CN106478840B - A kind of preparation method of cross-linked chitosan - Google Patents

Abstract

The invention discloses a preparation method of cross-linked chitosan. The steps are as follows: 1) remove the residual meat of crab shells, dry and pulverize to obtain crab shell powder; 2) treat with dilute alkali to remove protein and fat in the powder, and oxidize and decolorize; 3) wet grinding; 4) acid-soluble powder removal 5) Chitosan is obtained by deacetylation of concentrated alkali; 6) Cross-linking reaction occurs in acetic acid solution; 7) Secondary wet grinding, filtration, drying, and pulverization to obtain cross-linked chitosan. The invention has wide sources of raw materials, simple process, mild operating conditions, small equipment investment and energy consumption, and low cost. social benefits.

Description

A kind of preparation method of cross-linked chitosan

technical field

The invention relates to the field of resource utilization of crab shells, in particular to a preparation method of cross-linked chitosan.

Background technique

Chitin widely exists in crustaceans such as crabs and shrimps and the carapaces of insects, the cell walls of fungi, and the bone marrow and shells of molluscs such as squid and shellfish. Chitin is the largest amount of natural organic compound after cellulose on the earth, and it is also the largest amount of nitrogen-containing natural organic compound on the earth except protein. Chitosan is a product of partial deacetylation of chitin. ^The main chain of chitosan ^is rich in amino groups and hydroxyl groups, which can coordinate with ^heavy metal ^ions . ⁺ , Ag ⁺ , Hg ²⁺ , Bi ³⁺ , Pb ²⁺ , etc. have strong adsorption capacity, and are ideal materials for heavy metal ion wastewater treatment and precious metal recovery, and have broad application prospects in environmental protection, especially in water treatment. . In addition to good heavy metal ion chelating properties, chitosan also has good biological activity, biocompatibility and biodegradability, and has been widely used in the field of medicine. Chitosan is easily soluble in acidic solution, has poor stability and cannot be reused many times. Chitosan is often cross-linked to improve its stability in acidic solution to broaden the range of applications of chitosan.

Crab shell is one of the main raw materials for producing chitosan. In crab shells, chitin accounts for about 20%, protein accounts for about 30%, calcium carbonate accounts for about 50%, and there are also a small amount of pigments and fatty acids. Chitin is fibrous and intertwined into a random network, which constitutes the skeleton of crab shells, and combines with proteins to form proteoglycans, forming a layered structure; calcium carbonate is a honeycomb porous crystal structure, filling between layers in the gap.

Contents of the invention

The purpose of the invention is to provide a preparation method of cross-linked chitosan by utilizing the natural chitin-calcium carbonate composite structure in crab shells.

The preparation method of cross-linked chitosan comprises the following steps successively:

1) removing the residual meat on the crab shell, drying and pulverizing to obtain the crab shell powder;

2) Mix 1 mass part of crab shell powder with 1 to 10 mass parts of lye with a mass concentration of 1% to 10%, stir at room temperature to 100°C for 0.5h to 24h, press filter, and wash with water until neutral;

3) Add 1 to 10 parts by mass of an oxidant solution with a mass concentration of 0.1% to 5% into the powder, stir at room temperature to 100°C for 0.5h to 24h, press filter, and wash with water until the filtrate is colorless;

4) Add water and stir at a high speed to obtain slurry, wet grinding, and pressure filtration;

5) Add an acid solution with a mass concentration of 1% to 10% equivalent to 2 to 20 times the wet weight of the powder, stir at room temperature to 100°C for 0.2h to 5h, remove inorganic salts, press filter, and wash with water until neutral;

6) Add lye with a mass concentration of 30% to 50% equivalent to 1 to 10 times the wet weight of the powder, stir at room temperature to 100°C for 1h to 120h, press filter, wash with water until neutral, and obtain chitosan powdered sugar;

7) Dissolving the chitosan powder in 1%-6% acetic acid solution, adding a cross-linking agent solution, stirring until the gel precipitates, pressing, and washing with water;

8) Add water and stir at a high speed to obtain a slurry, perform secondary wet grinding, filter, dry, and pulverize to obtain cross-linked chitosan.

The above-mentioned technical scheme can also provide several following preferred modes:

The alkali described in step 2) and step 6) is sodium hydroxide, potassium hydroxide or calcium hydroxide.

The oxidant described in step 3) includes hydrogen peroxide, potassium permanganate, sodium hypochlorite or calcium hypochlorite.

The acid described in step 5) is hydrochloric acid, sulfuric acid, nitric acid, acetic acid, phosphoric acid, formic acid, silicic acid, boric acid, chloric acid, hypochlorous acid, iodic acid, hydrofluoric acid, hydroiodic acid, perchloric acid, chromic acid, One or a mixture of benzoic acid, oxalic acid, succinic acid, citric acid, salicylic acid, keto acid, stearic acid, lactic acid, oleic acid, linoleic acid and linolenic acid.

The cross-linking agent described in step 7) is glutaraldehyde or glyoxal, and the mass concentration of the cross-linking agent solution is 10%-40%.

The crabs include freshwater crabs or sea crabs, such as Chinese mitten crab, stone crab, Portunus trituberculatus, Portunus red star or Portunus pelagics, etc.

The invention has the advantages of wide sources of raw materials, simple process, mild operating conditions, small equipment investment and energy consumption, low cost, and good economic and social benefits.

Description of drawings

Fig. 1 is the appearance of the crosslinked chitosan that the embodiment of the present invention 1 makes.

Detailed ways

Example 1:

1) washing with water to remove the residual meat on the shell of the recovered mitten crab, drying and pulverizing to obtain crab shell powder; then the powder is followed up in turn;

2) Mix 1 mass part of crab shell powder with 1 mass part of 10% sodium hydroxide solution, stir at 100°C for 0.5h, press filter, and wash with water until neutral;

3) Add 1 part by mass of hydrogen peroxide solution with a mass concentration of 5% to the powder, stir at 100° C. for 0.5 h, press filter, and wash with water until the filtrate is colorless;

4) Add water and stir at high speed to obtain a slurry, place it in a vertical sand mill for wet grinding, and press filter;

5) Add a hydrochloric acid solution with a mass concentration of 10% equivalent to twice the wet weight of the powder, stir at room temperature for 5 hours, remove inorganic salts, press filter, and wash with water until neutral;

6) adding a sodium hydroxide solution having a mass concentration of 50% equivalent to 1 times the wet weight of the powder, stirring at room temperature for 120 hours, pressing, and washing with water until neutral to obtain chitosan powder;

7) dissolving the chitosan powder in 1% acetic acid solution, adding a glutaraldehyde solution with a mass concentration of 10%, stirring until the gel precipitates, pressing, and washing with water;

8) Adding water and stirring at a high speed to obtain a slurry, secondary wet grinding, pressure filtration, drying, and crushing to obtain cross-linked chitosan.

It can be seen from Figure 1 that the powder has high whiteness, small average particle size and uniform particle size distribution.

Example 2:

1) washing with water to remove the residual meat on the recovered stone crab shells, drying and pulverizing to obtain crab shell powder; and then performing subsequent processing on the powder in turn;

2) Mix 1 mass part of crab shell powder with 10 mass parts of 1% potassium hydroxide solution, stir at room temperature for 24 hours, press filter, and wash with water until neutral;

3) Add 10 parts by mass of potassium permanganate solution with a mass concentration of 0.1% to the powder, stir at room temperature for 24 hours, press filter, and wash with water until the filtrate is colorless;

4) Add water and stir at high speed to obtain a slurry, place it in a horizontal sand mill for wet grinding, and press filter;

5) Add sulfuric acid solution with a mass concentration of 1% equivalent to 20 times the wet weight of the powder, stir at 100°C for 5 hours, remove inorganic salts, press filter, and wash with water until neutral;

6) adding a sodium hydroxide solution with a mass concentration of 30% equivalent to 10 times the wet weight of the powder, stirring at 100° C. for 1 hour, pressing, and washing with water until neutral to obtain chitosan powder;

7) dissolving the chitosan powder in 6% acetic acid solution, adding a glyoxal solution with a mass concentration of 40%, stirring until the gel is precipitated, press filtering, and washing with water;

8) Adding water and stirring at a high speed to obtain a slurry, secondary wet grinding, pressure filtration, drying, and crushing to obtain cross-linked chitosan.

Example 3:

1) Washing with water to remove the residual meat on the shell of the recovered Portunus trituberculatus, drying and pulverizing to obtain crab shell powder; then performing subsequent processing on the powder in turn;

2) Mix 1 mass part of crab shell powder with 5 mass parts of 5% calcium hydroxide solution, stir at 50° C. for 10 h, press filter, and wash with water until neutral;

3) Add 5 parts by mass of sodium hypochlorite solution with a mass concentration of 2% to the powder, stir at 50° C. for 10 h, press filter, and wash with water until the filtrate is colorless;

4) Add water and stir at a high speed to obtain a slurry, place it in a stirring mill for wet grinding, and press filter;

5) Add a nitric acid solution with a mass concentration of 5% equivalent to 5 times the wet weight of the powder, stir at 40°C for 1 hour, remove inorganic salts, press filter, and wash with water until neutral;

6) adding a sodium hydroxide solution having a mass concentration of 35% equivalent to twice the wet weight of the powder, stirring at 40° C. for 90 hours, pressing, and washing until neutral to obtain chitosan powder;

7) dissolving the chitosan powder in 3% acetic acid solution, adding a glutaraldehyde solution with a mass concentration of 15%, stirring until the gel precipitates, pressing, and washing with water;

8) Adding water and stirring at a high speed to obtain a slurry, secondary wet grinding, pressure filtration, drying, and crushing to obtain cross-linked chitosan.

Example 4:

1) washing with water to remove the residual meat on the shell of Portunus red star crab, drying and pulverizing to obtain crab shell powder; then the powder is subjected to subsequent processing in sequence;

2) Mix 1 mass part of crab shell powder with 2 mass parts of 8% sodium hydroxide solution, stir at 60° C. for 8 hours, press filter, and wash with water until neutral.

3) Add 2 parts by mass of calcium hypochlorite solution with a mass concentration of 3% to the powder, stir at 40°C for 10 hours, press filter, and wash with water until the filtrate is colorless;

4) Add water and stir at high speed to obtain a slurry, place it in a peeling machine for wet grinding, and press filter;

5) Add a phosphoric acid solution with a mass concentration of 6% equivalent to 4 times the wet weight of the powder, stir at 50°C for 2 hours, remove inorganic salts, press filter, and wash with water until neutral;

6) adding a sodium hydroxide solution having a mass concentration of 41% equivalent to 4 times the wet weight of the powder, stirring at room temperature for 100 h, pressing, and washing with water until neutral to obtain chitosan powder;

7) dissolving the chitosan powder in 4% acetic acid solution, adding a glyoxal solution with a mass concentration of 20%, stirring until the gel is precipitated, pressing, and washing with water;

8) Adding water and stirring at a high speed to obtain a slurry, secondary wet grinding, pressure filtration, drying, and crushing to obtain cross-linked chitosan.

Example 5:

1) Washing with water to remove the residual meat on the shell of the recovered Portunus pelagics, drying and pulverizing to obtain crab shell powder; then performing subsequent processing on the powder in sequence;

2) Mix 1 mass part of crab shell powder with 4 mass parts of 4% sodium hydroxide solution, stir at 70°C for 6 hours, press filter, and wash with water until neutral;

3) Add 3 parts by mass of sodium hypochlorite solution with a mass concentration of 1% to the powder, stir at 60°C for 6 hours, press filter, and wash with water until the filtrate is colorless;

4) Add water and stir at high speed to obtain a slurry, place it in a ball mill for wet grinding, and press filter;

5) Add acetic acid solution with a mass concentration of 7% equivalent to 6 times the wet weight of the powder, stir for 3 hours at 50°C, remove inorganic salts, press filter, and wash with water until neutral;

6) adding a sodium hydroxide solution having a mass concentration of 39% equivalent to 5 times the wet weight of the powder, stirring at 50° C. for 5 hours, press-filtering, and washing with water until neutral to obtain chitosan powder;

7) dissolving the chitosan powder in 5% acetic acid solution, adding a glutaraldehyde solution with a mass concentration of 25%, stirring until the gel precipitates, pressing, and washing with water;

8) Adding water and stirring at a high speed to obtain a slurry, secondary wet grinding, pressure filtration, drying, and crushing to obtain cross-linked chitosan.

The above-mentioned embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. Various changes and modifications can be made by those skilled in the relevant technical fields without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (7)

1. a preparation method of crosslinked chitosan, is characterized in that, comprises the following steps successively: 1) removing the residual meat on the crab shell, drying and pulverizing to obtain the crab shell powder; 2) Mix 1 mass part of crab shell powder with 1 to 10 mass parts of lye with a mass concentration of 1% to 10%, stir at room temperature to 100°C for 0.5h to 24h, press filter, and wash with water until neutral; 3) Add 1 to 10 parts by mass of an oxidant solution with a mass concentration of 0.1% to 5% into the powder, stir at room temperature to 100°C for 0.5h to 24h, press filter, and wash with water until the filtrate is colorless; 4) Add water and stir at a high speed to obtain slurry, wet grinding, and pressure filtration; 5) Add an acid solution with a mass concentration of 1% to 10% equivalent to 2 to 20 times the wet weight of the powder, stir at room temperature to 100°C for 0.2h to 5h, remove inorganic salts, press filter, and wash with water until neutral; 6) Add lye with a mass concentration of 30% to 50% equivalent to 1 to 10 times the wet weight of the powder, stir at room temperature to 100°C for 1h to 120h, press filter, wash with water until neutral, and obtain chitosan powdered sugar; 7) Dissolving the chitosan powder in 1%-6% acetic acid solution, adding a cross-linking agent solution, stirring until the gel precipitates, pressing, and washing with water; 8) Add water and stir at a high speed to obtain a slurry, perform secondary wet grinding, filter, dry, and pulverize to obtain cross-linked chitosan. 2. the preparation method of a kind of cross-linked chitosan as claimed in claim 1 is characterized in that, step 2) and step 6) described in alkali is sodium hydroxide, potassium hydroxide or calcium hydroxide. 3. the preparation method of a kind of cross-linked chitosan as claimed in claim 1 is characterized in that, the oxidizing agent described in step 3) comprises hydrogen peroxide, potassium permanganate, sodium hypochlorite or calcium hypochlorite. 4. the preparation method of a kind of cross-linked chitosan as claimed in claim 1 is characterized in that, step 5) described acid is hydrochloric acid, sulfuric acid, nitric acid, acetic acid, phosphoric acid, formic acid, silicic acid, boric acid, chlorine Acid, hypochlorous acid, iodic acid, hydrofluoric acid, hydroiodic acid, perchloric acid, chromic acid, benzoic acid, oxalic acid, succinic acid, citric acid, salicylic acid, keto acid, stearic acid, lactic acid , oleic acid, linoleic acid and linolenic acid or a mixture of several. 5. the preparation method of a kind of cross-linked chitosan as claimed in claim 1 is characterized in that, step 7) described cross-linking agent is glutaraldehyde or glyoxal, and the mass concentration of cross-linking agent solution is 10% to 40%. 6. the preparation method of a kind of cross-linked chitosan as claimed in claim 1 is characterized in that, described crab comprises fresh water crab or sea crab. 7. the preparation method of a kind of cross-linked chitosan as claimed in claim 6 is characterized in that, described crab is Chinese mitten crab, stone crab, portunus trituberculatus, swimming crab with red star or portunus pelagics.