CN103145873B - Chitin deacetylation method - Google Patents

Abstract

The invention discloses a deacetylation method of chitin. The method comprises releasing pressure instantly at high temperature and high pressure to evaporate water in the chitin microparticle structure rapidly to form strong vapor pressure, thereby breaking the bond between acetyl group and nitrogen atom of chitin. The method has the advantages of large-scale treatment, quick reaction, less reaction variables, simple operation, low cost and environmental protection.

Description

Chitin deacetylation method

technical field

The invention relates to a method for deacetylating chitin, in particular to a method for deacetylating chitin by instantaneous pressure release.

Background technique

Chitin and chitosan are multifunctional, environmentally friendly, and biocompatible modern materials that can be used in a wide range of applications, such as agriculture, food/nutrition, biomedicine, materials Science, cosmetics, wastewater treatment, papermaking, textiles and other fields, so all countries in the world, whether developed or developing, are actively conducting research on these substances. Please refer to Figure 1, which is a schematic diagram of the chemical structural formula of chitin. Chitin is a high molecular polymer composed of N-acetylglucosamine sugar as a monomer and linked by β-1,4. It exists in the exoskeleton of arthropods, squid cartilage and the cell wall of fungi. Although chitin is abundant in nature and has the advantages of stable physical and chemical properties, its acetyl group is easy to form intramolecular/intermolecular hydrogen bonds to form a compact crystal domain structure, making chitin in general solvents The solubility is very low, which is not conducive to industrial utilization.

Therefore, how to effectively break the bond between the acetyl group and the nitrogen atom on chitin is an important issue in the industry. The derivative of chitin obtained by deacetylation is called chitosan, and the higher the ratio of deacetylated monomer (glucosamine sugar) to non-deacetylated monomer (N-acetylglucosamine sugar), The easier the chitosan molecule is to dissolve in weak acid, the industrial applicability can be significantly improved.

Currently, chitin deacetylation methods include microbial method, enzyme method and hot alkali method. The microbial method and the enzyme method respectively use microorganisms and chitin deacetylase (Chitindeacetylase) to deacetylate chitin. These two biological methods will not have the risk of breaking the chitin molecular chain bonds, and will not have serious chemical waste pollution problems, but the action time is long, and the yield and reaction conditions are limited by microorganisms or enzymes Tolerance, mass production is difficult, so it is rarely used as a method for mass production of chitosan.

The hot alkaline method is currently the main commercial method for preparing chitosan, which uses high temperature and strong alkali to deacetylate chitin. Among them, high-concentration lye (generally 30-60% NaOH) dissociates a large number of negatively charged hydroxide ions (OH ^- ) in the solvent, and the ions replace the oxygen atoms on the chitin acetyl group to become protons Receiver, and then destroy the intramolecular/intermolecular hydrogen bond and crystallization domain structure of chitin, making the bond between acetyl group and amine group more easily contact with a large number of hydroxide ions, and at high temperature (generally 100~ 130°C) for electron attack and fragmentation reactions.

In addition, some literature pointed out that appropriate pressure (about 1-20PSIG) can promote more hydroxide ions and water molecules to enter the chitin crystal region, which is beneficial to destroy hydrogen bonds and promote electron attack reactions in acetamide groups. Therefore, the degree of chitin deacetylation can be further enhanced. Compared with the microbial method and the enzyme method, although the hot alkali method has the advantages of rapid reaction, less reaction variables, and a high degree of deacetylation, however, this method will produce a large amount of waste liquid, including high-concentration spent alkali liquid and water-washed products. In addition, in addition to the huge cost caused by the use of a large amount of sodium hydroxide, pure water and waste liquid treatment, the hot alkali method is also prone to adverse consequences of polluting the environment.

Therefore, it is necessary to develop a new method for deacetylation of chitin, which has the advantages of rapid response, few reaction variables, and will not produce a large amount of waste liquid to pollute the environment and cause environmental protection problems, and can take into account simple operation, low equipment cost, The purpose of reducing costs.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for rapidly deacetylating chitin in a neutral environment, aiming at the above-mentioned deficiencies in the prior art.

The technical problem to be solved by the present invention is to provide a chitin deacetylation method that has the advantages of environmental protection and low cost in view of the above-mentioned deficiencies in the prior art.

The technical problem to be solved by the present invention is to provide a method for deacetylation of chitin with few reaction variables and simple operation in view of the above-mentioned deficiencies in the prior art.

The technical solution adopted by the present invention to solve the technical problems is to provide a method for chitin deacetylation, which at least includes the following steps:

(a) adjusting the moisture content of chitin to a predetermined moisture content;

(b) putting the chitin into a closed container;

(c) heating the closed container to a predetermined temperature so that the pressure in the closed container reaches a first pressure value; and

(d) releasing the pressure in the closed container so that the pressure in the closed container drops to a second pressure value;

Wherein, when the pressure in the airtight container drops from the first pressure value to the second pressure value, the water in the chitin will evaporate rapidly to break the gap between the chitin acetyl group and the nitrogen atom. covalent bond.

Preferably, the step (a) includes at least the following steps:

(a1) soaking chitin in a solution;

(a2) filtering off the solution while retaining the chitin; and

(a3) reducing the moisture content of the chitin to the predetermined moisture content.

Preferably, in the step (a3), the moisture of the chitin is lowered to the predetermined moisture content by drying at 50°C.

Preferably, the airtight container is a pressure container, and the first pressure value is greater than the gauge pressure of 1 kg/cm ² .

Preferably, the pressure vessel is an expansion gun, and the first pressure value is between 1-20 kg/cm ² gauge pressure.

Preferably, the predetermined temperature is at least 100°C.

Preferably, the predetermined water content of the chitin is between 10% and 90%.

Preferably, in the step (a1), the solution is an aqueous solution.

Preferably, the pH of the aqueous solution is at least 6.

Preferably, the pH value of the aqueous solution is between 6-8.

Preferably, the chitin is at least any one of α-chitin, β-chitin and γ-chitin.

The present invention also provides a method for chitin deacetylation, which at least includes the following steps:

(a) put chitin into a closed container;

(b) regulating the pressure in the closed container to a first pressure value; and

(c) releasing the pressure in the closed container so that the pressure in the closed container drops to a second pressure value;

Wherein, when the pressure in the airtight container drops from the first pressure value to the second pressure value, the water in the chitin will evaporate rapidly to break the gap between the chitin acetyl group and the nitrogen atom. covalent bond.

Preferably, the airtight container is a pressure container, and the first pressure value is greater than the gauge pressure of 1 kg/cm ² .

Preferably, the pressure vessel is an expansion gun, and the first pressure value is between 1-20 kg/cm ² gauge pressure.

Preferably, in the step (b), the pressure of the airtight container is regulated to the first pressure value by heating to a predetermined temperature.

Preferably, the predetermined temperature is at least 100°C.

Preferably, the step (a) further includes steps before:

(a1) Soaking the chitin in a solution.

Preferably, between the step (a1) and the step (a), further include steps:

(a2) Filtering off the solution while retaining the chitin.

Preferably, between the step (a2) and the step (a), further include steps:

(a3) reducing the moisture content of the chitin to a predetermined moisture content.

Preferably, in the step (a3), the predetermined water content of the chitin is between 10% and 90%.

Preferably, in the step (a1), the pH of the solution is at least 6.

Preferably, in the step (a1), the pH of the solution is between 6-8.

Preferably, the chitin is at least any one of α-chitin, β-chitin and γ-chitin.

The present invention utilizes the strong vapor pressure generated by instantaneous pressure release under high pressure to achieve the effect of deacetylation, and does not need to use a large amount of lye during the action, thereby greatly saving the cost of treating spent lye and washing waste liquid, and avoiding Waste liquid pollutes the environment, so the chitin deacetylation method of the present invention has the advantages of large-scale treatment, rapid reaction, less reaction variables, simple operation, low cost and environmental protection.

Description of drawings

Figure 1 is a schematic diagram of the chemical structural formula of chitin.

Fig. 2 is an example diagram of the block flow of the first preferred embodiment of the chitin deacetylation method of the present invention.

Fig. 3 is an example diagram of the block flow of the second preferred embodiment of the chitin deacetylation method of the present invention.

Fig. 4 is a schematic illustration of a specific implementation concept of the airtight container shown in the first preferred implementation method and the second preferred implementation method of the present invention.

detailed description

In view of the defects of the prior art, the present invention provides a new method for deacetylation of chitin, which uses high pressure to quickly return to normal pressure, and all the water in the chitin particle structure evaporates in an instant, resulting in Generates a strong vapor pressure and expands rapidly in all directions. During this process, the weaker bonds in the particle structure (such as hydrogen bonds, covalent bonds between acetyl groups and nitrogen atoms) will be broken, and the vapor pressure will be increased by These fractured pores vent.

In other words, it can be observed in the experiment that the degree of deacetylation of chitin that has been rapidly restored to normal pressure after high pressure is significantly higher than that of chitin that has not been rapidly released (p<0.05). Observation with an electron microscope revealed that after the high pressure was rapidly returned to normal pressure, the chitin particles became smaller, and each small particle showed a phenomenon of porosity, which proved that the rapid expansion did occur at the moment of pressure release. Phenomenon, the force that maintains the particle structure is destroyed, causing the particle structure to be broken into many smaller particles and densely covered with countless small pores.

Please refer to FIG. 2 , which is a block flow diagram of a chitin deacetylation method in a first preferred embodiment of the present invention. A preferred implementation method of chitin deacetylation of the present invention at least includes:

Step S1: adjusting the water content of chitin to a predetermined water content;

Step S2: put chitin into the airtight container 1;

Step S3: heating to a predetermined temperature, so that the pressure in the airtight container 1 reaches the first pressure value; and

Step S4: releasing the pressure in the airtight container 1, reducing the pressure in the airtight container 1 to a second pressure value to break the covalent bond A between the acetyl group and the nitrogen atom of chitin.

Wherein, step S1 includes at least:

Step a1: soaking chitin in the solution;

Step a2: filtering off the solution while retaining chitin; and

Step a3: reducing the water content of chitin to a predetermined water content.

In this preferred embodiment, step S1 is used to adjust the water content in the chitin particle structure. Wherein, in step a1, soaking chitin in the solution will cause the inside of the chitin particle structure to be filled with solution and swell and expand. The solution can be pure water, neutral aqueous solution, slightly acidic aqueous solution, alkaline aqueous solution, or other Liquid solutions; but not limited to.

In step a2, the excess solution is filtered out by mesh sieve or other methods, and the chitin is retained, so as to further adjust the water content inside and outside the chitin particle structure. In step a3, the water content of chitin can be reduced to a predetermined water content by means of an oven at 50°C or other temperature methods, and the predetermined water content is preferably 10-90%.

It should be noted that step S1 plays an important role in the subsequent deacetylation effect. Whether it is the degree of swelling or the water content inside and outside the chitin particle structure, it will affect the volume of the particle structure, the amount of steam after pressure release, and the amount of steam. Therefore, it is necessary to evaluate the action conditions of each sub-step in step S1 in order to achieve the best deacetylation effect.

Furthermore, step S2 puts chitin into the airtight container 1 for the subsequent step of boosting the pressure. The airtight container 1 can be an expansion gun (please refer to FIG. 4 for cooperation first), or other pressure vessels with instantaneous pressure release safety protection, but it is not limited thereto.

Moreover, step S3 heats the airtight container 1 to a predetermined temperature, so that the pressure in the airtight container 1 reaches a first pressure value. Wherein, the predetermined temperature needs to be greater than or equal to the boiling point of the solution at atmospheric pressure (gauge pressure is 0 kg/cm ² ), so that the pressure in the airtight container 1 reaches the first pressure value by the vapor generated when the solution evaporates. For example, when the solution is pure water, the predetermined temperature must be greater than or equal to 100°C. In addition, the first pressure value should be greater than atmospheric pressure, the greater the pressure, the better the effect of deacetylation, but too high may cause the degradation reaction of chitin molecular chain breakage.

Also, step S4 releases the pressure in the airtight container 1 instantaneously, reducing the pressure in the airtight container 1 to a second pressure value to break the covalent bond A between the acetyl group of chitin and the nitrogen atom. Wherein the second pressure value may be atmospheric pressure or other pressures lower than the first pressure value. Under the condition of safety and equipment permission, the second pressure value can even be less than atmospheric pressure (for example, the airtight container is placed in a negative pressure or under the environment of near vacuum, and after the airtight container is depressurized, it reaches a pressure lower than the atmospheric pressure. second pressure value).

The present invention further provides a second preferred embodiment. Please refer to FIG. 3 , which is a block flow diagram of a chitin deacetylation method in a second preferred embodiment of the present invention. Another preferred implementation method of chitin deacetylation of the present invention at least includes:

Step S11: putting chitin into the airtight container 111;

Step S12: regulating the pressure in the airtight container 111 to a first pressure value;

Step S13: releasing the pressure in the airtight container 111, reducing the pressure in the airtight container 111 to a second pressure value to break the covalent bond A' between the acetyl group of chitin and the nitrogen atom.

The method, condition and sequence of each step in the second preferred embodiment are the same as those in the first preferred embodiment, the only difference is that the first preferred embodiment includes a step S1 of adjusting the moisture content of chitin to a predetermined moisture content , and step S3 increases the pressure of the airtight container 1 by means of heating; of course, any person skilled in the art can make any equal changes, and is not limited to the content of the above-mentioned preferred implementation steps.

As for the second preferred embodiment, it does not include the step of adjusting the water content of chitin, and it is sufficient to only use the water contained in the chitin raw material, and step S12 is not limited to increasing the pressure by heating, and can also be Other boosting methods include compressing the volume of the airtight container 111 and the like.

Please refer to Table 1 below, which shows the changes in the degree of deacetylation of α-chitin after explosive expansion. Table 1 presents the results of the deacetylation degree of α-chitin treated with six groups of different conditions from top to bottom. In the first set of experiments, α-chitin was not treated with any adjustment of moisture, pressure increase, pH value or instantaneous pressure release, and the results showed that its degree of deacetylation was 25.2±1.9%. In the second set of experiments, α-chitin was first soaked in pure water with a pH value of 6.5 for 1 hour, and then the excess water was filtered off to retain α-chitin. At this time, the water content of α-chitin 60%. Put α-chitin into the expansion gun, and heat to make the pressure in the expansion gun reach the gauge pressure of 6kg/cm ² . Instantly open the tank cover of the expansion gun to achieve the effect of sudden pressure release. The result shows that the degree of deacetylation is 25.3±0.8%, which has no significant difference compared with the result of the first group. In the third group of experiments, α-chitin was first soaked in pure water with a pH value of 6.5 for 1 hour, and then the excess water was filtered to retain α-chitin. At this time, the water content of α-chitin 60%. Put α-chitin into the expansion gun, and heat to make the pressure in the expansion gun reach the gauge pressure of 9kg/cm ² . Instantly open the tank cover of the expansion gun to achieve the effect of sudden pressure release. The results showed that the degree of deacetylation was 27.3±2.5%, which was not significantly different from the results of the first group.

In the fourth set of experiments, α-chitin was first soaked in pure water with a pH value of 6.5 for 1 hour, and then the excess water was filtered off to retain α-chitin. At this time, the water content of α-chitin 60%. Put α-chitin into the expansion gun, and heat to make the pressure in the expansion gun reach the gauge pressure of 12kg/cm ² . Instantly open the tank cover of the expansion gun to achieve the effect of sudden pressure release. The result shows that the degree of deacetylation is 38.8±1.5%, which is significantly different from the result of the first group (p<0.05). In the fifth set of experiments, α-chitin was sequentially soaked in pure water with a pH value of 6.5 for 1 hour, excess water was filtered off to retain α-chitin, and oven-dried at 50°C for 3 hours, At this time, the moisture content of α-chitin was 47%. Put α-chitin into the expansion gun, and heat to make the pressure in the expansion gun reach the gauge pressure of 9kg/cm ² . Instantly open the tank cover of the expansion gun to achieve the effect of sudden pressure release. The result shows that the degree of deacetylation is 30.2±3.4%, which is significantly different from the result of the first group (p<0.05). In the sixth group of experiments, α-chitin was first soaked in sodium hydroxide aqueous solution with a pH value of 9.0 for 1 hour, and then the excess water was filtered off to retain α-chitin. At this time, α-chitin The moisture content is 60%. Put α-chitin into the expansion gun, and heat to make the pressure in the expansion gun reach the gauge pressure of 9kg/cm ² . Instantly open the tank cover of the expansion gun to achieve the effect of sudden pressure release. The result shows that the degree of deacetylation is 31.2±1.6%, which is significantly different from the result of the first group (p<0.05).

From the results of the first group to the fourth group in Table 1, it is known that in the method of removing α-chitin acetyl group by explosive expansion, the degree of deacetylation of α-chitin is related to the pressure before the expansion gun is released. The intensity range is positively correlated, that is, the stronger the pressure intensity before pressure release, the higher the deacetylation degree of α-chitin, and the effect is more significant when the gauge pressure before pressure release is above 12kg/cm ² . From the results of the third group and the fifth group in Table 1, in the method of removing the acetyl group of α-chitin by explosive expansion, the degree of deacetylation of α-chitin is related to the particle structure of α-chitin. related to the moisture content. From the results of the third group and the sixth group in Table 1, in the method of removing the acetyl group of α-chitin by explosive expansion, the degree of deacetylation of α-chitin is related to the particle structure of α-chitin. It is related to the pH value of the water, and the degree of deacetylation is higher under alkaline conditions. Based on the above results, it can be seen that in the method of removing α-chitin acetyl groups by explosive expansion, the degree of deacetylation of α-chitin is related to the pressure before pressure release, the water content of α-chitin, and the It is related to the pH value of the water in the butyl. After explosive expansion, the degree of deacetylation increased from 25.2±1.9% to 25.3±0.8%-38.8±1.5%, and the degree of deacetylation could increase by about 13%.

Table 1. Changes in deacetylation degree of α-chitin after explosive expansion.

^* unprocessed chitin

The above data are the results of 5 experiments, expressed as mean ± standard deviation. Different letters in a-c represent significant differences between the two groups of data (p<0.05); same letters represent no significant differences between the two groups of data.

Please refer to Table 2 below again, which is the change in deacetylation degree of β-chitin after explosive expansion. Table 2 presents the results of the degree of deacetylation of β-chitin from top to bottom after being treated with seven groups of different conditions. In the first set of experiments, β-chitin was not treated with any adjustment of moisture, pressure increase, pH value or instantaneous pressure release, and the results showed that its degree of deacetylation was 32.2±1.4%. In the second set of experiments, β-chitin was sequentially soaked in pure water with a pH value of 6.5 for 1 hour, excess water was filtered off to retain β-chitin, and then oven-dried at 50°C for 12 hours. At this time, the moisture content of β-chitin was 30%. Put β-chitin into the expansion gun and heat to make the pressure in the expansion gun reach the gauge pressure of 10kg/cm ² . Instantly open the tank cover of the expansion gun to achieve the effect of sudden pressure release. The results showed that the degree of deacetylation was 33.3±1.1%, which was not significantly different from the results of the first group. In the third set of experiments, β-chitin was sequentially soaked in pure water with a pH value of 6.5 for 1 hour, excess water was filtered off to retain β-chitin, and then oven-dried at 50°C for 6 hours. At this time, the moisture content of β-chitin was 60%. Put β-chitin into the expansion gun and heat to make the pressure in the expansion gun reach the gauge pressure of 10kg/cm ² . Instantly open the tank cover of the expansion gun to achieve the effect of sudden pressure release. The results showed that the degree of deacetylation was 33.8±2.5%, which was not significantly different from the results of the first group. In the fourth set of experiments, β-chitin was first soaked in pure water with a pH value of 6.5 for 1 hour, and then the excess water was filtered to retain β-chitin. At this time, the moisture content of β-chitin 80%. Put β-chitin into the expansion gun and heat to make the pressure in the expansion gun reach the gauge pressure of 10kg/cm ² . Instantly open the tank cover of the expansion gun to achieve the effect of sudden pressure release. The result shows that the degree of deacetylation is 35.2±1.6%, which is not significantly different from the result of the first group.

In the fifth set of experiments, β-chitin was soaked in pure water with a pH value of 6.5 for 1 hour, and the excess water was filtered to retain β-chitin. At this time, the moisture content of β-chitin was 80 %. Put β-chitin into the expansion gun and heat to make the pressure in the expansion gun reach the gauge pressure of 15kg/cm ² . Instantly open the tank cover of the expansion gun to achieve the effect of sudden pressure release. The result shows that the degree of deacetylation is 37.6±2.2%, which is significantly different from the result of the first group (p<0.05). In the sixth group of experiments, β-chitin was first soaked in pure water with a pH value of 6.5 for 1 hour, and then the excess water was filtered to retain β-chitin. At this time, the moisture content of β-chitin 80%. Put β-chitin into the expansion gun and heat to make the pressure in the expansion gun reach the gauge pressure of 20kg/cm ² . Instantly open the tank cover of the expansion gun to achieve the effect of sudden pressure release. The results showed that the degree of deacetylation was 41.4±3.1%, which was significantly different from the results of the first group (p<0.05). In the seventh group of experiments, β-chitin was first soaked in sodium hydroxide aqueous solution with a pH value of 9.0 for 1 hour, and then the excess water was filtered to retain β-chitin. At this time, β-chitin The moisture content is 80%. Put β-chitin into the expansion gun and heat to make the pressure in the expansion gun reach the gauge pressure of 10kg/cm ² . Instantly open the tank cover of the expansion gun to achieve the effect of sudden pressure release. The results showed that the degree of deacetylation was 35.5±0.3%, which was not significantly different from the results of the first group.

From the results of the first group, the fourth group to the sixth group in Table 2, in the method of removing β-chitin acetyl group by explosive swelling, the degree of deacetylation of β-chitin is related to the swelling gun release method. The pressure intensity before pressure is positively correlated, that is, the stronger the pressure intensity before pressure release, the higher the deacetylation degree of β-chitin, and the gauge pressure before pressure release is above 15kg/cm ² has a significant effect. From the results of the first group to the fourth group in Table 2, in the method of removing β-chitin acetyl group by explosive expansion, the degree of deacetylation of β-chitin may be related to the particle structure of β-chitin related to the moisture content. According to the results of the first group, the fourth group and the seventh group in Table 2, in the method of removing β-chitin acetyl group by explosive swelling, the degree of deacetylation of β-chitin may be the same as that of β-chitin The pH value of the water content of butin is related. Based on the above results, it can be seen that in the method of removing β-chitin acetyl groups by explosive expansion, the degree of deacetylation of β-chitin is related to the pressure before pressure release, and may be related to the water content of chitin and the chitin concentration. It is related to the pH value of the water in the particle structure. After explosive expansion, the degree of deacetylation increased from 32.2±1.4% to 33.3±1.1%-41.4±3.1%, and the degree of deacetylation increased by about 9%.

Table 2. Changes in deacetylation degree of β-chitin after explosive expansion.

^* unprocessed chitin

The above data are the results of 5 experiments, expressed as mean ± standard deviation. Different letters in a-c represent significant differences between the two groups of data (p<0.05); same letters represent no significant differences between the two groups of data.

According to the above, it can be known that the present invention utilizes the strong vapor pressure produced by the instantaneous pressure release under high pressure to achieve the result of deacetylation, and it is not necessary to use a large amount of lye during the action, which saves a lot of time spent on processing spent lye and washing waste. Therefore, this method is a new chitin deacetylation method that can be processed in large quantities, reacts quickly, has less reaction variables, is simple to operate, low in cost, and can take into account environmental protection.

As for the airtight container 1 and the airtight container 111 shown in the aforementioned first preferred implementation method and second preferred implementation method, for example, its preferred specific implementation structure can be the expansion gun shown in Figure 4 10, and it at least includes: a controller 11, a pressure sensor 12, a rotating tank 13, a heater 14 and a tank cover 15 and other components. Among them, in various preferred embodiments in which chitin is explosively expanded with the expanding gun 10, the chitin is first placed in the rotating groove 13 of the expanding gun 10, the rotating groove 13 is locked, and the heating After the device 14 is heated to the set first pressure value (which can be known by the pressure sensor 12), the tank cover 15 is opened instantly to achieve the purpose of deacetylating chitin by sudden pressure release. Of course, the expansion gun shown in FIG. 4 is only a preferred embodiment of the aforementioned airtight container, and is not limited thereto.

The above descriptions are only preferred embodiments and experimental data of the present invention, and are not intended to limit the scope of the claims of the present invention. Therefore, all other equivalent changes or modifications that do not depart from the spirit disclosed in the present invention should be included within the scope of the present invention.

Claims (11)

1. a method for chitin deacetylation, is characterized in that, the method at least comprises the following steps:

A () adjusts chitinous moisture to one predetermined moisture content, and this predetermined moisture content is between 47 ~ 90%;

B () inserts in this chitin to one encloses container;

C () heats this encloses container to one preset temperature, and make pressure to one first force value in this encloses container, and this first force value is more than or equal to gauge pressure 9kg/cm ²; And

D () discharges the pressure in this encloses container, and make Pressure Drop to one second force value in this encloses container;

Wherein, the pressure in this encloses container is down in the process of this second force value from this first force value, will make the moisture rapid evaporation in this chitin and the covalent linkage that interrupts between this chitin ethanoyl and nitrogen-atoms, obtains spherical chitosan; Further, this chitin be in α chitin, β chitin and γ chitin at least any one.

2. the method for chitin deacetylation as claimed in claim 1, it is characterized in that, this encloses container is a pressurized vessel, and this first force value is between gauge pressure 9 ~ 20kg/cm ².

3. the method for chitin deacetylation as claimed in claim 1, it is characterized in that, this encloses container is one swollen rifle, and this first force value is between gauge pressure 9 ~ 20kg/cm ².

4. the method for chitin deacetylation as claimed in claim 1, it is characterized in that, this preset temperature is at least 100 DEG C.

5. the method for chitin deacetylation as claimed in claim 1, it is characterized in that, this step (a) at least comprises the following steps:

(a1) chitin is soaked in a solution;

(a2) this solution of filtering, and retain this chitin; And

(a3) this chitinous moisture is downgraded to this predetermined moisture content.

6. the method for chitin deacetylation as claimed in claim 5, is characterized in that, in this step (a3), is dry under 50 DEG C of conditions and downgrade this chitinous moisture to this predetermined moisture content.

7. the method for chitin deacetylation as claimed in claim 5, it is characterized in that, in this step (a1), this solution is the aqueous solution.

8. the method for chitin deacetylation as claimed in claim 5, it is characterized in that, in this step (a1), this solution is the aqueous solution that pH value is at least 6.

9. the method for chitin deacetylation as claimed in claim 5, is characterized in that, in this step (a1), this solution be pH value between 6 ~ 8 the aqueous solution.

10. the method for chitin deacetylation as claimed in claim 1, it is characterized in that, this step (a) at least comprises the following steps:

(a1) this chitin is soaked in a solution.

The method of 11. chitin deacetylations as claimed in claim 1, it is characterized in that, this step (a) at least comprises the following steps:

(a1) this chitin is soaked in a solution; And

(a2) this solution of filtering, and retain this chitin.