CN109024031A - The method that steam blasting combination ultrasonic treatment prepares peanut shell nano-cellulose - Google Patents

Abstract

The invention belongs to the field of biomass nanomaterials, and in particular relates to a method for preparing nanocellulose by using peanut shells as raw materials and utilizing steam explosion combined with ultrasound. The method of the invention prepares the nanocellulose through steam explosion, sodium chlorite bleaching, enzymolysis treatment, ultrasonic treatment, centrifugation and freeze-drying. The preparation process of the present invention is simple and easy, the consumption of chemicals is small, and the yield is high, which is suitable for large-scale industrial production. The prepared nanocellulose has uniform particle size distribution, large aspect ratio and high crystallinity. The invention fully utilizes the thermomechanical chemical effect of steam explosion to effectively remove most of the hemicellulose and lignin, and utilizes the mechanical dispersion and cavitation effect of ultrasound to efficiently and rapidly prepare nanofibers. In the invention, peanut shells are used to replace traditional high-cost raw materials such as cotton or flax, which can not only increase the added value of peanut deep processing, but also reduce the production cost of nanocellulose.

Description

Method for preparing peanut shell nanocellulose by steam explosion combined with ultrasonic treatment

technical field

The invention belongs to the field of biomass nanomaterials, and in particular relates to a method for preparing nanocellulose by using peanut shells as raw materials and utilizing steam explosion combined with ultrasound.

Background technique

Nanocellulose is to remove the amorphous region and low crystallinity crystalline region in cellulose, and extract a cellulose crystal with a nanometer size (1-100nm). It has excellent mechanical properties, large specific surface area, high crystallinity, high hydrophilicity, high transparency, low density, good biodegradability and biocompatibility, and stable chemical properties, and can be widely used in biopharmaceuticals , food processing, functional materials, cosmetics and paper making and other fields.

Peanut is one of the three major oil crops in my country. As a by-product in the processing process, peanut shell has an annual output of about 5 million tons. At present, except for a small amount used as feed, most of the peanut shells are directly discarded or burned, resulting in waste of resources and environmental pollution. Peanut shells contain a large amount of cellulose. The use of peanut shells to prepare nanocellulose not only has low raw material prices, but also can replace high-cost cotton, flax, etc., and is conducive to the deep processing of agricultural and sideline products and the treatment of waste, bringing huge economic benefits. At the same time, it can reduce environmental pollution and open up a new way for the comprehensive utilization of peanuts.

At present, the preparation of nanocellulose mainly adopts the acid hydrolysis method, but this method consumes a large amount of acid and water, causing serious chemical pollution and high cost. Steam explosion technology is a physical method developed in recent years to separate plant fibers, which has the advantages of high efficiency, low cost, no pollution, short processing time, and less chemical consumption. After the cellulose raw material is steam-exploded, the structure is fluffy, the molecules are degraded, and the hemicellulose and lignin are easily removed. Ultrasonic treatment is a physical method with good mechanical dispersion and cavitation effects. The mechanical vibration energy and vibration waves formed by it can effectively destroy biomass fibers and decompose them into nanofibers. However, the method of steam explosion combined with ultrasonic treatment to prepare peanut shell nanocellulose is rarely reported.

Liu Xiao published "Preparation and Characterization of Peanut Shell Nanocellulose and Its Effect on Starch Film Properties" in his master's degree thesis of Shandong Agricultural University. The paper used peanut shell as raw material and prepared peanut shell nanocellulose Cellulose, through scanning electron microscopy, transmission electron microscopy, infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, etc., the peanut shell nanocellulose was characterized and analyzed, and the optimal conditions for acid hydrolysis to prepare peanut shell nanocellulose were obtained. The disadvantage of this method is that a large amount of acid and water will be consumed, the chemical pollution is serious, and the cost is high.

Therefore, it is necessary to improve the defects of the above-mentioned technical solutions, and invent a method for preparing peanut shell nanocellulose that is pollution-free, has short processing time, and consumes less chemicals.

Contents of the invention

In order to solve the above technical problems, the present invention provides a method for preparing peanut shell nanocellulose by combining steam explosion and ultrasonic treatment.

The present invention is achieved through the following technical solutions:

The method for preparing peanut shell nanocellulose by steam explosion in combination with ultrasonic treatment comprises the following steps:

(1) Pretreatment: cleaning raw material peanut shells, drying, crushing, and sieving to obtain peanut shell powder;

(2) Add water to the peanut shell powder in (1), place it in a steam explosion chamber after swelling, steam explosion, wash with hot water and filter, and retain the obtained filter residue;

(3) Adjust the pH of the filter residue in (2) to 4-6, add NaClO ₂ , keep a constant temperature water bath, stir, wash until neutral, and then filter to obtain a secondary filter residue;

(4) placing the secondary filter residue in a buffer solution, adding cellulase for hydrolysis, and inactivating the enzymatic solution;

(5) Ultrasonic treatment of the enzymolysis solution after deactivating the enzyme;

(6) Centrifuge the ultrasonically treated material in (5), collect the supernatant, and freeze-dry to obtain peanut shell nanocellulose powder.

Specifically, the method for preparing peanut shell nanocellulose by steam explosion in combination with ultrasonic treatment comprises the following steps:

(1) Pretreatment: Wash the peanut shell raw material with deionized water, dry, pulverize, and pass through a 100-mesh sieve;

(2) Steam explosion: add water to adjust the water content of the peanut shell powder described in step (1) to be 5-60wt%, swell for 12-24h, then place the material in the steam explosion chamber, and set the steam explosion pressure to 0.5-3.0MPa , the time is set to 20-100s, after the blasting treatment, wash with hot water at 50-70°C and filter, and the filter residue is peanut shell fiber from which most of the hemicellulose and lignin have been removed;

(3) Sodium chlorite bleaching: the filter residue obtained in step (2) and deionized water are placed in the reaction kettle according to the ratio of 1g to 20mL of mass-to-liquid ratio of material to liquid, and the pH of the solution is adjusted to 4-5 by acetic acid, and 15g/ L of NaClO2, in a constant temperature water bath at 40-60°C, stirring for 4-6 hours, washing the filter residue to neutrality and then filtering, the filter residue is peanut shell fiber from which residual hemicellulose and lignin have been removed;

(4) Enzymolysis treatment: use the disodium hydrogen phosphate-citric acid buffer solution with pH of 4-5 to make the peanut shell fiber obtained in step (3) into a 1-10wt% aqueous dispersion, add cellulase, and the amount of enzyme 500-4000U/g, placed in a constant temperature water bath at 40-60°C, stirred for 3-6 hours, and then boiled in a water bath for 10-20 minutes to inactivate the enzyme;

(5) Ultrasonic treatment: ultrasonically treat the peanut shell fiber enzymatic solution obtained in step (4) for 30-90min in an ice-water bath, the ultrasonic power is 1500-2000W, and the ultrasonic frequency is 20kHz;

(6) Centrifugation and freeze-drying: centrifuge the ultrasonically treated solution in step (5) at 10,000 r/min for 5-15 minutes, collect the supernatant, and freeze-dry the supernatant to obtain peanut shell nanocellulose powder.

The beneficial effects of the present invention are:

(1) The present invention uses peanut shells as raw material, which has rich sources and low price, not only replaces high-cost raw materials such as cotton and flax, but also effectively utilizes the by-products of peanut processing, which can generate huge economic and social benefits;

(2) The nanocellulose prepared by the present invention utilizes the method of steam explosion technology and ultrasonic treatment, which uses less chemical reagents and short processing time, and has the significant advantages of high efficiency and low cost;

(3) The nanocellulose prepared by the present invention has a diameter of 5-30nm and a length of 100-200nm, has excellent mechanical properties and biocompatibility, has high crystallinity, large aspect ratio, and large specific surface area, and can be widely used In the fields of medicine, food and functional materials.

Description of drawings

Fig. 1 is its suspension of peanut shell nanocellulose obtained in embodiment 1;

Fig. 2 is the scanning electron micrograph (2 μm) of the peanut shell nanocellulose obtained in embodiment 1;

Fig. 3 is the scanning electron micrograph (500nm) of the peanut shell nanocellulose obtained in embodiment 1;

Fig. 4 is the transmission electron micrograph (100nm) of the peanut shell nanocellulose obtained in embodiment 1;

Fig. 5 is the transmission electron micrograph (50nm) of the peanut shell nanocellulose obtained in embodiment 1;

Fig. 6 is the infrared spectrogram of peanut shell cellulose (a) and peanut shell nanocellulose (b);

Fig. 7 is the TG/DTG curve of peanut shell cellulose (a);

Figure 8 is the TG/DTG curve of peanut shell nanocellulose (b).

Detailed ways

The present invention will be further described below in conjunction with specific embodiments, so that those skilled in the art can better understand the present invention, but the present invention is not limited thereby.

Example 1

The method for preparing peanut shell nanocellulose by steam explosion in combination with ultrasonic treatment comprises the following steps:

(1) Pretreatment: Wash the peanut shell raw material with deionized water, dry, pulverize, and pass through a 100-mesh sieve to obtain peanut shell powder;

(2) steam explosion: add water to adjust the water content of the peanut shell powder described in step (1) to be 45wt%, and swell for 16h, then place the material in the steam explosion chamber, set the steam explosion pressure to 0.5MPa, and the time is 100s, After the blasting treatment, wash with hot water at 70°C and filter, and the resulting primary filter residue is peanut shell fiber from which most of the hemicellulose and lignin have been removed;

(3) Sodium chlorite bleaching: put the primary filter residue and deionized water obtained in step (2) in a reaction kettle at a material-to-liquid ratio of 1:20 (g/mL), adjust the pH of the solution to 4 with acetic acid, and add 15g /L of NaClO ₂ , in a constant temperature water bath at 40°C, stirred for 4 hours, filtered, and the resulting secondary filter residue was washed until neutral and then filtered. The secondary filter residue was peanut shell fiber from which residual hemicellulose and lignin were removed;

(4) Enzymolysis treatment: use the disodium hydrogen phosphate-citric acid buffer solution with pH of 4 to make the secondary filter residue obtained in step (3) into a 2wt% aqueous dispersion, add cellulase, and the enzyme consumption is 2000U/g , placed in a constant temperature water bath at 45°C, stirred for 5 hours, and then boiled in water for 20 minutes to inactivate the enzyme;

(5) Ultrasonic treatment: ultrasonically treat the peanut shell fiber enzymatic solution obtained in step (4) for 30 minutes in an ice-water bath, the ultrasonic power is 1500W, and the ultrasonic frequency is 20kHz;

(6) Centrifugation and freeze-drying: centrifuge the ultrasonically treated solution in step (5) at 10,000 r/min for 5 minutes, collect the supernatant, and freeze-dry the supernatant to obtain peanut shell nanocellulose powder.

Scanning electron microscope and transmission electron microscope analysis are carried out to the product in embodiment 1, scanning electron microscope analysis adopts scanning electron microscope to observe the morphology of sample, takes test sample and carries out gold-spraying treatment, observes.

Get the product in Example 1 and be mixed with the suspension of 1% weight percent (i.e. the sample in accompanying drawing 1), draw an appropriate amount of sample liquid and drop on the copper grid with a pipette gun, dry at room temperature, then adopt transmission electron microscope to observe its The microscopic shape and particle size, the acceleration voltage is 100KV, and the transmission electron microscope image is shown in Figure 4.

Fig. 1 is the picture of the peanut shell nanocellulose powder suspension of embodiment 1;

From the scanning electron microscope (Fig. 2-3) and the transmission electron microscope (Fig. 3-4) figures, it can be seen that the peanut shell nanocellulose prepared by the present invention presents a rod-like structure, and the peanut shell cellulose has an amorphous region and a small amount of crystalline region under the action of ultrasound. After being destroyed, the peanut shell cellulose is reduced from a micrometer size to a nanometer size, and the peanut shell nanocellulose has a diameter of 5-30nm and a length of 100-400nm.

From the infrared spectrum (Figure 4), it can be seen that the absorption peak at 897cm ^-1 comes from the deformation of glycosidic bond C ₁ -H caused by ring vibration and OH bending vibration, which is the characteristic peak of β-glycosidic bond between cellulose anhydroglucose units . The peak at 1058cm ^-1 corresponds to the stretching vibration of ether bonds in cellulose, and the peak of nanocellulose becomes slightly smaller here, which is due to a small amount of hydrolysis of cellulose during the ultrasonic process, resulting in the reduction of ether bonds. The peak at 1635cm ^-1 corresponds to water, because there are a large number of hydroxyl groups in the cellulose structure, which has strong water absorption. It can be seen that the peak corresponding to nanocellulose here is larger, indicating that its water absorption is stronger. Near 2903cm ^-1 , the nanocellulose obviously has a double-peak structure, which corresponds to the stretching vibration of the methyl group and methylene group, because the ultrasonic treatment makes the cellulose partially hydrolyzed, and the molecular chain is shortened. The restraint is weakened, and its activity is increased. The peak at 3340cm ^-1 corresponds to the stretching vibration peak of the hydroxyl group. It can be seen that the peak shape of the nanocellulose is wider here, indicating that the hydrogen bonds are increased here, because the specific surface area of the nanocellulose increases and more hydroxyl groups are exposed. , easy to contact with water to form more hydrogen bonds.

From the TG/DTG curve (Figure 5), it can be seen that the initial pyrolysis temperatures of peanut shell cellulose and peanut shell nanocellulose are 230°C and 180°C, respectively, and the initial pyrolysis temperature of nanocellulose is lower because nanofibers The larger specific surface area of cellulose makes it more exposed to heat, which promotes the pyrolysis of nanocellulose. It can be seen from the DTG curve that the temperature corresponding to the maximum thermal weight loss rate of nanocellulose is about 290°C, which is lower than 330°C of cellulose, and the maximum thermal weight loss rate of nanocellulose is significantly higher than that of cellulose, because nanocellulose is exposed to heat. The larger the area, the faster the pyrolysis. When the temperature reaches 500°C, nanocellulose has a higher residual rate of 44.5% compared to cellulose with a residual rate of 31.4%.

The product comparative table that the product of the present invention and acid hydrolysis obtain of table 1

sample Total production time (h) chemical reagent Cost (yuan/500g) acid hydrolysis 57 acid 21629 Example 1 29.5 / 11564

Can find out by the data comparison in the above table, with respect to acid hydrolysis, its total production time of the method of the present invention will reduce nearly half (about 48.2%), and the cost saving of every catty is about 46.5%; And the present invention The most significant advantage is that a large amount of acid reagents are not introduced in the reaction process, and subsequent waste liquid treatment is not required, which is environmentally friendly and also saves the cost of waste liquid treatment.

Example 2

The method for preparing peanut shell nanocellulose by steam explosion in combination with ultrasonic treatment comprises the following steps:

(1) Pretreatment: Wash the peanut shell raw material with deionized water, dry, pulverize, and pass through a 100-mesh sieve to obtain peanut shell powder;

(2) steam explosion: add water to adjust the water content of the peanut shell powder described in step (1) to be 50wt%, swell for 18h, then place the material in the steam explosion chamber, set the steam explosion pressure to 1.5MPa, and the time to be 80s, After the blasting treatment, wash with hot water at 65°C and filter to obtain a primary filter residue, which is peanut shell fiber from which most of the hemicellulose and lignin have been removed;

(3) Sodium chlorite bleaching: put the primary filter residue and deionized water obtained in step (2) in a reaction kettle at a material-to-liquid ratio of 1:20 (g/mL), adjust the pH of the solution to 4 with acetic acid, and add 15g /L NaClO2, in a constant temperature water bath at 45°C, stir for 4 hours, wash the filter residue to neutrality and then filter, the filter residue is peanut shell fiber from which residual hemicellulose and lignin have been removed;

(4) Enzymolysis treatment: use the disodium hydrogen phosphate-citric acid buffer solution with pH 4.6 to make the secondary filter residue obtained in step (3) into a 5wt% aqueous dispersion, add cellulase, and the enzyme dosage is 1000U/g , placed in a constant temperature water bath at 60°C, stirred for 6 hours, then boiled for 15 minutes to inactivate the enzyme;

(5) Ultrasonic treatment: ultrasonically treat the peanut shell fiber enzymatic solution obtained in step (4) for 45 minutes in an ice-water bath, the ultrasonic power is 1600W, and the ultrasonic frequency is 20kHz;

(6) Centrifugation and freeze-drying: centrifuge the ultrasonically treated solution in step (5) at 10,000 r/min for 10 minutes, collect the supernatant, and freeze-dry the supernatant to obtain peanut shell nanocellulose powder.

Example 3

The method for preparing peanut shell nanocellulose by steam explosion in combination with ultrasonic treatment comprises the following steps:

(1) Pretreatment: Wash the peanut shell raw material with deionized water, dry, pulverize, and pass through a 100-mesh sieve to obtain peanut shell powder;

(2) steam explosion: add water to adjust the water content of the peanut shell powder gained in step (1) to be 55wt%, and swell for 20h, then place the material in the steam explosion chamber, set the steam explosion pressure to 2.5MPa, and the time is 60s, After the blasting treatment, wash with hot water at 60°C and filter to obtain a primary filter residue, which is peanut shell fiber from which most of the hemicellulose and lignin have been removed;

(3) Sodium chlorite bleaching: put the primary filter residue obtained in step (2) and deionized water in a reaction kettle at a material-to-liquid ratio of 1:20 (g/mL), adjust the pH of the solution to 4.5 with acetic acid, and add 15g /L of NaClO2, in a constant temperature water bath at 60°C, stirred for 6 hours, filtered to obtain a secondary filter residue, washed to neutral and then filtered, the filter residue is peanut shell fiber from which residual hemicellulose and lignin have been removed;

(4) Enzymolysis treatment: use the disodium hydrogen phosphate-citric acid buffer solution with pH of 4.4 to make the secondary filter residue obtained in step (3) into a 7wt% aqueous dispersion, add cellulase, and the enzyme dosage is 3000U/g , placed in a constant temperature water bath at 55°C, stirred for 4 hours, and then boiled in water for 18 minutes to inactivate the enzyme;

(5) Ultrasonic treatment: ultrasonically treat the peanut shell fiber enzymatic solution obtained in step (4) for 60 minutes in an ice-water bath, the ultrasonic power is 1800W, and the ultrasonic frequency is 20kHz;

(6) Centrifugation and freeze-drying: centrifuge the ultrasonically treated solution in step (5) at 10,000 r/min for 10 minutes, collect the supernatant, and freeze-dry the supernatant to obtain peanut shell nanocellulose powder.

Example 4

The method for preparing peanut shell nanocellulose by steam explosion in combination with ultrasonic treatment comprises the following steps:

(1) Pretreatment: Wash the peanut shell raw material with deionized water, dry, pulverize, and pass through a 100-mesh sieve;

(2) Steam explosion: add water to adjust the steps (1) The water content of the peanut shell powder is 60wt%, swelling for 24h, then the material is placed in the steam explosion chamber, the steam explosion pressure is set to 3.0MPa, and the time is 20s, blasting treatment Finally, wash with hot water at 50°C and filter to obtain a primary filter residue, which is peanut shell fiber from which most of the hemicellulose and lignin have been removed;

(3) Sodium chlorite bleaching: put the primary filter residue obtained in step (2) and deionized water in a reaction kettle at a material-to-liquid ratio of 1:20 (g/mL), use acetic acid to adjust the pH of the solution to 5, and add 15g/mL L of NaClO2, in a constant temperature water bath at 60°C, stirred for 6 hours, filtered to obtain a secondary filter residue, washed to neutral and then filtered, the filter residue is peanut shell fiber from which residual hemicellulose and lignin have been removed;

(4) Enzymolysis treatment: use the disodium hydrogen phosphate-citric acid buffer solution with pH 5 to make the secondary filter residue obtained in step (3) into a 10wt% aqueous dispersion, add cellulase, and the enzyme dosage is 4000U/g , placed in a constant temperature water bath at 60°C, stirred for 5.8 hours, and then boiled in a water bath for 20 minutes to inactivate the enzyme;

(5) Ultrasonic treatment: use deionized water to make the peanut shell fiber obtained in step (4) into a 2.0wt% water dispersion, soak for 24h, then ultrasonically treat in an ice-water bath for 90min, the ultrasonic power is 2000W, and the ultrasonic frequency is 20kHz ;

(6) Centrifugation and freeze-drying: centrifuge the ultrasonically treated solution in step (5) at 10,000 r/min for 15 minutes, collect the supernatant, and freeze-dry the supernatant to obtain peanut shell nanocellulose powder.

Example 5

The product in embodiment 1-4 has carried out the test of aspect crystallinity, mechanical property, and concrete test method is as follows:

Observe the crystal structure of the sample through X-ray diffraction analysis. Take an appropriate amount of dried sample and put it into the X-ray diffraction tank. The diffraction angle 2θ range of the sample test is 5-40°, the test speed is 0.02°/s, The test is calculated as follows:

CrI=(I ₀₀₂ −I _am )/I ₀₀₂ ×100;

CrI is crystallinity, I ₀₀₂ is 2θ=22.8° diffraction intensity, I _am is 2θ=18° diffraction peak intensity.

Membrane preparation:

Prepare to weigh 5g of oxidized-esterified tapioca starch and dissolve it in 100mL of deionized water, add glycerin accounting for 30% of the mass of tapioca starch as a plasticizer, and add peanut shell nanocellulose at the same time, place it in a constant temperature water bath at 80°C, and use a magnetic stirrer at 450r /min water bath stirring for 30 minutes and high-speed disperser (24000r/min) homogenization for 2 minutes, gelatinization to form a uniform film solution, and the film-forming solution is degassed for 20 minutes under a vacuum of 0.09MPa to drive out the bubbles in the film-forming solution to prevent The formed membrane is porous. Weigh the film-forming solution at 0.15g/ ^cm2 and cast it on a glass plate coated with polytetrafluoroethylene film, place it in an electric blower drying oven, bake it at 50°C for 4 hours, and then take out the film for later use;

Regarding the detection of the film, it is mainly to detect its TS and E, namely the tensile strength and elongation at break;

The inventors cut the film into long strips, and then used a physical property tester to detect the mechanical properties of the film.

The tensile strength and elongation at break were calculated as follows:

TS=Lp/a×10 ^-6

E=△L/L×100%;

In the formula, TS is the tensile strength/MPa; Lp is the maximum tension/N when the membrane breaks, and a is the effective area of the membrane/m ² ;

E is the elongation at break % of the film, △L is the increase in length when the film breaks/mm, and L is the effective length of the film/mm;

The crystallinity of table 2 embodiment 1-4

Crystallinity (%) peanut shell fiber 69.45 Example 1 71.88 Example 2 71.92 Example 3 71.74 Example 4 71.83

As can be seen from the data in the above tables, compared with peanut shells, the crystallinity of the products in Examples 1-4 of the present invention is higher, mainly due to the adoption of the steam explosion treatment and ultrasonic combination process of the present invention, hydrogen ions enter the fiber The plain amorphous region breaks the hydrogen bond, and at this time, the amorphous region ruptures to generate some water-soluble substances, so that the crystallinity of the peanut shell nanocellulose is effectively improved.

The product tensile strength (MPa) detection in the embodiment 1-4 of table 3

Fiber Addition Example 1 Example 2 Example 3 Example 4 4% 8.75 8.81 8.79 8.83 5% 10.26 10.32 10.23 10.25 6% 11.48 11.44 11.38 11.42 7% 9.95 9.87 9.84 9.91

The product elongation at break detection in the embodiment 1-4 of table 4

The above embodiment is one of the more preferred specific implementations of the present invention, and common changes and substitutions made by those skilled in the art within the scope of the technical solution shall be included in the protection scope of the present invention.

Claims (9)

1. the method that steam blasting combination ultrasonic treatment prepares peanut shell nano-cellulose, includes the following steps:

(1) pre-process: cleaning raw material peanut shell is dried, is crushed, and sieving obtains peanut shell powder；

(2) add water in peanut shell powder in (1), swollen is placed on steam explosion chamber, steam blasting, and hot water is washed and filtered, and retains institute The filter residue obtained；

(3) filter residue in (2) is adjusted into pH to 4-6, NaClO is added₂, water bath with thermostatic control, stirring, washing obtains two to filtering after neutrality Secondary filter residue；

(4) secondary filter residue is placed in buffer solution, cellulose hydrolyzation is added, to enzymolysis liquid enzyme deactivation；

(5) enzymolysis liquid ultrasonication after enzyme deactivation；

(6) material after ultrasonic treatment in (5) is centrifuged, collects supernatant, freeze-drying obtains peanut shell nano-cellulose powder End.

2. the method that steam blasting combination ultrasonic treatment as described in claim 1 prepares peanut shell nano-cellulose, feature It is: (1) in, peanut husk as raw material is cleaned using deionized water, and sieve with 100 mesh sieve.

3. the method that steam blasting combination ultrasonic treatment as described in claim 1 prepares peanut shell nano-cellulose, feature It is:

(2) in, adding water to its water content in peanut shell powder in (1) is 5-60wt%, then material is placed in by swollen 12-24h Steam explosion chamber, steam blasting pressure are set as 0.5-3.0MPa, and the time is set as 20-100s, is washed after explosion treatment with 50-70 DEG C of hot water And filter, obtain filter residue.

4. the method that steam blasting combination ultrasonic treatment as described in claim 1 prepares peanut shell nano-cellulose, feature It is:

(3) in, (2) resulting filter residue and deionized water are placed in instead in the ratio that feed liquid mass volume ratio is 1g:20mL It answers in kettle, the pH for adjusting solution is 4-5, and the NaClO of 15g/L is added₂, the water bath with thermostatic control at 40-60 DEG C, stir 4-6h, will filter Wash heat is filtered after washing to neutrality, obtains secondary filter residue.

5. the method that steam blasting combination ultrasonic treatment as described in claim 1 prepares peanut shell nano-cellulose, feature It is: adjusts the pH to 4-5 of solution using acetum.

6. the method that steam blasting combination ultrasonic treatment as described in claim 1 prepares peanut shell nano-cellulose, feature It is:

(4) in, use pH that secondary filter residue obtained in (3) is made into 1- for disodium hydrogen phosphate-citric acid solution of 4-5 The aqueous dispersions of 10wt%, are then added cellulase, enzyme dosage 500-4000U/g, and the water bath with thermostatic control at 40-60 DEG C is stirred 3-6h is mixed, then boiling water bath 10-20min enzyme deactivation.

7. the method that steam blasting combination ultrasonic treatment as described in claim 1 prepares peanut shell nano-cellulose, feature It is:

(5) in, peanut shell fiber enzymolysis liquid obtained by (4) is ultrasonically treated 30-90min, ultrasonic power 1500- in ice-water bath 2000W, supersonic frequency 20kHz.

8. the method that steam blasting combination ultrasonic treatment as described in claim 1 prepares peanut shell nano-cellulose, feature It is:

The solution being ultrasonically treated in (5) is centrifuged 5-15min under 10000r/min, collects supernatant, supernatant is freezed dry Dry peanut shell nano-cellulose powder to obtain the final product.

9. the method that steam blasting combination ultrasonic treatment as described in claim 1 prepares peanut shell nano-cellulose, including under The step of stating:

(1) it pre-processes: peanut husk as raw material being spent into ionized water cleaning, is dried, is crushed, sieve with 100 mesh sieve；

(2) steam blasting: add the water content of water regulating step (1) the peanut shell powder for 5-60wt%, swollen 12-24h, so Material is placed in steam explosion chamber afterwards, steam blasting pressure is set as 0.5-3.0MPa, and the time is set as 20-100s, uses 50- after explosion treatment 70 DEG C of hot water are washed and are filtered, and filter residue is the peanut case fibre for removing most of hemicellulose, lignin；

(3) the resulting filter residue of step (2) and deionized water chlorite bleaching: are pressed into feed liquid mass volume ratio 1g:20mL Ratio be placed in reaction kettle, using acetic acid adjustment pH value of solution be 4-5, the NaClO of 15g/L is added₂, the constant temperature at 40-60 DEG C Water-bath is stirred 4-6h, will be filtered after residue washing to neutrality, and filter residue is the peanut shell fibre for removing remaining hemicellulose, lignin Dimension；

(4) enzymolysis processing: the disodium hydrogen phosphate-citric acid solution for being 4-5 with pH matches peanut case fibre obtained by step (3) At the aqueous dispersions of 1-10wt%, cellulase is added, enzyme dosage 500-4000U/g is placed in water bath with thermostatic control at 40-60 DEG C, Stir 3-6h, then boiling water bath 10-20min enzyme deactivation；

(5) it is ultrasonically treated: peanut shell fiber enzymolysis liquid obtained by step (4) being ultrasonically treated 30-90min in ice-water bath, ultrasound Power is 1500-2000W, supersonic frequency 20kHz；

(6) it is centrifuged, is freeze-dried: the solution of step (5) ultrasonic treatment being centrifuged 5-15min through 10000r/min, collects supernatant Supernatant is freeze-dried up to peanut shell nano-cellulose powder by liquid.