Method for preparing wheat straw cellulose microfibrils by auxiliary enzymatic pretreatment

A technology of cellulose microfibrils and enzyme pretreatment, which is applied in the direction of using microorganism/enzyme cellulose treatment, fiber raw material treatment, pulp beating/refining method, etc., can solve the increase of cost and environmental load, and high corrosion resistance , high energy consumption, achieve good economic and environmental benefits, reduce mechanical dissociation energy consumption, and reduce environmental pollution.

Inactive Publication Date: 2017-02-22
SHAANXI UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The existing technology mainly uses wood pulp as raw material to prepare cellulose microfibrils, and the simple use of mechanical high-pressure homogenization treatment to prepare cellulose microfibrils consumes a lot of energy, and the long-term strong mechanical action damages the crystal structure of the fibers, and the raw material fibers Longer, it is easy to block the high-pressure homogenizer and make the preparation process difficult to achieve continuous; the existing pretreatment combined with mechanical preparation also has certain defects and limitations, acid and alkali pretreatment require high corrosion resistance of the equipment, separation Obtaining pure CMF consumes a large amount of water and power resources, which increases the cost and environmental load; although the reaction speed of TEMPO oxidation pretreatment is fast, the width of the prepared CMF is relatively uniform, and the stability is good, but so far there is no way to recover TEMPO in industry. catalyst, and the preparation raw materials of this method are mainly kraft wood pulp after de-lignification, etc.

Method used

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  • Method for preparing wheat straw cellulose microfibrils by auxiliary enzymatic pretreatment
  • Method for preparing wheat straw cellulose microfibrils by auxiliary enzymatic pretreatment
  • Method for preparing wheat straw cellulose microfibrils by auxiliary enzymatic pretreatment

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0046]Sieve the wheat straw pulp, collect the fiber components trapped on the 100-mesh sieve, soak and swell with water for 12 hours, decompose for 30 minutes with a decomposer, squeeze out the water, and prepare the concentration with 0.05mol / L phosphate buffer solution 3% fiber suspension; then add domestic solid-state endoglucanase of 5% relative to the absolute dry mass of the fiber component for hydrolysis, keep the temperature at 45°C in a constant temperature water bath oscillating pot, and the oscillating frequency is 100r / min, the reaction The time is 120min. After the hydrolysis is completed, put it in a boiling water bath to boil and inactivate for 5 minutes, and then wash it thoroughly with distilled water to obtain the fiber slurry after enzyme pretreatment; then the fiber slurry is stirred by appropriate machinery, and the stirring speed is controlled at 8000r / min. 10min, and then it is prepared into 100mL of fiber suspension with a mass fraction of 0.5%. After t...

Embodiment 2

[0053] Other conditions are the same as in Example 1, only the addition amount of endoglucanase is 0.5%, 2%, ... 25% and 45% relative to the absolute dry mass of the fiber component, to prepare wheat straw cellulose microfibrils, and its performance The test results are shown in Table 1 below; wherein the scanning electron microscope picture (×100k) of the wheat straw cellulose microfibrils obtained by adding 25% enzyme amount and homogenizing 10 times is as attached image 3 shown.

[0054] Table 1 Performance test results of wheat straw cellulose microfibrils prepared with different enzyme additions

[0055] Enzyme addition 0.5％ 2％ 15％ 25％ 30％ 45％ Yield (%) 93 87 68 52 48 42 Width (nm) 40～120 40～110 35～85 30～80 30～65 25～60 Crystallinity 71.68 73.53 75.76 76.86 76.32 75.13 Polymerization 287 245 221 210 189 177 Energy consumption value (W h) 955.0 794.3 813.5 672.9 634.3 624.6

[0056] From the analys...

Embodiment 3

[0059] Other conditions are the same as in Example 1, only the amount of enzyme added is changed to 25% of the absolute dry mass of the relative fiber component, and the number of cycles of homogenization is successively 5, 10, 20, 30 and 40 times to prepare wheat straw cellulose microfibrils. The scanning electron microscope picture (×10k) of the wheat straw cellulose obtained by adding enzyme amount 25% and homogenizing 5 times is as attached Figure 4 As shown, the scanning electron microscope pictures (×100k) of the wheat straw cellulose microfibrils obtained by adding 25% enzyme amount and homogenizing 30 times are as attached Figure 5 shown.

[0060] The results showed that: when the number of homogenization was 5 times, the surface of the wheat straw fiber was obviously divided and fluffed, the fiber became shorter, and the microfibril structure was exposed, but the microfibrils were not completely dissociated; with the increase of the number of homogenization, When t...

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Abstract

The invention relates to a method for preparing wheat straw cellulose microfibrils by auxiliary enzymatic pretreatment, which comprises the following steps: firstly sieving wheat straw pulp, and collecting the fiber fraction trapped on a sieve mesh; preparing a 1-5 wt% fiber suspension with a buffer solution from the obtained fiber fraction, and adding cellulase into the fiber suspension for hydrolysis to obtain enzyme pretreated fiber slurry, wherein the addition amount of the cellulase is 0.5-25 wt% of the absolute dry mass of the fiber fraction; mechanically stirring and shearing the fiber slurry, preparing a 0.5-1.5 wt% fiber suspension, and carrying out circular homogenization treatment to obtain cellulose microfibril emulsion; and subjecting the cellulose microfibril emulsion to centrifugal separation and filtration in turn to obtain wheat straw cellulose microfibrils. The method provided by the invention can reduce the energy consumption of mechanical dissociation, and is favorable for reducing the amount of enzymes, so that the fibers in the slurry are dispersed uniformly, and the microfibrils can be separated smoothly by using a high pressure homogenizer.

Description

[0001] 【Technical field】 [0002] The invention belongs to the field of plant cellulose biomass refining, in particular to a method for assisting preparation of wheat straw cellulose microfibrils through enzyme pretreatment. [0003] 【Background technique】 [0004] Cellulose is the most abundant renewable natural polymer in nature, widely present in natural plants such as wood, grasses, cotton and hemp. Because cellulose has some disadvantages in performance, such as poor pyrolysis performance, chemical corrosion resistance, limited strength, etc., this limits its application range. Studies have found that when the fiber diameter reaches the nanometer level, it will have many new properties, and its crystallinity, hydrophilicity, Young's modulus, strength and transparency will all be greatly improved, making it have a wider range of applications. application range. Cellulose microfibril (CMF for short) prepared from natural cellulose has been widely used in the fields of nano...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C5/00D21H11/12D21D5/02D21D1/00
CPCD21C5/005D21D1/00D21D5/02D21H11/12
Inventor 李新平陈家杰王志杰杜敏朱晶航侯青青
Owner SHAANXI UNIV OF SCI & TECH
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