CN103613685A - Method for preparing chitin through subcritical hydrolysis of arthropod shells - Google Patents

Abstract

The invention relates to a method for preparing chitin through the subcritical hydrolysis of arthropod shells. The method comprises the following steps: crushing the arthropod shells to obtain powder, and mixing the powder with water to obtain a mixture; putting the mixture in a semi-batch reactor, carrying out extraction and purification at 200-360DEG C for 10-120min, and cooling to normal temperature after reaction ending; and filtering the finally obtained mixture, drying the obtained solid at 105-150DEG C until the mass of the solid is unchanged to obtain chitin, and reusing the obtained filtrate. The method utilizing the subcritical water treatment of the arthropod shells to prepare the chitin has the advantages of effective simplification of the technological step for the industrial preparation of the chitin, no environmental pollution, and effective reuse of the filtrate obtained after the above reaction.

Description

Method for preparing chitin by pyrolyzing arthropod shells with subcritical water

technical field

The invention belongs to the field of subcritical extraction, and relates to a biomass purification technology, in particular to a preparation method of chitin in arthropod shells.

Background technique

Chitin is widely present in the cell walls of fungi and exoskeletons of arthropods, and is the second most abundant polysaccharide in nature. Because the chemical structure of chitin is very similar to plant cellulose, chitin is also called animal fiber. Chitin is decomposed into chitosan and acetic acid under the action of strong alkali, and chitosan is named as the eighth vital element by the International Society of Medical Nutrition and Food, and has attracted more and more attention.

Chitin is widely used in industry, medicine and cosmetics. It can be used as wastewater purification materials, dyes, adhesives and wound healing agents, chitin can also activate cells, prevent cell aging, and promote cell metabolism.

All organisms containing chitin can be used as raw materials for the preparation of chitin. Considering the production cost, crab shells and shrimp shells are commonly used. Crab shells and shrimp shells are solid wastes produced in aquatic product processing, and random discharge will cause environmental pollution. With the development of my country's shrimp farming industry, shrimp processing produces a large number of shrimp heads and shells, which are good raw materials for the production of chitin.

The industrial preparation of chitin can be divided into three steps: deproteinization, demineralization and decolorization, as shown in Figure 1. The shells of arthropods such as shrimp and crab shells contain a large amount of inorganic salts, mainly calcium carbonate, a small amount of magnesium carbonate, and semi-trace and trace amounts of lead, mercury, arsenic, manganese, iron, etc. The hydrochlorides of these metals are easily soluble in water. Therefore, when the shells of arthropods are soaked with dilute hydrochloric acid, the inorganic salts in them are converted into hydrochlorides and dissolved in water. The inorganic salts can be removed by washing and separation. In addition to hydrochloric acid, formic acid and nitric acid can also be used. The protein is also abundant in arthropods. Protein is a kind of amphoteric compound, which can be dissolved in both alkali and acid. Generally speaking, it dissolves faster and safer in lye. At the same time, proteins are hydrolyzed a little slower in lye and faster in acid. When the arthropod shell is soaked in dilute acid, some of the protein will be dissolved; if soaked in dilute lye, all the protein in the shell can be dissolved and extracted. Of course, the protein in the shell can also be hydrolyzed with protease. So what's left is chitin.

However, this method uses a large amount of strong acid and strong alkali, and the process is cumbersome. Therefore, it is of great significance to research and develop a simple and environmentally friendly chitin preparation process.

Subcritical water is water that remains liquid under pressure at temperatures ranging from 100 to 374 degrees. Compared with water at normal temperature, subcritical water has a higher ion product and a lower dielectric constant. These two characteristics indicate that subcritical water can be used as an organic solvent and an acidic catalyst. Subcritical water can effectively convert proteins in fish processing waste into amino acids, and subcritical water can also decolorize dyes. At the same time, because the subcritical water has a high ion product, it can effectively dissolve the minerals in the biomass. Therefore, subcritical water treatment can effectively replace the three steps of deproteinization, demineralization and decolorization in Figure 1, while effectively simplifying the chitin preparation process, and does not pollute the environment.

Contents of the invention

The main purpose of the present invention is to prepare chitin by treating arthropod shells with subcritical water, mainly using arthropod shells as raw materials, and treating them in semi-batch or batch reactors with subcritical water. The steps are as follows:

1) Crush arthropod shells (crab shells, shrimp shells, cicada shells), and mix the powder with water at a mass ratio of 10-70%:90-30%.

2) Put the mixture into a semi-batch reactor, extract and purify at 200-360 ^o C for 10-120 minutes, and cool to normal temperature after the reaction.

3) Filter the obtained mixture, dry the solid at 105-150 ^o C until the quality of the solid remains unchanged to obtain chitin, and reuse the filtrate.

The invention uses subcritical water to treat arthropod shells to prepare chitin. The method effectively simplifies the process steps of industrial preparation of chitin, does not cause pollution to the environment, and at the same time, the filtrate after reaction can be effectively reused.

Description of drawings

Fig. 1 is the process flow diagram of existing industrial preparation chitin;

Fig. 2 is the concrete process flowchart of the present invention;

Figure 3 shows the specific flow of semi-batch subcritical water treatment;

Fig. 4 is the concrete flow process of intermittent subcritical water treatment;

In the figure: 1. reactor; 2. electric furnace; 3. arthropod shell; 4. thermocouple; 5. high-pressure pump; 6. filter; 7. pressure regulating valve; 8. water pump; 9. tank; 10. reaction 11. Electric furnace; 12. Arthropod shell.

Detailed ways

The present invention will be specifically described below through specific embodiments and Fig. 1 and Fig. 2 . However, the following examples are only for the specific description of the present invention, and are not intended to limit the present invention.

Example 1

The arthropod shells (crab shells, etc.) were pulverized in a pulverizer, and the crab shell powder was mixed with water at a ratio of 10% and 90% by mass, and put into a subcritical reaction device, and reacted at 200 ^o C for 120 minutes. After the reaction, cool and filter, and dry the residue at 105 ^o C until the quality of chitin remains unchanged, and the filtrate is reused.

Example 2

The arthropod shells (crab shells, etc.) were pulverized in a pulverizer, and the crab shell powder was mixed with water at a ratio of 20% and 80% by mass, and put into a subcritical reaction device, and reacted at 240 ^o C for 100 minutes. After the reaction was finished, cool and filter, and dry the residue at 110 ^o C until the quality of chitin was obtained, and the filtrate was reused.

Example 3

The arthropod shells (crab shells, etc.) were crushed in a pulverizer, and the crab shell powder was mixed with water at a ratio of 30% and 70% by mass, and put into a subcritical reaction device, and reacted at 280 ^o C for 80 minutes. After the reaction, cool and filter, and dry the residue at 120 ^o C until the quality remains unchanged to obtain chitin, and the filtrate is reused.

Example 4

The arthropod shells (crab shells, etc.) were pulverized in a pulverizer, and the crab shell powder was mixed with water at a ratio of 40% and 60% by mass, and put into a subcritical reaction device, and reacted at 300 ^o C for 60 minutes. After the reaction, cool and filter, and dry the residue at 130 ^o C until the quality of chitin remains unchanged, and the filtrate is reused.

Example 5

The arthropod shells (crab shells, etc.) were pulverized in a pulverizer, and the crab shell powder and water were mixed according to the mass percentage of 50% and 50%, and put into a subcritical reaction device, and reacted at 320 ^o C for 40 minutes. After the reaction was completed, cool and filter, and dry the residue at 140 ^o C until the quality of chitin remained unchanged, and the filtrate was reused.

Example 6

The arthropod shells (crab shells, etc.) were pulverized in a pulverizer, and the crab shell powder was mixed with water at a ratio of 60% and 40% by mass, and put into a subcritical reaction device, and reacted at 340 ^o C for 20 minutes. After the reaction, cool and filter, and dry the residue at 150 ^o C until the quality of chitin remains unchanged, and the filtrate is reused.

Example 7

The arthropod shells (crab shells, etc.) were pulverized in a pulverizer, and the crab shell powder was mixed with water at a ratio of 70% and 30% by mass, and put into a subcritical reaction device, and reacted at 360 ^o C for 10 minutes. After the reaction, cool and filter, and dry the residue at 150 ^o C until the quality of chitin remains unchanged, and the filtrate is reused.

As shown in Figure 3, the semi-batch subcritical water treatment device includes a reactor 1; an electric furnace 2; a high-pressure pump 5; a filter 6; a pressure regulating valve 7; a water pump 8; Its specific processing process is:

1. Put a certain amount of arthropod shell 3 powder into the reactor, and seal the reactor 1.

2. Regulate the high-pressure pump 5, control the flow rate (can be less at the beginning), open the electric furnace 2 and set the reaction temperature, adjust the pressure of the whole reaction system to the saturated vapor pressure of water during the corresponding reaction temperature by the pressure regulating valve 7, so that the water Remains liquid at high temperature.

3. When the temperature of reactor 1 reaches the reaction temperature, adjust the flow rate appropriately, then start to calculate the reaction time, cool down the reactor 1 after the reaction, and take out the reaction residue.

As shown in FIG. 4 , the intermittent subcritical water treatment device includes a thermocouple 4 , a reactor 10 and an electric furnace 11 . Its specific processing process is:

1. Put water and arthropod shell 12 powder mixed in a certain proportion into the reactor 10, and seal the reactor 10.

2. Set the temperature of the electric furnace 11 to heat the reactor, and start to calculate the reaction time when the reactor 10 reaches the reaction temperature.

3. After the reaction, cool down the reactor 10, filter and dry the reaction residue.

Claims (2)

1. with subcritical water pyrolysis arthropods shell, prepare chitinous method, it is characterized in that the method comprises the following steps:

1) arthropods shell is pulverized, and by this powder and water in mass ratio 10～70%:90～30% mix;

2) mixture is put into semibatch reactor, 200～360 ^ounder C temperature condition, purification by liquid extraction is 10～120 minutes, after reaction finishes, is cooled to normal temperature;

3) gained mixture is filtered, solid is 105～150 ^odry until the constant chitin that obtains of solid masses of C, filtrate recycle.

2. method according to claim 1, is characterized in that: described arthropods shell comprises crab shell shrimp shell and cicada shell.

Images