Chitin (powder)
Chitin
CAS: 1398-61-4
Molecular Formula: C6H11NO4X2
Chitin (powder) - Names and Identifiers
Chitin (powder) - Physico-chemical Properties
| Molecular Formula | C6H11NO4X2 |
| Molar Mass | 161.16 |
| Density | 1.3744 (rough estimate) |
| Melting Point | >300°C (dec.) |
| Boling Point | 737.18°C (rough estimate) |
| Water Solubility | insoluble |
| Solubility | dilute aqueous acid (pH <6.5).: soluble |
| Appearance | purified powder |
| Color | White |
| Merck | 14,2065 |
| Storage Condition | Room Temp |
| Stability | Stable. Incompatible with strong oxidizing agents. |
| Refractive Index | 1.6000 (estimate) |
| Physical and Chemical Properties | It is an off-white amorphous powder, odorless and tasteless. Can be dissolved in lithium chloride containing 8% of dimethyl acetamide or concentrated acid; Insoluble in water, dilute acid, alkali, ethanol or other organic solvents. In nature, chitin is widely found in the shells of crustaceans such as lower plant fungi, shrimp, crab and insects, and in the cell walls of higher plants. It is a linear polymer chemical book polysaccharide, namely natural neutral mucopolysaccharide. If the acetyl group is removed by concentrated alkali treatment, the chitosan is obtained. Chitin is chemically inactive, does not change with body fluids, does not cause foreign body reaction to tissues, non-toxic, with anti-thrombotic, high temperature Disinfection and other characteristics. Chitosan is alkaline polysaccharide, acid, anti-inflammatory effect, can reduce cholesterol, blood lipids. |
| Use | Uses pharmaceutical excipients, medical sutures, etc. It can be used as a sustained release agent, a lubricant, and a coating agent as an auxiliary material. Microgranules, tablets, capsules, microfilms and the like of the corresponding drug can be prepared by direct compression, wet granulation or coating. Can be made of dialysis membrane, ultrafiltration membrane and reverse osmosis membrane; And fiber and other cross-chain complex can be formed into molecular sieve. As a cross-linking agent with glutaraldehyde and the like, it can be immobilized with many enzymes or microbial cells, such as immobilized asparaginase. Can be used as artificial skin, artificial blood vessels, artificial kidney, etc. Chitosan can inhibit gastric ulcer, lower cholesterol, blood lipids. |
Chitin (powder) - Risk and Safety
| Risk Codes | R20/21/22 - Harmful by inhalation, in contact with skin and if swallowed. R36/37/38 - Irritating to eyes, respiratory system and skin. |
| Safety Description | S24/25 - Avoid contact with skin and eyes. S36 - Wear suitable protective clothing. S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. |
| WGK Germany | 3 |
| RTECS | FM6300000 |
| FLUKA BRAND F CODES | 3 |
| TSCA | Yes |
| HS Code | 32139000 |
Chitin (powder) - The chemistry and application of chitin
from hownet
Author:
Abstract:
chitin, also known as chitin and chitin, is an important component of the shells of many lower animals, especially arthropods, such as shrimp, crab and insects, it is also found in the cell walls of lower plants, such as bacteria and algae, and is widely distributed. The biosynthesis of chitin in nature is estimated to be billions of tons per year.
Key words:
chitin chemistry chitosan and its derivatives high molecular weight cellulose adsorption capacity heavy metal ions reaction time methacrylic acid complex adsorption
DOI:
CNKI:SUN:HXTB.0.1984-11-010
cited:
year:
1984
Last Update：2024-01-02 23:10:35
Chitin (powder) - Recent advances in the chemistry and application of chitin
from VIP Journal Professional Edition
Author:
Abstract:
In this paper, the general situation and development trend of chitin chemistry and application in recent years are reviewed, focusing on the chemical structure and physicochemical properties of chitin and the application of chitosan, chitooligosaccharides, glucosamine and its derivatives. At the same time also introduced some of the main activities of chitin chemistry at home and abroad
Key words:
chitin chemistry, chitosan, chitooligosaccharides, glucosamine, comment
DOI:
10.3321/j.issn:1671-8836.2000.02.031
cited:
year:
2000
Last Update：2023-08-16 22:05:47
Chitin (powder) - Ultrasonic degradation of deacetylated chitin
Last Update：2023-08-16 22:05:47
Chitin (powder) - Application of chitin and chitosan in industrial water treatment
from VIP Journal Professional Edition
Author:
Abstract:
The Structure and Properties of chitin and chitosan and their application in industrial water treatment were introduced. The unique effect of chitosan in the treatment of food processing wastewater was emphatically expounded.
Key words:
chitin chitosan Water Treatment Industrial water
DOI:
CNKI:SUN:GYSC.0.1996-02-000
cited:
year:
1996
Last Update：2023-08-16 22:05:47
Chitin (powder) - Chitin chemistry
Author:
Abstract:
Chitin is a natural polymer extracted from shrimp and crab shells. Chitosan is the product of deacetylation of chitin. This book systematically introduces the basic physical and chemical properties of chitin and chitosan, based on a detailed summary of the types of various derivatives, focusing on the main chain degradation, carboxylation, acylation, hydroxylation, alkylation, esterification, organic Progress in quaternary ammonium salts, graft copolymerization and organic-inorganic composite. This book can be read by scientific and technical personnel engaged in functional polymer materials, biological materials, daily chemical industry, environmental protection and biotechnology. It can also be used as polymer chemistry, biochemistry, medicine and health, environmental protection, reference books for teachers and students of colleges and universities specialized in food and agriculture.Key words:
publication date:
2008
cited:
Last Update：2023-08-16 22:05:47
Chitin (powder) - Reference Information
| EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
| Overview | Chitin is a nitrogen-containing polysaccharide, also known as chitin, chitin, chitin, chitin, chitin, cutin, etc. It is the second most abundant biopolymer in nature and is widely distributed. It is an important component of the shells of many lower animals, especially arthropods such as shrimp, crabs, insects, etc. Shrimp shells contain about 15% ~ 30%, crab shells contain about 15% ~ 20%. It is also a component of the cell membrane of lower plant fungi, including lichens, green algae, yeast, jellyfish and squid. It is estimated that the annual biosynthesis exceeds 1 billion tons, which is a huge renewable resource. The appearance is white or yellowish transparent. It is a 2-acetylglucosamine polymer. Its chemical structure is similar to that of natural cellulose. In addition to hydroxyl groups, the molecule also contains acetylamino and amino functional groups, which can be used for structural modification. There are many groups, which have more functional properties than cellulose and its derivatives. They are insoluble in water, ethanol, ether, salts, dilute acids and bases; soluble in acetic acid, it reacts with concentrated caustic soda solution to form glassy colloidal soluble chitin (also known as polyamine glucose, chitosan, sugar solution chitin, chitosan, etc.), which can be used to: ①Purified water and extract uranium from seawater Ion exchange resin; ②Filler and molecular sieve of gel chromatography column; ③Preparation of food packaging film or soluble in vivo surgical thread that can be degraded by organisms or enzymes; ④Water retention agent for cultivating plants or microorganisms; (5) Anti-shrink and anti-wrinkle treatment of textiles, fixation of direct dyes or vulcanized dyes. Chitin is insoluble in general acid and alkali, and its chemical properties are very stable, which is an important reason for restricting its long-term failure to develop. The chitosan after deacetylation is white to light yellow powder. Although it is also insoluble in water, alkali solution and organic solvent, it is soluble in dilute acid solution, including inorganic dilute acid (hydrochloric acid, nitric acid, etc.) And organic dilute acid (acetic acid, lactic acid, formic acid, ascorbic acid, malic acid, etc.). In the aqueous solution of multivalent organic acids such as citric acid and tartaric acid, it is dissolved when heated at a high temperature, and then it is gel-like after the temperature drops. Chitin is a β (1 → 4) polymer of 2-acetylamino -2-deoxy-D-glucose, a polysaccharide compound 2-amino -2-deoxy-D-glucose after acetyl group is removed by a polymer connected by β (1 → 4) glycosidic bonds, namely chitosan. Figure 2-7 shows the chemical structures of chitin, chitosan and cellulose, and the structures among the three are similar. Since the existing technology cannot completely remove the acetyl group of chitin and turn it into 100% chitosan, and it is difficult to completely separate the two, the existing chitosan products are usually a mixture of chitin and chitosan, but the chitosan content is required to be above 60%. However, chitosan as a functional food base requires chitosan content above 85%. |
| chitin derivative | chitin derivative is a product obtained by chemical modification of chitosan (Chitosan), and chitosan is chitin (Chitin) obtained by deacetylation, its structural formula is as follows: The molecular structure of chitosan and chitosan derivatives The chitosan derivatives overcome that chitosan is only soluble in acid, easy to degrade, and easy to precipitate in organic solvents, the weak point of poor physical and chemical stability has greatly expanded the application field of chitin. Chitosan can obtain different derivatives through chemical modification, hydrolysis and formation of chitosan metal complexes with metals. The methods of chemical modification are: ① Acylation reaction: Chitin and Chitosan react with acid chloride or acid anhydride to introduce aliphatic or aromatic acyl groups with different molecular weights on the macromolecular chain, which can improve solubility. ② alkylation reaction: alkylation reaction can be carried out on the hydroxyl group of chitin (O-alkylation) or the amino group of chitosan (N-alkylation). N-alkylation is more likely to occur, and the solubility of the product depends on the length of the alkyl chain. ③ Carboxylation reaction: Carboxymethylated chitin is prepared by the reaction of basic chitin and chloroacetic acid. ④ esterification reaction: C6-hydroxyl of chitosan can undergo esterification reaction with oxygen-containing inorganic acid, such as reaction with concentrated sulfuric acid, sulfur trioxide and chlorosulfonic acid to prepare chitosan sulfate. ⑤ chitosan quaternary ammonium salt reaction: chitosan is chemically modified with glycidyl trimethyl ammonium chloride, and quaternary ammonium salt groups can be introduced into chitosan molecules to prepare chitosan quaternary ammonium salt. ⑥ silanization reaction: chitin can be completely trimethylsilanized to obtain derivatives with good solubility and reactivity, and the protective group is easily removed. Therefore, it can be modified and modified under controlled conditions. ⑦ hydrolysis reaction: chitin and chitosan can be completely degraded or not completely degraded, either acid or enzymatic. ⑧ chitosan metal polymer (such as chitosan copper polymer (CCC) and chitosan zinc complex (CZC)) obtained by chemical reaction between chitosan and metal salts is a new type of organic polymer, which is widely used for anticorrosion. |
| production process | crustacean shells, such as shrimp shells and crab shells, are composed of two parts. The surface is a thin and transparent stratum corneum, the main component is calcium, and the inside is a thicker chitin layer. It is necessary to first dissolve calcium with acid, and then convert insoluble chitin into soluble chitin under the action of alkali. Process flow: washing raw materials → adding hydrochloric acid → soaking acid for decalcification → washing with dilute alkali → boiling alkali for degreasing and deproteinization → washing with acid → secondary acid for decalcification → washing with dilute alkali → secondary alkali for degreasing → water washing → water washing → chitin → adding concentrated alkali → alkali boiling for heat preservation and deacetylation → water washing → drying → packaging → soluble chitin. soak shrimp shells or crab shells with 5% hydrochloric acid for 1~2 days until no bubbles appear. After taking it out, rinse it with a lot of water until it is neutral. At this time, inorganic salts such as calcium carbonate in the carapace are removed and are soft. Soak the soft carapace with 8-10% caustic soda solution again for 1-2 days, heat and boil for 1-2 hours, take it out and wash it with a lot of water until neutral to remove stratum corneum and fat. Soak the soft carapace with 0.2% potassium permanganate solution for 1 hour, and remove the organic pigment on the carapace by oxidation. After taking out and rinsing with clear water, immerse in 1% sodium bisulfite solution for 10 minutes, then add a small amount of hydrochloric acid to make the solution acidic, and continue soaking for 20 minutes to remove manganese dioxide attached to the carapace. At this time, the carapace should be white to obtain insoluble chitin. Make soluble chitin, take out insoluble chitin and rinse it with clear water to neutral, immerse it in 40% caustic soda, heat to 40-60 ℃, soak for about 24 hours, turn it every 1 hour at the beginning, and then gradually extend it for 5-6 hours. Take it out after the specified time, rinse it with clear water to neutral, and dry it to be the finished product. A small amount of finished product is immersed in 1% acetic acid solution. If it can be dissolved in a short time, it is qualified. If it is insoluble, the reaction is incomplete, and the alkali leaching time can be appropriately extended to remedy it. Sealed with polyethylene plastic bags and packed in wooden cases or cartons. During storage and transportation, it is not allowed to be co-stored and mixed with toxic substances. |
| process flow chart of preparing chitin from shrimp and crab shells | chitin is the main component in carapace and is widely distributed in nature. Shrimp and crab shells are the main raw materials for extracting chitin. The content of chitin varies with the type of shell. The content in shrimp shell is about 14% ~ 25% and that in crab shell is about 10% ~ 25%. Chitin is a polyacetyl glucosamine, which belongs to nitrogen-containing polysaccharides. It is insoluble in water, organic solvents, acid and alkali solutions. Only after concentrated alkali treatment or other methods to remove the acetyl group in its molecule, it can be dissolved in dilute acid, called soluble chitin. chitin has the characteristics of alkali resistance, sun resistance, heat resistance, corrosion resistance, no weathering, no deliquescence, moth-proof, etc., and has firm adhesion to textiles, leather, etc., making it scratch, anti-crepe, Anti-shrinkage, wear resistance, strong color fixation ability, etc., so soluble chitin has a wide range of uses. Chitin production process flow chart |
| application field | chitin and products made of chitin have a wide range of uses due to their unique physical and chemical properties, such as moisture resistance, sun resistance, mildew resistance and corrosion resistance. Used in textile, printing and dyeing industry as fixing agent, fabric shrink-proof finishing agent, etc. The pharmaceutical industry manufactures anticancer drugs chlorourethromycin, artificial skin, surgical lines, and cholesterol-lowering alcohol drugs. Water treatment agents, flocculants and health food additives for environmental protection, beverage and food industries. Paper making, wood-based panels and other industries are used as adhesives. A new generation of biodegradable film for food packaging agricultural mulch. In agriculture, it is used in fertilizers, pesticide sustained-release agents, compound materials, seed dipping agents, and scientific research for enzyme fixation and interception, separation membrane artificial kidney, etc. For the development and application of chitin, Japan and the United States are the largest producers and the largest consumer market in the world. Chitin and its derivatives are widely used in cosmetics industry, such as shampoo, hair conditioner, bath lotion, hair gel, mousse, perfume, evening dew, aqua cosmetics, cream, lipstick and other series of products, with the following excellent performance and efficacy: (a) safe and non-toxic. (B) good film-forming property, air permeability and biocompatibility. It forms a film on the surface of the skin. Because the film is a three-dimensional network structure, various moisturizing factors and physiological functional substances can be embedded in it, and it has a continuous slow release effect. (c) good skin adhesion. (d) good stability: pH1 ~ 14 stable. Cold, thermal stability is good, good compatibility. (e) good skin conditioning, biodegradable, and meet environmental protection requirements. |
| toxicity | natural product, non-toxic. LD50 77.5 g/kg (mouse, oral). The Ames test was negative. |
| Anti-corrosion effect of chitin | Chitin itself is very stable and soluble in weak acids, such as acetic acid, lactic acid, citric acid, bran acid, etc. are often used in industrial processes to dissolve chitin, and its solubility is proportional to the acid concentration. Taking acetic acid as an example, 10g/L chitin needs to be dissolved in 1% acetic acid. Once dissolved, it can be further diluted with water. The degree of deacetylation of chitin also affects its ability to form a film. For those with higher deacetylation degree, it is easier to form a film after the aqueous solution is dried. It is used to form a film on the surface of meat and meat products, that is, it has anti-corrosion effect. Anti-mildew and preservation: Ham containing chitin is the most important example of Nippon Maru Ham. The addition of chitin in the production process is about 200mg/kg, which can inhibit the growth of bad molds. Chitin-containing pickles: Japan's Asahi Chemical, Asama Chemical and its downstream manufacturers all use chitin as a preservative to provide pickles to reduce the use of salt. Its process requires chitin with low viscosity and high deacetylation. Its process is such as soaking sashimi to keep fresh: 98% DAC chitin solution and 1% acetic acid solution, soaking for 3 hours with a final concentration of 50-200 mg/kg, which can reduce the number of raw bacteria and increase the service life of commodities by 24-36 hours. However, there are also process instructions. If it is also operated by soaking, the concentration of chitin should be increased as much as possible so that the dosage after soaking can have sufficient anti-bacteria and moisturizing ability. However, the viscosity also increases when the concentration is too high, so the viscosity must be reduced in a special way, but the effect of condensation and film formation is not lost. |
| usage limit | GB 2760-1996(g/kg): beer 0.4; Vinegar 1.0; Mayonnaise, sesame paste, peanut butter, hydrogenated vegetable oil, ice cream, vegetable fat powder 2.0; Lactic acid bacteria beverage 2.5; Jam 5.0. |
| use | pharmaceutical excipients, medical sutures, etc. Among them, it can be used as a sustained-release agent, lubricant, and coating agent as an auxiliary material. The microparticles, tablets, capsules, microfilm agents and the like of the corresponding drugs can be prepared by direct tabletting, wet granulation or coating. It can be made into dialysis membrane, ultrafiltration membrane and reverse osmosis membrane; and the cross-chain complex with fiber can be made into molecular sieve. With glutaraldehyde as cross-linking agent, it can be immobilized with many enzymes or microbial cells, such as immobilized asparaginase. Can be used for artificial skin, artificial blood vessels, artificial kidneys, etc. Chitosan can inhibit gastric ulcer, reduce cholesterol and blood lipid. chitin is widely used, for example:(1) chromatographic carrier (2) environmental protection: chitin and its derivatives have good chelation ability on various metals, especially some harmful metals that can cause serious environmental pollution, such as mercury, cadmium, copper, nickel, chromium, etc., so it is very promising in water purification and sewage treatment. (3) Purification of radioactive pollution: Many radioactive pollution causes derivatives of radioactive transitional elements, which can be removed by chitosan. (4) Comprehensive utilization of ore: It is an effective collector for zirconium, niobium, rubidium, etc. (5) Glass fiber finishing agent (6) Application in the dye industry: Chitin can be made into polymer-type dyes. (7) Additives for the paper industry (8) Finishing agents for other fabrics (9) Photographic industrial materials: The currently rapidly developing international photographic method (Polaroid) without liquid fixing and development is the use of chitin with wear resistance and photosensitive ability. (10) medical and surgical supplies: chitin hydrolysate a glucosamine salt for the treatment of enteritis, colon ulcer and pneumonia. D-glucosamine or N-acetylglucosamine is used as a chemotherapeutic agent for some tumors, and the effect is very good. Chitin has a certain effect of assisting bacteriolysis. It can also be used as blood anticoagulant, wound healing agent, etc. Use chitin to make surgical sutures, artificial skin and wound dressings, artificial blood and hemostatic sponges, contact glasses, and drug carriers. The use effect is good. Other uses include fillers for adhesives, cigarette paper, leather finishing agents, flocculants, etc. In addition, it has attracted extensive attention for enzyme immobilization, seasoning, beverage and daily chemical products. chitin is an important raw material for preparing chitosan and glucosamine series products. Chitin and its derivatives have important applications in medicine, chemical industry, health food and other fields, and have broad application prospects. It is used to make soluble chitin and glucosamine, can be used as an additive for cosmetics and functional foods, and can prepare photographic emulsion, etc. as adsorption clarifying agent and thickener. China stipulates that it can be used for jam, with a maximum usage of 5.0 g/kg; The maximum usage in lactic acid bacteria beverage is 2/5 g/kg; The maximum usage in hydrogenated vegetable oil, mayonnaise, peanut butter, sesame paste, ice cream and vegetable fat powder is 2.0 g/kg; The maximum usage in vinegar is 1.0 g/kg; The maximum usage in beer is 0/4 g/kg. Thickener, stabilizer, tannin remover. Mainly used for fruit juice, fruit wine, etc. to prevent discoloration and astringency. It can also be used as binder, glaing agent, filler, film forming agent and emulsifier. isolated from shrimp shell chitin for chitinase analysis. It is a polysaccharide composed of N-acetyl-D- glucomasine, and can also be used in the manufacture of glucosamine and chitosan. The quality requires purification before it can be used as a substrate for chitinase. An important raw material for the preparation of chitosan and glucosamine series products; chitin extracted from shrimp shells, suitable for chitin enzyme analysis; used for the fixation of α-amylase; through the immobilization of inulin enzyme to produce fructose; In the bacterial production of N,N′-diacetylchitodisaccharides, the preparation of keratin glue is a polysaccharide found in various organisms, especially crustacean shells. |
| Production method | After removing calcium carbonate from the shells of crustaceans such as shrimps and crabs in an acidic aqueous solution, use hot weak lye to remove protein. The carapace can also be crushed and the protein can be boiled with 2% dilute alkali solution for about 1.5h and separated, then 5% ~ 10% hydrochloric acid can be added to the insoluble substance to change calcium carbonate into calcium chloride and dissolve and remove, then centrifuged, washed with water and dried. chitin naturally exists in the shells of crustaceans. crab shells contain 15% ~ 20% and shrimp shells contain 15% ~ 30%. Shrimp and crab shells can be used as raw materials to extract chitin. Remove the meat from shrimp and crab shells, soak them in 4% ~ 6% hydrochloric acid for 3~4 days after washing, dissolve inorganic salts and remove them; After washing, soak in 10% o sodium hydroxide for 1~2 hours, wash off protein, bleach and oxidize with 1% KMnO4 to remove impurities after washing; After washing, elute the residual potassium permanganate with 1% sodium bisulfite solution, finally, it is thoroughly washed and dried to obtain the finished chitin. The chitin used in industry is taken from the carapace of crustaceans (freshwater and seafood shrimp, crabs, etc.). Some by-products of the brewing industry are also raw materials for chitin. For example, the use of Aspergillus niger fermentation to produce citric acid residues, as well as the use of Brucella, Brackella and Opora fermentation broth can provide a certain amount of deacetylated chitin. Chitin extraction: remove the meat of shrimp and crab shells and clean them. Soak in 4-6% hydrochloric acid to dissolve and soften inorganic salts in the shell. Wash with water and remove protein with 10% sodium hydroxide solution. After washing with water again, bleach and oxidation with 1% KMnO4 to remove impurities. After the third water washing, the residual MnO4 is eluted with 1% NaHSO3, and then fully washed with water and dried to obtain pure chitin. Raw material consumption (kg/t) shrimp and crab shell 1200035% industrial 13000 hydrochloric acid caustic soda (95% solid) 1500 potassium permanganate 135 sodium bisulfite 340 method 1. using shrimp and crab shell as raw materials to make shrimp and crab shells, clean, dry and pulverize, react with excess 2mol/L hydrochloric acid solution (1:10) for 4-5h, filter, and then treat with 2mol/L hydrochloric acid at about 0 ℃ for 12-20h, filter and wash to neutral. Shrimp and crab shells [2mol/L HCl]→[0 ℃, 12-20h] filter out solids and use excess 50-100g/L(5%-10%) sodium hydroxide or potassium hydroxide solution (1:8) for alkaline treatment for 3-4h, and the temperature is controlled at 90-95 ℃. Acid and alkali treatment can be repeated 1-2 times to remove calcium carbonate, phosphate, protein and pigment. Solid [NaOH]→[3-4h, 90-95 ℃] filter out solid [HCl]→ solid [NaOH]→ solid is washed with appropriate amount of absolute ethanol and ether, and dried under reduced pressure to obtain white solid chitin. Industrial production can be washed with water instead of organic solvent. The yield of shrimp shell is 20% and crab shell is about 15%. Solid [anhydrous ethanol, ether] → chitin is added with 400-450g/L(40%-45%) sodium hydroxide solution (1:15-20) from the finished chitin product, reacted at a temperature of about 110 ℃ for 1h, filtered, and washed with water to neutral. According to the requirements of different deacetylation degrees, repeat the treatment for 1-2 times, and dry under reduced pressure to obtain the deacetylation degree of 60%-99%. During the deacetylation process, due to solvation, part of the glycosidic bonds are hydrolyzed, resulting in a decrease in relative molecular weight. In order to avoid the destruction of macromolecules, chitosan can be obtained by adding 10g/L (1%) sodium borohydride (NaBH4) solution or introducing inert gas, such as placing chitin in 400g/L(40%) sodium hydroxide solution and reacting at 110 ℃ for 2.5-3h. Chitin Finished Product [NaOH]→[110 ℃, 1h, pH7] Chitin Method 2. The preparation method using snail shell as raw material Wash, dry and crush the snail shell, and sift through 80 mesh to obtain snail shell powder for later use. Take 400g of snail powder, add 10 times of 1mol/L hydrochloric acid of the raw material, stir for 24 hours at room temperature, filter, wash the residue to neutral, dry, and repeat the above operation twice to obtain desalted snail powder (71.5g). Take desalted snail shell powder, add 8 times the volume of 2.5mol/L sodium hydroxide solution, stir for 24 hours, filter and dry to obtain chitin (59.8g). The yield is about 15%. Chitin is dissolved in 50% sodium hydroxide solution, kept at 130-140 ℃ for 2 hours, filtered, washed with water until neutral, and further deacetylated to obtain chitosan. Methods The pupal skin of silkworm moth after eclosion was taken 3. the preparation method using pupal skin as raw material, dried at 60 ℃, and impregnated with equal volume of petroleum ether. Add 3 times the volume of 3% hydrochloric acid to defatted pupa skin and decalcification at room temperature for 12 hours. Add 30g/L(3%) sodium hydroxide solution to decalcified pupa skin, boil for 3-5h, and then remove protein to obtain gray chitin. Add 420g/L (42%) sodium hydroxide solution (add a small amount of NaBH4) to chitin, boil, filter every 2 hours, wash with water, replace with new lye once, continue to deacetyl until 8 hours, filter, wash with water to neutral, and dry naturally to obtain white chitosan. The yield is 10%-13%, the degree of deacetylation can reach 91%, the intrinsic viscosity is 790-890 ml/g, and the relative molecular mass is 0.81 × 106-1.34 × 106. The preparation of chitosan with low molecular weight can be prepared by hydrogen peroxide degradation method, controlling different concentrations and reaction time of hydrogen peroxide, and chitosan with relative molecular weight ranging from 4.31 × 104-1.32 × 104 can be prepared. The operation is simple, the time is less, and no special reagents and equipment are needed. |
| category | toxic substances |
| toxicity classification | poisoning |
| acute toxicity | intravenous-rat LD50: 50 mg/kg |
| flammability hazard characteristics | thermal decomposition discharges toxic nitrogen oxide smoke |
| storage and transportation characteristics | warehouse low temperature ventilation and drying |
| fire extinguishing agent | water, carbon dioxide, foam, dry powder |
| toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
Last Update：2024-04-09 20:52:54
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