Hyperbranched polyamidoamine-chitosan aerogel and preparation method thereof

Abstract

The invention discloses hyperbranched polyamidoamine-chitosan aerogel and a preparation method thereof, and belongs to the field of adsorption materials. The preparation method comprises the following steps: (1) synthesizing hyperbranched polyamidoamine; (2) dissolving chitosan in a dilute acetic acid solution, adding hyperbranched polyamidoamine into the solution, stirring to form clear liquid, and adding a cross-linking agent to form hyperbranched polyamidoamine-chitosan gel; and (3) carrying out freeze drying on the hyperbranched polyamidoamine-chitosan gel to obtain the hyperbranched polyamidoamine-chitosan aerogel. The preparation method is simple, the preparation cost is low, in addition, the hyperbranched polyamidoamine-chitosan aerogel obtained through the method has a three-dimensional network structure, hexavalent chromium ions can enter the material easily, the adsorption performance of the hyperbranched polyamidoamine-chitosan aerogel is improved, and the service life of the material is prolonged. Good application prospects are realized in the technical fields of heavy metal ion treatment and the like.

Description

Technical Field

[0001] The invention belongs to the field of adsorption materials and relates to a hyperbranched polyamidoamine-chitosan aerogel and a preparation method thereof. Background Art

[0002] Heavy metal pollution has a serious impact on human life. Among the common heavy metal ions, chromium ions have attracted people's attention because of their great toxicity. They are mainly derived from industries such as leather tanning, electroplating and pigment manufacturing. In nature, chromium ions mainly exist in the form of trivalent chromium and hexavalent chromium, among which the toxicity of hexavalent chromium is much greater than that of trivalent chromium. Hexavalent chromium can cause chromosome mutations. Long-term exposure to hexavalent chromium can cause nausea, upper abdominal pain and bleeding, and even cause lung cancer and digestive tract cancer (Polyhedron 15 (1995) 3667-3689). In China, the concentration of hexavalent chromium in drinking water is less than 0.05 mg / L, and the concentration of hexavalent chromium in industrial wastewater is less than 0.5 mg / L. Therefore, it is very important to find an ideal adsorbent material to remove hexavalent chromium ions in industrial wastewater to reduce its threat to humans.

[0003] Common methods for removing hexavalent chromium ions include: ion exchange, electrochemical reduction, chemical precipitation, membrane filtration, and adsorption. When using the ion exchange method, the ion exchange resin is easily contaminated by organic matter; the electrochemical reduction method and membrane filtration method have high costs; and the chemical precipitation method is prone to secondary pollution. In comparison, the adsorption method has attracted people's attention due to its advantages such as high removal efficiency, low preparation cost, and no secondary pollution.

[0004] Chitosan is abundant in nature, the raw materials are easily available, it has good compatibility with organisms, and it can be degraded. It is a kind of natural polymer material with great development prospects (Progress in Polymer Science 31(7)(2006)603-632). In addition, chitosan molecules contain a large number of amine groups and hydroxyl groups, which make it easy to adsorb heavy metal ions. Therefore, chitosan is an ideal adsorption material. Compared with common chitosan powder, chitosan aerogel has more advantages, such as easy recycling and high porosity. However, due to its relatively small number of amine groups, the adsorption efficiency of chitosan aerogel for hexavalent chromium is not very high. This disadvantage limits the application range of chitosan aerogel adsorbents. In order to increase the scope of use of chitosan aerogel, it is a better strategy to introduce a large number of amine groups into chitosan to form chitosan aerogel derivatives.

[0005] Hyperbranched polyamidoamine has the advantages of low viscosity, no chain entanglement, good solubility, a large number of amino functional groups and a three-dimensional network structure. It has been valued and favored by a large number of researchers and is regarded as an important direction for the development of polymer science in the 21st century. This patent aims to provide a method for preparing hyperbranched polyamidoamine-chitosan aerogel and preliminarily explore the ability of this material to adsorb hexavalent chromium. Summary of the invention

[0006] The present invention aims to provide a hyperbranched polyamidoamine-chitosan aerogel and a preparation method thereof. The present invention adopts hyperbranched polyamidoamine and chitosan as raw materials, and adopts a coordination strategy of dissolution and cross-linking to prepare the hyperbranched polyamidoamine-chitosan aerogel. The present invention is simple to prepare, low in cost, and environmentally friendly in materials, and has good application prospects in the fields of heavy metal ion adsorption and the like.

[0007] The technical solution of the present invention is as follows:

[0008] A hyperbranched polyamidoamine-chitosan aerogel and a preparation method thereof, comprising the following steps:

[0009] (1) Using diethylenetriamine and dimethyl maleate as raw materials, stirring in an ice bath for 4-6 hours, then heating to 90-110° C., and reacting in an open air for 7-10 hours, a viscous yellow liquid, namely a hyperbranched polyamidoamine, is obtained.

[0010] (2) Dissolve chitosan in a dilute acetic acid solution, add the hyperbranched polyamide amine obtained in step (1) to the above solution, stir for 2-4 hours to obtain a transparent solution, then slowly add a crosslinking agent dropwise to the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 4-6 hours.

[0011] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with water for multiple times, and then freeze-dried to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0012] Furthermore, in the above technical solution, in step (1), the molar ratio of diethylenetriamine to dimethyl maleate is 1.5:1-2.5:1, preferably 2:1.

[0013] Furthermore, in the above technical solution, in step (2), the mass ratio of chitosan to dilute acetic acid solution is 1:40-1:100, preferably 1:50.

[0014] Furthermore, in the above technical solution, in step (2), the mass concentration of the dilute acetic acid solution is 1-5%, preferably 2%.

[0015] Furthermore, in the above technical solution, in step (2), the mass ratio of the hyperbranched polyamidoamine to the dilute acetic acid solution is 3:100-4:100.

[0016] Furthermore, in the above technical solution, in step (2), the cross-linking agent is epichlorohydrin or glutaraldehyde, and glutaraldehyde is preferably used.

[0017] Furthermore, in the above technical solution, in step (2), the mass ratio of the cross-linking agent to the dilute acetic acid solution is 1:25-1:100.

[0018] Furthermore, in the above technical solution, in step (3), the water used for washing is deionized water or tap water, with deionized water being preferred.

[0019] Furthermore, in the above technical solution, in step (3), the freeze-drying temperature is less than -60°C, and the freeze-drying time is greater than or equal to 48 hours. Preferably, the freeze-drying temperature is -70°C, and the freeze-drying time is 48 hours.

[0020] Beneficial effects of the present invention:

[0021] (1) One of the raw materials used in the present invention is chitosan, which has the advantages of being cheap, readily available, green and non-toxic. In addition, the preparation process of the hyperbranched polyamidoamine-chitosan aerogel is relatively simple and the production cost is low.

[0022] (2) Hyperbranched polyamide-chitosan aerogel presents a three-dimensional network structure and contains a large number of amino groups, and has good heavy metal ion adsorption capacity.

[0023] (3) The prepared hyperbranched polyamidoamine-chitosan aerogel has the advantages of stable structure and easy recycling, and is a novel heavy metal ion adsorbent that has never been reported. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The embodiments of the present invention are described in detail with reference to the accompanying drawings, wherein

[0025] Figure 1 : Infrared spectrum of the hyperbranched polyamidoamine-chitosan aerogel prepared in Example 4.

[0026] Figure 2 : Scanning electron microscopy image of the hyperbranched polyamidoamine-chitosan aerogel prepared in Example 4.

[0027] Figure 3 : Adsorption capacity of hexavalent chromium by the hyperbranched polyamidoamine-chitosan aerogel prepared in Example 4.

[0028] Figure 4: Recycling diagram of the hyperbranched polyamidoamine-chitosan aerogel prepared in Example 4. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below with reference to the examples, but the embodiments of the invention are not limited thereto. The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0030] Example 1

[0031] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0032] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0033] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (1.5 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0034] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0035] Example 2

[0036] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0037] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0038] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (1.6 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0039] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0040] Example 3

[0041] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0042] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0043] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (1.7 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0044] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0045] Example 4

[0046] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0047] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0048] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (1.8 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0049] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0050] Example 5

[0051] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0052] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0053] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (1.9 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0054] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0055] Example 6

[0056] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0057] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0058] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (2.0 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0059] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0060] Example 7

[0061] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0062] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0063] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (1.5 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1.5 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0064] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0065] Example 8

[0066] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0067] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0068] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (1.6 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1.5 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0069] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0070] Example 9

[0071] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0072] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0073] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (1.7 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1.5 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0074] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0075] Example 10

[0076] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0077] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0078] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (1.8 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1.5 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0079] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0080] Embodiment 11

[0081] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0082] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0083] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (1.9 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1.5 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0084] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0085] Example 12

[0086] Preparation of a hyperbranched polyamidoamine-chitosan aerogel:

[0087] (1) Diethylenetriamine (41.3 g, 0.4 mol) and dimethyl maleate (28.8 g, 0.2 mol) were added to a 250 mL four-necked flask and stirred for 5 h in an ice bath. The temperature was then raised to 100° C. and the mixture was allowed to react in an open state for 8 h to obtain a viscous yellow liquid, i.e., a hyperbranched polyamidoamine.

[0088] (2) Dissolve 1 g of chitosan in 2% acetic acid solution (50 g), add the hyperbranched polyamide amine (2.0 g) obtained in step (1) to the above solution, stir for 3 h to obtain a transparent solution, then slowly drop 1.5 g of glutaraldehyde into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 5 h.

[0089] (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with deionized water for multiple times, and freeze-dried at -70°C for 48 hours to obtain a hyperbranched polyamidoamine-chitosan aerogel.

[0090] Example 13

[0091] The basic characterization method and characterization results of the hyperbranched polyamidoamine-chitosan aerogel prepared by the present invention are as follows:

[0092] 1. Molecular structure of hyperbranched polyamidoamine-chitosan aerogel

[0093] Characterization method: Fourier transform infrared spectrometer (Tensor II, USA) was used at 4000-500 cm -1 The molecular structure of hyperbranched polyamidoamine-chitosan aerogel was characterized by reflection method in the wavenumber range.

[0094] Characterization results: as attached Figure 1 As shown, Example 4 at 3380cm -1 The characteristic peak at 1628cm is attributed to the stretching vibration of OH and NH. -1 The characteristic peak at 1556 cm -1 and 1403cm -1 The characteristic peak of C=N is at 1067cm -1 The characteristic peak at is attributed to the stretching vibration of COC.

[0095] 2. Microstructure of hyperbranched polyamidoamine-chitosan aerogel

[0096] Characterization method: The microstructure of hyperbranched polyamidoamine-chitosan aerogel was observed using a scanning electron microscope (Sigma 300, USA).

[0097] Characterization results: as attached Figure 2 As shown, the existence of a three-dimensional porous structure can be observed in Example 4, which is conducive to the entry of heavy metal ions into the interior of the hyperbranched polyamidoamine-chitosan aerogel, thereby improving the adsorption efficiency of the hyperbranched polyamidoamine-chitosan aerogel for heavy metal ions.

[0098] Embodiment 14

[0099] The performance test results of the hyperbranched polyamidoamine-chitosan aerogel prepared by the present invention are as follows:

[0100] 1. Adsorption properties of hyperbranched polyamidoamine-chitosan aerogels

[0101] Test results: as attached Figure 3 As shown, the adsorption capacity of Example 4 for hexavalent chromium ions is greater than 370 mg / g, indicating that the hyperbranched polyamidoamine-chitosan aerogel prepared in Example 4 has a good removal ability for hexavalent chromium ions.

[0102] 2. Recycling performance of hyperbranched polyamidoamine-chitosan aerogel

[0103] Test results: as attached Figure 4 As shown, after four cycles of use, the hyperbranched polyamidoamine-chitosan aerogel prepared in Example 4 still has a removal efficiency of more than 70%, indicating that the hyperbranched polyamidoamine-chitosan aerogel has excellent recycling performance.

Claims

1. A method for preparing a hyperbranched polyamidoamine-chitosan aerogel, comprising the following steps: (1) Using diethylenetriamine and dimethyl maleate as raw materials, stirring in an ice bath for 4-6 hours, then heating to 90-110° C., and reacting in an open air for 7-10 hours, a viscous yellow liquid, namely a hyperbranched polyamidoamine, is obtained. (2) Dissolve chitosan in a dilute acetic acid solution, add the hyperbranched polyamide amine obtained in step (1) to the above solution, stir for 2-4 hours to obtain a transparent solution, then dropwise add a crosslinking agent into the transparent solution while stirring to obtain a hyperbranched polyamide amine-chitosan gel, and then cure at room temperature for 4-6 hours. (3) The hyperbranched polyamidoamine-chitosan gel obtained in step (2) is washed with water for multiple times, and then freeze-dried to obtain a hyperbranched polyamidoamine-chitosan aerogel.

2. The method for preparing a hyperbranched polyamidoamine-chitosan aerogel according to claim 1, characterized in that: In step (1), the molar ratio of diethylenetriamine to dimethyl maleate is 1.5:1-2.5:1, preferably 2:

1.

3. The method for preparing a hyperbranched polyamidoamine-chitosan aerogel according to claim 1, characterized in that: In step (2), the mass ratio of chitosan to dilute acetic acid solution is 1:40-1:100, preferably 1:

50.

4. The method for preparing a hyperbranched polyamidoamine-chitosan aerogel according to claim 1, characterized in that: In step (2), the mass concentration of the dilute acetic acid solution is 1-5%, preferably 2%.

5. The method for preparing a hyperbranched polyamidoamine-chitosan aerogel according to claim 1, characterized in that: In step (2), the mass ratio of the hyperbranched polyamidoamine to the dilute acetic acid solution is 3:100-4:

100.

6. The method for preparing a hyperbranched polyamidoamine-chitosan aerogel according to claim 1, characterized in that: In step (2), the cross-linking agent is epichlorohydrin or glutaraldehyde, and glutaraldehyde is preferably used.

7. The method for preparing a hyperbranched polyamidoamine-chitosan aerogel according to claim 1, characterized in that: In step (3), the water used for washing is deionized water or purified water, preferably deionized water.

8. The method for preparing a hyperbranched polyamidoamine-chitosan aerogel according to claim 1, characterized in that: In step (3), the freeze drying temperature is less than -60°C, and the freeze drying time is greater than or equal to 48 hours. Preferably, the freeze drying temperature is -70°C, and the freeze drying time is 48 hours.

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