Method for removing lignocellulose hydrolysate inhibitor by using chitosan

Abstract

The invention provides a method for removing a lignocellulose hydrolysate inhibitor by using chitosan, and belongs to the technical field of biomass processing and utilization, and the method comprises the following steps: soaking crushed poplar in a dilute acid solution according to a solid-to-liquid ratio of 1: 7, adding chitosan into the solution, and carrying out a high-temperature reaction; after the reaction is finished, cooling a reaction system to room temperature, and carrying out solid-liquid separation to obtain a pretreated solid and a diluted acid pretreatment solution; rinsing the pretreated solid, washing the substrate with distilled water until the pH value is close to neutral, and rinsing for three times to obtain a pretreated material; according to the method, chitosan is added in the pretreatment process, so that dilute acid pretreatment inhibitors are reduced, and meanwhile, the problems that fermentation inhibitors challenge microbial fermentation and the enzyme digestibility of pretreated solids is limited under various pretreatment intensities in dilute acid pretreatment are solved. And the characteristics of the pretreated material are improved, the cellulose accessibility is improved, the surface structure is improved, and better conditions are provided for further utilization of biomass.

Description

Technical Field

[0001] The invention relates to the technical field of biomass processing and utilization, and in particular to a method for in-situ removal of inhibitors in a lignocellulose pretreatment liquid by directly adding chitosan into a dilute sulfuric acid pretreatment. Background Art

[0002] As an abundant natural resource, lignocellulosic biomass consists of cellulose, hemicellulose and lignin, and is a potential sustainable raw material for the production of biofuels and high-value chemicals. Dilute acid pretreatment is a widely used biomass pretreatment technology. By treating lignocellulose with low concentration (<5%) of sulfuric acid or hydrochloric acid, it can decompose the stubborn structure of biomass and improve the efficiency of subsequent bioconversion. However, this technology has some problems that need to be solved:

[0003] On the one hand, microbial fermentation inhibitors produced during the pretreatment process, such as carbonyl compounds, weak acids and phenols, will seriously hinder the utilization of fermentable sugars in the pretreatment liquid by microorganisms. Among them, carbonyl compounds, especially aromatic aldehyde compounds, are the most toxic to microorganisms, and they inhibit the proliferation and normal metabolism of microorganisms by reacting with key proteins in the microbial metabolic pathway.

[0004] On the other hand, acid treatment can cause irreversible condensation of lignin in lignocellulose, forming a physical barrier to the enzymatic hydrolysis of the pretreated substrate, and working together with fermentation inhibitors to limit the enzymatic digestibility of the pretreated substrate. This hinders the subsequent enzymatic hydrolysis process and reduces the overall efficiency of biomass conversion.

[0005] A Chinese patent with publication number CN102719490B discloses a method for detoxifying wood fiber hydrolyzed sugar solution, which uses organic modified bentonite as an adsorbent to adsorb and remove hydrophobic inhibitors in the wood fiber hydrolyzed sugar solution; wherein the organic modified bentonite is bentonite modified with a cationic surfactant to make it hydrophobic.

[0006] Such existing technologies for detoxification using surfactants, activated carbon, bentonite, etc., have problems such as high additional processing costs, low universality for strains, poor detoxification effects, and poor product fermentability. Summary of the invention

[0007] The purpose of the present invention is to overcome the defects of the prior art in that the detoxification agent has high additional processing cost, low universality for strains, and limited detoxification effect, and provide a method for pretreatment using chitosan, which can avoid additional detoxification steps by directly adding chitosan in the pretreatment, thereby achieving in situ removal of inhibitors in lignocellulose pretreatment liquid.

[0008] In order to achieve the above objectives and other objectives, the present invention is implemented by the following technical solutions:

[0009] First, the present invention provides a method for removing inhibitors from lignocellulose hydrolysate by using chitosan, wherein chitosan is directly added to dilute acid pretreatment to remove inhibitors from lignocellulose hydrolysate in situ, comprising the following steps:

[0010] S1, soaking the crushed poplar wood in a dilute acid solution at a solid-liquid ratio of 1:7, adding chitosan to the solution, and reacting at high temperature;

[0011] S2, after the reaction is completed, the reaction system in step S1 is cooled to room temperature, and solid-liquid separation is performed to obtain chitosan-dilute acid pretreated solid and chitosan-dilute acid pretreated liquid;

[0012] S3, rinsing the chitosan-dilute acid pretreated solid obtained in step S2, washing the substrate with distilled water until the pH value is close to neutral, and performing the rinsing process three times to obtain the chitosan-dilute acid pretreated material.

[0013] In one embodiment, the dilute acid is dilute sulfuric acid.

[0014] In one embodiment, the concentration of the dilute sulfuric acid is 2% to 5%.

[0015] In one embodiment, the added amount of chitosan is 1% to 5%.

[0016] In one embodiment, the reaction temperature is 170° C. to 180° C., and the reaction time is 60 min.

[0017] In one embodiment, the viscosity of chitosan is 100-200 mPa, and the degree of deacetylation is greater than 95%.

[0018] Secondly, the present invention also provides another method for removing inhibitors from lignocellulose hydrolysate by using chitosan, wherein the method comprises the following steps:

[0019] S1, soaking the crushed poplar wood in a dilute acid solution at a solid-liquid ratio of 1:7 for high temperature reaction;

[0020] S2, after the reaction is completed, the reaction system in step S1 is cooled to room temperature, and the solid-liquid separation is performed to obtain a dilute acid pretreatment liquid;

[0021] S3, adjusting the pH of the dilute acid pretreatment solution obtained in step S2 to 6 with sodium hydroxide, adding chitosan and reacting at 80° C. to obtain a chitosan-detoxified dilute acid pretreatment solution.

[0022] In one embodiment, the dilute acid is dilute sulfuric acid, the concentration of the dilute sulfuric acid is 2% to 5%, and the added amount of chitosan is 1% to 4%.

[0023] In one embodiment, in step S1, the reaction temperature is 170° C. to 180° C., and the reaction time is 60 min.

[0024] In one embodiment, the viscosity of chitosan is 100-200 mPa, and the degree of deacetylation is greater than 95%.

[0025] The present invention reduces inhibitors generated by dilute acid pretreatment by adding chitosan during the pretreatment process or using chitosan for detoxification after pretreatment, and solves the challenges brought by fermentation inhibitors to subsequent microbial fermentation and the problem of limited enzyme digestibility of pretreated materials under dilute acid pretreatment at various pretreatment intensities. It also improves the characteristics of the pretreated substrate, increases the accessibility of cellulose, improves its surface structure, and provides better conditions for further utilization of biomass. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The results show the effect of chitosan detoxification on glucose consumption of Saccharomyces cerevisiae in the present invention.

[0027] Figure 2 The results show the effect of chitosan detoxification on the ethanol production of Saccharomyces cerevisiae in the present invention.

[0028] Figure 3 It shows the effect of adding chitosan in the pretreatment of the present invention on the glucose consumption of Saccharomyces cerevisiae in the dilute acid pretreatment liquid with different pretreatment intensities.

[0029] Figure 4 It shows the effect of adding chitosan in the pretreatment of the present invention on the ethanol yield of Saccharomyces cerevisiae in dilute acid pretreatment liquid with different pretreatment intensities.

[0030] Figure 5 It shows the effect of adding chitosan in the pretreatment of the present invention on the enzymatic hydrolysis process of the pretreated material.

[0031] Figure 6 It shows the effect of chitosan addition on the degree of lignin surface coverage in the pretreatment of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the embodiments.

[0033] Unless otherwise specified, all raw materials used in the examples are commercially available.

[0034] Example 1

[0035] This embodiment provides a method for removing inhibitors from a lignocellulose dilute acid pretreatment liquid by using chitosan for detoxification, comprising the following steps:

[0036] S1, 50g of crushed poplar wood was immersed in 3% sulfuric acid solution at a solid-liquid ratio of 1:7, and kept at 170°C for 60min, with the pressure controlled at 0.67Mpa;

[0037] S2, after the reaction is completed, the reaction system in step S1 is cooled to room temperature, and the liquid part obtained by solid-liquid separation is a dilute acid pretreatment liquid;

[0038] S3, adjusting the pH of the dilute acid pretreatment liquid obtained in step S2 to 6 with sodium hydroxide, adding chitosan to react at 80° C. to obtain a chitosan detoxified dilute acid pretreatment liquid, and storing the obtained chitosan detoxified dilute acid pretreatment liquid at 4° C. for further bioconversion.

[0039] In step S3, the viscosity of chitosan is 100-200 MPa, and the degree of deacetylation is greater than 95%.

[0040] Embodiment 2 to Embodiment 5

[0041] The difference between Examples 2 to 5 and Example 1 is that the amount of chitosan added is different.

[0042] Example 6

[0043] This embodiment provides a method for directly reducing inhibitors in a lignocellulose pretreatment liquid obtained by dilute acid pretreatment by directly adding chitosan to the dilute acid pretreatment, comprising the following steps:

[0044] S4, 50 g of the crushed poplar wood was immersed in a 3% sulfuric acid solution at a solid-liquid ratio of 1:7, and 4% (w / w) chitosan was added to the solution, and the solution was kept at 170° C. for 60 min, and the pressure was controlled to be 0.67 MPa;

[0045] S5, after the reaction is completed, the reaction system in step S4 is cooled to room temperature, and solid-liquid separation is performed to obtain a chitosan-dilute acid pretreated solid and a chitosan-dilute acid pretreated liquid;

[0046] S6, rinsing the pretreated solid obtained in step S5, washing the substrate with distilled water until the pH value is close to neutral, and then mixing it with a grinder for 10 seconds. The rinsing process is performed three times, and the obtained chitosan-dilute acid pretreated material is stored at 4° C. for further inspection and bioconversion.

[0047] In step S4, the viscosity of chitosan is 100-200 MPa, and the degree of deacetylation is greater than 95%.

[0048] Example 7

[0049] The only difference between this embodiment and embodiment 6 is that the concentration of the dilute acid is 4%.

[0050] Example 8

[0051] The difference between Example 8 and Example 6 is that the pretreatment temperature is 180° C. and the dilute acid concentration is 2%.

[0052] Comparative Example 1:

[0053] The difference between this comparative example and Examples 1 and 6 is that no chitosan is added during pretreatment and no detoxification step is performed.

[0054] Comparative Example 2:

[0055] The only difference between this comparative example and Example 7 is that chitosan is not added during pretreatment.

[0056] Comparative Example 3:

[0057] The only difference between this comparative example and Example 8 is that chitosan is not added during pretreatment.

[0058] The reaction conditions of the embodiments and comparative examples are shown in Table 1:

[0059] Table 1 Reaction conditions of examples and comparative examples

[0060]

[0061]

[0062] Results Analysis

[0063] Analysis Example 1: Effect of chitosan detoxification on the fermentation performance of dilute acid pretreated liquid

[0064] Saccharomyces cerevisiae was inoculated into the dilute acid pretreatment solution obtained in Examples 1 to 5 and Comparative Example 1 at 2.0 g / L, and fermented at 30°C and 150 rpm for 48 hours. During the fermentation process, sugar consumption and ethanol production were monitored at different time points such as 0, 3, 6, 12, 24, and 48 hours. The results are shown in FIG. Figure 1 and Figure 2 shown.

[0065] Depend on Figure 1 and Figure 2It can be seen that the dilute acid pretreatment liquid that was originally unable to ferment can achieve partial fermentation after the detoxification process of chitosan at a concentration of 1% and 2% (w / v) (Examples 1 and 2). Specifically, Saccharomyces cerevisiae can consume less than 10g / L of glucose and produce 2.55-3.00g / L of ethanol in the detoxified pretreatment liquid containing 18.11-18.95g / L of glucose. With the increase in the amount of chitosan added, when 3%, 4% and 5% (w / v) chitosan (Examples 3 to 5) are used in the detoxification, the original 17.32-19.53g / L of glucose in the pretreatment liquid can be completely converted to produce 7.80-8.60g / L of ethanol. This proves that different doses of chitosan produce different detoxification effects, indicating that chitosan can react proportionally with inhibitors in the pretreatment liquid, thereby achieving the detoxification effect.

[0066] Analysis Example 2: Effect of in-situ addition of chitosan on the fermentation performance of dilute acid pretreatment liquids with different concentrations

[0067] Saccharomyces cerevisiae was inoculated into the dilute acid pretreatment liquid obtained in Examples 6 to 8 and Comparative Examples 1 to 3 at 2.0 g / L, and fermented at 30° C. and 150 rpm for 48 hours. During the fermentation process, sugar consumption and ethanol production were monitored at different time points such as 0, 3, 6, 12, 24, and 48 hours.

[0068] Depend on Figure 3 and Figure 4 It can be seen that in the pretreatment without adding pretreatment at a pretreatment temperature of 170°C and a concentration of 3% and 4% H2SO4, the fermentation performance of the pretreatment liquid obtained was very poor, and the glucose consumed by Saccharomyces cerevisiae within 48 hours was less than 1g / L. However, in the dilute acid pretreatment at 170°C and 3% H2SO4 reaction conditions, 4% (w / w) chitosan was added, and 18.93g / L of glucose in the pretreatment liquid was completely consumed by Saccharomyces cerevisiae, and 8.62g / L of ethanol was produced. Similarly, after adding chitosan under the pretreatment conditions of 170°C and 4% H2SO4, the glucose in the pretreatment liquid was also successfully partially fermented by Saccharomyces cerevisiae, and the glucose consumption of the yeast increased from nearly zero to 10.42g / L (from 21.90g / L to 11.48g / L), and the ethanol production was 4.55g / L. The experimental results show that adding chitosan to the dilute acid pretreatment of poplar wood can achieve an excellent in-situ detoxification effect. Even if the dilute acid pretreatment conditions are harsh, the addition of chitosan can make the dilute acid pretreatment liquid that was originally unfermentable completely or partially fermented.

[0069] Analysis Example 3: Effect of Chitosan on Inhibitor Concentration in Dilute Acid Pretreatment Solution

[0070] The contents of monosaccharides and common fermentation inhibitors in the pretreated liquids of Example 6 and Comparative Example 1 were detected by HPLC and GC / MS, respectively. The results are shown in Tables 2 and 3.

[0071] Table 2 HPLC quantitative analysis of monosaccharides and common monosaccharide degradation products in pretreatment solution

[0072] Pretreatment liquid Glucose (g / L) Xylose(g / L) Arabinose(g / L) Formic acid(g / L) Acetic acid (g / L) Example 6 2.12 8.03 0.46 1.92 12.36 Comparative Example 1 3.35 9.60 0.65 0 15.11

[0073] The concentration of monosaccharides and common monosaccharide degradation products, such as formic acid and acetic acid, in the pretreatment liquid is an important representation of the pretreatment intensity. By observing them, it can be determined whether the addition of chitosan strongly inhibits the degradation of lignocellulose by pretreatment. As shown in Table 2, the concentrations of glucose and xylose in Example 6 (2.12 g / L and 8.03 g / L) are slightly lower than those in Comparative Example 1 (3.35 g / L and 9.60 g / L), but at the same time, the formic acid content in Example 6 (1.92 g / L) is 1.07 g / L more than that in Comparative Example 1 (0.85 g / L), and the acetic acid content is 2.76 g / L less (Comparative Example 1 is 15.11 g / L, and Example 6 is 9.60 g / L). This shows that chitosan, as an additive, does not reduce the release of monosaccharides and related degradation products related to the pretreatment intensity, and therefore does not reduce the content of fermentation inhibitors in the pretreatment liquid by inhibiting the hydrolysis process of the pretreatment. The specific inhibitor reduction is basically derived from the reaction between the inhibitor and chitosan.

[0074] Table 3 GC / MS quantitative analysis of carbonyl compounds in pretreatment solution

[0075]

[0076]

[0077] As shown in Table 3, the total content of carbonyl compounds in Comparative Example 1 decreased from 7522.84 mg / L to 3427.84 mg / L in Example 6, with a decrease of 54.43%. The fermentation performance of the pretreatment liquid was greatly improved, which proved that the addition of chitosan greatly reduced the presence of carbonyl compounds in the pretreatment liquid, thereby achieving a good in-situ detoxification effect of the pretreatment liquid. Taking the three carbonyl compounds with the most prominent decrease as an example, the contents of 1-(4-hydroxy-3,5-dimethoxyphenyl)propane-1,2-dione, isobutylaldehyde and (4-hydroxy-3,5-dimethoxybenzoyl)acetaldehyde in the pretreatment liquid of Example 6 were respectively reduced from 363 mg / L, 45.92 mg / L and 71.92 mg / L in Comparative Example 1 to 20.51 mg / L, 10.31 mg / L and 16.29 mg / L, with decreases of 94%, 78% and 77%, respectively. Furfural, vanillin and its two derivatives 5-methylfurfural and homovanillin are considered to have a significant inhibitory effect on the fermentation of pretreatment liquid.

[0078] After adding chitosan in the present application, these four compounds were reduced from 5821mg / L, 165.93mg / L, 181.25mg / L and 58.09mg / L to 2427.08mg / L, 86.93mg / L, 134.49mg / L and 15.62mg / L, respectively, and the effective removal rates were 58%, 48%, 26% and 73%, respectively. This is consistent with the improvement of the fermentation performance in the analysis example 1, and the reduction of the content of these key carbonyl compounds is the reason why the fermentation performance of the chitosan-added pre-treated liquid is greatly improved. In addition, 5-hydroxymethylfurfural (HMF) is considered to have a relatively low inhibitory effect, which may explain why the HMF content (325.72mg / L) in Example 6 is 28% higher than that in Comparative Example 1 (254.14mg / L), but the fermentation performance of Example 6 is still significantly higher than that in Comparative Example 1. In addition, except for the less toxic phenol (content increased by 48%), which did not show a significant decrease in content, the content of 2,5-furan carboxaldehyde also increased by 8%. The structure of this aldehyde is similar to the chemical structure of the known more toxic cinnamaldehyde, but it may be that its content in Comparative Example 1 (58.62 mg / L) and Example 6 (63.02 mg / L) is low and equivalent, so it does not have much effect on the fermentability of the pretreatment liquid. In addition, the contents of the other 9 carbonyl compounds measured in Table 3 are also reduced to varying degrees (9%-73%). Therefore, the main role of chitosan additives in the dilute acid pretreatment process is to reduce the generation of carbonyl compounds in the pretreatment liquid, and it is a high-quality in-situ detoxification agent in lignocellulose pretreatment.

[0079] Analysis Example 4: Effect of chitosan addition on enzymatic hydrolysis performance of dilute acid pretreated materials

[0080] First, the chemical composition and cellulose accessibility of the pretreatment solution in Example 6 and Comparative Example 1 were detected, wherein the cellulose accessibility was detected by exposing the lignocellulosic material to direct red dye at 50°C and 150rpm for 24 hours, with a substrate concentration of 1% (w / v), and measuring the absorbance of the supernatant after centrifugation in the sample and reference solution by UV-vis at 498nm, and establishing a fitted Langmuir absorbance isotherm based on the corresponding adsorbed dye to evaluate the maximum adsorption amount of the dye as a substrate cellulose accessibility. The results are shown in Table 5.

[0081] Table 5 Chemical composition and accessibility of pretreated materials

[0082]

[0083] The xylan content in the original poplar wood is 15.31%, and after dilute acid pretreatment without and with chitosan, the xylan content in Comparative Example 1 and Example 6 is reduced to 2.76% and 2.07%, respectively, which shows that even with the addition of chitosan, the dilute acid pretreatment is very efficient in removing hemicellulose. In addition, the glucan and xylan content in Comparative Example 1 (63.04%, 2.06%) and the glucan and xylan content in Example 6 (57.85%, 2.72%) are similar. It is verified again that the addition of chitosan does not affect the originally high pretreatment intensity of dilute acid pretreatment. In addition, the addition of chitosan during dilute acid pretreatment can increase the ethanol extract content from 3.86% to 4.41%. It is possible to speculate that the enzymatic hydrolysis efficiency of Example 6 may be higher than that of Comparative Example 1 due to its higher ethanol extract content. In addition, the chemical composition analysis of the pretreated material also shows that although the contents of acid-soluble lignin and acid-insoluble lignin in Comparative Example 1 and Example 6 are very similar, the delignification rate of Example 6 (25.37%) is higher than that of Comparative Example 1 (23.62%). It can also be inferred that the addition of chitosan in the pretreatment may help remove lignin during the pretreatment process.

[0084] Therefore, the presence of chitosan can protect xylan from further decomposition to a certain extent. However, the significant difference in furfural concentrations may still be mainly due to the "in situ detoxification" effect of chitosan during pretreatment.

[0085] Secondly, the enzymatic hydrolysis yield of the pretreatment solution in Example 6 and Comparative Example 1 was analyzed: Novozym 22C 10FPIU / g glucanase (filter paper enzyme activity: 92FPIU / g, β-glucosidase activity: 343IU / mL) was used for enzymatic hydrolysis. The enzymatic hydrolysis conditions were 2% (w / v) glucanase, 50mL system, pH 4.8, sodium citrate buffer, and the reaction was carried out on a shaker at 50°C and 150rpm for 72h, and the operation was repeated. The hydrolyzed samples were extracted at different time points (0, 3, 6, 12, 24, 48 and 72h) and analyzed by high performance liquid chromatography to determine the amount of glucose produced during the enzymatic hydrolysis process.

[0086] The results are as follows Figure 5 As shown, the cellulose enzymatic hydrolysis efficiency of the pretreated liquid in Example 6 was increased from 32.72% to 41.50%, with an increase of up to 26.83%.

[0087] Analysis Example 5: Effect of chitosan addition on the physicochemical properties of dilute acid pretreated materials

[0088] XPS analysis of the dilute acid pretreated solids was performed using an AXIS UltraDLD from Kratos Analytical, Manchester, UK, using a monochromatic Al-Ka radiation source and a hybrid trough lens configuration with a coverage area of ​​approximately 300mm×700mm. The residual lignin content was quantified by analyzing the aliphatic carbon area, and the degree of lignin surface coverage was inferred from the oxygen-to-carbon ratio (O / C). The results are shown in Figure 6 As shown in Figure 2, after adding chitosan, the proportion of carbon-carbon bonds (CC) on the surface of the material increased from 33.55% ( Figure 6 b) rose to 43.33% ( Figure 6 a), while the total proportion of carbon-oxygen double bonds (C=O) and carbon-oxygen single bonds (CO) increased from 66.45% ( Figure 6 b) decreased to 56.67% ( Figure 6 a). The presence of C=O and CO characterizes the presence of polysaccharides (cellulose and hemicellulose) in the pretreated material, while CC bonds are related to the lignin content on the surface of the pretreated material.

[0089] Therefore, the changes in the elemental composition of the surface of the pretreated materials after adding chitosan showed that the lignin content on the surface of the materials increased, while the cellulose and hemicellulose contents decreased. Figure 6 c shows the XPS total spectrum showing the changes in the types of elements on the surface of the pretreated material. In the full spectrum of Example 6, a new nitrogen peak appeared near 400 eV. Based on the common chemical composition of lignocellulose, this new nitrogen peak indicates that the chitosan fragment may react to the pretreated material under high temperature and pressure conditions, which may be derived from the addition reaction of the chitosan fragment on the lignin unit during the pretreatment process.

[0090] In summary, the present invention reduces the inhibitors of dilute acid pretreatment by detoxifying chitosan pretreated with dilute acid and directly adding chitosan during the pretreatment process, while solving the challenges of fermentation inhibitors to microbial fermentation and the problem of limited enzyme digestibility of pretreated materials under various pretreatment intensities of dilute acid pretreatment. It also improves the characteristics of the pretreated substrate, increases the accessibility of cellulose, improves the surface structure of the pretreated material, and provides better conditions for the further utilization of biomass.

Claims

1. A method for removing inhibitors from lignocellulose hydrolysate by using chitosan, characterized in that: The following steps are involved: S1, soaking the crushed poplar wood in a dilute acid solution at a solid-liquid ratio of 1:7, adding chitosan to the solution, and reacting at high temperature; S2, after the reaction is completed, the reaction system in step S1 is cooled to room temperature, and solid-liquid separation is performed to obtain chitosan-dilute acid pretreated solid and chitosan-dilute acid pretreated liquid; S3, rinsing the chitosan-dilute acid pretreated solid obtained in step S2, washing the substrate with distilled water until the pH value is close to neutral, and performing the rinsing process three times to obtain the chitosan-dilute acid pretreated material.

2. The method for removing inhibitors from lignocellulose hydrolysate by using chitosan according to claim 1, characterized in that: The dilute acid is dilute sulfuric acid.

3. The method for removing inhibitors from lignocellulose hydrolysate by using chitosan according to claim 2, characterized in that: The concentration of the dilute sulfuric acid is 2% to 5%.

4. The method for removing inhibitors from lignocellulose hydrolysate by using chitosan according to claim 3, characterized in that: The added amount of the chitosan is 1% to 5%.

5. The method for removing inhibitors from lignocellulose hydrolysate by using chitosan according to claim 4, characterized in that: The reaction temperature is 170°C to 180°C, and the reaction time is 60 minutes.

6. The method for removing inhibitors from lignocellulose hydrolysate by using chitosan according to claim 1, characterized in that: The viscosity of chitosan is 100-200 MPa, and the degree of deacetylation is greater than 95%.

7. A method for removing inhibitors from lignocellulose hydrolysate using chitosan, characterized in that: The following steps are involved: S1, soaking the crushed poplar wood in a dilute acid solution at a solid-liquid ratio of 1:7 for high temperature reaction; S2, after the reaction is completed, the reaction system in step S1 is cooled to room temperature, and the solid-liquid separation is performed to obtain a dilute acid pretreatment liquid; S3, adjusting the pH of the dilute acid pretreatment solution obtained in step S2 to 6 with sodium hydroxide, adding chitosan and reacting at 80° C. to obtain a chitosan-detoxified dilute acid pretreatment solution.

8. The method for removing inhibitors from lignocellulose hydrolysate by using chitosan according to claim 7, characterized in that: The dilute acid is dilute sulfuric acid, the concentration of the dilute sulfuric acid is 2% to 5%, and the added amount of the chitosan is 1% to 4%.

9. The method for removing inhibitors from lignocellulose hydrolysate by using chitosan according to claim 7, characterized in that: In step S1, the reaction temperature is 170°C to 180°C, and the reaction time is 60 minutes.

10. The method for removing inhibitors from lignocellulose hydrolysate by using chitosan according to claim 7, characterized in that: The viscosity of chitosan is 100-200 MPa, and the degree of deacetylation is greater than 95%.

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