapt.
2.2.3 scanning electron microscope analysis
For further understanding before and after three kinds of xylanase treatments and the variation of bleach rear fiber exterior appearance, observe with the bleached pulp that environmental scanning electronic microscope is processed slurry and correspondence to magma, enzyme.
2.2.3.1ECF bleached pulp scanning electron microscopic observation
Choose KP magma, process X 1the KP slurry, the process X that process 2the KP slurry, the process X that process 3the KP slurry, ODED bleached pulp, the X that process 1oDED bleached pulp, X 2oDED bleached pulp, X 3oDED bleached pulp, obtain the stereoscan photograph shown in Fig. 1～Fig. 8 according to the requirement of 2.1.8.
From Fig. 1,2,3,4, under the environmental scanning electronic microscope of 1600 times, Aspen KP is starched, X 1the KP slurry, the X that process 2the KP slurry and the X that process 3the electromicroscopic photograph on the KP pulp fibres surface of processing can be found out significantly, does not pass through zytase X 1, X 2, X 3the fiber surface of the KP slurry of processing is smooth, and close structure exists without tiny or microfibre.The fiber surface of starching through the KP of three kinds of xylanase treatments becomes loose, soft, and cavity and gap appear in fiber surface, has fiber fines like free state, and the surface area of fiber increases.
From Fig. 5,6,7,8, under the environmental scanning electronic microscope of 1600 times, Aspen KP slurry is through ODED bleaching, X 1the KP slurry, the X that process 2the KP slurry and the X that process 3the KP processing can find out through the electromicroscopic photograph of ODED bleached pulp fiber surface, and the fiber fines of fiber surface that does not pass through the ODED bleached pulp of xylanase treatment is little, but changes to some extent compared with magma, and curling phenomenon appears in fiber surface.KP slurry through enzyme processing is larger through the pulp freeness of ODED bleached pulp, and fiber surface is more loose, coarse and mixed and disorderly, and it is more soft that fiber becomes, and this illustrates to a certain extent through the bleached pulp of enzyme processing and more easily pulls an oar, more energy efficient.
2.2.4 AFM Analysis
Fast-growing poplar KP slurry, ODED, XODED slurry before and after three kinds of xylanase treatments are carried out to scanning under AFM, analyze the situation of change of understanding single fiber surface in the paper pulp of xylanase treatment front and back.This is tested and adopts light and handy contact mode to observe the fiber surface situation of change of the bleached pulp of magma, enzyme processing slurry and correspondence.
Choose KP magma, ODED bleached pulp, through X 2and X 3process ODED bleached pulp and obtain the two and three dimensions picture as the AFM of Fig. 9～16 according to the requirement of 2.1.9.
Find by atomic force microscope observation, in two dimensional image, magma single fiber surface has or not several more stiff small fine fibres compositions, and the microfibre on the slurry single fiber surface of magma after ODED bleaching becomes more tiny, shows in fiber bleached process that fiber attenuates to shorten; Through the paper pulp of xylanase treatment, after bleaching, single fiber surface has or not several soft microfibre groups, and does not have or not several stiff microfibre groups through the single fiber surface of enzyme pulp treatment; In 3-D view, the concavo-convex degree of the single fiber of enzyme processing is than obvious without the single fiber of enzyme processing, and single fiber surface is more loose, pulp freeness is larger, and micro-flexibility increases, more favourable making beating and reduction energy consumption.This is consistent with bleaching experiment data above, and these further show that the effect of floating of helping of zytase is significantly, effectively.
2.3 brief summary
2.3.1 the affect result of xylanase treatment on fast-growing poplar sulfate pulp ECF bleaching
With with not with the paper pulp of xylanase treatment after ECF bleaching, the former whiteness and viscosity are higher, become the physical property of paper also to make moderate progress, concrete outcome is as follows:
XODED floats order at ClO 2in the situation of total consumption 1%, the whiteness of bleached pulp is up to 88.1%ISO, minimum 87.6%ISO; The whiteness of ODED bleached pulp is 85.1%ISO, processes than not exceeding 2.5-3.0%ISO by the whiteness of slurry after the floating of enzyme processing, and kept higher pulp viscosity and lower Kappa number through enzyme;
The ECF bleached pulp of XODED above and ODED is copied and is made 60g/m through making beating 2paper, the former making beating loss of whiteness value is compared with the latter still less; The former folding strength on average exceeds 40 times compared with the latter, and burst index on average exceeds 0.45Nmg -1, fracture length on average exceeds 0.35KM, and it is very little that tear index differs.
The bleaching effect that relatively correspondence of three kinds of xylanase treatment paper pulp is floated order is found: the effect of the pulp treatment of three kinds of enzymes difference to some extent, from the initial effect that affects oxygen delignification, has influence on ECF always and respectively float the bleaching results of order.Wherein help float effect best be X 2, be secondly X 1, be finally X 3.But on the whole, these three kinds of enzymes help that to float effect all obvious.In the time reaching identical or close beating degree, the former required making beating revolution still less, can be saved beating energy consumption 20% left and right.
2.3.2 ESEM result
Under the environmental scanning electronic microscope of 1600 times and 3000 times, can be clearly seen that: smooth through the fiber surface of the KP slurry of xylanase treatment, close structure, without tiny or microfibre existence.The fiber of processing KP slurry through xylan shows to become loose, soft, and cavity and gap appear in fiber surface, has fiber fines like free state, and the surface area of fiber increases.
Aspen KP slurry attenuates compared with magma to some extent through ECF bleaching, xylanase treatment and untreated KP paper pulp fiber, occurs curling phenomenon.After the KP slurry bleaching of enzyme processing, the pulp freeness of paper pulp is larger, and fiber surface is more loose, coarse and mixed and disorderly, and it is more soft that fiber becomes, and this can explain to a certain extent through the bleached pulp of enzyme processing and more easily pull an oar, more energy efficient.
2.3.3 atomic force microscope observation result
Under AFM, observe, in two dimensional image, several more stiff microfibres that have or not on magma single fiber surface form; After enzyme is processed and is not bleached by the magma of enzyme processing, it is more soft and very thin that single fiber surface becomes, in 3-D view, the concavo-convex degree of the single fiber of enzyme processing is than obvious without the single fiber of enzyme processing, single fiber surface, surface is more loose, pulp freeness is larger, and more favourable making beating is energy-conservation.

Claims (2)

1. a bleaching process of the KP of fast-growing poplar slurry biochemical process ECF, is characterized in that: step is as follows:
(1) boiling: get quick growth poplar wood sheet, put into digester boiling, obtain magma, then wash, screen, obtain paper pulp;
(2) xylanase pretr eatment;
(3) ECF bleaching: the above-mentioned paper pulp through enzyme processing is bleached, and bleaching process is that ODED floats order, and the step of bleaching is: first, to carry out oxygen delignification or strengthening oxygen delignification through the paper pulp of enzyme processing; After oxygen delignification finishes, paper pulp is washed, then carry out D section ClO 2 bleaching; After D section ClO 2 bleaching finishes, paper pulp is washed, then carry out the processing of E section; After the processing of E section finishes, paper pulp is washed, then carry out the processing of second D section, complete;
Design parameter is: Oxygen Delignification of Fast-Growing is: starch dense 10%, NaOH consumption 2.5%, oxygen is pressed 0.6MPa, 100 DEG C of temperature, time 80min, MgSO 4consumption 0.5%; D section: ClO2 consumption is 0.5%, original ph 5, temperature 70 C, starch dense 10%, time 120min; E section: NaOH consumption 2%, starch dense 10%, temperature 70 C; Second D section: ClO 2consumption is 0.5%, original ph 5, temperature 70 C, starch dense 10%, time 120min;
The concrete mode of described xylanase pretr eatment is: adjusting pulp density is 10%, then uses zytase X 1, X 2or X 3process, in processing procedure, rub once at interval of 10～15min, after processing, take out, put into boiling water bath 10min, make zytase inactivation cessation reaction, clean paper pulp with running water;
Described zytase X 1, X 2or X 3the concrete technology condition of processing is as follows: X 1the process conditions of processing: enzyme dosage 8IU/L, 50～55 DEG C of temperature, pH8, time 120min; X 2the process conditions of processing: enzyme dosage 6IU/g, 55～60 DEG C of temperature, pH8～9, time 120min; X 3the process conditions of processing: enzyme dosage 8IU/g, temperature 50 C, pH8～9, time 120min;
Described zytase X 1purchased from Novozymes Company, the letter zytase Pulpzyme HC of trade name Novi, article number CKN00117 and CDN00429, liquid state, cellulose-less enzyme is lived; Zytase X2, X3 be all purchased from the biological Co., Ltd of the green micro-health in Shenzhen, trade name zytase, and article number LV-1 and LV-2, be white powder solid, and all cellulase is not lived.
2. the bleaching process of the KP of fast-growing poplar according to claim 1 slurry biochemical process ECF, it is characterized in that: the concrete mode of described boiling is: the quick growth poplar wood sheet of getting length 15～25mm, width 10～20mm, thickness 3～5mm, after natural air drying, carry out boiling, make fast-growing poplar sulfate magma, the condition of boiling is: alkali charge 20%, and to over dry raw material, Na 2o meter; Sulphidity 24%, liquor ratio 1:4,165 DEG C of boiling maximum temperatures, the 15min that exits in the time of 105 DEG C, heating-up time 120min, temperature retention time 90min; After boiling, wash, screen, obtain paper pulp.
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CN106592321B (en) * 2016-12-30 2018-07-03 齐鲁工业大学 The method that a kind of biochemical process ECF bleached kraft pulps of Fast growth poplar prepare paper base material
CN109554946B (en) * 2018-12-03 2021-03-16 齐鲁工业大学 Method for preparing paper-based material by using ionic liquid and ultrasonic-assisted ECF (ECF bleaching) sulfate pulp
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