CN107573442B - A method of chitosan is prepared using supercritical carbon dioxide reaction technology - Google Patents
A method of chitosan is prepared using supercritical carbon dioxide reaction technology Download PDFInfo
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- CN107573442B CN107573442B CN201710956888.XA CN201710956888A CN107573442B CN 107573442 B CN107573442 B CN 107573442B CN 201710956888 A CN201710956888 A CN 201710956888A CN 107573442 B CN107573442 B CN 107573442B
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- carbon dioxide
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
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Abstract
The invention discloses a kind of methods for preparing chitosan using supercritical carbon dioxide reaction technology, using supercritical carbon dioxide as reaction system, carry out deacetylation to chitin using strong organic base.The relatively strong penetrating power and greater density and solubility similar to liquid that the supercritical fluid that the present invention uses has similar gas; greatly reduce the dosage of alkali; carbon dioxide no pollution to the environment; simultaneous reactions temperature is low, action time is short (30min-3 hours); acetyl group and heteroproteins dispel rate height; available deacetylation high (being not less than 92%), protein content low (less than 0.2%), less degradation chitosan; significantly improve the efficiency for preparing chitosan; water is not used simultaneously, greatly reduces discharge of wastewater.
Description
Technical field
The present invention relates to biodegradable class field of medical materials, and in particular to a kind of to react skill using supercritical carbon dioxide
The method that art prepares chitosan.
Background technique
Chitosan (chitosan), also known as chitosan are the chitins (chitin) being widely present by nature
It is obtained by deacetylation, chemical name is Chitosan [(1-4) -2- amino-B-D glucose.Deacetylation degree
(D.D) amido (NH on macromolecular chain is determined2) content number, and D.D increase, due to amido protonate and make chitosan
Charged group increases in dilute acid soln, and charge density of polyelectrolyte increases, and result will lead to its structure, property and performance
On variation.The biological functionality and compatibility of this natural polymer, blood compatibility, safety, microbic resolvability etc.
Excellent performance is by all trades and professions extensive concern, in medicine, food, chemical industry, cosmetics, water process, METAL EXTRACTION and recycling, biochemistry
Application study with the numerous areas such as biomedical engineering achieves major progress.
The primary raw material for preparing chitosan derives from shrimp shell and crab shell that aquatic products processing factory discards, and main component has carbonic acid
Calcium, protein and chitin (20% or so).It is actually decalcification by the process that shrimp and crab shells prepare chitosan, deproteinized matter, takes off
The process of color and desacetoxy.The method for preparing chitosan both at home and abroad at present includes that acid-base method, enzyme process, oxidation degradation method and machinery add
Engineering method.Acid-base method is to convert soluble calcium chloride for the calcium carbonate of indissoluble using dilute hydrochloric acid and separate with solution, then with dilute
Alkali dissolves out protein, and chitin can be obtained using decoloration and the processes such as washing, dry, then anti-by desacetoxyization
It answers, chitin can be made to slough the acetate in molecule, be changed into chitosan.Enzyme process is then to remove egg using ethylenediamine decalcification, with enzyme
The process of white matter.Machining rule is to pass through the processes such as drying, crushing, grinding, sorting, fine screen using selected shrimp and crab shells.
The method of most common of them is acid-base method, but there are still many problems for this method, as acid-base property is too strong, degradation speed is slow, degradation produces
The object degree of polymerization is low, product purification is difficult, production cost is high etc..
The preparation method of chitosan, which generallys use, at present is placed in chitin in 45%-50% sodium hydroxide solution
110 DEG C of 100- hydrolysis.The test that studies for a long period of time is thought, when naoh concentration is lower than 30%, no matter reaction temperature is how high, anti-
Between seasonable how long, acetyl group removal efficiency is also only 50% or so.And when one timing of naoh concentration, deacetylation speed
Accelerate as the temperature rises, such as when naoh concentration is 50%, reaction temperature is 140 DEG C, and 20min acetyl group is de-
Except rate is 85% or so, and for 24 hours in 25 DEG C of Shi Zexu or so.For chitin under hot concentrated alkali effect, key reaction is acetamide hydrolysis
Acetyl group is removed, while the hydrolytic degradation side reaction of main chain also occurs, it is therefore necessary to the strict control reaction time.This preparation side
Method disadvantage is as follows: 1, highly basic is significantly excessive, generates a large amount of salkali waste, and environmental pollution is larger；2, since concentration of lye is big, temperature
Height, the time is long, and degradation of chitosan is more；3, since aqueous systems penetration power is poor, acetyl group and heteroproteins are dispelled not enough thoroughly, residual
Value is high.
Summary of the invention
The present invention utilizes overcritical titanium dioxide in view of the shortcomings of the prior art, provide a kind of new method for preparing chitosan
Carbon reaction technology significantly improves the efficiency for preparing chitosan.
Specific technical solution of the present invention is as follows:
A method of preparing chitosan using supercritical carbon dioxide reaction technology, using supercritical carbon dioxide as
Reaction system carries out deacetylation to chitin using strong organic base.
The strong organic base is selected from one or more of sodium ethoxide, sodium methoxide.
The chitin: the molar ratio 1:1-5 of strong organic base.It is preferred that 1:1,1:3.1:5.
A preferred embodiment of the invention, reaction also use entrainer.The entrainer is selected from methanol, ethyl alcohol, acetone, second
One or more of acetoacetic ester.Entrainer can promote the dissolution of organic base, improve the deacetylation of product, preferably crust
Element: the molar ratio of entrainer is 1:1-1:2.
Reaction preferable reaction temperature of the present invention is 20~60 DEG C, reaction pressure 10-50Mpa, reaction time 30min
~3 hours.
Supercritical fluid is more than critical-temperature and critical pressure, and the fluid between gas and liquid has concurrently
The double properties and advantage of gas liquid:
(1) dissolubility is strong
Density is and hundreds times bigger than gas close to liquid, since the solubility of substance and the density of solvent are directly proportional,
Supercritical fluid has and solvability similar in liquid solvent.
(2) diffusion is good
Because viscosity is close to gas, 2 orders of magnitude small compared with liquid.Diffusion coefficient is liquid between gas and liquid
10-100 times.It is easy to the characteristic for spreading and moving with gas, mass transfer rate is significantly larger than liquid.
(3) easily controllable
In Near The Critical Point, the minor change of pressure and temperature, the variation that fluid density can be caused very big, to make
Biggish change occurs for solubility.(most important to extracting and being stripped).
In recent years, supercritical fluid technique is widely used for various aspects by people, such as supercritical fluid extraction, overcritical
Water oxidation technology, supercritical fluid drying, supercritical fluid dyeing, supercritical fluid prepare ultrafine dust, shooting flow body colour
Spectrum, there has been no the reports that chitosan is prepared for degradation of chitin at present.
Advantages of the present invention:
(1) supercritical carbon dioxide reaction technology is used for degradation of chitin for the first time and prepares chitosan by the present invention, due to super
The relatively strong penetrating power and greater density and solubility similar to liquid that critical fluids have similar gas, so that the dosage of alkali is big
Big to reduce, simultaneous reactions temperature low (degree of room temperature -60), action time are short (30min-3 hours), significantly improve and prepare chitosan
Efficiency, while not using water, greatly reduce water wasting discharge, also, carbon dioxide no pollution to the environment is very suitable to chitosan
Industrialized production.
(2) preparation method of the present invention dispels rate height to acetyl group and heteroproteins, and chitosan obtained is deacetylated
Degree high (being not less than 92%), protein content are low (less than 0.2%), significantly improve the quality of chitosan.
Specific embodiment
Term as used in the present invention generally there are those of ordinary skill in the art usually to manage unless otherwise indicated
The meaning of solution.
The present invention is described in further detail combined with specific embodiments below and referring to data.It should be understood that the embodiment is
In order to demonstrate the invention, it rather than limits the scope of the invention in any way.
In the examples below, the various processes and method being not described in detail are conventional methods as known in the art.Under
Material used in example, reagent, device, instrument, equipment etc. are stated, unless otherwise specified, is commercially obtained.
The present invention is further described combined with specific embodiments below.
Embodiment 1-4
Chitosan is prepared respectively using method of the present invention referring to the condition of table 1.
Table 1
| Embodiment 1 | Embodiment 2 | Embodiment 3 | Embodiment 4 | |
| Organic base | Sodium methoxide | Sodium methoxide | Sodium ethoxide | Sodium methoxide |
| Organic alkali concentration (W/V%) | 20% | 10% | 20% | 30% |
| Chitin: organic base (molar ratio) | 1:1.2 | 1:1.2 | 1:1.5 | 1:2 |
| Entrainer | / | Methanol | Ethyl alcohol | Isopropanol |
| Chitin: entrainer (molar ratio) | / | 1:1 | 1:1.5 | 1:2 |
It is placed in chitin and organic alkali solution in the high-temperature high-pressure reaction kettle of 1000ml, is passed through CO2It is discharged empty in kettle
Then at a set temperature (20~60 DEG C) gas boosts to setting pressure 10-50Mpa, and keep the temperature 60min.To after reaction
Cooling water temperature is passed through in the cooling tube of reaction kettle inner wall to spiraling, then, the liquid product that discharge degradation generates, and open
Reaction kettle takes out solid residue.Finally, first being impregnated solid residue 10 minutes with 100ml water, a water was changed every 20 minutes,
Dry 12h in 60 DEG C of thermostatic drying chamber is placed into, yield is calculated.
The measurement of deacetylating degree of chitosan:
0.3~0.5g of chitosan is accurately weighed, 0.1mol/L hydrochloric acid 30ml is added and makes it dissolve, with one aniline blue of methyl orange
De- second phthalein degree to terminal with 0.lmolL/ sodium hydroxide titration is calculated as follows for indicator:
NH2%=[(C1V1-C2V2The G of) × 0.016/ (100 1 W)] × 100%
Deacetylation==(NH2%/9.94%)×100%
In formula: C1: concentration of hydrochloric acid solution (mol/L)；C2: concentration of sodium hydroxide solution (mol/L)；V1: and the hydrochloric acid of addition
Liquor capacity (ml)；V2: titrate the sodium hydroxide solution volume (ml) of consumption；G: sample weight (g);W: sample water content (%)；
0.016: with the comparable amino amount (g) of 1mol/L hydrochloric acid 1ml.
Use library Mas bright blue colorimetric method for determining protein content.
Chitosan is made in embodiment 1-4 deacetylation and protein content are measured, the results are shown in Table 2.
Table 2
| Embodiment 1 | Embodiment 2 | Embodiment 3 | Embodiment 4 | |
| Yield | 85 | 87 | 81 | 83 |
| Deacetylation % | 92 | 95 | 97 | 96 |
| Protein content % | 0.09 | 0.07 | 0.06 | 0.05 |
Claims (4)
1. a kind of method for preparing chitosan using supercritical carbon dioxide reaction technology, it is characterised in that utilize overcritical dioxy
Change carbon as reaction system, deacetylation is carried out to chitin using strong organic base, the strong organic base is selected from sodium ethoxide, first
One or more of sodium alkoxide, the chitin: the molar ratio 1:1-5 of strong organic base.
2. the method as described in claim 1, it is characterised in that also use entrainer.
3. method according to claim 2, it is characterised in that the entrainer is in methanol, ethyl alcohol, isopropanol, acetone
It is one or more of.
4. the method according to claim 1, it is characterised in that reaction temperature is 20~60 DEG C, and reaction pressure is
10-50Mpa, reaction time 30min~3 hour.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1217957C (en) * | 2003-04-24 | 2005-09-07 | 中国科学院兰州化学物理研究所 | Method for preparing high-qualtiy chitosan |
| CN101200505B (en) * | 2007-11-29 | 2011-01-19 | 湖北东方天琪生物工程股份有限公司 | Method for preparing high deacetylate degree and high viscosity chitosan by using shrimp shell |
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Non-Patent Citations (1)
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| "Direct chitosan scaffold formation via chitin whiskers by a supercritical carbon dioxide method: a green approach";Kumari Rinki等;《Journal of Materials Chemistry》;20090907;第19卷;第8651–8655页 * |
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