CN111320711A - Chitosan with high deacetylation degree and high molecular weight and preparation method thereof - Google Patents
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Abstract
The invention relates to chitosan with high deacetylation degree and high molecular weight and a preparation method thereof, and the preparation method comprises the steps of dissolving chitin in a strong alkali solution to obtain a chitin-strong alkali solution, increasing the content of strong alkali in the chitin-strong alkali solution to 35-45 wt% by supplementing the strong alkali solution at the temperature of 0-10 ℃, and performing deacetylation reaction at the temperature of 70-100 ℃ to prepare the chitosan, wherein the strong alkali is KOH or NaOH, the deacetylation reaction is performed in an oil bath heater or a microwave reactor, the deacetylation degree of the prepared chitosan is 80-95%, and the viscosity-average molecular weight is 7.9 × 105～9.0×105g/mol. The preparation method of the invention carries out deacetylation under homogeneous phase conditions, reduces the concentration of strong base and the temperature of deacetylation reaction, has simple process and mild conditions, and obviously improves the molecular weight of chitosan; the prepared chitosan has high deacetylation degree and high molecular weight, and has great application prospect.
Description
Technical Field
The invention belongs to the technical field of chitosan preparation, and relates to chitosan with high deacetylation degree and high molecular weight and a preparation method thereof.
Background
Chitosan is also called chitosan and is obtained by deacetylation of chitin (chitin) widely existing in nature. Since the first discovery of chitosan by Rouget of the law in 1859, due to the excellent properties of chitosan such as biological functionality and compatibility, blood compatibility, safety, microbial degradability, etc., this natural polymer has attracted more and more attention from various industries, and has now been widely used in many fields such as medicine, food, chemical industry, cosmetics, water treatment, metal extraction and recovery, biochemistry and biomedical engineering.
Chitosan is mainly prepared by deacetylation of chitin at high temperature under concentrated NaOH, the deacetylation reaction of chitin is essentially hydrolysis reaction of amido bond under alkaline condition, but the intermolecular and intermolecular hydrogen bond interaction of chitin enables the chitin to form a microfibrous reticular high-degree crystalline ordered structure, and the crystalline regions of chitin and the amorphous regions of chitin are arranged in a staggered manner, so that the crystalline regions of chitin are regularly, straightly and tightly arranged in three-dimensional space, the amorphous regions are formed by randomly curling and mutually intertwining loose molecular chains, and in the deacetylation process of chitin, due to the semi-crystalline structure of chitin, OH is seriously hindered-Attack on the acetamido group, which greatly affects the deacetylation effect. To increase the deacetylation effect, the OH promotion concentration needs to be increased by increasing the NaOH concentration-The steric hindrance is overcome, and the reaction temperature is increased to promote the hydrolysis of the acetamido into the amino group so as to realize the deacetylation of the chitin. However, the chitin powder directly reacts under the conditions of high concentrated alkali and high temperature, and due to the excessively high alkali concentration and the excessively high reaction temperature, although deacetylation of chitin is promoted, the breakage of the carbon chain skeleton of chitosan to cause molecular chain breakage is also promoted, so that the molecular weight of chitosan is reduced, chitosan with high molecular weight is difficult to find, and the high deacetylation degree and the high molecular weight of chitosan cannot be considered at the same time. For example, patent CN200710168573.5 discloses a method for preparing chitosan with high deacetylation degree and high viscosity by using shrimp shellCarrying out microwave deacetylation reaction under the conditions that the alkali concentration is 40-50 wt% and the temperature is 100 ℃, and continuing deacetylation reaction on the obtained chitosan and an ethanol solution of NaOH after the reaction, wherein although the chitosan with high deacetylation degree can be prepared, the operation is complicated, the alkali concentration and the reaction temperature are high, and the prepared chitosan has low molecular weight; patent CN201310676454.6 discloses a method for preparing chitosan with ultrahigh deacetylation degree from euphausia superba, which comprises removing mineral proteins and lipids, and then performing reflux deacetylation at 110 ℃ in 50% sodium hydroxide solution, although chitosan with high deacetylation degree can be prepared, the molecular weight of chitosan can be seriously affected by high temperature and high alkali concentration.
The molecular weight of chitosan directly affects the mechanical properties of chitosan, and the application of chitosan in various fields is seriously affected by the lower molecular weight of chitosan at present.
Therefore, the development of a preparation method which can simultaneously realize high deacetylation degree and high molecular weight of chitosan has practical significance.
Disclosure of Invention
The invention aims to provide a preparation method capable of simultaneously considering the high deacetylation degree and the high molecular weight of chitosan aiming at the defect that the high deacetylation degree and the high molecular weight of chitosan are difficult to simultaneously consider in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of chitosan with high deacetylation degree and high molecular weight comprises the steps of dissolving chitin in a low-concentration strong alkali solution to obtain a chitin-strong alkali solution, increasing the content of strong alkali in the chitin-strong alkali solution to 35-45 wt% by supplementing a high-concentration strong alkali solution at the temperature of 0-10 ℃, and performing deacetylation reaction at the temperature of 70-100 ℃ to obtain the chitosan with high deacetylation degree and high molecular weight.
The method improves the content of strong base in the chitin-strong base solution by supplementing the strong base solution, for example, if a strong base solid is directly added into the chitin-strong base solution, the strong base solid is dissolved and releases heat, so that the chitin-strong base solution is rapidly gelatinized, the chitin-strong base solution is changed into a solid by rapid gelatinization and has no fluidity, and the deacetylation reaction is not facilitated, in addition, the temperature of the supplemented strong base solution is specially controlled to be 0-10 ℃, and the purpose is to avoid system gelatinization and weaken the fluidity, so that adverse influence is generated on the deacetylation reaction.
The invention dissolves chitin in low-concentration strong alkali solution, the system is homogeneous phase system (solution state), the micro-fiber structure and crystal region are destroyed, the molecular chain arrangement becomes disordered, the space becomes larger, OH-The chitosan is easier to permeate and contact with acetylamino, the deacetylation concentration can be increased by increasing the alkali content of the solution at the moment, the chitosan is finally prepared by deacetylation reaction, the system is a homogeneous phase system at the moment, excessive alkali concentration and reaction temperature are not needed, the reaction conditions are mild, the phenomenon that chitosan glycosidic bond is broken due to excessive temperature to influence viscosity-average molecular weight of the chitosan is avoided, in addition, amino groups are randomly distributed along a chitosan chain after homogeneous deacetylation, and compared with block distribution of acetyl groups caused by heterogeneous deacetylation, the chitosan prepared by the method disclosed by the invention is better in water solubility.
The strong base solution is added in two steps, the concentration of the strong base solution added in the first step is low, the purpose is to dissolve chitin under the freezing condition and change the chitin into a homogeneous state, the concentration of the strong base solution added in the second step is high, and the high-concentration strong base solution is supplemented to reach the concentration with the best deacetylation reaction efficiency, because the concentration of the strong base solution is related to the number of formed alkalization centers, the higher the concentration is, the easier the alkalization centers are formed, the higher the reaction degree is, and the range of 35-45 wt% is a proper range of the strong base solution which is beneficial to the deacetylation reaction, compared with the one-step addition, the two-step addition can effectively prevent the solution temperature from being high, the chitin-strong base solution is rapidly gelatinized, has.
As a preferred technical scheme:
the method for preparing the chitosan with high deacetylation degree and high molecular weight as described above comprises the following steps: adding chitin powder into a strong base solution a with the strong base content of 15-25 wt% to obtain a dispersion, and then carrying out a treatment at the temperature of-T DEG CFreezing for 6-8 h under the condition, wherein T is less than 35, filtering or centrifuging to obtain an undissolved part to obtain a chitin-strong alkali solution. The content of the strong base in the strong base solution a is increased, the freezing point of the strong base solution a is reduced, the interlinkage among chitin molecular chains can be further weakened or broken, the crystallization performance of the chitin molecular chains is further damaged, and the dissolution of the chitin is influenced, so that the content of the strong base and the freezing temperature need to be comprehensively considered. The invention destroys the micro-fiber structure and crystal region in the chitin through low-temperature treatment, thereby leading the molecular chain arrangement to be disordered, leading the molecular chain spacing to be enlarged, and further reducing OH-Difficulty of penetrating into the chitin and contacting with the acetamido.
According to the preparation method of the chitosan with high deacetylation degree and high molecular weight, the average particle size of the chitin powder is 50-80 meshes, the deacetylation degree is 5-15%, and the crystallinity degree is 45-55%. The chitin powder of the present invention is not limited thereto, and the examples are only given herein.
According to the preparation method of the chitosan with high deacetylation degree and high molecular weight, the content of the chitin powder in the dispersion liquid is 3-6 wt%. The chitin powder content is too high, the mass fraction of the dissolved chitin is too high, the viscosity of the freeze-thaw liquid is too high, and the chitin powder can be prevented from being uniformly mixed with a high-concentration strong alkali solution; the chitosan prepared by using the chitin powder with too small content is less, and the cost is wasted.
The preparation method of the chitosan with high deacetylation degree and high molecular weight comprises the following steps of: and (3) supplementing a strong base solution b into the chitin-strong base solution, wherein the corresponding strong bases of the strong base solution a and the strong base solution b are the same or different.
In the above method for preparing chitosan with high deacetylation degree and high molecular weight, the strong alkali solution a or the strong alkali solution b is a NaOH solution or a KOH solution, more preferably, the strong alkali corresponding to the strong alkali solution a and the strong alkali corresponding to the strong alkali solution b are the same and are both KOH, and when the concentrations are the same, the ability of the KOH solution to dissolve the chitin powder is stronger than that of the NaOH solution.
According to the preparation method of the chitosan with high deacetylation degree and high molecular weight, the deacetylation reaction is carried out by microwave heating, specifically, the microwave heating is carried out in a microwave reactor, the power of the microwave reactor during the deacetylation reaction is 450-810W, and the reaction is aggravated due to excessive power, so that the degradation of molecular chains is caused, and the molecular weight is reduced; too little power and insufficient energy will prolong the reaction time and reduce the reaction efficiency, or the deacetylation reaction is heated by an oil bath, in particular in an oil bath heater. The heating method for deacetylation is not limited thereto, but two heating methods are listed here, and other heating methods are also applicable to the present invention.
According to the preparation method of the chitosan with high deacetylation degree and high molecular weight, the deacetylation reaction time is 2-6 h. The deacetylation time is not limited thereto, and those skilled in the art can select the reaction time according to the actual application scenario.
According to the preparation method of the chitosan with high deacetylation degree and high molecular weight, the chitosan can be separated out along with the reaction, the chitosan is insoluble in water and strong alkali solution, and after the deacetylation reaction is finished, the chitosan is washed and dried.
The invention also provides the chitosan with high deacetylation degree and high molecular weight, which is prepared by the preparation method of the chitosan with high deacetylation degree and high molecular weight, wherein the deacetylation degree is 80-95%, and the viscosity average molecular weight is 7.9 × 105～9.0×105g/mol, the molecular weight of the finally prepared product depends on two aspects, on one hand, the molecular weight of the raw material is relatively high, on the other hand, the molecular weight of the raw material is reduced slightly in the preparation process, and on the premise that the raw material is the same, the deacetylation degree of the chitosan prepared by the method is 0.1-0.3 times higher than that of the chitosan prepared by the general method (namely 1.1-1.3 times of that of the prior art), and the molecular weight of the chitosan is 2.1-2.6 times higher (namely 3.1-3.6 times of that of the prior art).
The invention mechanism is as follows:
the process for preparing chitosan in the prior art comprises the following steps: the method comprises the steps of directly adding chitin into a proper amount of high-concentration strong alkali solution (the concentration is generally 30-50 wt%), and then carrying out deacetylation reaction at high temperature (the temperature is generally 60-100 ℃), wherein a reaction system is a heterogeneous system, namely a high-concentration alkali dispersion liquid of chitin, the deacetylation reaction firstly occurs in an amorphous region due to the existence of a crystalline region in the chitin, the crystalline region needs to be effectively deacetylated only at very high alkali concentration and high temperature, the reaction difficulty degree of the crystalline region and the amorphous region can cause the block distribution of amino groups, the acetyl distribution on chitosan molecular chains after deacetylation is not uniform, the high alkali concentration can also damage the carbon chain skeleton of the chitin, so that the molecular chains are broken, and the molecular weight is rapidly reduced.
The invention dissolves chitin into strong alkali solution by adopting freeze thawing operation, the system is homogeneous phase system (solution state), the micro-fiber structure and crystal region are destroyed, the molecular chain arrangement becomes disordered, the space becomes larger, OH-The chitosan is prepared by performing deacetylation reaction, wherein the chitosan is prepared by performing deacetylation reaction, and the chitosan is prepared by performing the deacetylation reaction on the chitosan chain under the condition that the alkali content of the solution is increased and the deacetylation concentration is increased.
Has the advantages that:
(1) the preparation method of the chitosan with high deacetylation degree and high molecular weight, disclosed by the invention, has the advantages of simple process and mild conditions;
(2) the chitosan with high deacetylation degree and high molecular weight has high deacetylation degree and high molecular weight, and the material prepared from the chitosan has good mechanical properties.
Drawings
FIG. 1 is a schematic diagram of the preparation of chitosan with high degree of deacetylation and high molecular weight according to the present invention.
Detailed Description
The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
Example 1
A method for preparing chitosan with high deacetylation degree and high molecular weight comprises the following steps:
(1) adding chitin powder into KOH solution with KOH content of 18 wt% to obtain dispersion, freezing at-30 deg.C for 6.5h, and filtering out undissolved part to obtain chitin-strong alkali solution, wherein the chitin powder has average particle size of 80 mesh, deacetylation degree of 15%, crystallinity degree of 45%, and chitin powder content of 4 wt% in the dispersion;
(2) under the condition that the temperature is 0 ℃, adding KOH solution into the chitin-strong alkali solution to increase the KOH content in the chitin-strong alkali solution to 41 wt%;
(3) performing deacetylation reaction at the temperature of 100 ℃ to prepare the chitosan with high deacetylation degree and high molecular weight, wherein the deacetylation reaction is performed in a microwave reactor, the power of the microwave reactor during the deacetylation reaction is 630W, the deacetylation reaction time is 3h, and after the deacetylation reaction is finished, cleaning and drying are performed.
The obtained chitosan with high deacetylation degree and high molecular weight has the deacetylation degree of 83% and viscosity average molecular weight of 8.2 × 105g/mol。
The preparation process is schematically shown in FIG. 1, before the step (1) of filtering chitin powder, the system is shown in the left side of FIG. 1 and is a heterogeneous system, for example, the system is subjected to deacetylation reaction under high-concentration alkali and high-temperature conditions, and due to the semi-crystalline structure of chitin, OH-The deacetylation reaction is preferentially carried out in the amorphous region, OH-The crystal region is difficult to infiltrate; after filtering chitin powder, the system is a homogeneous system as shown in the right side of figure 1, the chitin is dissolved, the crystal region disappears, and OH-Can be fully contacted with acetylamino on the molecular chain of chitin, so that the high-efficiency deacetylation can be realized.
Comparative example 1
A preparation method of chitosan comprises the following steps: adding chitin powder into a KOH solution with the strong base content of 41 wt% to obtain a dispersion liquid, wherein the average particle size of the chitin powder is 80 meshes, the deacetylation degree is 15%, the crystallinity degree is 45%, the content of the chitin powder in the dispersion liquid is 4 wt%, performing deacetylation reaction at the temperature of 100 ℃ to obtain chitosan, performing the deacetylation reaction in a microwave reactor, the power of the microwave reactor during the deacetylation reaction is 630W, the deacetylation reaction time is 3h, and after the deacetylation reaction is finished, cleaning and drying.
The degree of deacetylation of the obtained chitosan was 37%, and since it was insoluble in acetic acid, the molecular weight could not be measured.
Comparative example 2
A method of producing chitosan, substantially the same as in comparative example 1, except that the KOH solution thereof had a KOH content of 60 wt%.
The deacetylation degree of the prepared chitosan is 78%, and the viscosity average molecular weight is 5.0 × 105g/mol。
Compared with the comparative examples 1 and 1-2, the deacetylation reaction is carried out in a homogeneous system, excessive alkali concentration and reaction temperature are not needed, the reaction conditions are mild, and both the deacetylation degree and the molecular weight can be well considered.
Example 2
A method for preparing chitosan with high deacetylation degree and high molecular weight comprises the following steps:
(1) adding chitin powder into KOH solution with KOH content of 15 wt% to obtain dispersion, freezing at-33 deg.C for 8h, and filtering out undissolved part to obtain chitin-strong alkali solution, wherein the chitin powder has average particle size of 60 mesh, deacetylation degree of 5%, crystallinity degree of 50%, and chitin powder content of 3 wt% in the dispersion;
(2) under the condition that the temperature is 5 ℃, adding KOH solution into the chitin-strong alkali solution to increase the KOH content in the chitin-strong alkali solution to 35 wt%;
(3) performing deacetylation reaction at the temperature of 70 ℃ to prepare the chitosan with high deacetylation degree and high molecular weight, wherein the deacetylation reaction is performed in a microwave reactor, the power of the microwave reactor during the deacetylation reaction is 720W, the deacetylation reaction time is 2h, and after the deacetylation reaction is finished, cleaning and drying are performed.
The prepared chitosan with high deacetylation degree and high molecular weight has the deacetylation degree of 90 percent and the viscosity-average molecular weight of 9.0 × 105g/mol, and on the premise of the same raw materials, the deacetylation degree of the chitosan prepared by the method is 0.2 times higher than that of the chitosan prepared by the general method, and the molecular weight of the chitosan is 2.6 times higher than that of the chitosan prepared by the general method.
Example 3
A method for preparing chitosan with high deacetylation degree and high molecular weight comprises the following steps:
(1) adding chitin powder into KOH solution with KOH content of 22 wt% to obtain dispersion, freezing at-34 deg.C for 7h, centrifuging to obtain undissolved part to obtain chitin-strong alkali solution, wherein the chitin powder has average particle size of 50 mesh, deacetylation degree of 10%, crystallinity of 45%, and chitin powder content of 6 wt% in the dispersion;
(2) under the condition that the temperature is 10 ℃, adding KOH solution into the chitin-strong alkali solution to increase the KOH content in the chitin-strong alkali solution to 45 wt%;
(3) performing deacetylation reaction at the temperature of 90 ℃ to prepare the chitosan with high deacetylation degree and high molecular weight, wherein the deacetylation reaction is performed in a microwave reactor, the power of the microwave reactor during the deacetylation reaction is 810W, the deacetylation reaction time is 5h, and after the deacetylation reaction is finished, cleaning and drying are performed.
The prepared chitosan with high deacetylation degree and high molecular weight has the deacetylation degree of 86 percent and the viscosity-average molecular weight of 8.6 × 105g/mol, and on the premise of the same raw materials, the deacetylation degree of the chitosan prepared by the method is 0.16 times higher than that of the chitosan prepared by the general method, and the molecular weight of the chitosan is 2.4 times higher than that of the chitosan prepared by the general method.
Example 4
A method for preparing chitosan with high deacetylation degree and high molecular weight comprises the following steps:
(1) adding chitin powder into a KOH solution with the NaOH content of 19 wt% to obtain a dispersion liquid, freezing for 7.5h at the temperature of-30 ℃, centrifuging to obtain an undissolved part to obtain a chitin-strong alkali solution, wherein the chitin powder has the average particle size of 70 meshes, the deacetylation degree of 12%, the crystallinity degree of 52%, and the chitin powder content of 5.2 wt% in the dispersion liquid;
(2) under the condition that the temperature is 8 ℃, adding NaOH solution into the chitin-strong alkali solution to increase the sum of the contents of NaOH and KOH in the chitin-strong alkali solution to 40 wt%;
(3) performing deacetylation reaction at 85 ℃ to prepare the chitosan with high deacetylation degree and high molecular weight, wherein the deacetylation reaction is performed in a microwave reactor, the power of the microwave reactor during the deacetylation reaction is 450W, the deacetylation reaction time is 2h, and after the deacetylation reaction is finished, cleaning and drying are performed.
The prepared chitosan with high deacetylation degree and high molecular weight has the deacetylation degree of 88 percent and the viscosity-average molecular weight of 7.9 × 105g/mol, and on the premise of the same raw materials, the deacetylation degree of the chitosan prepared by the method is 0.18 times higher than that of the chitosan prepared by the general method, and the molecular weight of the chitosan is 2.2 times higher than that of the chitosan prepared by the general method.
Example 5
A method for preparing chitosan with high deacetylation degree and high molecular weight comprises the following steps:
(1) adding chitin powder into NaOH solution with 25 wt% of NaOH content to obtain dispersion, freezing at-33 deg.C for 6h, centrifuging to obtain undissolved part to obtain chitin-strong alkali solution, wherein the chitin powder has an average particle size of 50 mesh, a deacetylation degree of 15%, a crystallinity of 55%, and a chitin powder content of 6 wt% in the dispersion;
(2) under the condition that the temperature is 4 ℃, adding KOH solution into the chitin-strong alkali solution to increase the sum of the contents of NaOH and KOH in the chitin-strong alkali solution to 38 wt%;
(3) performing deacetylation reaction at 100 ℃ to obtain chitosan with high deacetylation degree and high molecular weight, wherein the deacetylation reaction is performed in an oil bath heater, the deacetylation reaction time is 4h, and after the deacetylation reaction is finished, cleaning and drying are performed.
The prepared chitosan with high deacetylation degree and high molecular weight has the deacetylation degree of 80 percent and the viscosity average molecular weight of 8.4 × 105g/mol, and on the premise of the same raw materials, the deacetylation degree of the chitosan prepared by the method is 0.1 time higher and the molecular weight of the chitosan prepared by the method is 2.4 times higher than that of the chitosan prepared by the general method.
Example 6
A method for preparing chitosan with high deacetylation degree and high molecular weight comprises the following steps:
(1) adding chitin powder into NaOH solution with NaOH content of 17 wt% to obtain dispersion, freezing at-31 deg.C for 8 hr, and filtering to obtain chitin-strong alkali solution, wherein the chitin powder has average particle size of 60 mesh, deacetylation degree of 11%, crystallinity degree of 50%, and chitin powder content of 4.5 wt% in the dispersion;
(2) under the condition that the temperature is 5 ℃, adding NaOH solution into the chitin-strong alkali solution to increase the NaOH content in the chitin-strong alkali solution to 35 wt%;
(3) performing deacetylation reaction at 88 deg.C in an oil bath heater for 6 hr, and cleaning and drying.
The prepared chitosan with high deacetylation degree and high molecular weight has the deacetylation degree of 90 percent and the viscosity-average molecular weight of 7.9 × 105g/mol, and on the premise of the same raw materials, the deacetylation degree of the chitosan prepared by the method is 0.2 times higher than that of the chitosan prepared by the general method, and the molecular weight of the chitosan is 2.2 times higher than that of the chitosan prepared by the general method.
Claims (10)
1. A preparation method of chitosan with high deacetylation degree and high molecular weight is characterized in that: dissolving chitin in a strong alkali solution to obtain a chitin-strong alkali solution, increasing the content of strong alkali in the chitin-strong alkali solution to 35-45 wt% by supplementing the strong alkali solution at the temperature of 0-10 ℃, and performing deacetylation reaction at the temperature of 70-100 ℃ to obtain the chitosan with high deacetylation degree and high molecular weight.
2. The method for preparing chitosan with high deacetylation degree and high molecular weight as claimed in claim 1, wherein the dissolving process comprises: adding chitin powder into a strong base solution a with the strong base content of 15-25 wt% to obtain a dispersion, freezing for 6-8 h at the temperature of-T ℃, wherein T is less than 35, and filtering or centrifuging out undissolved parts to obtain the chitin-strong base solution.
3. The method of claim 2, wherein the chitosan powder has an average particle size of 50-80 mesh, a deacetylation degree of 5-15%, and a crystallinity degree of 45-55%.
4. The method for preparing chitosan with high deacetylation degree and high molecular weight as claimed in claim 2, wherein the content of chitin powder in the dispersion is 3-6 wt%.
5. The method for preparing chitosan with high deacetylation degree and high molecular weight as claimed in claim 2, wherein the method for increasing the content of strong base in the chitin-strong base solution to 35-45 wt% comprises: and (3) supplementing a strong base solution b into the chitin-strong base solution, wherein the corresponding strong bases of the strong base solution a and the strong base solution b are the same or different.
6. The method for preparing chitosan with high deacetylation degree and high molecular weight as claimed in claim 5, wherein the alkali solution a or the alkali solution b is NaOH solution or KOH solution.
7. The method for preparing chitosan with high deacetylation degree and high molecular weight according to claim 1, wherein the deacetylation reaction is performed by microwave heating, specifically in a microwave reactor, the power of the microwave reactor during the deacetylation reaction is 450-810W, or the deacetylation reaction is performed by oil bath heating, specifically in an oil bath heater.
8. The method for preparing chitosan with high deacetylation degree and high molecular weight according to claim 1, wherein the deacetylation reaction time is 2-6 h.
9. The method for preparing chitosan with high deacetylation degree and high molecular weight as claimed in claim 1, wherein the deacetylation reaction is completed, and then washing and drying are performed.
10. The high deacetylation degree and high molecular weight chitosan obtained by the method for preparing high deacetylation degree and high molecular weight chitosan according to any one of claims 1 to 9, wherein the deacetylation degree is 80 to 95%, and the viscosity average molecular weight is 7.9 × 105～9.0×105g/mol。
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| CN111675773A (en) * | 2020-07-20 | 2020-09-18 | 济南格莱威医疗科技有限公司 | Preparation method and application of chitosan with controllable molecular weight range |
| CN112972489A (en) * | 2021-03-19 | 2021-06-18 | 季华实验室 | Chitosan-based composition with weight-losing and lipid-lowering functions as well as preparation method and application thereof |
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| CN112972489A (en) * | 2021-03-19 | 2021-06-18 | 季华实验室 | Chitosan-based composition with weight-losing and lipid-lowering functions as well as preparation method and application thereof |
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