CN110130135B - Method for pretreating lignocellulose raw material by using sodium acetate and sodium sulfite - Google Patents
Method for pretreating lignocellulose raw material by using sodium acetate and sodium sulfite Download PDFInfo
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Abstract
A method for synergistically pretreating lignocellulose raw materials by using sodium acetate and sodium sulfite as pretreatment media and utilizing a high-temperature oil bath pot and a high-temperature high-pressure sterilization pot for synergistic pretreatment comprises the following steps of: s1: weighing raw material powder, putting the raw material powder into a reaction bottle, adding an acetic acid solution, uniformly mixing, putting the mixture into a high-temperature oil bath kettle for reaction, and after the reaction is finished, cooling, filtering, washing and drying at a low temperature to obtain dry powder A; s2: weighing the powder A, putting the powder A into a reaction bottle, adding an alkaline sodium sulfite solution, uniformly mixing, putting into a high-temperature high-pressure sterilization pot for reaction, and cooling, filtering, washing and drying at low temperature after the reaction is finished to obtain the pretreated lignocellulose raw material. The invention takes acetic acid and alkaline sodium sulfite as pretreatment media, adopts different heat treatment temperatures, and utilizes a high-pressure oil bath pot and a high-temperature high-pressure sterilization pot to carry out synergistic pretreatment, so that the output of the pretreated cellulose is obviously increased.
Description
Technical Field
The invention belongs to the technical field of substrates containing cellulose materials, and particularly relates to a method for pretreating a lignocellulose raw material by using sodium sulfite acetate in a synergistic manner.
Background
The wood biomass yield in China is very high, but the wood biomass resource utilization rate in China is very low, and the comprehensive utilization technology of biomass resources is not mature. Chemical heat treatment is a key step in the conversion of lignocellulosic biomass to energy. Cellulose can be efficiently utilized, and saccharification of hemicellulose is also changed. Thermochemical treatment is a key step for realizing high-efficiency utilization of cellulose and saccharification and conversion of hemicellulose in renewable wood biological energy sources. The insoluble lignin can be quickly removed or the hemicellulose in the cell wall can be physically separated through the pretreatment process, so that the polysaccharide in the plant cell wall is chemically decomposed, and the output of the lignocellulose is increased.
At present, due to the fact that a raw material pretreatment method and technological parameters are not optimized, the pretreatment process is complex, time consumption is long, the solvent amount is large, economic cost is high, and environmental load is large. Therefore, the pretreatment method of the woody biomass material is further optimized, is scientifically simple, feasible, economical and efficient, and is the main direction of energy conversion of the woody biomass material. The method selects the efficient and convenient pretreatment solvent, optimizes the pretreatment time point and temperature parameters, and effectively performs the pretreatment process operation, thereby being a main way for improving the pretreatment efficiency and reducing the cost.
Disclosure of Invention
The invention aims to provide a method for pretreating a lignocellulose raw material by using sodium acetate and sodium sulfite as pretreatment media, which fully utilizes the synergistic effect of acetic acid, sodium hydroxide and sodium sulfite to improve the basic material property of the material, destroys the barrier of lignin and solves the problems of high pretreatment difficulty and low treatment efficiency caused by coating of lignin.
In order to achieve the purpose, the invention is realized by the following scheme:
a method for synergistically pretreating lignocellulose raw materials by using sodium acetate and sodium sulfite as pretreatment media and utilizing a high-temperature oil bath pot and a high-temperature high-pressure sterilization pot for synergistic pretreatment comprises the following steps of:
s1: weighing 12-15 parts of raw material powder, putting the raw material powder into a reaction bottle, adding an acetic acid solution with a material-liquid ratio of 1:8-12g/ml, uniformly mixing, screwing a reaction bottle cover, putting the reaction bottle cover into a high-temperature oil bath kettle, setting the temperature of the high-temperature oil bath kettle to be 165-175 ℃, keeping the high-temperature working time to be 25-35min, taking out the reaction bottle after the reaction is finished, cooling to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying in a low-temperature oven to obtain dried powder A;
s2: weighing 10-12 parts of powder A, placing the powder A into a reaction bottle, adding an alkaline sodium sulfite solution with a material-liquid ratio of 1:8-12g/ml, uniformly mixing, screwing a reaction bottle cover, placing the reaction bottle cover into a high-temperature and high-pressure sterilization pot, setting the temperature of the high-temperature and high-pressure sterilization pot at 118-122 ℃, working for 55-65min, taking out the reaction product after the reaction is finished, cooling the reaction product to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying at low temperature to obtain the pretreated lignocellulose raw material.
Further, the temperature of acetic acid pretreatment was set to 170 ℃ in step S1, the treatment time was 30min, and the temperature of sodium hydroxide and sodium sulfite treatment was 121 ℃ and the treatment time was 60min in step S2.
Further, the temperature of low-temperature drying in the steps S1, S2 and S3 is 40-50 ℃, and the moisture content of the dried powder is less than 10%.
Further, the raw material powder is paulownia powder, paulownia is beaten into wood shavings, dried and then crushed into fine particles by a crusher, and the fine particles are sieved by a 80-mesh sieve, and dried at a low temperature of 40-50 ℃ until the moisture content is less than 10 percent to obtain the raw material powder.
Further, the mass concentration of the acetic acid solution is 3-4.5%.
Further, the mass concentration of the acetic acid solution was 4%.
Further, the alkaline sulfurous acid solution is a mixed solution containing sodium sulfite with a mass concentration of 3.5-5% and sodium hydroxide with a mass concentration of 0.8-1.5%.
Further, the alkaline sodium sulfite solution is a mixed solution containing sodium sulfite of 4% by mass concentration and sodium hydroxide of 1% by mass concentration.
The invention has the beneficial effects that:
the invention takes acetic acid and alkaline sodium sulfite as pretreatment media, adopts different heat treatment temperatures, and utilizes a high-temperature oil bath pot and a high-temperature high-pressure sterilization pot to carry out synergistic pretreatment, so that the output of the pretreated cellulose is obviously increased. The acetic acid and the alkaline sodium sulfite are used as pretreatment media, the basic material property of the material is improved by fully utilizing the synergistic effect of the acetic acid and the alkaline sodium sulfite, the barrier of lignin is destroyed, and the problems of high pretreatment difficulty and low efficiency caused by the coating of the lignin are solved. The method has the advantages that the high-temperature oil bath pot and the high-temperature high-pressure sterilization pot are utilized to carry out acetic acid and alkaline sodium sulfite synergistic pretreatment on paulownia, the heating temperature is stable and controllable, the pretreatment effect of higher cellulose content and glucose yield in the enzymolysis process can be obtained, the operation is simple, convenient and safe, the cellulose recovery rate is high, the cost is low, the economy and environmental protection are realized, and the method is superior to a single solvent.
Drawings
FIG. 1 is a flow diagram of a process for the co-pretreatment of lignocellulosic feedstock with acetic acid and sodium sulfite alkalinity provided by the practice of the present invention;
FIG. 2 is a graph of different pre-treatment infrared spectra of paulownia provided by practice of the present invention;
FIG. 3 is a graph of enzyme gradients versus glucose and xylan hydrolysis yield changes provided by practice of the present invention;
FIG. 4 is a graph showing the variation of the yield of cellulose and xylan in the 30fpu second-generation enzyme-treated paulownia raw material under 48h and 72h conditions provided by the implementation of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A method for cooperatively pre-treating a lignocellulose raw material by sodium acetate comprises the following steps:
s1: weighing 12g of raw material powder, putting the raw material powder into a reaction bottle, adding an acetic acid solution with a material-liquid ratio of 1:10g/ml, wherein the mass concentration of the acetic acid solution is 4%, uniformly mixing, screwing a reaction bottle cover, putting the reaction bottle cover into a high-temperature oil bath kettle, setting the temperature of the high-temperature oil bath kettle to be 170 ℃, working at a high temperature for 30min, taking out the reaction bottle after the reaction is finished, cooling to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying at a low temperature of 45 ℃ until the moisture content is less than 10% to obtain dried powder A;
the raw material powder is paulownia powder, and the preparation method comprises the following steps: pulverizing paulownia into wood shavings, drying, pulverizing into fine granules by a pulverizer, sieving with a 80-mesh sieve, and drying at 45 deg.C until the water content is less than 10% to obtain raw material powder.
S2: weighing 10g of powder A, placing the powder A into a reaction bottle, adding an alkaline sodium sulfite solution with a material-liquid ratio of 1:10g/ml, wherein the alkaline sodium sulfite solution is a mixed solution containing 4% of sodium sulfite and 1% of sodium hydroxide, uniformly mixing, screwing a reaction bottle cover, placing the reaction bottle cover into a high-temperature and high-pressure sterilization pot, setting the temperature of the high-temperature and high-pressure sterilization pot at 121 ℃, working for 60min, taking out the reaction product after the reaction is finished, cooling the reaction product to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying the reaction product at a low temperature of 45 ℃ until the moisture content is less than 10% to obtain the pretreated lignocellulose raw material.
Example 2
A method for cooperatively pre-treating a lignocellulose raw material by sodium acetate comprises the following steps:
s1: weighing 15g of raw material powder, putting the raw material powder into a reaction bottle, adding an acetic acid solution with a material-liquid ratio of 1:12g/ml, wherein the mass concentration of the acetic acid solution is 4%, uniformly mixing, screwing a reaction bottle cover, putting the reaction bottle cover into a high-temperature oil bath kettle, setting the temperature of the high-temperature oil bath kettle to be 165 ℃, working at a high temperature for 25min, taking out the reaction bottle after the reaction is finished, cooling to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying at a low temperature of 45 ℃ until the moisture content is less than 10% to obtain dried powder A;
the raw material powder is paulownia powder, and the preparation method comprises the following steps: pulverizing paulownia into wood shavings, drying, pulverizing into fine granules by a pulverizer, sieving with a 80-mesh sieve, and drying at 45 deg.C until the water content is less than 10% to obtain raw material powder.
S2: weighing 12g of powder A, placing the powder A into a reaction bottle, adding an alkaline sodium sulfite solution with a material-liquid ratio of 1:12g/ml, wherein the alkaline sodium sulfite solution is a mixed solution containing 4% of sodium sulfite and 1% of sodium hydroxide, uniformly mixing, screwing a reaction bottle cover, placing the reaction bottle cover into a high-temperature and high-pressure sterilization pot, setting the temperature of the high-temperature and high-pressure sterilization pot at 118 ℃, working for 55min, taking out the reaction product after the reaction is finished, cooling the reaction product to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying the reaction product at a low temperature of 45 ℃ until the moisture content is less than 10% to obtain the pretreated lignocellulose raw material.
Example 3
S1: weighing 12g of raw material powder, putting the raw material powder into a reaction bottle, adding an acetic acid solution with a material-liquid ratio of 1:10g/ml, wherein the mass concentration of the acetic acid solution is 4%, uniformly mixing, screwing a reaction bottle cover, putting the reaction bottle cover into a high-temperature oil bath kettle, setting the temperature of the high-temperature oil bath kettle to be 165 ℃, working at a high temperature for 25min, taking out the reaction bottle after the reaction is finished, cooling to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying at a low temperature of 45 ℃ until the moisture content is less than 10% to obtain dried powder A;
the raw material powder is paulownia powder, and the preparation method comprises the following steps: pulverizing paulownia into wood shavings, drying, pulverizing into fine granules by a pulverizer, sieving with a 80-mesh sieve, and drying at 45 deg.C until the water content is less than 10% to obtain raw material powder.
S2: weighing 10g of powder A, placing the powder A into a reaction bottle, adding an alkaline sodium sulfite solution with a material-liquid ratio of 1:10g/ml, wherein the alkaline sodium sulfite solution is a mixed solution containing 4% of sodium sulfite and 1% of sodium hydroxide, uniformly mixing, screwing a reaction bottle cover, placing the reaction bottle cover into a high-temperature and high-pressure sterilization pot, setting the temperature of the high-temperature and high-pressure sterilization pot at 118 ℃, working for 55min, taking out the reaction product after the reaction is finished, cooling the reaction product to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying the reaction product at a low temperature of 45 ℃ until the moisture content is less than 10% to obtain the pretreated lignocellulose raw material.
Example 4
S1: weighing 15g of raw material powder, putting the raw material powder into a reaction bottle, adding an acetic acid solution with a material-liquid ratio of 1:10g/ml, wherein the mass concentration of the acetic acid solution is 4%, uniformly mixing, screwing a reaction bottle cover, putting the reaction bottle cover into a high-temperature oil bath kettle, setting the temperature of the high-temperature oil bath kettle to be 170 ℃, working at a high temperature for 30min, taking out the reaction bottle after the reaction is finished, cooling to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying at a low temperature of 45 ℃ until the moisture content is less than 10% to obtain dried powder A;
the raw material powder is paulownia powder, and the preparation method comprises the following steps: pulverizing paulownia into wood shavings, drying, pulverizing into fine granules by a pulverizer, sieving with a 80-mesh sieve, and drying at 45 deg.C until the water content is less than 10% to obtain raw material powder.
S2: weighing 12g of powder A, placing the powder A into a reaction bottle, adding an alkaline sodium sulfite solution with a material-liquid ratio of 1:10g/ml, wherein the alkaline sodium sulfite solution is a mixed solution containing 4% of sodium sulfite and 1% of sodium hydroxide, uniformly mixing, screwing a reaction bottle cover, placing the reaction bottle cover into a high-temperature and high-pressure sterilization pot, setting the temperature of the high-temperature and high-pressure sterilization pot at 121 ℃, working for 30min, taking out the reaction product after the reaction is finished, cooling the reaction product to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying the reaction product at a low temperature of 45 ℃ until the moisture content is less than 10% to obtain the pretreated lignocellulose raw material.
Comparative test
Taking the example 1 of the invention as an experimental group 1, namely co-pretreating a lignocellulose raw material by using acetic acid, sodium sulfite and sodium hydroxide to obtain a pretreated lignocellulose raw material I.
Experimental group 2: a lignocellulosic feedstock II without any treatment;
experimental group 3: treating a lignocellulose raw material with acetic acid, weighing 12g of raw material powder, putting the raw material powder into a reaction bottle, adding an acetic acid solution with a material-liquid ratio of 1:10g/ml, wherein the mass concentration of the acetic acid solution is 4%, uniformly mixing, screwing a reaction bottle cap, putting the reaction bottle cap into a high-temperature oil bath pot, setting the temperature of the high-temperature oil bath pot to be 170 ℃, working at a high temperature for 30min, taking out the reaction bottle after the reaction is finished, cooling to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing with distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, drying at a low temperature of 45 ℃ until the moisture content is less than 10% to obtain a pretreated lignocellulose raw material III, wherein the raw material powder is paulownia powder, and the preparation method comprises the following steps: pulverizing paulownia into wood shavings, drying, pulverizing into fine particles by a pulverizer, sieving with a 80-mesh sieve, and drying at 45 ℃ until the moisture content is less than 10% to obtain raw material powder;
experimental group 4: pretreating a lignocellulose raw material by using acetic acid and sodium sulfite, weighing 10g of powder A, putting the powder A into a reaction bottle, adding a sodium sulfite solution with a material-to-liquid ratio of 1:10g/ml, uniformly mixing the sodium sulfite solution with the mass concentration of 4%, screwing a reaction bottle cover, putting the reaction bottle cover into a high-temperature and high-pressure sterilization pot, setting the temperature of the high-temperature and high-pressure sterilization pot at 121 ℃, working for 60min, taking out the reaction bottle after the reaction is finished, cooling the reaction bottle to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying the reaction bottle at a low temperature of 45 ℃ until the moisture content is less than 10%.
The products obtained from the 4 above mentioned sets of experiments were analyzed:
1. and performing structural characterization on the pretreated sample by Fourier infrared spectroscopy, thermogravimetric analysis and a scanning electron microscope, and analyzing the content changes of cellulose, hemicellulose and lignin before and after pretreatment of the sample.
(1) The products obtained by the 4 groups of experiments are subjected to FTIR infrared spectrum image acquisition, a testing instrument adopts Nicolet FTIR IS10, and the testing wavelength range IS 400-4000 cm-1Spectral resolution of 32cm-1The number of scans was 64. The contents of the three main components of the paulownia, namely cellulose, hemicellulose and lignin, are changed after pretreatment, so that the infrared absorption spectrogram with certain change can be displayed in different wave bands, as shown in figure 2.
The method judges the component changes of cellulose, hemicellulose and lignin based on the attribution of infrared spectrum absorption functional groups in the change of each chemical component of the pretreated paulownia, the change of degradation temperature and rate of raw materials by thermogravimetric analysis and a map observed by a scanning electron microscope. The attribution condition of the functional groups of the bamboo wood is greatly changed under different treatment conditions, and for the convenience of comparison, the functional groups corresponding to the main wave band values in the infrared spectrum superposition chart are summarized in tables 1 to 3:
TABLE 1 functional groups corresponding to cellulose absorption peaks
TABLE 2 functional groups corresponding to hemicellulose absorption peaks
TABLE 3 functional groups corresponding to lignin absorption peaks
The comprehensive change of the spectra of cellulose, hemicellulose and lignin, the characteristic absorption peak of cellulose is 2924cm-1And 3412cm-1. Hemicellulose is distinguished from other components by a characteristic of 1740cm-1C ═ O stretching vibration absorption peaks at the nearby acetyl group and carboxyl group. 1640cm-1Here is the stretching vibration of lignin carbonyl conjugated aryl ketone C ═ O, and it can be seen from the spectrogram that 1740cm of pretreated raw material-1And 1640cm-1The absorption peaks appeared after different pretreatments became less evident, indicating that after pretreatment, the hemicellulose was degraded. At 1640cm-1Nearby absorption peaks, steepening of the bands of the pretreatment feed profile, sayThe content of lignin is reduced.
The cellulose is a linear macromolecular compound formed by D-glucosyl, and the infrared sensitive group of the cellulose is hydroxyl; cellulose has a free hydroxyl group at C4 and has a specific X-ray pattern. Hemicellulose is an inhomogeneous glycan composed of two or more monosaccharides, and contains infrared-sensitive groups such as acetyl groups, hydroxyl groups and the like, and lignin-based phenylalkanes are an aromatic polymer compound formed by connecting carbon-carbon bonds through ether bonds, and the molecule of the aromatic polymer compound contains a plurality of infrared-sensitive groups such as methoxy CH2O, hydroxyl groups, carbonyl groups C ═ O, double bonds C ═ O, benzene rings and the like.
It can be seen from fig. 2 that the content of functional groups before and after the pretreatment of paulownia has changed, and the degree of change of different treatment modes is different, and it can be seen from the figure that the cellulose content after the pretreatment is totally increased, the content of hemicellulose and lignin is reduced, and the synergistic pretreatment effect of acetic acid and alkaline sodium sulfite is the best.
(2) And selecting a TGA/DSC3 type thermogravimetric thermal difference analyzer, using nitrogen as protective gas, setting the flow rate of the protective gas to be 20mL/min, setting the heating rate to be 10 ℃/min, and setting the pyrolysis reaction temperature to be 50-600 ℃.
According to the analysis of the thermal stability of paulownia before and after pretreatment, the highest pyrolysis temperature of three major elements of wood is lignin, and the thermal stability of paulownia after pretreatment is reduced. Compared with the control, the temperature corresponding to the maximum mass loss rate of the paulownia thermal treatment material is reduced, which indicates that the pretreatment material shortens the time for reaching the maximum mass loss rate, and thus indicates that the content of lignin is reduced after pyrolysis.
(3) The scanning electron microscope is the scanning electron microscope with the serial number of S3400, the objective lens distance is 10.1mm and the working voltage is 5.00KV, the observation and the focusing are started after the objective lens distance is enlarged to 3000 times, and a proper target is found and then the target is clicked for storage.
The observation of the surface of a sample can find the separation degree of lignin parts of paulownia before and after pretreatment and different pretreatment methods, the comparison picture finds that cellulose with smooth and strip-shaped surface is not found before the pretreatment, and the finding after the pretreatment shows that the pretreatment is separated from lignin wrapped on the cellulose.
2. The cellulose, lignin, xylan contents of the 4 groups of experimental products, determined according to the standard method of the U.S. department of energy (NREL), are shown in table 4 below:
TABLE 4 variation of chemical composition of samples under different pretreatment conditions
As can be seen from table 4, the main chemical components before and after the paulownia pretreatment are significantly changed, and the contents of the components obtained by different treatment modes are different, the same points are that the content of cellulose after the treatment tends to be significantly increased, the content of lignin is reduced, and the content of hemicellulose is reduced, wherein the synergistic pretreatment effect of acetic acid and alkaline sodium sulfite is the best under the condition of three pretreatment media.
3. The 4 groups of experimental products are tested at 50 ℃ and the test rotating speed is as follows: 240r/min preparation of enzyme hydrolysis sample: 10, 20, 30(FPU/g DM) CTEC2 second-generation enzyme was used as a control for 3 different concentration gradients. 48h and 72h were chosen as time points for enzymatic hydrolysis for analysis.
The yield of fermentation sugars in the enzymatic hydrolysis of cellulose is an important and most direct indicator for evaluating the quality of the pretreatment. In order to verify the cellulose enzymolysis effect after synergistic pretreatment of acetic acid and sodium sulfite under alkaline conditions, the invention adopts 10, 20 and 30(FPU/g DM) CTEC2 second-generation enzyme as 3 comparisons with different concentration gradients. 48h and 72h were chosen as time points for enzymatic hydrolysis for analysis. The analysis results are shown in fig. 3 and 4 below:
as can be seen from FIGS. 3 and 4, the hydrolysis effect of the pretreated cellulase is significantly improved, and particularly, the hydrolysis effect is better after the synergistic treatment of acetic acid and sodium sulfite under alkaline conditions.
And the effects of the second-generation enzymes with three contents all achieve the purpose of pretreating the raw material of the paulownia by enzymolysis, but the best effect of the second-generation enzyme treatment of 30fpu on the pretreatment of the raw material of the paulownia, acetic acid and alkaline sodium sulfite is that the glucose yield reaches 72.05, and the xylan yield reaches 77.80%.
The effect of the pretreatment of the paulownia raw material by the paulownia + acetic acid + alkaline sodium sulfite is not greatly improved within 48 hours and 72 hours under the degradation of the 30fpu second-generation enzyme, the glucose yield reaches 68.88 percent and the xylan yield reaches 73.48 percent by using the 30fpu second-generation enzyme to treat the paulownia raw material pretreated by the paulownia + acetic acid + alkaline sodium sulfite, wherein the time is saved most.
In conclusion, the invention takes acetic acid, sodium sulfite and sodium hydroxide as pretreatment media, adopts different heat treatment temperatures, utilizes a high-pressure oil bath pot and a high-temperature high-pressure sterilization pot to carry out synergistic pretreatment, researches the main chemical components before and after the pretreatment of the paulownia, and carries out the synergistic inspection on the change of the chemical components of the bamboo wood before and after the pretreatment through Fourier transform infrared spectroscopy analysis, thermogravimetric analysis and a scanning electron microscope. The results show that: the output of the pretreated cellulose is obviously increased, the change rule of the yield of the cellulose under different treatment medium conditions is that the synergistic treatment effect of the acetic acid and the alkaline sodium sulfite is the most obvious, then the synergistic treatment of the sodium sulfite and the acetic acid is carried out, and finally only the acetic acid is carried out. The content of cellulose, lignin and xylan in the pretreated paulownia determined by the standard method of the United states department of energy (NREL) and the enzyme hydrolysis experiment of the cellulose can fully demonstrate that the yield of the pretreated cellulose is obviously increased.
In the description herein, references to the description of "one embodiment," "an example," "a specific example," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.
Claims (5)
1. A method for synergistically pretreating a lignocellulose raw material by using sodium acetate and sodium sulfite is characterized in that acetic acid and alkaline sodium sulfite are used as pretreatment media, and a high-temperature oil bath pot and a high-temperature high-pressure sterilization pot are utilized for synergistic pretreatment, and the method specifically comprises the following steps:
s1: weighing 12-15 parts of raw material powder, putting the raw material powder into a reaction bottle, beating paulownia into wood shavings, drying, crushing into fine particles by a crusher, sieving by a sieve of 80 meshes, and drying at the low temperature of 40-50 ℃ until the moisture content is less than 10% to obtain the raw material powder; adding an acetic acid solution with a material-liquid ratio of 1:8-12g/mL, wherein the mass concentration of the acetic acid solution is 3-4.5%, uniformly mixing, screwing a reaction bottle cap, putting the reaction bottle cap into a high-temperature oil bath kettle, setting the temperature of the high-temperature oil bath kettle to 165-175 ℃, keeping the high-temperature working time to 25-35min, taking out the reaction bottle after the reaction is finished, cooling to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, carrying out suction filtration washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying in a low-temperature oven to obtain dry powder A;
s2: weighing 10-12 parts of powder A, putting the powder A into a reaction bottle, and then adding an alkaline sodium sulfite solution with the material-liquid ratio of 1:8-12g/mL, wherein the alkaline sodium sulfite solution is a mixed solution containing 3.5-5% of sodium sulfite and 0.8-1.5% of sodium hydroxide; and (3) screwing a reaction bottle cap after uniform mixing, putting the reaction bottle cap into a high-temperature high-pressure sterilization pot, setting the temperature of the high-temperature high-pressure sterilization pot at 122 ℃, working for 55-65min, taking out the reaction product after the reaction is finished, cooling the reaction product to room temperature, pouring turbid liquid in the reaction bottle into a suction filtration funnel, performing suction filtration and washing by using distilled water, repeatedly cleaning and suction filtration until the extracted liquid is neutral, and drying at low temperature to obtain the pretreated lignocellulose raw material.
2. The method of claim 1, wherein the acetic acid pretreatment temperature is set to 170 ℃ and the treatment time is 30min in step S1, and the sodium hydroxide and sodium sulfite treatment temperature is 121 ℃ and the treatment time is 60min in step S2.
3. The method of claim 1, wherein the temperature of the low temperature drying in steps S1 and S2 is 40-50 ℃, and the moisture content of the dried powder is less than 10%.
4. The method of claim 1, wherein the concentration of acetic acid in the aqueous solution is 4% by weight.
5. The method of claim 1, wherein the alkaline sodium sulfite solution is a mixed solution comprising 4% sodium sulfite and 1% sodium hydroxide by mass.
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