A protein-edible gum covalent grafted composite starch aerogel and its preparation method and application

Abstract

The present invention belongs to the field of material technology, discloses a kind of protein-edible glue covalent graft composite starch aerogel and its preparation method and application, specifically discloses a kind of preparation method of aerogel, comprises the following steps: (1) preparation of covalent graft: protein and edible glue are mixed and dissolved, dried, and carried out Maillard reaction to obtain covalent graft; After starch gelatinization, pH is adjusted, and cross-linking agent, the covalent graft of step (1) are mixed, reacted, pH is adjusted to neutral, dried, and aerogel is obtained. The present invention combines protein-edible glue by glycosylation modification for the first time, makes it produce stronger environmental stability, then cross-links and compounds with protein-edible glue graft copolymer by starch, improves the combination of starch and copolymer. The prepared aerogel can form more holes, and the structure is more stable, thereby providing more binding sites, and the result embodied is that the adsorption amount to metal is larger.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials, and in particular relates to a protein-edible gum covalent graft composite starch aerogel and a preparation method and application thereof. Background Art

[0002] The rapid development of modern industry has made the problem of water pollution caused by heavy metal ions increasingly prominent, posing a serious threat to people's lives and health, and is an urgent problem that needs to be solved. Heavy metal ions have several major characteristics: (1) Toxic and harmful. After entering the human body, they can quickly combine with proteins, amino acids and other substances in the body, easily forming organic compounds of heavy metal ions. Long-term accumulation causes chronic poisoning of certain organs and even induces cell cancer. (2) Difficult to degrade. After entering the human body, heavy metal ions will not be decomposed and transformed with the metabolism of cells. (3) Bioaccumulation. Heavy metal ions will be enriched through the food chain, and the accumulation multiples through the food chain can reach thousands to millions of times, posing a serious threat to human health and food safety.

[0003] Hydrogels are specialized macromolecules that contain large amounts of water within their internal structure, enabling them to mimic biological tissues and are particularly well-suited for biomedical and tissue engineering applications. Due to their highly hydrophilic three-dimensional network structure and biocompatibility, they have found widespread application in fields such as biomedicine, agriculture, and the petroleum industry. As a novel adsorbent material, hydrogels contain functional groups that react with heavy metal ions, enabling their removal from wastewater. Consequently, their use in heavy metal wastewater treatment is increasing year by year.

[0004] Starch molecular chains contain a large number of hydroxyl groups and can be used as raw materials for constructing natural biomacromolecule-based hydrogels. During the gelatinization and retrogradation process of native starch, the molecular chains interact with each other through hydrogen bonds, entanglement, and rearrangement to form a starch gel network with a larger pore size. Starch-based hydrogels are mainly prepared by single chemical crosslinking, physical crosslinking, or adding small molecules to form chemically or physically crosslinked single-layer network starch hydrogels. However, due to the weak interaction between the molecular chains in the gel network and the uneven network, starch hydrogels have poor mechanical strength and small specific surface area, which greatly limits their scope of application. Summary of the Invention

[0005] The first aspect of the present invention aims to provide a method for preparing aerogel.

[0006] The second aspect of the present invention aims to provide an aerogel.

[0007] The third aspect of the present invention aims to provide the preparation method of the first aspect of the present invention and / or the application of the aerogel of the second aspect of the present invention.

[0008] The fourth aspect of the present invention aims to provide a heavy metal adsorbent.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] The first aspect of the present invention is to provide a method for preparing an aerogel, comprising the following steps:

[0011] (1) Preparation of covalent grafted products: Protein and edible gum are mixed and dissolved, dried, and subjected to Maillard reaction to obtain covalent grafted products;

[0012] (2) After gelatinizing the starch, adjusting the pH, mixing with a cross-linking agent and the covalent grafted product of step (1), reacting, adjusting the pH to neutral, and drying to obtain an aerogel.

[0013] Preferably, the protein comprises at least one of soy protein isolate, rice gluten, wheat protein, and peanut protein isolate.

[0014] More preferably, the protein is soy protein isolate.

[0015] Preferably, the edible gum includes at least one of guar gum, gum arabic, xanthan gum, carrageenan, sodium alginate, and locust bean gum.

[0016] Preferably, the cross-linking agent includes at least one of epichlorohydrin, sodium tripolyphosphate, sodium trimetaphosphate, and sodium hexametaphosphate.

[0017] Preferably, the mass ratio of the protein to the edible gum is 1:(0.5-3).

[0018] Further preferably, the mass ratio of the protein to the edible gum is 1:(1-2.5).

[0019] More preferably, the mass ratio of the protein to the edible gum is 1:(1-2).

[0020] Preferably, the protein concentration in the solution after the protein and edible gum are mixed and dissolved is 1% to 10%.

[0021] More preferably, the protein concentration in the solution after the protein and edible gum are mixed and dissolved is 1% to 6%.

[0022] More preferably, the protein concentration in the solution after the protein and edible gum are mixed and dissolved is 2% to 5%.

[0023] More preferably, the pH value of the solution is 7-10; further preferably 7-9.

[0024] Preferably, the Maillard reaction is carried out under the following conditions: 55-70° C., 70%-90% relative humidity, and sealed reaction for 20-30 hours.

[0025] More preferably, the Maillard reaction is carried out under the conditions of 55-65° C. and 75%-85% relative humidity for 20-26 hours in a sealed container.

[0026] More preferably, the Maillard reaction is carried out under the conditions of 55-65° C. and 79%-85% relative humidity for 20-24 hours in a sealed container.

[0027] Preferably, in step (2), the mass ratio of the starch to the covalent graft is 1:(0.5-2).

[0028] Further preferably, in step (2), the mass ratio of the starch to the covalent graft is 1:(0.5-1.8).

[0029] More preferably, in step (2), the mass ratio of the starch to the covalent graft is 1:(0.8-1.6).

[0030] Preferably, the reaction conditions in step (2) are stirring at 30-60° C. for 4-30 hours.

[0031] More preferably, the reaction conditions in step (2) are stirring at 30-60° C. for 4-25 hours.

[0032] More preferably, the reaction conditions in step (2) are stirring at 30-60° C. for 6-24 h.

[0033] Preferably, the concentration of the starch aqueous solution during starch gelatinization in step (2) is 4% to 8%.

[0034] Preferably, the mass ratio of the starch to the cross-linking agent in step (2) is 1:(0.01-0.1).

[0035] Further preferably, the mass ratio of the starch to the cross-linking agent in step (2) is 1:(0.01-0.05).

[0036] Preferably, the standing condition in step (2) is standing at 4-6°C for 20-25 hours.

[0037] Preferably, the starch gelatinization condition in step (2) is heating at 100° C. for 20 to 30 minutes.

[0038] Preferably, the pH value of the starch is adjusted to 9-11 after gelatinization in step (2).

[0039] Preferably, the starch in step (2) comprises at least one of pea starch, tapioca starch, waxy corn starch, corn starch, potato starch, rice starch, and lotus seed starch.

[0040] The second aspect of the present invention is to provide an aerogel prepared by the preparation method of the first aspect of the present invention.

[0041] The third aspect of the present invention is to provide the preparation method of the first aspect of the present invention and / or the use of the aerogel of the second aspect of the present invention in any one of (a1) to (a3):

[0042] (a1) adsorption of heavy metals;

[0043] (a2) Preparation of heavy metal adsorbent

[0044] (a3) Separation, enrichment and / or purification of heavy metals.

[0045] Preferably, the heavy metal includes at least one of copper, lead, zinc, tin, nickel, cobalt, antimony, mercury, cadmium and bismuth.

[0046] Preferably, the adsorption of heavy metals includes adsorbing heavy metals in polluted water, soil, and the like.

[0047] A fourth aspect of the present invention is to provide a heavy metal adsorbent comprising the aerogel according to the third aspect of the present invention.

[0048] Preferably, the heavy metal adsorbent can be used to adsorb heavy metals in polluted water, soil, etc., and can be used for separation, enrichment and / or purification of heavy metals.

[0049] The beneficial effects of the present invention are:

[0050] The present invention combines protein and edible gum for the first time through glycosylation modification, resulting in a strong environmental stability. Then, starch and the protein-edible gum graft copolymer are cross-linked and compounded to improve the binding of starch and the copolymer. The prepared aerogel can form more pores and has a more stable structure, thereby providing more binding sites, which results in a greater adsorption capacity for metals. All raw materials of the aerogel preparation method provided by the present invention are derived from food grade, which is highly safe, and the preparation process is simple and easy to control, which can achieve large-scale production, is environmentally friendly, low cost, and convenient to store and transport, making it easy to large-scale production and popularize.

[0051] The aerogel provided by the present invention has the advantages of high specific surface area, high porosity, excellent adsorption performance, and large adsorption capacity. It has a strong adsorption capacity for heavy metal ions in aqueous systems with good fluidity and food systems, and can be used to adsorb heavy metals from aqueous solutions. Experimental verification shows that the aerogel provided by the present invention can achieve a swelling ratio of 9.37 to 14.68 g / g, adsorbs 126.46 to 180.69 mg / g of heavy metal copper, and 92.74 to 142.37 mg / g of heavy metal lead. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a scanning electron microscope image of the soy protein isolate-guar gum covalent grafted composite starch aerogel prepared in Example 1.

[0053] Figure 2 This is a scanning electron microscope image of the soy protein isolate-guar gum covalent graft mixed starch aerogel prepared in Comparative Example 1.

[0054] Figure 3 This is a scanning electron microscope image of the soy protein isolate-guar gum composite starch aerogel prepared in Comparative Example 2.

[0055] Figure 4 This is a physical picture of the soy protein isolate-guar gum covalent grafted composite starch aerogel prepared in Example 1.

[0056] Figure 5 This is a physical picture of the soy protein isolate-guar gum covalent graft mixed starch aerogel prepared in Comparative Example 1.

[0057] Figure 6 This is a physical picture of the soy protein isolate-guar gum composite starch aerogel prepared in Comparative Example 2. DETAILED DESCRIPTION

[0058] The present invention will now be described in detail with reference to specific embodiments, but the scope of the present invention is not limited thereto.

[0059] Unless otherwise specified, the materials and reagents used in this example were obtained from commercial sources.

[0060] Example 1

[0061] A method for preparing a soy protein isolate-guar gum covalent grafted composite starch aerogel with heavy metal adsorption capacity comprises the following steps:

[0062] (1) Preparation of soy protein isolate-guar gum covalent grafted products

[0063] 10 g of soy protein isolate and 10 g of guar gum were added to 200 mL of water, magnetically stirred for 2 hours to fully dissolve, the pH was adjusted to 7, and a solution with a protein concentration of 5% was prepared. The solution was then vacuum freeze-dried at -60°C. The freeze-dried sample was fully ground and reacted in a sealed container at 55°C and 79% relative humidity for one day to undergo a Maillard reaction. The reaction product was a soy protein isolate-guar gum covalent graft, which was stored at 4°C for future use.

[0064] (2) Preparation of soy protein isolate-guar gum covalent grafted composite starch aerogel

[0065] Dissolve 10g of soy protein isolate-guar gum covalent grafted product in 200mL of water, stir magnetically until fully dissolved, and obtain soy protein isolate-guar gum covalent grafted product solution. Add 10g of waxy corn starch to water and stir to prepare a 5% starch solution, heat at 100℃ for 20min until the starch is fully gelatinized, cool, adjust the pH to 9, add 0.1g of sodium trimetaphosphate, and then add 200mL of soy protein isolate-guar gum covalent grafted product solution to the above starch solution and stir at 60℃ for 6h. After the end, adjust the pH to neutral, put it into a mold, let it stand at 4℃ for 24h, and then freeze-dry it at -60℃ in a vacuum to prepare a soy protein isolate-guar gum covalent grafted product composite starch aerogel, as shown in the figure. Figure 5 shown.

[0066] Example 2

[0067] A method for preparing a soy protein isolate-gum arabic covalent graft composite starch aerogel with heavy metal adsorption capacity comprises the following steps:

[0068] (1) Preparation of soy protein isolate-gum arabic covalent grafts

[0069] 8 g of soy protein isolate and 10 g of gum arabic were added to 228 mL of water and magnetically stirred for 2 hours to fully dissolve. The pH was adjusted to 8 to prepare a solution with a protein concentration of 3.5%. The solution was then vacuum freeze-dried at -60°C. The freeze-dried sample was fully ground and reacted in a sealed container at 60°C and 82% relative humidity for one day to undergo a Maillard reaction. The reaction product was a soy protein isolate-guar gum covalent graft, which was stored at 4°C for future use.

[0070] (2) Preparation of soy protein isolate-gum arabic covalent grafted composite starch aerogel

[0071] Dissolve 10g of soy protein isolate-gum arabic covalent graft in 200mL of water and stir magnetically until fully dissolved to obtain a soy protein isolate-gum arabic covalent graft solution. Add 8g of corn starch to water and stir to prepare a 4% starch solution. Heat at 100°C for 20 minutes until the starch is fully gelatinized. After cooling, adjust the pH to 11, add 0.3g of sodium tripolyphosphate, and then add 200mL of soy protein isolate-gum arabic covalent graft solution to the starch solution and stir at 40°C for 8 hours. After completion, adjust the pH to neutral, place in a mold, let stand at 4°C for 24 hours, and then freeze-dry at -60°C to produce a soy protein isolate-gum arabic covalent graft composite starch aerogel.

[0072] Example 3

[0073] A method for preparing a soy protein isolate-xanthan gum covalent grafted composite starch aerogel with heavy metal adsorption capacity comprises the following steps:

[0074] (1) Preparation of soy protein isolate-xanthan gum covalent grafted products

[0075] 6 g of soy protein isolate and 10 g of xanthan gum were added to 150 mL of water and magnetically stirred for 2 hours to fully dissolve. The pH was adjusted to 9 to prepare a solution with a protein concentration of 4%, and then vacuum freeze-dried at -60°C. The freeze-dried sample was fully ground and reacted in a sealed container at 65°C and 85% relative humidity for one day to undergo a Maillard reaction. The reaction product was a soy protein isolate-xanthan gum covalent graft, which was stored at 4°C for future use.

[0076] (2) Preparation of soy protein isolate-xanthan gum covalent grafted composite starch aerogel

[0077] 10g of soy protein isolate-xanthan gum covalent graft was dissolved in 200mL of water and magnetically stirred until fully dissolved to obtain a soy protein isolate-guar gum covalent graft solution. 7g of potato starch was added to water and stirred to prepare a 7% starch solution. The solution was heated at 100°C for 20 minutes until the starch was fully gelatinized. After cooling, the pH was adjusted to 10, 0.14g of sodium hexametaphosphate was added, and 200mL of the soy protein isolate-xanthan gum covalent graft solution was added to the starch solution and stirred at 50°C for 16 hours. After completion, the pH was adjusted to neutral, the solution was placed in a mold, and allowed to stand at 4°C for 24 hours. It was then freeze-dried at -60°C in a vacuum to produce a soy protein isolate-xanthan gum covalent graft composite starch aerogel.

[0078] Example 4

[0079] A method for preparing a soy protein isolate-sodium alginate covalent graft composite starch aerogel with heavy metal adsorption capacity comprises the following steps:

[0080] (1) Preparation of soy protein isolate-sodium alginate covalent graft

[0081] 5 g of soy protein isolate and 10 g of sodium alginate were added to 200 mL of water and magnetically stirred for 2 h to fully dissolve. The pH was adjusted to 7 to prepare a solution with a protein concentration of 2.5%, and then vacuum freeze-dried at -60°C. The freeze-dried sample was fully ground and reacted in a sealed container at 65°C and 79% relative humidity for one day to undergo a Maillard reaction. The reaction product was a soy protein isolate-sodium alginate covalent graft, which was stored at 4°C for future use.

[0082] (2) Preparation of soy protein isolate-sodium alginate covalent grafted composite starch aerogel

[0083] Dissolve 10g of soy protein isolate-sodium alginate covalent graft in 200mL of water and stir magnetically until fully dissolved to obtain a soy protein isolate-sodium alginate covalent graft solution. Add 12g of cassava starch to water and stir to prepare an 8% starch solution. Heat at 100°C for 20 minutes until the starch is fully gelatinized. After cooling, adjust the pH to 11, add 0.6g of epichlorohydrin, and then add 200mL of the soy protein isolate-guar gum covalent graft solution to the starch solution and stir at 60°C for 24 hours. After completion, adjust the pH to neutral, place in a mold, and let stand at 4°C for 24 hours. Then, vacuum freeze-dry at -60°C to produce a soy protein isolate-sodium alginate covalent graft composite starch aerogel.

[0084] Example 5

[0085] A method for preparing a rice gluten-guar gum covalent grafted composite starch aerogel with heavy metal adsorption capacity is disclosed. The preparation method is the same as that of Example 1, except that the protein used is rice gluten instead of soy protein isolate.

[0086] Example 6

[0087] A method for preparing a wheat protein-guar gum covalent grafted composite starch aerogel with heavy metal adsorption capacity is disclosed. The preparation method is the same as that of Example 1, except that the protein used is wheat protein instead of soy protein isolate.

[0088] Example 7

[0089] A method for preparing a peanut protein isolate-guar gum covalent grafted composite starch aerogel with heavy metal adsorption capacity is disclosed. The preparation method is the same as that of Example 1, except that the protein used is peanut protein isolate instead of soy protein isolate.

[0090] Comparative Example 1

[0091] A method for preparing a soy protein isolate-guar gum covalent grafted mixed starch aerogel with heavy metal adsorption capacity comprises the following steps:

[0092] (1) Preparation of soy protein isolate-guar gum covalent grafted products

[0093] 10 g of soy protein isolate and 10 g of guar gum were added to 200 mL of water and magnetically stirred for 2 hours to fully dissolve. The pH was adjusted to 7 to prepare a solution with a protein concentration of 5%, and then vacuum freeze-dried at -60°C. The freeze-dried sample was fully ground and reacted in a sealed container at 55°C and 79% relative humidity for one day to undergo a Maillard reaction. The reaction product was a soy protein isolate-guar gum covalent graft, which was stored at 4°C for future use.

[0094] (2) Preparation of soy protein isolate-guar gum covalent grafted composite starch aerogel

[0095] 10g of soy protein isolate-guar gum covalent grafted product was dissolved in 200mL of water and magnetically stirred until fully dissolved to obtain a soy protein isolate-guar gum covalent grafted product solution. 10g of waxy corn starch was added to water and stirred to prepare a 5% starch solution. The solution was heated at 100°C for 20 minutes until the starch was fully gelatinized. After cooling, the pH was adjusted to 9, 0.1g of sodium trimetaphosphate was added, and the solution was stirred at 60°C for 6 hours. Afterwards, the pH was adjusted to neutral, and 200mL of the soy protein isolate-guar gum covalent grafted product solution was added to the starch solution after the reaction and stirred at 60°C for 6 hours. The solution was placed in a mold, allowed to stand at 4°C for 24 hours, and then freeze-dried at -60°C in a vacuum to produce a soy protein isolate-guar gum covalent grafted product mixed starch aerogel.

[0096] Comparative Example 2

[0097] A method for preparing a soy protein isolate-guar gum composite starch aerogel with heavy metal adsorption capacity comprises the following steps:

[0098] (2) Preparation of soy protein isolate-guar gum mixture

[0099] 10 g of soy protein isolate and 10 g of guar gum were respectively added to 200 mL of water, magnetically stirred for 2 hours to fully dissolve, the pH was adjusted to 7, a 5% solution was prepared, and vacuum freeze-dried at -60°C; the freeze-dried samples were fully ground, placed in a sealed container at 55°C and 79% relative humidity for one day, and then placed at 4°C and fully stirred to prepare a soy protein isolate-guar gum mixture for later use.

[0100] (2) Preparation of soy protein isolate-guar gum mixture composite starch aerogel

[0101] 10g of soy protein isolate-guar gum mixture was dissolved in 200mL of water and fully dissolved after magnetic stirring to obtain a soy protein isolate-guar gum mixture solution. 10g of waxy corn starch was added to water and stirred to prepare a 5% starch solution. The solution was heated at 100°C for 20min until the starch was fully gelatinized. After cooling, the pH was adjusted to 9, 0.1g of sodium trimetaphosphate was added, and 200mL of soy protein isolate-guar gum mixture solution was added to the above starch solution and stirred at 60°C for 6h. After the end, the pH was adjusted to neutral, the mixture was placed in a mold, and after standing at 4°C for 24h, it was vacuum freeze-dried at -60°C to prepare a soy protein isolate-guar gum mixture composite starch aerogel.

[0102] Effect embodiment

[0103] The properties of the aerogels prepared in the examples and comparative examples were measured as follows:

[0104] The surface morphology of the aerogel was characterized by scanning electron microscopy (SEM).

[0105] Swelling properties: The swelling properties of the gel were determined by the weighing method. The weighed aerogel (W) was immersed in a beaker filled with deionized water and then placed at 25°C for 48 hours. The sample was taken out and the water on the surface of the aerogel was wiped with filter paper. The sample (W) was weighed. t ), the aerogel swelling ratio is calculated according to the following formula: Swelling ratio (g / g) = (W t -W) / W.

[0106] Heavy Metal Adsorption Capacity: Copper and lead ion solutions of varying concentrations were prepared using CuSO₄·5H₂O and Pb(NO₃)₂. The weighed aerogels were immersed in a beaker containing the copper or lead ion solutions and then incubated at 25°C for 48 hours. The heavy metal concentrations before and after adsorption were measured using an atomic absorption spectrophotometer. The adsorption capacity of the aerogels was calculated using the following formula: Adsorption capacity (mg / g) = (initial heavy metal concentration in the solution before adsorption - heavy metal concentration in the solution after adsorption) * volume / adsorbent mass.

[0107] The surface morphology of the aerogels prepared in Example 1 and Comparative Examples 1-2 was observed using a scanning electron microscope (SEM). Figures 1 to 3 As shown, the SEM images of Example 1 and Comparative Examples 1-2 show smaller voids, which means a larger specific surface area and thus a stronger adsorption capacity.

[0108] The swelling properties and adsorption capacities of heavy metals lead and copper for the aerogels prepared in Examples 1-7 and Comparative Examples 1-2 were calculated, and the results are shown in Table 1. The difference between Example 1 and Examples 5, 6, and 7 lies in the type of protein used. Analysis shows that the aerogel prepared using soy protein isolate exhibits the best adsorption capacities for copper and lead (adsorption capacities of 180.69 mg / g and 142.37 mg / g, respectively), likely due to differences in protein structure. Comparative Example 1, in contrast to Example 1, exhibits significantly inferior swelling rate (8.01 g / g) and adsorption capacities for heavy metals copper and lead (adsorption capacities of 103.77 mg / g and 79.39 mg / g, respectively) to the aerogel prepared using Example 1 (swelling rate of 14.68 g / g and adsorption capacities of 180.69 mg / g and 142.37 mg / g, respectively). Comparative Example 2, compared to Example 1, exhibits significantly lower swelling ratios (8.32 g / g) and adsorption capacities for heavy metals copper and lead (114.21 mg / g and 84.33 mg / g, respectively) than the aerogel prepared using Example 1, except that the soy protein isolate and guar gum do not undergo a Maillard reaction. Overall, the preparation methods of Examples 1-7 significantly improve the swelling ratio of the aerogels and their adsorption of heavy metals copper and lead compared to the comparative example.

[0109] Table 1 Swelling characteristics of each aerogel and adsorption capacity of heavy metals lead and copper

[0110]

[0111] While the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A method for preparing an aerogel, comprising the following steps: (1) Preparation of covalent grafted products: protein and edible gum are mixed and dissolved, dried, and subjected to Maillard reaction to obtain covalent grafted products; (2) gelatinizing the starch and adjusting the pH, mixing with a cross-linking agent and the covalent grafted product of step (1), reacting, adjusting the pH to neutral, and drying to obtain an aerogel; The edible gum includes at least one of guar gum, gum arabic, xanthan gum, carrageenan, sodium alginate, and locust bean gum; The mass ratio of the protein to the edible gum in step (1) is 1:(0.5-3); In step (2), the mass ratio of the starch to the covalent graft is 1:(0.5-2), and the mass ratio of the starch to the cross-linking agent is 1:(0.01-0.1).

2. The preparation method according to claim 1, characterized in that The protein is at least one of soy protein isolate, rice gluten, wheat protein, and peanut protein isolate.

3. The preparation method according to claim 1, characterized in that The cross-linking agent includes at least one of epichlorohydrin, sodium tripolyphosphate, sodium trimetaphosphate, and sodium hexametaphosphate.

4. The preparation method according to any one of claims 1 to 3, characterized in that The protein and edible gum are mixed and dissolved in a solution having a protein concentration of 1% to 10%.

5. The preparation method according to any one of claims 1 to 3, characterized in that The Maillard reaction is carried out under the following conditions: 55-70° C. and 70%-90% relative humidity in a sealed container for 20-30 hours.

6. The preparation method according to claim 5, characterized in that The reaction conditions in step (2) are stirring at 30-60° C. for 4-30 hours, and the pH is adjusted to 9-11 after the starch is gelatinized.

7. An aerogel prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the aerogel according to claim 7 in any one of (a1) to (a3): (a1) adsorption of heavy metals; (a2) preparing heavy metal adsorbents; (a3) Separation, enrichment and / or purification of heavy metals.

9. A heavy metal adsorbent comprising the aerogel according to claim 7.

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