CN108373511B - Cellulose nanocrystal and preparation method thereof based on redox system - Google Patents
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Abstract
The embodiment of the invention relates to a cellulose nanocrystal and a preparation method thereof based on a redox system. The preparation method comprises the following steps: swelling and crushing the cellulose raw material, and washing; dispersing the pretreated cellulose raw material in an aqueous solution containing an oxidizing agent and a reducing agent to carry out hydrolysis reaction; and carrying out post-treatment on the obtained hydrolysate to obtain the stably dispersed cellulose nanocrystal suspension. The preparation method uses the reducing agent and the oxidant as the auxiliary agent to participate in the hydrolysis reaction of the cellulose, and reduces the activation energy required by the oxidant to damage an amorphous region through the interaction between the oxidant and the reducing agent in the reaction system, so that the reaction is carried out under a mild condition and the reaction rate can be improved, therefore, the addition of the reducing agent improves the preparation efficiency to a certain extent, reduces the using amount of the oxidant, reduces the preparation energy consumption and saves the preparation cost.
Description
Technical Field
The invention relates to the field of nano materials and preparation thereof, in particular to a cellulose nanocrystal and a preparation method thereof, and further relates to a cellulose nanocrystal and a preparation method thereof based on a redox system.
Background
Cellulose is a natural biological material which is present in the largest amount in nature, and is widely present in organisms such as green plants and marine animals. By removing the amorphous regions in the cellulose raw material, nano-sized cellulose nanocrystals can be obtained. The cellulose nanocrystal has the characteristics of low density, high strength, high length-diameter ratio and the like; the composite material also has the advantages of high specific surface area, reactive surface, high crystallinity and the like, is a reinforcing agent with excellent performance, and has great application value in the field of high-performance composite material preparation. In addition, the cellulose nanocrystal can be stably dispersed in a water phase system and can be grafted with a proper monomer by taking water as a reaction medium, which cannot be achieved by cellulose in other forms, so that the application range of the cellulose nanocrystal is widened to a certain extent.
In the prior art, the preparation of cellulose nanocrystals mostly adopts an acidolysis method, a Tempo reagent oxidation method and the like; wherein: the acidolysis method has low yield, is easy to cause acid pollution to the environment, can greatly increase the production cost even if the recovery of the acid is realized, and is not suitable for industrial large-scale production; the preparation process of the Tempo reagent oxidation method is complex and harsh, the time consumption is long, the Tempo reagent is expensive, and the industrial production cost is high. Therefore, the development of a simple, convenient and rapid cellulose nanocrystal efficient preparation method with low cost and high yield is of great significance.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
Object of the Invention
The invention aims to provide a cellulose nanocrystal and a preparation method thereof based on a redox system; the preparation method uses the reducing agent and the oxidant as the auxiliary agent to participate in the hydrolysis reaction of the cellulose, and the interaction between the oxidant and the reducing agent in the reaction system reduces the activation energy required by the oxidant to damage an amorphous region, so that the reaction is carried out under a mild condition and the reaction rate can be improved, therefore, the addition of the reducing agent improves the preparation efficiency to a certain extent, reduces the using amount of the oxidant, reduces the preparation energy consumption and saves the preparation cost.
Technical scheme
In order to achieve the above object, an embodiment of the present invention provides a method for preparing cellulose nanocrystals based on a redox system, which includes the following steps:
(1) pretreatment: swelling and crushing the cellulose raw material, and washing;
(2) oxidation-reduction hydrolysis: dispersing the pretreated cellulose raw material in an aqueous solution containing an oxidizing agent and a reducing agent to carry out hydrolysis reaction;
(3) and (3) post-treatment: and carrying out post-treatment on the obtained hydrolysate to obtain the stably dispersed cellulose nanocrystal suspension.
In one possible embodiment, the pretreated cellulosic feedstock is dispersed in an aqueous solution comprising an oxidizing agent and a reducing agent to perform the hydrolysis reaction in a manner that: dispersing the pretreated cellulose raw material in an aqueous solution containing an oxidant and a reducing agent for hydrolysis reaction for a period of time, and then mechanically defibering the reaction system by using mechanical force and continuing the reaction; optionally, the pretreated cellulose raw material is dispersed in an aqueous solution containing an oxidant and a reducing agent to perform a reaction for 0.5 to 12 hours, and then the reaction system is subjected to mechanical defibration treatment by mechanical force and then continuously reacted for 0.5 to 10 hours.
In one possible embodiment, the oxidizing agent includes one or more of hydrogen peroxide, sodium peroxide, potassium peroxide, calcium peroxide, magnesium peroxide, zinc peroxide, strontium peroxide, peroxymonosulfuric acid, peroxydisulfuric acid, potassium peroxymonosulfate, sodium peroxymonosulfate, ammonium persulfate, potassium persulfate, sodium persulfate, lithium permanganate, sodium permanganate, potassium permanganate, ammonium permanganate, calcium permanganate, barium permanganate, zinc permanganate, magnesium permanganate, mercury permanganate, cadmium permanganate, rubidium permanganate, potassium hypochlorite, sodium hypochlorite, potassium hypobromite, sodium hypobromite, potassium hypoiodite, potassium ferrate, sodium ferrate, potassium nitrate, sodium nitrate, potassium chlorate, sodium chlorate, potassium perchlorate, sodium perchlorate, potassium bromate, potassium perbromite, sodium perbromite, potassium bismuthate, sodium bismuthate.
In a possible embodiment, the reducing agent includes one or more of lithium aluminum hydride, lithium hydride, sodium hydride, potassium hydride, calcium hydride, cuprous hydride, sodium borohydride, potassium borohydride, sodium sulfite, ammonium sulfite, potassium sulfite, sodium bisulfite, potassium bisulfite, ammonium bisulfite, ferrous sulfate, zinc chloride, formic acid, oxalic acid, succinic acid, ethanol, and methanol.
In one possible embodiment, the mass ratio of the cellulose raw material to the used oxidant is 1: 0.1-30, optionally 1: 0.5-20, and further optionally 1: 1-10, and further optionally 1: 1-2.
In a possible embodiment, the mass ratio of the oxidant used to the reductant used is 1: 0.05-2, optionally 1: 0.2-2, and further optionally 1: 0.75-1.2.
In a possible embodiment, the concentration of the oxidizing agent in the aqueous solution containing the oxidizing agent and the reducing agent is 0.5% to 20% by mass, optionally 1% to 15% by mass, further optionally 1% to 5% by mass or 5% to 10% by mass.
In one possible embodiment, the temperature for the hydrolysis reaction is 20 to 100 ℃ when the pretreated cellulose raw material is dispersed in an aqueous solution containing an oxidizing agent and a reducing agent.
In one possible embodiment, the mechanical force is provided by one or more of a ball mill, ultrasound, high speed homogenizer, cell disruptor, or a milling device.
When mechanical force is provided by the ball mill, the mechanical defibering method comprises the following steps: pouring the reaction system into a ball mill for continuous ball milling for 1-30 min;
when the mechanical force is provided by ultrasound, the mechanical defibration method is as follows: placing the reaction system in an ultrasonic cleaning machine for ultrasonic treatment, and continuously carrying out ultrasonic treatment for 1-60 min, wherein the ultrasonic treatment temperature is 10-40 ℃, the ultrasonic power is 50-100%, and the ultrasonic frequency is 50-2000 Hz;
when the mechanical force is provided by a high-speed homogenizer, the mechanical defibering method is as follows: quickly treating the reaction system by using a high-speed homogenizer for 1-10 times, wherein each time of treatment is 1-5 min, and the rotating speed is 1000-30000 rpm/min;
when mechanical force is provided for the cell disruptor, the mechanical defibration method is as follows: placing the reaction system in a cell crushing instrument, and continuously crushing for 1-30 min with the crushing power of 20-80%;
when mechanical force is provided to the grinding equipment, the mechanical defibering method is as follows: and (3) placing the reaction system in grinding equipment, and continuously grinding for 1-30 min.
In one possible embodiment, the cellulosic feedstock comprises microcrystalline cellulose, plant cellulose, pulp cellulose, or alpha-cellulose; or natural cellulose which is commonly found in nature.
In a possible embodiment, the swelling treatment is to perform soaking swelling on the cellulose raw material with an alkali solution, wherein the alkali solution is a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution or a sodium bicarbonate aqueous solution with the mass percentage of 1% -8%, optionally 2% -7%, and further optionally 3% -5%.
In a possible embodiment, the time for soaking and swelling the cellulose raw material with the alkali liquor is 1-48 hours, optionally 5-36 hours, and further optionally 8-24 hours.
In a possible embodiment, when the cellulose raw material is soaked and swelled with the alkali liquor, the dosage ratio of the cellulose raw material to the alkali liquor is 10-70 g:1L, namely, 1L of alkali liquor is needed for every 10-70 g of the cellulose raw material.
In one possible embodiment, the washing is with deionized water to a pH similar to or the same as the pH of the deionized water.
In one possible embodiment, subjecting the resulting hydrolysate to a post-treatment comprises: centrifuging the obtained hydrolysate, repeatedly washing the precipitate with deionized water, centrifuging until the supernatant is in light blue or milky suspension state, dialyzing the supernatant, and ultrasonically dispersing.
In a possible implementation mode, when the obtained hydrolysate is centrifuged, the rotating speed of a centrifuge is 3000-12000 rpm, and the centrifugation times are 2-8 times.
In one possible embodiment, the pH of the upper layer solution is similar to or the same as that of deionized water.
The embodiment of the invention also provides the cellulose nanocrystal prepared by the preparation method, wherein the yield of the cellulose nanocrystal is over 70%, the average length of the cellulose nanocrystal is 50-300 nm, and the average diameter of the cellulose nanocrystal is 5-20 nm.
Advantageous effects
The auxiliary agent used in the reaction system in the embodiment of the invention comprises an oxidant and a reducing agent, and the oxidant and the reducing agent have the following functions: (1) the strong oxidizing property of the oxidant in the reaction system can damage the loosely arranged amorphous region in the cellulose supermolecular structure and reserve the tightly arranged crystalline region, thereby increasing the crystal region proportion to prepare the cellulose nanocrystal; (2) the reducing agent is added into the reaction system, so that the interaction between the oxidizing agent and the reducing agent can be utilized to reduce the activation energy required by the oxidizing agent to destroy the amorphous region, the reaction is carried out under a mild condition and the reaction rate can be improved, the addition of the reducing agent improves the preparation efficiency to a certain extent, the use amount of the oxidizing agent is reduced, the preparation energy consumption is reduced, and the preparation cost is saved.
In the embodiment of the invention, the cellulose nanocrystal is efficiently prepared by a chemical-mechanical combination method: after the pretreated cellulose raw material is treated for a period of time by using an auxiliary agent oxidant and a reducing agent, the size of a cellulose chain is reduced and the entanglement of the cellulose chain becomes loose, mechanical defibrination treatment is carried out on a reaction system by using mechanical force; the size of the treated cellulose is greatly reduced, the specific surface area is increased, the reaction rate is further improved, the reaction time is shortened, the preparation efficiency is improved, the energy consumption is reduced, the use amount of chemical reagents is reduced to a certain extent, and the preparation cost is saved.
According to the embodiment of the invention, the size and yield of the prepared cellulose nanocrystal can be regulated and controlled by regulating the proportion of the cellulose raw material to the oxidant, the proportion of the oxidant to the reducing agent and/or the hydrolysis time, the length of the cellulose nanocrystal prepared by the method is 50-300 nm, the diameter of the cellulose nanocrystal is 5-20 nm, and the yield can exceed 70%.
In the embodiment of the invention, the total time and yield required for preparing the cellulose nanocrystal can be regulated and controlled by regulating and controlling the hydrolysis time before and after the cellulose is subjected to mechanical defibrination and the mechanical treatment time and strength, the total time required for preparing the cellulose nanocrystal is shortened, the dosage of chemical reagents is reduced, and the yield of the cellulose nanocrystal is improved; compared with the system without mechanical force treatment, the required reaction time can be shortened by more than 60 percent, the yield can be improved by more than 20 percent, and the reduction of the auxiliary agent can reach more than 50 percent.
Other features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.
Drawings
One or more embodiments are illustrated by the corresponding figures in the drawings, which are not meant to be limiting.
FIG. 1 is an atomic force microscope photograph of cellulose nanocrystals prepared in example 1 of the present invention.
FIG. 2 is a particle size distribution curve of the cellulose nanocrystals prepared in example 1 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention. 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.
Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.
Any of the following examples should not necessarily be construed as preferred or advantageous over other examples unless explicitly supported.
Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. In some instances, methods, means, elements well known to those skilled in the art have not been described in detail so as not to obscure the present invention.
Example 1
Soaking 5g of paper pulp cellulose in 250mL of 4% sodium hydroxide solution for swelling for 24h, crushing the paper pulp cellulose into cotton floccules by a stirrer, washing the paper pulp cellulose with deionized water until the pH value of the paper pulp cellulose is the same as that of the deionized water, and drying the paper pulp cellulose; the sequence of swelling and crushing in the step has no obvious influence on the result, and the swelling can be carried out firstly and then the crushing can be carried out, and the crushing can be carried out firstly and then the swelling can be carried out;
dispersing the pretreated cellulose raw material in 300mL of deionized water, adding 5g of hydrogen peroxide and 1g of ferrous sulfate, stirring at 60 ℃ for 1h, performing mechanical defibrination treatment at 49% power for 20min by using a cell crusher, and continuing to react at 60 ℃ for 4h to stop the reaction, wherein the total reaction time is 5 h. And after the reaction is finished, centrifuging the cellulose hydrolysate for 10min by using a high-speed centrifuge at the rotating speed of 8000rpm/min, repeatedly washing and centrifuging the precipitate by using deionized water until the supernatant is in a light blue or milky suspension state, dialyzing the supernatant until the pH of the supernatant is the same as that of the deionized water, and ultrasonically dispersing to obtain the stably dispersed cellulose nanocrystal suspension. The cellulose nanocrystals obtained were measured to have an average length of 268nm, an average diameter of 17nm, a yield of 48%, and a particle size dispersion index (PDI) (PDI is calculated from the length of the cellulose nanocrystals) of 0.3.
The morphology and the particle size distribution of the prepared cellulose nanocrystals are shown in fig. 1 and fig. 2, and it can be seen from fig. 1 that the cellulose nanocrystals prepared by the method are in a typical rod-like structure and in a monodisperse state, which indicates that no aggregation occurs between the cellulose nanocrystals; from fig. 2, it can be seen that the prepared cellulose nanocrystal grain size distribution index is narrower, which illustrates that the prepared cellulose nanocrystal length distribution is relatively uniform.
In addition, the oxidant hydrogen peroxide in this embodiment can be matched with ferrous sulfate, and also can be matched with reducing agents such as sodium hydride, sodium borohydride, sodium sulfite and the like to obtain cellulose nanocrystals, wherein the matching effect with ferrous sulfate is the best.
Example 2
The oxidant used was ammonium persulfate, the reductant used was sodium sulfite, and the other conditions (e.g., type, amount of raw materials, and process flow) were the same as in example 1, to obtain a stable suspension of cellulose nanocrystals, which was measured to have an average length of about 283nm, an average diameter of 19nm, a yield of 50%, and a PDI of 0.3.
In addition, the oxidant ammonium persulfate in this embodiment may be matched with sodium sulfite, and may also be matched with reducing agents such as formic acid, succinic acid, ethanol, methanol, sodium hydride, sodium borohydride and the like to obtain cellulose nanocrystals, wherein the matching effect with sodium sulfite is the best.
Example 3
The oxidant used was sodium permanganate, the reducing agent used was formic acid, and all other conditions (e.g., type, amount of raw materials, and process flow) were the same as in example 1, to obtain a stable suspension of cellulose nanocrystals, which was measured to have an average length of about 253nm, an average diameter of 18nm, a yield of 49%, and a PDI of 0.3.
In addition, the oxidant sodium permanganate in this embodiment can be matched with formic acid, and can also be matched with reducing agents such as oxalic acid, succinic acid, ferrous sulfate, methanol, sodium hydride, sodium borohydride and the like to obtain the cellulose nanocrystal, wherein the matching effect with formic acid is the best.
Example 4
The oxidant used was sodium ferrate, the reducing agent used was oxalic acid, and all other conditions (e.g., type, amount of raw materials, and process flow) were the same as in example 1, to obtain a stable suspension of cellulose nanocrystals, which was measured to have an average length of about 293nm, an average diameter of 20nm, a yield of 46%, and a PDI of 0.3.
In addition, the oxidant sodium ferrate in this embodiment may be matched with oxalic acid, as well as formic acid, succinic acid, ferrous sulfate, sodium sulfite, sodium hydride, sodium borohydride and other reducing agents to obtain cellulose nanocrystal, wherein the matching effect with oxalic acid is the best.
Example 5
The addition amount of the reducing agent ferrous sulfate was different, the addition amount of the ferrous sulfate was 5g, and the other conditions (such as the types of raw materials, the amounts of raw materials, the process flow and the like) were the same as those in example 1, so as to obtain a stable cellulose nanocrystal suspension, and the measured average length of the obtained cellulose nanocrystals was about 219nm, the average diameter was 15nm, the yield was 59%, and the PDI was 0.2.
Example 6
The addition amount of the reducing agent ferrous sulfate was different, the addition amount of the ferrous sulfate was 10g, and the other conditions (such as the types and amounts of raw materials, the process flow, and the like) were the same as those in example 1, so as to obtain a stable cellulose nanocrystal suspension, and the average length of the obtained cellulose nanocrystals was about 183nm, the average diameter was 12nm, the yield was 68%, and the PDI was 0.2.
Example 7
The reaction time of the reaction system before and after mechanical defibering is different, the reaction time before defibering is 2h, the reaction time after defibering is 3h, the total reaction time is 5h, and the rest conditions (such as the types, the amounts of raw materials, the process flow and the like) are the same as those of the example 1, so that stable cellulose nanocrystal suspension is obtained, the average length of the obtained cellulose nanocrystal is about 227nm, the average diameter is 16nm, the yield is 52%, and the PDI is 0.2.
Example 8
The reaction time of the reaction system before and after mechanical defibering is different, the reaction time before defibering is 3h, the reaction time after defibering is 2h, the total reaction time is 5h, and the rest conditions (such as the types, the amounts of raw materials, the process flow and the like) are the same as those of the example 1, so that stable cellulose nanocrystal suspension is obtained, the average length of the obtained cellulose nanocrystal is about 203nm, the average diameter is 13nm, the yield is 55%, and the PDI is 0.2.
Example 9
The reaction time of the reaction system before and after mechanical defibering is different, the reaction time before defibering is 2h, the reaction time after defibering is 4h, the total reaction time is 6h, and the rest conditions (such as the types, the amounts of raw materials, the process flow and the like) are the same as those of the example 7, so that stable cellulose nanocrystal suspension is obtained, and the measured average length of the obtained cellulose nanocrystal is about 195nm, the average diameter is 13nm, the yield is 63%, and the PDI is 0.2.
Example 10
The addition amounts of the oxidant hydrogen peroxide and the reductant ferrous sulfate are different, the addition amount of the hydrogen peroxide is 10g, the addition amount of the ferrous sulfate is 2g, and the rest conditions (such as the types and the amounts of raw materials, the technological process and the like) are the same as those of the example 1, so that the stable cellulose nanocrystal suspension is obtained, and the average length of the obtained cellulose nanocrystal is about 235nm, the average diameter is 16nm, the yield is 58%, and the PDI is 0.2.
Example 11
The addition amount of the reducing agent ferrous sulfate was varied, the addition amount of ferrous sulfate was 10g, and all other conditions (e.g., the kind and amount of raw materials, and the process flow) were the same as in example 10, to obtain a stable cellulose nanocrystal suspension, and the average length of the obtained cellulose nanocrystals was about 189nm, the average diameter was 16nm, the yield was 66%, and the PDI was 0.2.
Example 12
The addition amount of the reducing agent ferrous sulfate was varied, the addition amount of ferrous sulfate was 20g, and all other conditions (e.g., the kind and amount of raw materials, and the process flow) were the same as in example 10, to obtain a stable cellulose nanocrystal suspension, and the cellulose nanocrystals obtained by measurement had an average length of about 132nm, an average diameter of 6nm, a yield of 75%, and a PDI of 0.2.
TABLE 1
Comparative example 1
The reaction was carried out without adding ferrous sulfate as a reducing agent, and all other conditions (e.g., the kind and amount of raw materials, and the process flow) were the same as those in example 1, the average length of the obtained cellulose microfibrils was 750nm, the average diameter was 30nm, which was much longer than the length of the cellulose nanocrystals obtained in example 1, the yield of the cellulose microfibrils was 39%, which was much lower than that in example 1, and the length distribution was also broad, and the PDI was 0.4. This shows that the reducing agent has an important effect on improving the reaction efficiency, and the cellulose nanocrystals with shorter length can be obtained by adding the reducing agent under the same reaction conditions and reaction time, and the yield is also higher.
Comparative example 2
The mechanical defibrination treatment is not needed in the midway of the reaction, the reaction is directly completed, all other conditions (such as raw material types, dosage, process flow and the like) are the same as the example 1, stable cellulose nanocrystal suspension is obtained, the average length of the obtained cellulose nanocrystals is about 459nm through measurement, the average diameter is 25nm, the yield is 42%, and the PDI is 0.4.
Comparative example 3
The mechanical defibrination treatment is not needed in the midway of the reaction, the reaction is directly completed, all other conditions (such as raw material types, dosage, process flow and the like) are the same as the example 2, stable cellulose nanocrystal suspension is obtained, the average length of the obtained cellulose nanocrystals is about 519nm, the diameter is 26nm, the yield is 40%, and the PDI is 0.5.
Comparative example 4
The mechanical defibrination treatment is not needed in the midway of the reaction, the reaction is directly completed, all other conditions (such as raw material types, dosage, process flow and the like) are the same as the example 3, the stable cellulose nanocrystal suspension is obtained, the average length of the obtained cellulose nanocrystals is about 487nm through measurement, the diameter is 24nm, the yield is 40%, and the PDI is 0.4.
Comparative example 5
The mechanical defibrination treatment is not needed in the midway of the reaction, the reaction is directly completed, all other conditions (such as raw material types, dosage, process flow and the like) are the same as the example 4, stable cellulose nanocrystal suspension is obtained, the average length of the obtained cellulose nanocrystal is about 567nm, the diameter is 26nm, the yield is 38%, and the PDI is 0.5.
Comparative examples 2 to 5 correspond to examples 1 to 4, respectively, and comparative examples 2 to 5 are results of the reactions of examples 1 to 4 completed without mechanical defibration treatment by a cell crusher in the middle of the reactions. From the results of comparative examples 2 to 5, it was found that cellulose nanocrystals could be obtained even without the intermediate mechanical defibration treatment. However, under the condition that the reaction temperature and the total reaction time are the same, the cellulose nanocrystals with shorter average length, finer average diameter and narrower distribution can be obtained by mechanical defibering treatment, and the yield is higher, which indicates that the introduction of the mechanical defibering treatment has an important effect on improving the preparation efficiency.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (16)
1. A preparation method of cellulose nanocrystals based on a redox system is characterized by comprising the following steps: swelling and crushing the cellulose raw material, and washing; dispersing the pretreated cellulose raw material in an aqueous solution containing an oxidizing agent and a reducing agent to carry out hydrolysis reaction; performing post-treatment on the obtained hydrolysate to obtain a stably dispersed cellulose nanocrystal suspension; wherein: the mode of dispersing the pretreated cellulose raw material in the aqueous solution containing the oxidant and the reducing agent to carry out the hydrolysis reaction is as follows: dispersing the pretreated cellulose raw material in an aqueous solution containing an oxidant and a reducing agent for hydrolysis reaction for a period of time, and then mechanically defibering the reaction system by using mechanical force and continuing the reaction; the mechanical force is provided by one or more of a high-speed homogenizer, a cell disruptor or a grinding device:
when the mechanical force is provided by a high-speed homogenizer, the mechanical defibering method is as follows: quickly treating the reaction system by using a high-speed homogenizer for 1-10 times, wherein each time of treatment lasts for 1-5 min, and the rotating speed is 1000-30000 rpm;
when mechanical force is provided for the cell disruptor, the mechanical defibration method is as follows: placing the reaction system in a cell crushing instrument, and continuously crushing for 1-30 min;
when mechanical force is provided to the grinding equipment, the mechanical defibering method is as follows: placing the reaction system in grinding equipment, and continuously grinding for 1-30 min; the aqueous solution comprising an oxidizing agent and a reducing agent is: an aqueous solution comprising hydrogen peroxide and ferrous sulfate; or an aqueous solution comprising ammonium persulfate and sodium sulfite.
2. The method of claim 1, wherein: dispersing the pretreated cellulose raw material in an aqueous solution containing an oxidant and a reducing agent, performing hydrolysis reaction for 0.5-12 h, performing mechanical defibrination treatment on a reaction system by using mechanical force, and continuing the hydrolysis reaction for 0.5-10 h.
3. The method of claim 1, wherein: the mass ratio of the cellulose raw material to the oxidant is 1: 0.1-30.
4. The production method according to claim 3, characterized in that: the mass ratio of the cellulose raw material to the used oxidant is 1: 0.5 to 20.
5. The production method according to claim 3, characterized in that: the mass ratio of the cellulose raw material to the oxidant is 1: 1-10.
6. The production method according to claim 3, characterized in that: the mass ratio of the cellulose raw material to the oxidant is 1: 1-2.
7. The method of claim 1, wherein: the mass ratio of the oxidant to the reducing agent is 1: 0.05-2.
8. The method of claim 7, wherein: the mass ratio of the oxidant to the reducing agent is 1: 0.2-2.
9. The method of claim 7, wherein: the mass ratio of the oxidant to the reducing agent is 1: 0.75-1.2.
10. The method of claim 1, wherein: the temperature for dispersing the pretreated cellulose raw material in an aqueous solution containing an oxidant and a reducing agent to carry out hydrolysis reaction is 20-100 ℃.
11. The method of claim 1, wherein: the mass percentage concentration of the oxidant in the aqueous solution containing the oxidant and the reducing agent is 0.5-20%.
12. The method of claim 11, wherein: the mass percentage concentration of the oxidant in the aqueous solution containing the oxidant and the reducing agent is 1-15%.
13. The method of claim 11, wherein: the mass percentage concentration of the oxidant in the aqueous solution containing the oxidant and the reducing agent is 1-5%.
14. The method of claim 11, wherein: the mass percentage concentration of the oxidant in the aqueous solution containing the oxidant and the reducing agent is 5-10%.
15. The production method according to claim 1, wherein the cellulose raw material comprises microcrystalline cellulose, plant cellulose, pulp cellulose, or α -cellulose.
16. A cellulose nanocrystal obtained by the production method according to any one of claims 1 to 15.
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