Biomass composite sponge constructed based on tanning principle and method and application

Abstract

The invention discloses a biomass composite sponge constructed based on a tanning principle, and a method and application thereof, and belongs to the technical field of biomass. The method disclosed by the invention comprises the following steps: S1, stirring a protein solution, adding a cross-linking agent for cross-linking, and then incubating to obtain a cross-linked protein solution; s2, stirring the polysaccharide solution, adding a cross-linking agent for cross-linking, and then incubating to obtain a cross-linked polysaccharide solution; s3, mixing the cross-linked protein solution and the cross-linked polysaccharide solution to obtain a composite solution, adding a cross-linking agent into the composite solution for cross-linking, and then stirring to obtain a mixture; the mixture is poured into a mold for freezing and freeze drying, and the biomass composite sponge constructed based on the tanning principle is obtained. The method is simple in preparation process operation, the selected materials are economical and environment-friendly, and the method has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of biomass technology, specifically relating to a biomass composite sponge constructed based on the principle of tanning, its method, and its application. Background Technology

[0002] Traditional composite sponges are mostly made from petroleum-based polymer materials. Although these materials have certain mechanical properties and porous structures, they have obvious defects. On the one hand, they have poor biocompatibility and are difficult to degrade naturally, causing environmental pollution after disposal. On the other hand, their pore structure is mostly artificially controlled, resulting in weak bonding with functional materials and poor load stability, which limits their application in the field of microplastics processing.

[0003] Currently, common technologies for treating microplastics (MPs) from aquatic environments include coagulation-flocculation, flotation, filtration, electrocoagulation, advanced oxidation, and photocatalytic degradation. These methods primarily rely on differences in density, particle size, hydrophobicity, and conductivity of microplastics to achieve separation, but significant limitations remain. Coagulation processes use coagulants to aggregate suspended particles into flocs, which are then removed by sedimentation or filtration. Traditional coagulants such as aluminum sulfate and ferric chloride can remove some MPs through charge neutralization, but their residual metal ions can easily cause secondary pollution, posing a potential toxic threat to the ecosystem. While flotation can effectively separate MPs larger than 5 μm, it is affected by impurities in the environment and requires supplementary separation methods. Filtration, while effective at capturing large-diameter MPs, has lower efficiency for fine particles due to membrane pore limitations and clogging issues. Photocatalytic degradation can effectively degrade some microplastics, but it is energy-intensive, has a long degradation cycle, and the catalyst is prone to secondary pollution. Summary of the Invention

[0004] The purpose of this invention is to provide a biomass composite sponge constructed based on the tanning principle, as well as its method and application, in order to solve the problems of secondary pollution and ecotoxicity of traditional materials.

[0005] To achieve the above objectives, the present invention employs the following technical solution: To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a method for constructing biomass composite sponges based on the principle of tanning, comprising the following steps: S1: After stirring the protein solution, a cross-linking agent is added to cross-link the protein solution, followed by incubation to obtain a cross-linked protein solution. S2: After stirring the polysaccharide solution, a cross-linking agent is added to cross-link it, followed by incubation to obtain a cross-linked polysaccharide solution; S3: The cross-linked protein solution and the cross-linked polysaccharide solution are mixed to obtain a composite solution. A cross-linking agent is added to the composite solution for cross-linking, and then the mixture is stirred to obtain a mixture. The mixture is poured into a mold for freezing and freeze-drying to obtain a biomass composite sponge constructed based on the tanning principle.

[0006] Further, in S1, the stirring is carried out at 60~70℃ for 30~50 min, and the stirring speed is 500 r / min; the crosslinking agent is added under the temperature conditions of the above solution, and the addition time is controlled to be 1~3 min; the incubation is carried out at 60~70℃ for 30~50 min.

[0007] Furthermore, in S1, the protein in the protein solution is one of gelatin, casein, and silk fibroin; the cross-linking agent is one of tannic acid, citric acid, and transglutaminase.

[0008] Further, in S1, the mass-volume concentration of the protein solution is 2% to 6%; the volume of the protein solution is 90 to 120 mL; and the amount of the cross-linking agent is 0.2% to 0.5% of the volume of the protein solution.

[0009] Furthermore, in S2, the polysaccharide in the polysaccharide solution is one of oxidized starch, chitosan, and sodium alginate; the crosslinking agent is epichlorohydrin, genipin, and Ca. 2+ One of them.

[0010] Furthermore, in S2, before stirring the polysaccharide solution, the polysaccharide solution is continuously stirred at a speed of 500 r / min within a temperature range of 92±2℃ and reacted for 60±5min, and then the pH value is adjusted to 9~11 using NaOH solution; The polysaccharide solution was stirred at a speed of 500 r / min; the cross-linking was carried out at 90~92 ℃ for 5~8 min; the incubation temperature was 90~92 ℃ and the time was 40~60 min.

[0011] Further, in S3, the volume ratio of the cross-linked protein solution to the cross-linked polysaccharide solution is (3~4) mL: (1~2) mL.

[0012] Further, in S3, the crosslinking agent is gallic acid, a metal leather tanning agent, or an acrylic acid; the amount of the crosslinking agent is 1% to 1.2% of the volume of the composite solution. The stirring is carried out at 20~25℃ and 500~600r / min for 20~30min.

[0013] Furthermore, in S3, the freezing is carried out in a low-temperature refrigerator for 12 to 24 hours; the freeze-drying is carried out at -60 to -80°C for 36 to 48 hours.

[0014] The present invention also discloses a biomass composite sponge based on the tanning principle prepared by the above preparation method.

[0015] This invention also discloses the application of the above-mentioned biomass composite sponge constructed based on the tanning principle in microplastic treatment or oil-water separation.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for constructing biomass composite sponges based on the tanning principle. This method utilizes stepwise precise cross-linking based on the tanning principle, drawing on the mechanism of chemical cross-linking in the tanning process to strengthen the material structure. Employing a "stepwise cross-linking" strategy, the method first chemically cross-links protein and polysaccharide solutions separately to form a pre-stabilized network. Subsequently, the two are mixed in a certain proportion for further cross-linking, constructing an interpenetrating three-dimensional network. The protein skeleton provides rigid support, while the polysaccharide component imparts water absorption and elasticity, significantly improving the structural stability, mechanical properties, and load-bearing stability of the composite sponge. Furthermore, the entire preparation process is simple to operate, uses economical and environmentally friendly materials, and has broad application prospects. In terms of design, it adopts a green path of biomass polysaccharide / protein composites, avoiding the environmental hazards of traditional petroleum-based materials. In terms of preparation, it integrates stepwise chemical cross-linking and freeze-drying technologies to achieve controllable preparation of a three-dimensional network with high porosity and high specific surface area. Through the selection of biodegradable raw materials, the material possesses excellent environmental friendliness, biodegradability, and sustainability. Attached Figure Description

[0017] Figure 1 Photos and SEM images of different sponges; Among them: a-Sodium alginate / silk fibroin sponge, b-Oxidized starch / gelatin sponge, c-Chitosan / casein sponge photos; d-Sodium alginate / silk fibroin sponge, e-Oxidized starch / gelatin sponge, f-Chitosan / casein sponge SEM images. Figure 2 Performance data for starch / gelatin composite sponges; Wherein: a- adsorption of PS nanoplastics by starch / gelatin composite sponge at different adsorption times; b- fluorescence spectra of PS nanoplastics at different concentrations. Detailed Implementation

[0018] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0019] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0020] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0021] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0022] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0023] To address the shortcomings of existing technologies, this invention proposes a novel biomass composite sponge and its preparation method, aiming to provide a simple, low-cost, and environmentally friendly microplastic adsorbent material to significantly improve the removal efficiency of microplastics in the aquatic environment and provide a feasible and sustainable solution for microplastic pollution control.

[0024] This invention provides a method for constructing biomass composite sponges based on the principle of tanning, comprising the following steps: Step 1: Prepare a protein solution of a certain concentration. Then take a certain amount of the protein solution and stir it continuously at 65~70℃ for 30~40 min (500~600 r / min). Slowly add the cross-linking agent into the above system within 1 min to cross-link it. Then incubate at 60~70℃ for 30~40 min to obtain the cross-linked protein solution. Store the cross-linked protein solution in a water bath at 40~50℃ for later use. The protein solution concentration is 2% to 6%, the protein types are gelatin, casein, and silk fibroin, the cross-linking agents are tannic acid, glyoxal, and transglutaminase (TG enzyme), and the amount of cross-linking agent is 0.2% to 0.5% of the protein solution volume. Step 2: Prepare a polysaccharide solution of a certain concentration. Stir continuously at 500-600 r / min within a temperature range of 92±2℃ for 60±5 min until a homogeneous solution is formed. Then, adjust the pH of the system to 9-11 using NaOH solution. Subsequently, while stirring at 500 r / min, add a certain amount of cross-linking agent to the above solution and cross-link within 5-8 min. Incubate at 90-92℃ for 40-60 min to complete the cross-linking process, obtaining the cross-linked polysaccharide solution. The concentration of the polysaccharide solution is 3%-5%, and the types of polysaccharides are oxidized starch, chitosan, and sodium alginate. The types of cross-linking agents are epichlorohydrin, genipin, and Ca2+. 2+ The amount of cross-linking agent used is 0.8% to 1.2% of the volume of the polysaccharide solution; Step 3: Mix the cross-linked protein solution and the cross-linked polysaccharide solution at a certain volume ratio, then add a cross-linking agent to further chemically cross-link, forming a complex network structure. Stir at 20~25℃ and 500~600r / min for 20~30min to obtain a mixture. Then pour the mixture into a mold and place it in a low-temperature freezer for quick freezing for 12~24h. After freezing, use a freeze dryer at -60~-80℃ for 36~48h to obtain a biomass composite sponge. The volume ratio of the protein solution to the polysaccharide solution is (3~4)mL:(1~2)mL. The types of cross-linking agents are gallic acid, metal leather tanning agents, and acrylic acids. The amount of cross-linking agent is 1%~1.2% of the volume of the composite solution.

[0025] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0026] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0027] Example 1 A method for constructing biomass composite sponges based on the tanning principle includes the following steps: Step 1: Prepare a 6% silk fibroin solution. Then, take a certain amount of the silk fibroin solution and stir continuously at 70°C for 30 min (500 r / min). Within 1 min, slowly add the cross-linking agent transglutaminase (TG enzyme) to the above system (0.5%, v / v) for cross-linking. Then, incubate at 60°C for 20 min to obtain the cross-linked protein solution. Store the cross-linked protein solution in a 40°C water bath for later use. Step 2: Prepare a 4% sodium alginate solution. Stir continuously at 600 rpm for 60 minutes within a temperature range of 90°C until a homogeneous solution is formed. Then, adjust the pH of the system to 11 using a 0.1 mol / L NaOH solution. Subsequently, while stirring at 600 rpm, add Ca to the above solution. 2+ Chelating crosslinking (1.2%, v / v) was performed within 3 min, followed by incubation at 92 °C for 50 min to ensure the crosslinking reaction was fully carried out and the crosslinking process was completed, resulting in a crosslinked polysaccharide solution. Step 3: The cross-linked silk fibroin solution and the cross-linked sodium alginate solution were mixed at a volume ratio of 3 mL:2 mL, and the cross-linking agent acrylic acid was added. The mixture was stirred at 20°C for 20 min (600 r / min). The mixture was then poured into a mold and quick-frozen in a low-temperature freezer for 20 h. Finally, it was frozen at -60°C for 48 h using a freeze dryer to obtain sodium alginate / silk fibroin biomass composite sponge.

[0028] Example 2 A method for constructing biomass composite sponges based on the tanning principle includes the following steps: Step 1: Prepare a 4% gelatin solution. Then, take a certain amount of gelatin solution and stir continuously at 70°C for 30 min (500 r / min). Within 1 min, slowly add the cross-linking agent tannic acid (0.3%, v / v) to the above system for cross-linking. Then, incubate at 70°C for 30 min to obtain the cross-linked protein solution. Store the cross-linked protein solution in a 50°C water bath for later use. Step 2: Prepare a 4% oxidized starch suspension. Stir continuously at 500 r / min within a temperature range of 90℃ for 60 min until a homogeneous solution is formed. Then, adjust the pH of the system to 10 with 0.1 mol / L NaOH solution. Subsequently, add epichlorohydrin (1%, v / v) to the above solution while stirring at 500 r / min and crosslink within 5 min. Then, incubate at 92℃ for 40 min to complete the crosslinking process and obtain the crosslinked polysaccharide solution. Step 3: The cross-linked gelatin solution and the cross-linked oxidized starch solution were mixed at a volume ratio of 4 mL:2 mL, and gallic acid, a cross-linking agent, was added. The mixture was stirred at 20°C for 20 min (600 r / min). The mixture was then poured into a mold and quick-frozen in a low-temperature freezer for 24 h. Finally, it was frozen at -60°C for 48 h using a freeze dryer to obtain the oxidized starch / gelatin biomass composite sponge.

[0029] Example 3 A method for constructing biomass composite sponges based on the tanning principle includes the following steps: Step 1: Prepare a 5% casein solution. Then, take a certain amount of casein solution and stir continuously at 70°C for 25 min (600 r / min). Within 1 min, slowly add the cross-linking agent citric acid (0.4%, v / v) to the above system for cross-linking. Then, incubate at 68°C for 30 min to obtain the cross-linked protein solution. Store the cross-linked protein solution in a water bath at 45°C for later use. Step 2: Prepare a 4% chitosan solution. Stir continuously at 500 r / min within a temperature range of 90℃ for 60 min until a homogeneous solution is formed. Then, adjust the pH of the system to 9 with 0.1 mol / L NaOH solution. Subsequently, add genipin crosslinking agent (0.8%, v / v) to the above solution while stirring at 500 r / min and crosslink within 5 min. Then, incubate at 90℃ for 50 min to allow the crosslinking reaction to proceed fully and complete the crosslinking process to obtain the crosslinked polysaccharide solution. Step 3: The cross-linked casein solution and the cross-linked chitosan solution were mixed at a volume ratio of 3 mL:1 mL, and a cross-linking agent (metal leather tanning agent) was added. The mixture was stirred at 25°C for 25 min (600 r / min). The mixture was then poured into a mold and quick-frozen in a low-temperature freezer for 12 h. Finally, it was frozen at -80°C for 36 h using a freeze dryer to obtain a chitosan / casein biomass composite sponge.

[0030] Figure 1 (a) is a sodium alginate / silk fibroin composite sponge. Sodium alginate solution reacts with Ca... 2+(a) Metal ions form a white gel, thus the prepared composite sponge is white; (b) Oxidized starch / gelatin composite sponge, as shown in the figure, the prepared sponge is yellow, due to the Maillard reaction of gelatin and oxidized starch to produce yellow products, and the cross-linking reaction in the preparation process. The hydrolysis products of epichlorohydrin may react with the carboxyl groups of oxidized starch to produce pale yellow ester byproducts; (c) Chitosan / casein sponge, the sponge prepared by cross-linking chitosan and genipin is light yellow. Figure (d) SEM image of sodium alginate / silk fibroin sponge, (e) SEM image of oxidized starch / gelatin sponge and (f) SEM image of chitosan / casein sponge. The SEM images show that the three types of sponges prepared have a porous structure and can effectively adsorb microplastics.

[0031] Figure 2 (a) shows the adsorption of PS nanoplastics by the oxidized starch / gelatin composite sponge at different adsorption times. As time increases, the absorbance of the remaining solution gradually decreases, indicating that the composite sponge has a certain adsorption capacity for microplastics. (b) shows the fluorescence spectra of PS nanoplastics at different concentrations. PS nanoplastics have a characteristic fluorescence peak at 520 nm, and the intensity is linearly correlated with the concentration (25-500 mg / L).

[0032] This invention utilizes a biomass composite sponge prepared from a polysaccharide solution and a protein solution to replace traditional adsorbent materials such as activated carbon, biochar, and synthetic polymer sponges. Oxidized starch not only possesses excellent biocompatibility and biodegradability, but its abundant hydroxyl and carboxyl groups on its molecular chain significantly enhance the material's hydrophilicity, reactivity, and cross-linking ability. It exhibits better compatibility with biomass components such as gelatin, and through physical blending and cross-linking, a more stable bond structure can be formed to enhance the material's load-bearing stability. Furthermore, its introduction helps construct a rich porous network, further improving the composite sponge's water absorption, structural stability, and mechanical properties, laying a solid foundation for its application in fields such as microplastic remediation.

[0033] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for constructing biomass composite sponges based on the principle of tanning, characterized in that, Includes the following steps: S1: After stirring the protein solution, a cross-linking agent is added to cross-link the protein solution, followed by incubation to obtain a cross-linked protein solution. S2: After stirring the polysaccharide solution, a cross-linking agent is added to cross-link it, followed by incubation to obtain a cross-linked polysaccharide solution; S3: The cross-linked protein solution and the cross-linked polysaccharide solution are mixed to obtain a composite solution. A cross-linking agent is added to the composite solution for cross-linking, and then the mixture is stirred to obtain a mixture. The mixture is poured into a mold for freezing and freeze-drying to obtain a biomass composite sponge constructed based on the tanning principle.

2. The method for constructing biomass composite sponges based on the tanning principle according to claim 1, characterized in that, In S1, stirring is carried out at 60~70℃ for 30~50 min at a stirring speed of 500 r / min; the crosslinking agent is added under the temperature conditions of the above solution, and the addition time is controlled to be 1~3 min; the incubation is carried out at 60~70℃ for 30~50 min.

3. The method for constructing biomass composite sponges based on the tanning principle according to claim 1, characterized in that, In S1, the protein in the protein solution is one of gelatin, casein, and silk fibroin; the cross-linking agent is one of tannic acid, glyoxal, and transglutaminase.

4. The method for constructing biomass composite sponges based on the tanning principle according to claim 1, characterized in that, In S1, the mass-volume concentration of the protein solution is 2% to 6%; the volume of the protein solution is 90 to 120 mL; and the amount of the cross-linking agent is 0.2% to 0.5% of the volume of the protein solution.

5. A method for constructing biomass composite sponges based on the tanning principle according to claim 1, characterized in that, In S2, before stirring the polysaccharide solution, the polysaccharide solution was continuously stirred at 500 r / min within a temperature range of 92±2℃ and reacted for 60±5min. Then, the pH value was adjusted to 9~11 using NaOH solution. The polysaccharide solution was stirred at a speed of 500 r / min; the cross-linking was carried out at 90~92 ℃ for 5~8 min; the incubation temperature was 90~92 ℃ and the time was 40~60 min.

6. The method for constructing biomass composite sponges based on the tanning principle according to claim 1, characterized in that, In S3, the volume ratio of the cross-linked protein solution to the cross-linked polysaccharide solution is (3~4) mL: (1~2) mL.

7. The method for constructing biomass composite sponges based on the tanning principle according to claim 1, characterized in that, In S3, the crosslinking agent is gallic acid, metal leather tanning agent, or acrylic acid; the amount of the crosslinking agent is 1% to 1.2% of the volume of the composite solution; the stirring is carried out at 20 to 25°C and 500 to 600 r / min for 20 to 30 minutes.

8. A method for constructing biomass composite sponges based on the tanning principle according to claim 1, characterized in that, In S3, the freezing is carried out in a low-temperature refrigerator for 12 to 24 hours; the freeze-drying is carried out at -60 to -80°C for 36 to 48 hours.

9. A biomass composite sponge constructed based on the principle of tanning, characterized in that, It is prepared by the method described in any one of claims 1 to 8.

10. Application of a biomass composite sponge constructed based on the tanning principle in microplastic treatment or oil-water separation.

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