CN104785227A - Chitosan-grafting amino acid magnetic composite microsphere as well as preparation method and application - Google Patents

Abstract

The invention discloses a chitosan-grafted amino acid magnetic composite microsphere. The microsphere has a core-shell structure, which uses a chitosan-amino acid complex as a shell and a magnetic material as a core; the complex is obtained by grafting chitosan and amino acid; the amino acid is gluten One of aminoamide, glutamic acid, ornithine; the content of amino acid in the complex is 5~80wt%; the magnetic material is Fe or Fe ₃ O ₄ , and the magnetic material is the total weight of chitosan and amino acid 10-20% of that. The chitosan-grafted amino acid magnetic composite microspheres prepared by the present invention can be used as a water treatment agent to effectively remove harmful substances (such as dye substances, metal ions, etc.) It has many functions such as ion adsorption, deodorization, decolorization and effective reduction of COD value, and can be completed in a short period of time, thereby improving the use efficiency of materials. It has a certain degree of universality, and is applicable to wastewater from printing and dyeing, electroplating and other enterprises.

Description

A chitosan-grafted amino acid magnetic composite microsphere, its preparation and application

technical field

The invention relates to a novel composite material and its application in the field of water environment treatment, in particular to a chitosan-grafted amino acid magnetic composite microsphere, its preparation and application.

technical background

In recent years, with rapid economic development and rapid industrial development, water pollution has become increasingly serious; and water is a basic need for human survival. At the same time, the continuous improvement of people's material living standards has also put forward higher requirements for water quality. As far as the current water pollution characteristics are concerned, soluble organic substances and refractory biodegradable compounds in water are increasing year by year, but the current conventional water treatment methods are not effective in removing this type of pollutants. The production of secondary pollutants harmful to the environment will undoubtedly have adverse effects on environmental protection and sustainable development. Therefore, seeking water treatment agents that are highly efficient, environmentally friendly, economical and free from secondary pollution is a research hotspot and frontier topic in the field of water treatment.

Natural polymers are macromolecules in animals, plants, and microbial resources in nature. They are easily decomposed into water, carbon dioxide, etc. after being discarded. They have a wide range of sources and are non-toxic. They are environmentally friendly materials. In addition, it is worth mentioning that natural polymer materials are a kind of renewable resources completely separated from petroleum resources, which can be said to be inexhaustible. It is precisely because of the above-mentioned excellent properties that natural polymer materials have been widely used in many fields such as biology, medicine and food processing. In the field of water treatment, due to the large number of active groups such as free hydroxyl groups and amine groups distributed on the molecular chain of natural polymers, which have a flocculation effect, it has been regarded as one of the best substitute materials for water treatment agents currently in use.

Among them, chitosan is one of the most excellent natural polymer materials. Chitin, the precursor of chitosan, widely exists in crustaceans such as shrimps and crabs, insects and algae, and is the second largest natural polymer compound after cellulose in the world. Chitosan is the product of deacetylation of chitin, and its molecular chain contains reactive groups -NH ₂ and -OH. It will form cationic polyelectrolyte in acidic solution, showing good flocculation performance. In addition, chitosan also has a good complexation effect, so that it can produce complexation with transition metal ions, humic acid substances and surfactants in water to achieve the removal of water-soluble organic pollutants. In this way, chitosan has comprehensive properties such as flocculation, metal ion adsorption and water-soluble organic matter removal. Undoubtedly, the development of water treatment agents based on chitosan is one of the important directions in the current water treatment field.

However, as adsorbent materials, including chitosan, in order to obtain a large specific surface area to improve its adsorption performance, the particle size of the adsorbent is very small, which often makes it difficult to effectively and quickly remove the pollutants after adsorption and removal. Separation in water bodies. In addition, in order to further improve the water treatment performance of chitosan, under the premise of ensuring its biocompatibility, a large number of other active functional groups are grafted or compounded onto the chitosan chain, and a simple and quick separation method is sought to overcome the Chitosan is not easy to be separated from water quickly, and the preparation of high-efficiency water treatment agent with good separation effect is undoubtedly of great significance to promote the in-depth application of chitosan in water treatment.

Contents of the invention

The object of the invention is to provide a chitosan-grafted amino acid magnetic composite microsphere, its preparation and application. The microsphere material can effectively remove harmful substances in the water body through adsorption, complexation, etc., and can be effectively separated from the water body by magnetic separation technology, recycled and reused.

Realize the technical scheme of the present invention is:

A chitosan-grafted amino acid magnetic composite microsphere, the microsphere has a core-shell structure, it takes the chitosan-amino acid complex as the shell, and the magnetic material as the core; the complex is formed through the shell Obtained by grafting method of glycan and amino acid;

The amino acid is one of glutamine, glutamic acid, ornithine; the content of the amino acid in the complex is 5-80wt%; the magnetic material is Fe or Fe ₃ O ₄ , and the magnetic material is chitosan 10-20% of the total weight of sugars and amino acids.

The magnetic composite microspheres are prepared by a reverse-phase suspension cross-linking method. The specific method is: mixing and dispersing chitosan, amino acid and magnetic materials in an aqueous solution, then using cyclohexane as the oil phase, and cross-linking with glutaraldehyde made.

The preparation method of above-mentioned chitosan-grafted amino acid magnetic composite microspheres specifically comprises the following steps:

1) Dissolving chitosan and amino acid in an aqueous solution first, and preparing an aqueous solution of 2-10wt% chitosan and amino acid;

2) Then disperse the magnetic material in the above solution by ultrasound, add cyclohexane, stir evenly, and cross-link with glutaraldehyde to form polymer magnetic composite microspheres.

The volume ratio of the added amount of the cyclohexane to the chitosan-amino acid mixed aqueous solution is 1-10.

The consumption of said glutaraldehyde is 0.1-10% of that of chitosan.

During the cross-linking process, the pH value of the reaction solution is controlled to be 7-10, the cross-linking temperature is 35-65° C., and the cross-linking time is 0.5-3 hours.

The application of the chitosan-grafted amino acid magnetic composite microsphere as a water treatment agent in the treatment of dye wastewater. Used to remove harmful substances in wastewater.

The chitosan-grafted amino acid magnetic composite microsphere of the invention is used for absorbing heavy metal ions in water. The heavy metal ion is preferably Cu ²⁺ . But not limited to the adsorption of Cu ²⁺ , other heavy metal ions such as lead, zinc, iron, cobalt, nickel, manganese, cadmium, mercury, tungsten, molybdenum, gold, silver and other heavy metal ions also have a good adsorption effect.

The chitosan-grafted amino acid magnetic composite microspheres of the present invention are separated and enriched by using a magnetic separation technology after the water treatment is completed, and are recovered and reused. Compared with the prior art, the present invention has the remarkable advantages of:

1. The chitosan-grafted amino acid magnetic composite microsphere material involved in the invention can be used as a water treatment agent to effectively remove harmful substances (such as dye substances, metal ions, etc.) Flocculation, metal ion adsorption, deodorization, decolorization and effective reduction of COD value and many other functions can be completed in a relatively short time, thereby improving the use efficiency of materials. It has a certain degree of universality, and is applicable to wastewater from printing and dyeing, electroplating and other enterprises.

2. Moreover, since both chitosan and amino acid are biodegradable materials, they have the characteristics of non-toxicity and no secondary pollution, and have a wide range of applications; in addition, they can be effectively separated, enriched, and recycled by magnetic separation technology after treatment. Reuse, thereby further reducing costs.

3. Compared with pure chitosan, the chitosan-grafted amino acid complex has active groups such as carboxylic acid groups and amide groups added to the molecular chain in addition to amino and hydroxyl active groups. It has a strong adsorption and removal effect on pollutants that have affinity with carboxylic acid groups and amide groups in sewage. Therefore, chitosan-grafted amino acid composite microspheres have both dual functions, and undoubtedly its actual sewage treatment capacity has been greatly improved. In addition, both chitosan and amino acid are biodegradable materials, so the material has important characteristics such as non-toxicity and no secondary pollution.

4. The chitosan-grafted amino acid magnetic composite microsphere material of the present invention is a high-efficiency water treatment agent that can treat different polluted water bodies, especially suitable for advanced treatment of water bodies that still have residual harmful substances after conventional treatment . Moreover, the implementation process is relatively simple. For the advanced treatment of the current water body: there is no need to modify the original water treatment process on a large scale, and only need to add another process on the basis of the original process.

5. The preparation method of the chitosan-grafted amino acid magnetic composite microsphere material of the present invention has simple operation and short synthesis time, and the main raw materials used can be natural polymer products with abundant sources, with low cost and suitable for large-scale industrial production. An economical preparation method for obtaining high-quality water treatment agents.

Description of drawings

Figure 1 is the infrared spectrum of magnetic composite microspheres made of two different polymer materials: chitosan microspheres (a), chitosan-grafted glutamine magnetic composite microspheres (b).

Figure 2 is a comparison of the removal of methylene blue (MB) and crystal violet (CV) impurities in water by magnetic composite microspheres made of two different polymer materials, MB (■/□: chitosan microspheres/ Chitosan-grafted glutamine magnetic composite microspheres), CV (●/○: chitosan microspheres/chitosan-grafted glutamine magnetic composite microspheres).

Figure 3 is the effect diagram of methylene blue (MB) and crystal violet (CV) removed by adsorption, before and after 1 minute of separation with an external magnetic field.

Detailed ways

The following examples further describe the present invention, but the examples are only for illustrating the present invention rather than limiting the present invention.

Example 1

Mix and dissolve chitosan and glutamine (weight ratio: 2:1) in an aqueous solution to prepare a 3% solution. After the solution is uniform, disperse the magnetic particles Fe ₃ O ₄ in the above polymer solution by ultrasonic (Magnetic particles account for 10% of the total weight of chitosan and glutamine), add cyclohexane (the volume ratio of cyclohexane to chitosan/glutamine mixed solution is 5:1), adjust the pH value to 8, Add glutaraldehyde aqueous solution (glutaraldehyde accounts for 1% of the weight of chitosan), and cross-link at 50°C for 1 hour to obtain chitosan-grafted glutamine magnetic composite microsphere samples. The infrared spectra of pure chitosan microspheres and chitosan-grafted glutamine magnetic composite microspheres are shown in Figure 1. From Figure 1(b), it can be seen that the broad peaks at wavenumber 3250cm ^-1 are characteristic absorption peaks of OH and NH; 1560cm ^{- 1} is the characteristic absorption peak of the carbonyl group, which proves that glutamine has been grafted onto the molecular chain of chitosan.

The microsphere is used as a water treatment agent, and methylene blue and crystal violet are used as simulated dye sewage, and the removal of dye impurities in the above water body is measured by a spectrophotometer at wavelengths: 662 and 585 nm, respectively. As shown in Figure 2, Figure 2 uses the above-mentioned magnetic composite microspheres as a water treatment agent to detect the removal of methylene blue and crystal violet impurities in water. Compared with simple chitosan microspheres, the adsorption capacity is greatly improved. In addition, after the adsorption is completed, the chitosan-grafted amino acid magnetic composite microspheres are completely separated from the water body in one minute by using magnetic separation technology under the action of an external magnetic field; the effect diagram of the rapid magnetic separation is shown in Figure 3.

In addition, the microsphere was used as a water treatment agent, and the Cu ²⁺ -containing sewage was used as a simulated sewage, and the removal of Cu ²⁺ in the above-mentioned water body was measured by atomic absorption spectroscopy. After 1 hour, the removal rate reached more than 90%.

Example 2

Mix and dissolve chitosan and glutamic acid (weight ratio: 19:1) in an aqueous solution to prepare a 2% solution. After the solution is uniform, disperse the magnetic particles Fe ₃ O ₄ in the above polymer solution by ultrasonic (Magnetic particles account for 10% of the total weight of chitosan and glutamic acid), add cyclohexane (the volume ratio of cyclohexane to chitosan/glutamic acid mixed solution is 1:1), adjust the pH value to 9, Add glutaraldehyde aqueous solution (glutaraldehyde accounts for 3% of the weight of chitosan), and cross-link at 65°C for 3 hours to obtain a sample of chitosan-glutamic acid magnetic composite microspheres (glutamic acid accounts for the total weight of the polymer material). 5% of the weight). Its performance is similar to embodiment 1.

Example 3

Dissolve chitosan and ornithine in an aqueous solution with a mass mixing ratio _of 1:4 to prepare a solution with a total mass concentration of 10%. After the solution is uniform, magnetic particles _Fe3O4 are dispersed in the above polymer solution by ultrasonic Medium (magnetic particles account for 20% of the total weight of chitosan and ornithine), add cyclohexane (the volume ratio of cyclohexane to chitosan/ornithine mixed solution is 10:1), adjust the pH value to 10 , adding glutaraldehyde aqueous solution (glutaraldehyde accounted for 0.1% of the weight of chitosan), and cross-linked at 35 ° C for 0.5 hours to obtain a sample of chitosan-ornithine magnetic composite microspheres (ornithine accounted for polymer 80% of the total weight of the material). Its performance is similar to embodiment 1.

Example 4

Dissolve chitosan and glutamic acid in an aqueous solution with a mass mixing ratio of 1:2 to prepare a solution with a total concentration of 6%. After _the solution is uniform, magnetic particles _Fe3O4 are dispersed in the above polymer solution by ultrasonic (Magnetic particles account for 15% of the total weight of chitosan and glutamic acid), add cyclohexane (the volume ratio of cyclohexane to chitosan/glutamic acid mixed solution is 7:1), after adjusting the pH value to 8, Add glutaraldehyde aqueous solution (glutaraldehyde accounts for 7% of the weight of chitosan), and cross-link at 45°C for 2 hours to obtain chitosan-glutamic acid magnetic composite microsphere samples. Its performance is similar to embodiment 1.

Example 5

Dissolve chitosan and glutamine in an aqueous solution with _a mass mixing ratio of 1:1 to prepare a 1% solution. After the solution is uniform, magnetic particles _Fe3O4 are dispersed in the above polymer solution by ultrasonic (magnetic Particles account for 10% of the total weight of chitosan and glutamine), add cyclohexane (the volume ratio of cyclohexane to chitosan/glutamine mixed solution is 2:1), adjust the pH value to 10, add pentyl A dialdehyde aqueous solution (glutaraldehyde accounts for 10% of the weight of chitosan) was cross-linked at 60°C for 2.5 hours to obtain a chitosan-glutamine magnetic composite microsphere sample. Its performance is similar to embodiment 1.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the above disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (10)

1. A chitosan-grafted amino acid magnetic composite microsphere is characterized in that, the microsphere has a core-shell structure, and it is a shell with a chitosan-amino acid complex, and a magnetic material is a core; The complex is obtained by grafting chitosan and amino acid; The amino acid is one of glutamine, glutamic acid, ornithine; the content of the amino acid in the complex is 5-80wt%; The magnetic material is Fe or Fe ₃ O ₄ , and the magnetic material is 10-20% of the total weight of chitosan and amino acid. 2. chitosan-grafted amino acid magnetic composite microspheres according to claim 1, is characterized in that, described magnetic composite microspheres adopts reverse phase suspension cross-linking method to prepare, and concrete method is: chitosan, amino acid It is mixed with magnetic materials and dispersed in aqueous solution, then cyclohexane is used as oil phase, and cross-linked by glutaraldehyde. 3. a preparation method of chitosan-grafted amino acid magnetic composite microspheres, is characterized in that, specifically comprises the steps: 1) Dissolving chitosan and amino acid in an aqueous solution first, and preparing an aqueous solution of 2-10wt% chitosan and amino acid; 2) Then disperse the magnetic material in the above solution by ultrasound, add cyclohexane, stir evenly, and cross-link with glutaraldehyde to form polymer magnetic composite microspheres. 4. the preparation method of chitosan-grafted amino acid magnetic composite microsphere according to claim 3, is characterized in that, the add-on of described cyclohexane and chitosan-amino acid mixed aqueous solution volume ratio are: 1- 10. 5. the preparation method of chitosan-grafted amino acid magnetic composite microspheres according to claim 3, is characterized in that, the consumption of described glutaraldehyde is the 0.1-10% of chitosan consumption. 6. the preparation method of chitosan-grafted amino acid magnetic composite microspheres according to claim 3 is characterized in that, the pH value of cross-linking process control reaction solution is 7-10, and cross-linking temperature is 35-65 ℃ , the crosslinking time is 0.5-3 hours. 7. The application of a chitosan-grafted amino acid magnetic composite microsphere as a water treatment agent in the treatment of dye wastewater. 8. A chitosan-grafted amino acid magnetic composite microsphere is used for adsorbing heavy metal ions in water. 9. The chitosan-grafted amino acid magnetic composite microsphere according to claim 8 is used for adsorbing Cu ²⁺ . 10. The chitosan-grafted amino acid magnetic composite microsphere according to claim 1, characterized in that, after the water treatment is completed, the composite microsphere is separated and enriched by magnetic separation technology and recycled for reuse.