Marine coral reef ecological restoration method based on foamed aluminum base material

Abstract

The invention relates to the technical field of marine ecological engineering, in particular to a marine coral reef ecological restoration method based on a foamed aluminum base material, which comprises the following steps: preparing a modified foamed aluminum main body structure, constructing a modified bioactive surface layer, filling a modified phase change material capsule, and putting a restoration unit. According to the invention, the foamed aluminum main body structure provides a stable three-dimensional through porous network, and a natural reef habitat environment is simulated; a hydroxyapatite coating or a polymer layer constructed on the surface of the coral bone-imitating material remarkably improves the coral larva attachment and colonization efficiency through coral bone-imitating inorganic components or specific polypeptides respectively; the phase-change material capsules filled inside buffer water temperature fluctuation through phase-change latent heat, a stable micro-thermal environment is provided for coral growth, the functions of all the components are complementary and synergistic, foamed aluminum provides a carrier for surface functionalization, the surface active layer optimizes a biological interface, the internal temperature adjusting unit guarantees ecological suitability, and an efficient repairing system is formed. The coral reef ecological restoration effect is obviously improved.

Description

Technical Field

[0001] This invention relates to the field of marine ecological engineering technology, specifically to a method for the ecological restoration of marine coral reefs based on aluminum foam substrate. Background Technology

[0002] Coral reefs are among the most biodiverse ecosystems on Earth, but due to factors such as global climate change, ocean acidification, and human destruction, coral reefs worldwide are rapidly degrading. Artificial coral reef restoration is an important means of restoring coral ecosystems. Its core is to provide suitable attachment substrates for coral larvae and create living space for corals and reef organisms.

[0003] In the existing technology, the artificial reefs used in the field of marine coral reef ecological restoration have the following problems: insufficient biocompatibility of the material surface, which makes it difficult for corals to attach; single function, which lacks the ability to actively regulate the microenvironment of water temperature fluctuations and nutrient supply; and poor synergy between the components, which makes it difficult to build a stable symbiotic ecosystem.

[0004] Based on this, the present invention provides a method for ecological restoration of marine coral reefs based on aluminum foam substrate. Summary of the Invention

[0005] The purpose of this invention is to provide a method for ecological restoration of marine coral reefs based on aluminum foam substrate. The aluminum foam substrate prepared by this invention not only has high porosity and compressive strength, but also has a large number of fish aggregations, which is more beneficial to ecological restoration.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for marine coral reef ecological restoration based on aluminum foam substrate, comprising the following steps: S1: Prepare a modified aluminum foam main structure, which is made of open or semi-open aluminum foam and contains trace elements of iron and silicon that promote the formation of microbial films, forming an interconnected three-dimensional porous network. It is constructed into a three-dimensional geometry with at least one coral fixing surface and a fish fry attachment area. S2: Construct a modified bioactive surface layer on the surface of the modified aluminum foam main structure and the surface of the internal pores. This surface layer is a micro-nano hierarchical hydroxyapatite coating grown in situ on the surface of the aluminum foam by hydrothermal method, or a modified polymer layer loaded with coral-affinity peptides. S3: Modified phase change material capsules are filled in some pores inside the modified aluminum foam main structure, slow-release nutrient blocks are set on the main structure, and fish fry breeding substrate is placed in the fish fry attachment area to form a microenvironment regulation and fish fry breeding unit. S4: Fix the coral fragments to the slots or binding points of the modified aluminum foam main structure, release fish fry to the fry attachment area, and release the restoration unit to the target sea area through biodegradable connecting components to complete the ecological restoration of the coral reef.

[0007] Preferably, the preparation steps of the modified aluminum foam body structure are as follows: aluminum ingots are placed in a resistance furnace and heated until completely melted, modified titanium hydride foaming agent is added, and stirred to disperse it evenly; the molten mixture is quickly poured into a mold with a textured surface for attaching fish fry, and left to stand in an atmospheric environment, using residual heat to fully decompose and foam the titanium hydride, and then naturally cooled to room temperature; the cooled aluminum foam blank is mechanically processed to remove the dense outer layer, thereby obtaining the modified aluminum foam body structure.

[0008] Preferably, the amount of the modified titanium hydrogenation foaming agent added is 1.0-1.5% of the mass of the aluminum ingot.

[0009] Preferably, the preparation steps of the modified foaming agent are as follows: placing titanium hydride powder in a constant temperature drying oven and drying for 4-6 hours to completely remove physically adsorbed water; then preparing silica sol as a pre-oxidation medium, mixing the dried titanium hydride powder with silica sol, and mixing in a planetary ball mill for 1-2 hours to ensure that the titanium hydride particles are uniformly coated by silica sol; transferring the uniformly mixed slurry to an alumina crucible and placing it in a programmable temperature controlled muffle furnace, heating in an air atmosphere and holding at a constant temperature for 1-2 hours; after the holding time is completed, cooling to room temperature with the furnace, and then gently crushing the sintered block material and passing it through a 200-mesh standard sieve to obtain the surface-modified titanium hydride foaming agent powder.

[0010] Preferably, the silica sol has a mass fraction of 1-3%, and the sol is prepared by diluting silica sol with deionized water; the titanium hydride powder and silica sol are mixed at a mass ratio of 1:(1.5-2).

[0011] Preferably, the preparation steps of the hydrothermal in-situ grown micro / nano hierarchical hydroxyapatite coating are as follows: Calcium nitrate and disodium hydrogen phosphate are dissolved in deionized water at a molar ratio of Ca:P of 10:6 to prepare a solution with a total concentration of 0.1-0.2 mol / L, and the pH is adjusted to 9-10 with ammonia. The foamed aluminum main structure is ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water for 15-20 minutes each, and then dried. The cleaned foamed aluminum is placed in a polytetrafluoroethylene reactor, and the sample is completely immersed in the reaction solution and placed in an oven for 6-12 hours. After the reaction, the foamed aluminum is removed, rinsed with deionized water until neutral, and dried. Subsequently, an aqueous solution of ferric ammonium citrate and sodium silicate is impregnated into the porous structure of the hydroxyapatite coating using a vacuum impregnation method, and then dried again to achieve the loading of trace elements and obtain the hydroxyapatite coating.

[0012] Preferably, the preparation steps of the modified polymer layer are as follows: chitosan is dissolved in dilute acetic acid solution, sodium alginate is dissolved in deionized water solution, and the two solutions are mixed in equal volumes. Peptide is added and stirred evenly. The above mixed solution is coated on a designated area of ​​aluminum foam that has been modified with hydroxyapatite coating by repeated impregnation-coating or vacuum-assisted impregnation. Then, it is placed in calcium chloride solution for crosslinking and curing. The crosslinked aluminum foam is gently rinsed with deionized water and dried for 4-8 hours to obtain the modified polymer layer.

[0013] Preferably, the polypeptide is a biomimetic polypeptide containing the Arg-Gly-Asp sequence; the mass fraction of the dilute acetic acid solution is 1-2%, the mass concentration of the solution prepared with chitosan is 2-3%, and the mass concentration of the sodium alginate solution is 2-3%.

[0014] Preferably, the preparation steps of the modified phase change material capsule are as follows: Thermally conductive graphene nanosheets are mixed with molten docosane and then sheared at high speed for 30 minutes to achieve uniform dispersion, forming a thermally enhanced phase change core material; sodium alginate is dissolved in deionized water and stirred evenly to form solution A; chitosan is dissolved in an aqueous acetic acid solution and stirred evenly to form solution B; the thermally enhanced phase change core material is heated and kept in a molten state, then mixed with solution A, and emulsified using a high-speed homogenizer for 3-5 minutes to form an oil-in-water primary emulsion; subsequently, the primary emulsion is added dropwise to solution B using a dropper or injection device, forming a composite gel wall at the droplet interface, and allowed to stand for 1-2 hours to complete the curing reaction; the gel capsule is filtered out and transferred to a calcium chloride solution for secondary crosslinking for 30 minutes; after crosslinking, the surface salt of the capsule is washed with deionized water, and finally vacuum dried for 6-12 hours to obtain the modified phase change material capsule.

[0015] Preferably, the thermally conductive graphene nanosheets have a mass fraction of 5-10%; the sodium alginate has a mass fraction of 2-4%, the chitosan has a mass fraction of 1-2%, and the acetic acid aqueous solution has a mass fraction of 1%; the volume ratio of the thermally conductive enhanced phase change core material to solution A is 1:3; and the calcium chloride solution has a mass fraction of 2-5%.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, the three-dimensional porous network of the modified aluminum foam main structure not only provides corals and fish fry with a huge specific surface area and complex physical habitat, but also serves as an excellent carrier, successfully loading trace elements such as iron and silicon. These trace elements work synergistically with the bioactive coating constructed on the surface to effectively promote the early colonization and rapid formation of microbial films, laying a solid ecological foundation for coral larvae attachment and fish aggregation, thereby transforming the traditional inert reef into a biologically active ecological cornerstone.

[0017] 2. In this invention, the modified polymer layer loaded with coral-affinity peptides provides coral larvae with active, high-affinity biochemical recognition signals through its specific peptide sequences, greatly improving the directional attachment efficiency of corals. At the same time, the polymer layer is firmly bonded to the modified aluminum foam body structure, and the huge specific surface area of ​​aluminum foam expands the range of its biological activity. The two work synergistically to enhance physical anchoring and biological induction, solving the problem of insufficient biocompatibility of traditional materials.

[0018] 3. In this invention, modified phase change material capsules absorb or release latent heat through a phase change process, which can effectively buffer diurnal and seasonal water temperature fluctuations in the marine environment, providing a crucial stable microthermal environment for temperature-sensitive corals. These capsules are filled in the internal pores of the foam aluminum main structure. The excellent thermal conductivity of the foam aluminum ensures rapid heat transfer and uniform distribution. The two work synergistically in thermal management to jointly construct an intelligent and efficient temperature buffer unit, which significantly improves the survival rate of corals under heat stress. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application are described clearly and completely.

[0021] Example 1: A method for ecological restoration of marine coral reefs based on aluminum foam substrate, comprising the following steps: S1: Prepare a modified aluminum foam main structure, which is made of open or semi-open aluminum foam and contains trace elements of iron and silicon that promote the formation of microbial films, forming an interconnected three-dimensional porous network. It is constructed into a three-dimensional geometry with at least one coral fixing surface and a fish fry attachment area. S2: Construct a modified bioactive surface layer on the surface of the modified aluminum foam main structure and the surface of the internal pores. This surface layer is a micro-nano hierarchical hydroxyapatite coating grown in situ on the surface of the aluminum foam by hydrothermal method, or a modified polymer layer loaded with coral-affinity peptides. S3: Modified phase change material capsules are filled in some pores inside the modified aluminum foam main structure, slow-release nutrient blocks are set on the main structure, and fish fry breeding substrate is placed in the fish fry attachment area to form a microenvironment regulation and fish fry breeding unit. S4: Fix the coral fragments to the slots or binding points of the modified aluminum foam main structure, release fish fry to the fry attachment area, and release the restoration unit to the target sea area through biodegradable connecting components to complete the ecological restoration of the coral reef.

[0022] The preparation steps of the modified aluminum foam body structure are as follows: aluminum ingots are placed in a resistance furnace and heated to 750°C until completely melted. Modified titanium hydride foaming agent is added and stirred at 300 rpm for 5 minutes to disperse it evenly. The molten mixture is quickly poured into a mold preheated to 200°C with a textured surface for attaching fish fry. The mold is then left to stand in an atmospheric environment, allowing the residual heat to fully decompose and foam the titanium hydride. The mixture is then allowed to cool naturally to room temperature. The cooled aluminum foam blank is then machined to remove the dense outer layer, resulting in a modified aluminum foam body structure with a density of 0.2 g / cm³ and an average pore size of 3 mm.

[0023] The amount of modified titanium hydride foaming agent added is 1.0% of the mass of aluminum ingot.

[0024] The preparation steps of the modified foaming agent are as follows: Select industrial-grade titanium hydride powder with an average particle size of 50μm, dry it in a constant temperature drying oven at 60℃ for 4h to completely remove physically adsorbed water; then prepare silica sol as a pre-oxidation medium, mix the dried titanium hydride powder with silica sol, and mix the mixture at a low speed of 200rpm for 1h in a planetary ball mill to ensure that the titanium hydride particles are uniformly coated by silica sol; transfer the uniformly mixed slurry to an alumina crucible and place it in a programmable temperature controlled muffle furnace, heat it to 450℃ at a heating rate of 3℃ / min in an air atmosphere, and hold it at this temperature for 1h; after the holding period, cool it to room temperature with the furnace, and then gently crush the sintered block material and pass it through a 200-mesh standard sieve to obtain the surface-modified titanium hydride foaming agent powder.

[0025] The silica sol has a mass fraction of 1%, and the sol is made by diluting silica sol with deionized water; titanium hydride powder and silica sol are mixed at a mass ratio of 1:1.5.

[0026] The preparation steps of the hydrothermal in-situ grown micro / nano hierarchical hydroxyapatite coating are as follows: Calcium nitrate and disodium hydrogen phosphate are dissolved in deionized water at a molar ratio of Ca:P of 10:6 to prepare a solution with a total concentration of 0.1 mol / L. The pH is adjusted to 9 with ammonia. The aluminum foam substrate is ultrasonically cleaned for 15 min each in acetone, anhydrous ethanol, and deionized water, and then dried. The cleaned aluminum foam is placed in a polytetrafluoroethylene reactor, and the sample is completely immersed in the reaction solution. The reactor is then placed in an oven at 120℃ for 6 h. After the reaction, the aluminum foam is removed, rinsed with deionized water until neutral, and dried at 80℃. Subsequently, an aqueous solution of ferric ammonium citrate and sodium silicate is impregnated into the porous structure of the hydroxyapatite coating using a vacuum impregnation method. The coating is dried again to achieve the loading of trace elements and obtain the hydroxyapatite coating.

[0027] The preparation steps of the modified polymer layer are as follows: Chitosan is dissolved in dilute acetic acid solution, sodium alginate is dissolved in deionized water solution, and the two solutions are mixed in equal volumes. Peptide is added and stirred evenly. The above mixed solution is coated on the designated area of ​​aluminum foam that has been modified with hydroxyapatite coating by repeated impregnation-coating or vacuum-assisted impregnation method. Then it is placed in calcium chloride solution for crosslinking and curing for 5 min. The crosslinked aluminum foam is gently rinsed with deionized water and dried at 40℃ for 4 h to form a water-based gel layer with excellent biocompatibility, thus obtaining the modified polymer layer.

[0028] The polypeptide is a biomimetic polypeptide containing the Arg-Gly-Asp sequence; the mass fraction of the dilute acetic acid solution is 1%, the mass concentration of the solution prepared with chitosan is 2%, and the mass concentration of the sodium alginate solution is 2%.

[0029] Thermally conductive graphene nanosheets were mixed with molten docosane at 60°C and sheared at 1000 rpm for 30 minutes to achieve uniform dispersion, forming a thermally enhanced phase change core material. Sodium alginate was dissolved in deionized water and stirred until homogeneous, designated as solution A. Chitosan was dissolved in an aqueous acetic acid solution and stirred until homogeneous, designated as solution B. The thermally enhanced phase change core material was heated to 40°C and kept in a molten state, then mixed with solution A. The mixture was emulsified using a high-speed homogenizer at 8000 rpm for 3 minutes to form an oil-in-water primary emulsion. The primary emulsion was then added dropwise to solution B using a dropper or injection device. Sodium ions on the surface of the sodium alginate droplets underwent ion exchange and polyelectrolyte deposition with hydrogen ions and chitosan molecules in solution B, immediately forming a composite gel wall at the droplet interface. The gel was allowed to stand for 1 hour to complete the curing reaction. The gel capsules were filtered out and transferred to a calcium chloride solution for secondary cross-linking for 30 minutes. Calcium ions (Ca... 2+It can form a more stable "egg box" structure with the carboxyl groups on the sodium alginate molecular chain, significantly enhancing the mechanical strength and long-term stability of the capsule wall and preventing it from breaking under seawater pressure. After cross-linking, the salt on the capsule surface is washed with deionized water, and finally vacuum dried at 40°C for 6 hours to obtain solid spherical modified phase change material capsules with a particle size of 1 mm.

[0030] The thermally conductive graphene nanosheets have a mass fraction of 5%; sodium alginate has a mass fraction of 2%; chitosan has a mass fraction of 1%; and the aqueous acetic acid solution has a mass fraction of 1%. The volume ratio of the thermally conductive enhanced phase change core material to solution A is 1:3; and the calcium chloride solution has a mass fraction of 2%.

[0031] Example 2: A method for ecological restoration of marine coral reefs based on aluminum foam substrate, comprising the following steps: S1: Prepare a modified aluminum foam main structure, which is made of open or semi-open aluminum foam and contains trace elements of iron and silicon that promote the formation of microbial films, forming an interconnected three-dimensional porous network. It is constructed into a three-dimensional geometry with at least one coral fixing surface and a fish fry attachment area. S2: Construct a modified bioactive surface layer on the surface of the modified aluminum foam main structure and the surface of the internal pores. This surface layer is a micro-nano hierarchical hydroxyapatite coating grown in situ on the surface of the aluminum foam by hydrothermal method, or a modified polymer layer loaded with coral-affinity peptides. S3: Modified phase change material capsules are filled in some pores inside the modified aluminum foam main structure, slow-release nutrient blocks are set on the main structure, and fish fry breeding substrate is placed in the fish fry attachment area to form a microenvironment regulation and fish fry breeding unit. S4: Fix the coral fragments to the slots or binding points of the modified aluminum foam main structure, release fish fry to the fry attachment area, and release the restoration unit to the target sea area through biodegradable connecting components to complete the ecological restoration of the coral reef.

[0032] The preparation steps of the modified aluminum foam body structure are as follows: aluminum ingots are placed in a resistance furnace and heated to 775℃ until completely melted. Modified titanium hydride foaming agent is added and stirred at 400 rpm for 7 minutes to disperse it evenly. The molten mixture is quickly poured into a mold preheated to 225℃ with a textured surface for attaching fish fry. The mold is then left to stand in an atmospheric environment, and the residual heat is used to fully decompose and foam the titanium hydride. The mixture is then allowed to cool naturally to room temperature. The cooled aluminum foam blank is then machined to remove the dense outer layer, resulting in a modified aluminum foam body structure with a density of 0.4 g / cm³ and an average pore size of 4 mm.

[0033] The amount of modified titanium hydride foaming agent added is 1.2% of the mass of aluminum ingot.

[0034] The preparation steps of the modified foaming agent are as follows: Industrial-grade titanium hydride powder with an average particle size of 75μm is selected and dried in a constant temperature drying oven at 60℃ for 5h to completely remove physically adsorbed water; then, silica sol is prepared as a pre-oxidation medium, and the dried titanium hydride powder is mixed with silica sol and mixed at a low speed of 250rpm for 1.5h in a planetary ball mill to ensure that the titanium hydride particles are uniformly coated by silica sol; the uniformly mixed slurry is transferred to an alumina crucible and placed in a programmable temperature controlled muffle furnace, heated to 500℃ at a heating rate of 4℃ / min in an air atmosphere, and held at this temperature for 1.5h; after the holding period, the furnace is cooled to room temperature, and the sintered block material is gently crushed and passed through a 200-mesh standard sieve to obtain the surface-modified titanium hydride foaming agent powder.

[0035] The silica sol has a mass fraction of 2%, and the sol is made by diluting silica sol with deionized water; titanium hydride powder and silica sol are mixed at a mass ratio of 1:1.8.

[0036] The preparation steps of the hydrothermal in-situ grown micro / nano hierarchical hydroxyapatite coating are as follows: Calcium nitrate and disodium hydrogen phosphate are dissolved in deionized water at a molar ratio of Ca:P of 10:6 to prepare a solution with a total concentration of 0.15 mol / L. The pH is adjusted to 9.5 with ammonia. The aluminum foam substrate is ultrasonically cleaned for 17 min each in acetone, anhydrous ethanol, and deionized water, and then dried. The cleaned aluminum foam is placed in a polytetrafluoroethylene reactor, and the sample is completely immersed in the reaction solution. The reactor is then placed in an oven at 130℃ for 9 h. After the reaction, the aluminum foam is removed, rinsed with deionized water until neutral, and dried at 90℃. Subsequently, an aqueous solution of ferric ammonium citrate and sodium silicate is impregnated into the porous structure of the hydroxyapatite coating using a vacuum impregnation method. The coating is dried again to achieve the loading of trace elements and obtain the hydroxyapatite coating.

[0037] The preparation steps of the modified polymer layer are as follows: Chitosan is dissolved in dilute acetic acid solution, sodium alginate is dissolved in deionized water solution, and the two solutions are mixed in equal volumes. Peptide is added and stirred evenly. The above mixed solution is coated on the designated area of ​​aluminum foam that has been modified with hydroxyapatite coating by repeated impregnation-coating or vacuum-assisted impregnation method. Then, it is placed in calcium chloride solution for crosslinking and curing for 7 min. The crosslinked aluminum foam is gently rinsed with deionized water and dried at 50°C for 6 h to form a water-based gel layer with excellent biocompatibility, thus obtaining the modified polymer layer.

[0038] The polypeptide is a biomimetic polypeptide containing the Arg-Gly-Asp sequence; the mass fraction of the dilute acetic acid solution is 1.5%, the mass concentration of the solution prepared with chitosan is 2.5%, and the mass concentration of the sodium alginate solution is 2.5%.

[0039] Thermally conductive graphene nanosheets were mixed with molten docosane at 60°C and sheared at 1250 rpm for 30 minutes to achieve uniform dispersion, forming a thermally enhanced phase change core material. Sodium alginate was dissolved in deionized water and stirred until homogeneous, designated as solution A. Chitosan was dissolved in an aqueous acetic acid solution and stirred until homogeneous, designated as solution B. The thermally enhanced phase change core material was heated to 40°C and kept in a molten state, then mixed with solution A. The mixture was emulsified using a high-speed homogenizer at 9000 rpm for 4 minutes to form an oil-in-water primary emulsion. The primary emulsion was then added dropwise to solution B using a dropper or injection device. Sodium ions on the surface of the sodium alginate droplets underwent ion exchange and polyelectrolyte deposition with hydrogen ions and chitosan molecules in solution B, immediately forming a composite gel wall at the droplet interface. The solidification reaction was completed after standing for 1.5 hours. The gel capsules were filtered out and transferred to a calcium chloride solution for secondary cross-linking for 30 minutes. Calcium ions (Ca... 2+ It can form a more stable "egg box" structure with the carboxyl groups on the sodium alginate molecular chain, significantly enhancing the mechanical strength and long-term stability of the capsule wall and preventing it from breaking under seawater pressure. After cross-linking, the salt on the capsule surface is washed with deionized water, and finally vacuum dried at 40°C for 9 hours to obtain solid spherical modified phase change material capsules with a particle size of 2 mm.

[0040] The thermally conductive graphene nanosheets have a mass fraction of 7.5%; sodium alginate has a mass fraction of 3%, chitosan has a mass fraction of 1.5%, and acetic acid aqueous solution has a mass fraction of 1%; the volume ratio of the thermally conductive enhanced phase change core material to solution A is 1:3; and the calcium chloride solution has a mass fraction of 3.5%.

[0041] Example 3: A method for ecological restoration of marine coral reefs based on aluminum foam substrate, comprising the following steps: S1: Prepare a modified aluminum foam main structure, which is made of open or semi-open aluminum foam and contains trace elements of iron and silicon that promote the formation of microbial films, forming an interconnected three-dimensional porous network. It is constructed into a three-dimensional geometry with at least one coral fixing surface and a fish fry attachment area. S2: Construct a modified bioactive surface layer on the surface of the modified aluminum foam main structure and the surface of the internal pores. This surface layer is a micro-nano hierarchical hydroxyapatite coating grown in situ on the surface of the aluminum foam by hydrothermal method, or a modified polymer layer loaded with coral-affinity peptides. S3: Modified phase change material capsules are filled in some pores inside the modified aluminum foam main structure, slow-release nutrient blocks are set on the main structure, and fish fry breeding substrate is placed in the fish fry attachment area to form a microenvironment regulation and fish fry breeding unit. S4: Fix the coral fragments to the slots or binding points of the modified aluminum foam main structure, release fish fry to the fry attachment area, and release the restoration unit to the target sea area through biodegradable connecting components to complete the ecological restoration of the coral reef.

[0042] The preparation steps of the modified aluminum foam body structure are as follows: aluminum ingots are placed in a resistance furnace and heated to 800℃ until completely melted. Modified titanium hydride foaming agent is added and stirred at 500rpm for 10min to disperse it evenly. The molten mixture is quickly poured into a mold preheated to 250℃ with a textured surface for attaching fish fry. The mold is then left to stand in an atmospheric environment, and the residual heat is used to fully decompose and foam the titanium hydride. The mixture is then allowed to cool naturally to room temperature. The cooled aluminum foam blank is then machined to remove the dense outer layer, resulting in a modified aluminum foam body structure with a density of 0.6g / cm³ and an average pore size of 5mm.

[0043] The amount of modified titanium hydride foaming agent added is 1.5% of the mass of aluminum ingot.

[0044] The preparation steps of the modified foaming agent are as follows: Select industrial-grade titanium hydride powder with an average particle size of 100μm, dry it in a constant temperature drying oven at 60℃ for 6h to completely remove physically adsorbed water; then prepare silica sol as a pre-oxidation medium, mix the dried titanium hydride powder with silica sol, and mix the mixture at a low speed of 300rpm for 2h in a planetary ball mill to ensure that the titanium hydride particles are uniformly coated by silica sol; transfer the uniformly mixed slurry to an alumina crucible and place it in a programmable temperature controlled muffle furnace, heat it to 550℃ at a heating rate of 5℃ / min in an air atmosphere, and hold it at this temperature for 2h; after the holding period, cool it to room temperature with the furnace, and then gently crush the sintered block material and pass it through a 200-mesh standard sieve to obtain the surface-modified titanium hydride foaming agent powder.

[0045] The silica sol has a mass fraction of 3%, and the sol is made by diluting silica sol with deionized water; titanium hydride powder and silica sol are mixed at a mass ratio of 1:2.

[0046] The preparation steps of the hydrothermal in-situ grown micro / nano hierarchical hydroxyapatite coating are as follows: Calcium nitrate and disodium hydrogen phosphate are dissolved in deionized water at a molar ratio of Ca:P of 10:6 to prepare a solution with a total concentration of 0.2 mol / L. The pH is adjusted to 10 with ammonia. The aluminum foam substrate is ultrasonically cleaned for 20 min each in acetone, anhydrous ethanol, and deionized water, and then dried. The cleaned aluminum foam is placed in a polytetrafluoroethylene reactor, and the sample is completely immersed in the reaction solution. The reactor is then placed in an oven at 140℃ for 12 h. After the reaction, the aluminum foam is removed, rinsed with deionized water until neutral, and dried at 100℃. Subsequently, an aqueous solution of ferric ammonium citrate and sodium silicate is impregnated into the porous structure of the hydroxyapatite coating using a vacuum impregnation method. The coating is dried again to achieve the loading of trace elements, thus obtaining the hydroxyapatite coating.

[0047] The preparation steps of the modified polymer layer are as follows: Chitosan is dissolved in dilute acetic acid solution, sodium alginate is dissolved in deionized water solution, and the two solutions are mixed in equal volumes. Peptide is added and stirred evenly. The above mixed solution is coated on the designated area of ​​aluminum foam that has been modified with hydroxyapatite coating by repeated impregnation-coating or vacuum-assisted impregnation method. Then it is placed in calcium chloride solution for crosslinking and curing for 10 min. The crosslinked aluminum foam is gently rinsed with deionized water and dried at 60℃ for 8 h to form a water-based gel layer with excellent biocompatibility, thus obtaining the modified polymer layer.

[0048] The polypeptide is a biomimetic polypeptide containing the Arg-Gly-Asp sequence; the mass fraction of the dilute acetic acid solution is 2%, the mass concentration of the solution prepared with chitosan is 3%, and the mass concentration of the sodium alginate solution is 3%.

[0049] Thermally conductive graphene nanosheets were mixed with molten docosane at 60°C and sheared at 1500 rpm for 30 minutes to achieve uniform dispersion, forming a thermally enhanced phase change core material. Sodium alginate was dissolved in deionized water and stirred until homogeneous, designated as solution A. Chitosan was dissolved in an aqueous acetic acid solution and stirred until homogeneous, designated as solution B. The thermally enhanced phase change core material was heated to 40°C and kept in a molten state, then mixed with solution A. The mixture was emulsified using a high-speed homogenizer at 10000 rpm for 5 minutes to form an oil-in-water primary emulsion. The primary emulsion was then added dropwise to solution B using a dropper or injection device. Sodium ions on the surface of the sodium alginate droplets underwent ion exchange and polyelectrolyte deposition with hydrogen ions and chitosan molecules in solution B, immediately forming a composite gel wall at the droplet interface. The mixture was allowed to stand for 2 hours to complete the curing reaction. The gel capsules were filtered out and transferred to a calcium chloride solution for secondary cross-linking for 30 minutes. Calcium ions (Ca... 2+It can form a more stable "egg box" structure with the carboxyl groups on the sodium alginate molecular chain, significantly enhancing the mechanical strength and long-term stability of the capsule wall and preventing rupture under seawater pressure. After cross-linking, the salt on the capsule surface is washed with deionized water, and finally vacuum dried at 40°C for 12 hours to obtain solid spherical modified phase change material capsules with a particle size of 3 mm.

[0050] The thermally conductive graphene nanosheets have a mass fraction of 10%; sodium alginate has a mass fraction of 4%; chitosan has a mass fraction of 2%; and acetic acid aqueous solution has a mass fraction of 1%. The volume ratio of the thermally conductive enhanced phase change core material to solution A is 1:3; and the calcium chloride solution has a mass fraction of 5%.

[0051] Comparative Example 1: The difference between this comparative example and Example 1 is that commercially available titanium hydride foaming agent was used when preparing the aluminum foam body structure in this comparative example.

[0052] Comparative Example 2 differs from Example 1 in that the modified bioactive surface layer in this comparative example is the original aluminum foam surface without any functional coating treatment.

[0053] Comparative Example 3 differs from Example 1 in that commercially available ordinary paraffin phase change microcapsules are used in this comparative example.

[0054] Performance testing: Performance tests were conducted on the aluminum composite panels prepared in Examples 1, 2, 3, Comparative Examples 1, 2, and 3. Porosity test: Weigh the dry sample to obtain its dry weight, then impregnate it under vacuum to fully saturate the pores with water, and then weigh its apparent weight in water and its wet weight in the saturated state respectively; finally, by calculating the ratio of the difference between the saturated wet weight and the dry weight to the difference between the saturated wet weight and the apparent weight, the open pores of the sample can be accurately determined. Test standard: GB / T5164-2022. Compressive strength test: First, prepare a cubic or cylindrical specimen of specified size, ensuring that the compression surface is flat and parallel; then, align the specimen and install it between the pressure plates of the testing machine, and compress it at a constant displacement rate, while simultaneously recording the load-displacement curve; finally, based on the generated stress-strain curve, take the average stress between 20% and 40% of the specimen strain as the compressive strength of the aluminum foam, according to GB / T 7314-2017. Fish aggregation test: An underwater camera system was deployed in the designated sea area where the restoration unit was deployed. Fixed-point observations were conducted for 7 consecutive days at 1, 3 and 6 months after deployment, with 1 hour of video recorded each day at dawn, noon and dusk. Subsequently, through professional analysis, the maximum instantaneous number of fish appearing around the restoration unit at the same time in each video was counted. Finally, the average value of the data from all observation periods was taken as the fish aggregation number (tails / unit) of that unit. Test standard: GB 17378-2007.

[0055] The obtained test data are recorded in Table 1 below:

[0056] By comparing and analyzing the relevant data in Table 1, it can be seen that the foamed aluminum substrate prepared by the marine coral reef ecological restoration method based on foamed aluminum substrate of the present invention not only has high porosity and compressive strength, but also a large number of fish aggregations, which is more beneficial to ecological restoration. This indicates that the marine coral reef ecological restoration method based on foamed aluminum substrate provided by the present invention has a broader market prospect and is more suitable for promotion.

[0057] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for marine coral reef ecological restoration based on a foamed aluminum substrate, characterized in that, The method comprises the following steps: S1: preparing a modified aluminum foam main structure, which is made of open-cell or semi-open-cell aluminum foam, internally mixed with iron and silicon trace elements for promoting the formation of microbial films, forms a three-dimensional porous network penetrating each other, and is configured to have a three-dimensional geometric shape with at least one coral fixing surface and a fish fry attachment area; S2: constructing a modified bioactive surface layer on the surface and internal pore surface of the modified aluminum foam main structure, which is a micro-nano hierarchical hydroxyapatite coating grown in situ on the surface of the aluminum foam by a hydrothermal method, or a modified polymer layer loaded with coral affinity polypeptides; S3: filling modified phase change material capsules in part of the pores of the modified aluminum foam main structure, setting slow-release nutrient blocks on the main structure, and placing fish fry breeding substrate in the fish fry attachment area to form a microenvironment regulation and fish fry breeding unit; S4: fixing the coral broken branches on the clamping grooves or binding points of the modified aluminum foam main structure, placing fish fry in the fish fry attachment area, and placing the repair unit into the target sea area through the degradable connecting member to complete the coral reef ecological restoration.

2. The method for marine coral reef ecological restoration based on the aluminum foam substrate according to claim 1, characterized in that, The preparation steps of the modified aluminum foam main structure are as follows: an aluminum ingot is heated to complete melting in a resistance furnace, a modified titanium hydride foaming agent is added, and stirring is performed to uniformly disperse the foaming agent; the molten mixture is quickly poured into a mold with a fish fry attachment area concave-convex texture, and is left to stand in an atmospheric environment, the titanium hydride is fully decomposed and foamed by using residual heat, and is naturally cooled to room temperature; the cooled aluminum foam blank is mechanically processed to remove the skin dense layer, and the modified aluminum foam main structure is obtained.

3. The method for marine coral reef ecological restoration based on the aluminum foam substrate according to claim 2, characterized in that: The addition amount of the modified titanium hydride foaming agent is 1.0-1.5% of the mass of the aluminum ingot.

4. The method for marine coral reef ecological restoration based on the aluminum foam substrate according to claim 2, characterized in that, The preparation steps of the modified foaming agent are as follows: titanium hydride powder is dried in a constant-temperature drying box for 4-6h to completely remove physically adsorbed water; silica sol is prepared as a pre-oxidation medium, the dried titanium hydride powder is mixed with the silica sol, and the mixture is mixed in a planetary ball mill for 1-2h to ensure that the titanium hydride particles are uniformly coated with the silica sol; the uniformly mixed slurry is transferred to an alumina crucible, and is placed in a program-controlled muffle furnace, heated and kept at a constant temperature for 1-2h in an air atmosphere; after the heat preservation is completed, the furnace is cooled to room temperature, the sintered block material is gently broken, and then is passed through a 200-mesh standard sieve to obtain the surface-modified titanium hydride foaming agent powder.

5. The method for marine coral reef ecological restoration based on the aluminum foam substrate according to claim 4, characterized in that: The mass fraction of the silica sol is 1-3%, and the sol is prepared by diluting a silica sol with deionized water; the titanium hydride powder and the silica sol are mixed in a mass ratio of 1:(1.5-2).

6. The method for marine coral reef ecological restoration based on the aluminum foam substrate according to claim 1, characterized in that, The preparation steps of the hydrothermal method in-situ growth of micro-nano hierarchical hydroxyapatite coating are as follows: dissolving calcium nitrate and disodium hydrogen phosphate in deionized water to prepare a solution with a total concentration of 0.1-0.2 mol / L, and adjusting the pH to 9-10 with ammonia water; sequentially ultrasonic cleaning the foam aluminum main structure in acetone, anhydrous ethanol and deionized water for 15-20 min, and drying; placing the cleaned foam aluminum into a polytetrafluoroethylene reaction kettle, pouring the reaction solution to completely immerse the sample, and placing in an oven for 6-12 h; taking out the foam aluminum after reaction, washing with deionized water until neutral, and drying, then using a vacuum immersion method to immerse an aqueous solution of ferric ammonium citrate and sodium silicate into the porous structure of the hydroxyapatite coating, and drying again to load trace elements, thereby obtaining the hydroxyapatite coating.

7. The method for marine coral reef ecological restoration based on the aluminum foam substrate according to claim 1, characterized in that, The preparation steps of the modified polymer layer are as follows: dissolving chitosan in a dilute acetic acid solution, dissolving sodium alginate in a deionized water solution, mixing the two solutions in equal volumes, adding polypeptides and stirring uniformly; using a repeated immersion-drawing method or a vacuum assisted immersion method to coat the above mixed solution on the designated area of the foam aluminum with a completed hydroxyapatite coating modification, and then placing it in a calcium chloride solution for crosslinking and solidification; gently rinsing the crosslinked foam aluminum with deionized water and drying for 4-8 h to obtain the modified polymer layer.

8. The method for marine coral reef ecological restoration based on the aluminum foam substrate according to claim 7, characterized in that, The polypeptide is a biomimetic polypeptide containing an Arg-Gly-Asp sequence; the mass fraction of the dilute acetic acid solution is 1-2%, and the mass concentration of the chitosan solution is 2-3%; the mass concentration of the sodium alginate solution is 2-3%.

9. The method for marine coral reef ecological restoration based on the aluminum foam substrate according to claim 1, characterized in that, The preparation steps of the modified phase change material capsule are as follows: mixing heat-conducting graphene nanosheets with molten docosane and high-speed shearing for 30 min to uniformly disperse, thereby forming a heat-conducting enhanced phase change core material; dissolving sodium alginate in deionized water and stirring uniformly as solution A, and dissolving chitosan in an acetic acid aqueous solution and stirring uniformly as solution B; heating the heat-conducting enhanced phase change core material to keep it in a molten state, then mixing it with solution A, using a high-speed homogenizer to emulsify for 3-5 min to form an oil-in-water primary emulsion, then using a dropping or injection device to drop the primary emulsion into solution B drop by drop, forming a composite gel wall at the droplet interface, and standing for 1-2 h to complete the solidification reaction; filtering out the gel capsule and transferring it to a calcium chloride solution for secondary crosslinking for 30 min; after crosslinking is completed, washing the capsule surface salt with deionized water, and finally vacuum drying for 6-12 h to obtain the modified phase change material capsule.

10. The method for marine coral reef ecological restoration based on the aluminum foam substrate according to claim 9, characterized in that: The mass fraction of the heat-conducting graphene nanosheet is 5-10%; the mass fraction of the sodium alginate is 2-4%, the mass fraction of the chitosan is 1-2%, and the mass fraction of the acetic acid aqueous solution is 1%; the volume ratio of the heat-conducting enhanced phase change core material to solution A is 1:3; and the mass fraction of the calcium chloride solution is 2-5%.

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