Catalytic adsorption bovine collagen-based porous gel material and preparation method thereof

Abstract

This invention belongs to the field of composite material technology, and particularly relates to a porous gel material based on bovine collagen for the catalytic adsorption of low-concentration radionuclide resources in seawater, and its preparation method. The porous gel material comprises: bovine collagen powder, graphene oxide, montmorillonite, and a zirconium-based metal-organic framework; the porous gel material has a three-dimensional porous network structure with a pore size distribution of 80–800 nm and a specific surface area ≥300 m². 2 / g, porosity ≥75%. The preparation method includes preparing dispersions of montmorillonite, graphene oxide, bovine collagen solution, and zirconium-based metal-organic framework material; obtaining a composite precursor solution and an initial gel through crosslinking and dispersing agents; and then subjecting the initial gel to freeze-thaw cycles and vacuum freeze-drying. The target product of this invention possesses high adsorption capacity, excellent catalytic activity, good mechanical stability, and good dispersibility.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, and particularly relates to a porous gel material based on bovine collagen for the catalytic adsorption of low-concentration radionuclide resources in seawater and its preparation method. Background Technology

[0002] The Bohai Sea contains abundant low-concentration radionuclide resources (such as uranium, thorium, and neptunium), with uranium reserves of approximately 4.5 billion tons, thousands of times greater than terrestrial uranium reserves. Achieving efficient enrichment and recovery of these radionuclides is crucial for ensuring a sustainable supply of nuclear energy. Simultaneously, scenarios such as thermal discharge from nuclear power plants and nearshore radioactive pollution necessitate precise control of low-concentration radionuclides in the Bohai Sea, addressing both resource utilization and environmental safety needs. Currently, the recovery technologies for low-concentration radionuclides in seawater mainly rely on adsorption, extraction, and membrane separation methods. Among these, adsorption has become the mainstream technology due to its ease of operation, low cost, and environmental friendliness, with the core being the development of high-performance adsorption materials. However, traditional adsorption materials such as activated carbon, ion exchange resins, montmorillonite-like natural minerals, and polymer gels generally suffer from low adsorption capacity, poor selectivity, and insufficient mechanical stability. Under long-term immersion in seawater, excessive swelling can cause the porous structure to collapse, leading to decreased adsorption performance and insufficient adsorption efficiency.

[0003] Metal-organic frameworks (MOFs) exhibit great potential in the field of nuclide adsorption due to their ultra-high specific surface area, tunable pore structure, and abundant active sites. Among them, the UiO series zirconium-based MOFs possess excellent chemical stability (withstanding complex environments such as acids, alkalis, and seawater) thanks to the strong coordination between zirconium nodes and ligands. Furthermore, functional group modifications (such as amino and carboxyl groups) can significantly enhance their coordination adsorption capacity for nuclides. They also possess certain catalytic activity, promoting nuclide valence state conversion to improve recovery efficiency. However, when used alone, the UiO series zirconium-based MOFs suffer from poor mechanical properties, easy pulverization, and poor dispersibility in water, leading to difficulties in solid-liquid separation and hindering their direct application in continuous seawater treatment scenarios. To address these application bottlenecks, researchers have attempted to combine the UiO series zirconium-based MOFs with carrier materials. Graphene oxide (GO) serves as an excellent dispersion and support due to its high specific surface area, good conductivity, and abundant oxygen-containing functional groups. Montmorillonite (MMT), on the other hand, possesses a layered porous structure, low cost, and good mechanical reinforcement. The gel system formed by the combination of the two can construct a three-dimensional porous network, providing a good substrate for loading UiO series zirconium-based metal-organic frameworks. However, existing GO / MMT gel supports suffer from insufficient active sites and poor control over the dispersibility of UiO series zirconium-based metal-organic frameworks. Furthermore, they have not achieved a synergistic effect between the catalytic performance of UiO series zirconium-based metal-organic frameworks and the adsorption performance of the support. Most composite systems simply add adsorption functions without utilizing the catalytic activity of UiO series zirconium-based metal-organic frameworks to achieve integrated "adsorption-conversion" of radionuclides, resulting in the need to improve radionuclide recovery efficiency and selectivity. To this end, this patent proposes to further optimize the internal structure of the GO / MMT gel system based on the three-dimensional helical structure contained in BHC, to construct more highly stable porous networks, and its active groups and environmental friendliness can effectively solve the problems of poor mechanical strength, functional component aggregation, and secondary pollution caused by traditional gel matrix materials. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing technologies and provide a catalytic adsorption bovine collagen-based porous gel material and its preparation method that can solve the problems of low adsorption capacity, poor selectivity, easy desorption of nuclides, and difficulty in separation and recovery of traditional adsorption materials in the fields of marine ecological environment restoration and marine nuclide resource utilization. The target product has high adsorption capacity, excellent catalytic activity, good mechanical stability and dispersibility.

[0005] The present invention also provides an application of the above-mentioned porous gel material in the adsorption and recovery of radionuclides in seawater or radionuclide-containing water bodies.

[0006] To solve the above-mentioned technical problems, the present invention is implemented as follows: A porous gel material based on bovine collagen for catalytic adsorption is disclosed, comprising the following components: bovine collagen powder (BHC), graphene oxide (GO), montmorillonite (MMT), and zirconium-based metal-organic framework; the material possesses a three-dimensional porous network structure with a pore size distribution of 80–800 nm and a specific surface area ≥300 m². 2 / g, porosity ≥75%.

[0007] Furthermore, the zirconium-based metal-organic framework material is at least one of UiO-66, UiO-67, or UiO-68.

[0008] Furthermore, the bovine collagen powder (BHC) is derived from at least one of bovine leather scraps, shaved bovine hide shavings, or trimming waste.

[0009] Furthermore, the montmorillonite (MMT) is sodium-based montmorillonite or calcium-based montmorillonite.

[0010] Furthermore, the graphene oxide (GO) has a sheet size of 0.5–5 μm and an oxygen-containing functional group content of 18–25%.

[0011] The preparation method of the above-mentioned porous gel material based on bovine collagen adsorption includes the following steps: (1) Prepare montmorillonite (MMT) dispersion, graphene oxide (GO) dispersion, bovine collagen (MMT) dispersion and zirconium-based metal-organic framework material dispersion respectively; (2) Mix the above dispersions in proportion, add crosslinking agent and dispersant, and stir to obtain composite precursor solution; (3) The precursor solution is injected into the mold and cross-linked to form the initial gel; (4) The initial gel is subjected to freeze-thaw cycle treatment and then vacuum freeze-drying to obtain the target product, a catalytic adsorption bifunctional bovine collagen-based porous gel material for the utilization of low-concentration radionuclide resources in seawater.

[0012] Furthermore, the crosslinking agent is Zr. 4+ Al 3+ At least one of glutaraldehyde or epichlorohydrin is used, in an amount of 5 to 20% of the total mass of graphene oxide (GO) and montmorillonite (MMT).

[0013] Furthermore, the freeze-thaw cycle is performed 4 to 6 times, with a freezing temperature of -30 to -15°C and a freezing time of 2 to 4 hours, a thawing temperature of 25 to 35°C and a thawing time of 1 to 2 hours; followed by vacuum freeze-drying at -60 to -40°C for 16 to 30 hours.

[0014] The above-mentioned catalytic adsorption bifunctional bovine collagen-based porous gel material is used for the adsorption and recovery of nuclides in seawater or water containing nuclides; the nuclides include at least one of uranium, thorium, and neptunium.

[0015] This invention aims to address the pain points of traditional adsorbent materials in marine ecological environment restoration and marine radionuclide resource utilization, such as "low adsorption capacity, poor selectivity, easy desorption of radionuclides, and difficulty in separation and recovery." It introduces a catalytically active UiO series zirconium-based metal-organic framework into a GO / MMT gel system to form a composite gel material with high adsorption capacity, excellent catalytic activity, good mechanical stability, and good dispersibility. Through the synergistic effect of adsorption and catalysis, it achieves resource utilization of low-concentration radionuclides in the Bohai Sea. Compared with traditional adsorbent materials commonly used in marine ecological environment restoration and marine radionuclide resource utilization, its efficiency is increased by more than 40%.

[0016] This invention uses zirconium-based metal-organic frameworks of MMT, GO and UiO series as raw materials, and goes through steps such as component pretreatment, precursor solution preparation, initial cross-linking into gel, and freeze-thaw cycle shaping to obtain a catalytic adsorption bifunctional synergistic porous gel material for the utilization of low-concentration radionuclide resources in seawater.

[0017] The ultrasonic exfoliation technique used in the component pretreatment process utilizes the cavitation effect of ultrasound to generate localized instantaneous high pressure and shear force, effectively disrupting the weak interactions between MMT layers and exfoliating them into single-layer or few-layer thin sheets with a thickness of 1–6 nm. Ultrasonic exfoliation significantly increases the specific surface area of ​​MMT (3–5 times higher than the unexfoliated state), fully exposing adsorption active sites such as silanol groups and aluminum oxide octahedra between the layers. The exfoliated thin-layer structure can interweave and overlap with GO sheets, providing a rigid support framework for constructing a three-dimensional interpenetrating porous network, preventing structural collapse during subsequent freeze-drying and seawater immersion, and directly improving the mechanical stability of the material. Simultaneously, MMT exfoliation promotes the formation of radionuclide mass transfer channels and hierarchical pore systems, accelerating the diffusion of low-concentration radionuclides from seawater to adsorption-catalytic active sites. Ultrasonic dispersion ensures full utilization of GO's high specific surface area, allowing the abundant oxygen-containing functional groups on the GO surface to form hydrogen bonds with the silanol groups of the MMT exfoliated sheets. Simultaneously, it provides coordination sites for the crosslinking agent, strengthening the interfacial bonding between GO and MMT and preventing phase separation of the composite gel matrix during use. Furthermore, the uniformly dispersed GO sheets act as "molecular bridges," providing a uniform loading substrate for the UiO series zirconium-based metal-organic framework. Combined with dispersants, this further inhibits the aggregation of the UiO series zirconium-based metal-organic framework, ensuring the uniform distribution of its catalytic adsorption bifunctional sites within the material, achieving a synergistic effect of nuclide "capture-conversion".

[0018] Due to the strong van der Waals forces and electrostatic attraction between particles, UiO series zirconium-based metal-organic frameworks naturally tend to form micron-sized aggregates, which mask their internal catalytic adsorption active sites and make it difficult to uniformly load them in a composite gel matrix. This invention employs a combined process of "ethanol-water mixed solvent + ultrasonic dispersion," achieving enhanced dispersion through solvent adaptation and synergistic ultrasonic energy. Specifically, this process de-agglomerates and exposes active sites: the high-frequency vibration and cavitation effect generated by ultrasound in the liquid medium rapidly breaks down the interparticle forces of the UiO series zirconium-based metal-organic framework aggregates, dispersing them into monodisperse or a few aggregated nanoparticles. This fully exposes zirconium-based nodes, ligand functional groups, and other catalytic adsorption active sites, providing a sufficient reaction interface for subsequent nuclide coordination and catalytic conversion. An ethanol-water mixed solvent with a volume ratio of 1:1 to 3 was selected. On the one hand, ethanol can reduce the interfacial tension on the surface of UiO series zirconium-based metal-organic framework particles and inhibit the re-agglomeration of particles after dispersion. On the other hand, the aqueous phase can form good compatibility with the GO / MMT composite precursor liquid (water-based system), avoiding phase separation due to solvent differences during subsequent drop addition, and ensuring that UiO series zirconium-based metal-organic framework particles are uniformly integrated into the three-dimensional gel network.

[0019] The use of crosslinking agents in the precursor solution preparation process can effectively construct a GO / MMT three-dimensional interpenetrating porous network, thereby forming the core component for stable support of the UiO series zirconium-based metal-organic framework. 4+ With Al 3+ As a high-valence metal cation, it possesses the dual functions of "multi-site coordination crosslinking" and "performance enhancement." From a mechanistic perspective, it can form stable bonds with the abundant oxygen-containing functional groups on the GO surface and the silanol groups on the MMT exfoliated sheets through coordination bonds, "bridging" the dispersed GO sheets and MMT sheets to form a three-dimensional network, preventing structural collapse of the gel during freeze-drying and seawater immersion. Simultaneously, Zr... 4+ It can coordinate with the zirconium-based metal cluster sites of the UiO series zirconium-based metal-organic framework to supplement them, repairing defect sites that may appear during dispersion or subsequent reactions, and maintaining their catalytic adsorption activity. Glutaraldehyde and epichlorohydrin are cross-linked through covalent bonds, focusing on "strengthening interfacial bonding" and "enhancing environmental tolerance". In terms of mechanism, the aldehyde group of glutaraldehyde can undergo Schiff base reaction with the oxygen-containing functional groups on the surface of GO, MMT and UiO series zirconium-based metal-organic frameworks to form stable covalent bonds; the epoxy group of epichlorohydrin can undergo ring-opening reaction with the hydroxyl groups of GO and MMT to construct a covalent cross-linked network, further improving the chemical stability of the gel matrix. The interactive use of the above-mentioned inorganic and organic cross-linking agents can also achieve synergistic effects of "coordination cross-linking-covalent cross-linking". The inorganic cross-linking agent dominates the construction of the mechanical framework, and the organic cross-linking agent fills the interfacial bonding gaps, solving the defects of "uneven distribution of cross-linking points" of single inorganic cross-linking agents and "insufficient mechanical strength" of single organic cross-linking agents.

[0020] The use of dispersants during precursor solution preparation effectively improves the dispersion uniformity of UiO series zirconium-based metal-organic frameworks in gel matrix materials with three-dimensional porous network structures. Polyvinylpyrrolidone (PVP) exhibits excellent water and alcohol solubility, making it perfectly compatible with the ethanol-water dispersion system of UiO series zirconium-based metal-organic frameworks without the risk of phase separation. Furthermore, its molecular chain length can be controlled by the degree of polymerization, it is non-toxic, readily soluble in water, and can be removed during subsequent freeze-drying with solvent evaporation or in the water washing step, leaving no residual pollution and avoiding impact on the purity of radionuclide adsorption. In addition, PPVP can form weak interactions with crosslinking agents (such as glutaraldehyde), further anchoring the UiO series zirconium-based metal-organic framework and reducing the shedding rate during seawater immersion. Sodium dodecylbenzenesulfonate achieves dispersion through a dual mechanism of electrostatic repulsion and steric hindrance. The hydrophobic benzene ring in its molecular structure adsorbs onto the surface of hydrophobic ligands in the UiO series zirconium-based metal-organic framework via van der Waals forces, while the hydrophilic sulfonic acid groups face the aqueous phase, resulting in a uniform negative charge on the surface of the UiO series zirconium-based metal-organic framework, forming an electrostatic repulsion layer. Simultaneously, the extension of the sodium dodecylbenzenesulfonate molecular chain constructs auxiliary steric hindrance, enhancing dispersion stability, significantly reducing the overall viscosity of the gel system, improving the mixing uniformity of the precursor solution, and avoiding catalytic activity "dead zones" caused by localized agglomeration.

[0021] The use of PTFE molds during the initial crosslinking process ensures that no chemical reactions occur with GO, MMT, UiO series zirconium-based metal-organic frameworks, crosslinking agents, or dispersants in the composite precursor solution throughout the gel molding process. It also prevents the dissolution of impurity ions or small molecules, effectively avoiding interfacial contamination between the mold and the material and ensuring the complete preservation of the catalytic adsorption active sites of the UiO series zirconium-based metal-organic framework. Simultaneously, the initial gel is a soft colloid containing a large amount of solvent, exhibiting strong viscosity and a tendency to adhere to the mold surface. PTFE, with its extremely low surface energy and excellent non-stick properties, allows the initial gel formed after crosslinking with the composite precursor solution to be completely peeled from the mold without the need for a release agent. This ensures the integrity of the gel's three-dimensional morphology, preventing cracks and damage during demolding and allowing the porous structure formed by subsequent freeze-thaw treatment to remain continuous, significantly accelerating the mass transfer rate of radionuclides from seawater to the active sites.

[0022] In the freeze-thaw cycle setting process, the use of liquid nitrogen directional freezing can quickly freeze the free water in the initial gel into tiny ice crystals. This avoids the problem of large ice crystals compressing the gel network and disrupting the dispersion of the UiO series zirconium-based metal-organic framework in the gel matrix caused by slow freezing. It also improves the local enrichment of the UiO series zirconium-based metal-organic framework due to gravity sedimentation during freezing, which is beneficial for forming a multi-level directional pore system of "micropores (UiO series zirconium-based metal-organic framework) - mesopores (MMT interlayer) - macropores (directional channels)". Simultaneously, the liquid nitrogen directional freezing method can achieve gradient heat transfer through unilateral contact with liquid nitrogen, allowing ice crystals to grow along the heat transfer direction to form interconnected directional channels, thereby effectively reducing mass transfer resistance. Vacuum freeze-drying replaces traditional thermal drying with "ice crystal sublimation under vacuum," and its core advantages are "preservation of porous structure + protection of active components". The low-temperature vacuum environment allows ice crystals to sublimate and detach directly from the gel. Without liquid water, the directional channels and multi-level porous structure formed by liquid nitrogen directional freezing are fully preserved, maintaining a high pore connectivity rate to ensure rapid seawater penetration to the active sites within the material. Simultaneously, the low-temperature environment avoids the shedding or structural transformation of the UiO series zirconium-based metal-organic framework caused by thermal drying, effectively inhibiting the oxidation of GO and interlayer re-aggregation of MMT in the gel. This prevents a significant increase in the swelling rate during subsequent seawater immersion and maintains good mechanical properties.

[0023] The applications of the gel material prepared in this invention include: filling the granular or blocky porous gel material obtained by the above method into an adsorption column to treat seawater at a flow rate of 1-5 BV / h; or using it for the enrichment and recovery of radionuclides in nuclear power plant wastewater and nearshore radioactive contaminated seawater; and for the deep removal of low-concentration radionuclides in seawater desalination pretreatment. Furthermore, during the preparation of the gel material, the types and amounts of raw materials added, as well as the process parameters, should be selected according to the specific process parameters required by the product and the actual product performance to ensure a complete and thorough reaction.

[0024] Compared with the prior art, the present invention brings the following beneficial effects: (1) The method of the present invention integrates three core advantages of porous adsorption, catalytic conversion and gel structure characteristics to meet the recycling needs of low-concentration nuclides in seawater. Through the synergistic mechanism of "adsorption enrichment-catalytic fixation-stable storage", it solves the pain points of traditional materials such as "low adsorption capacity, poor selectivity, easy desorption of nuclides and difficulty in separation and recovery", and has significant technical advantages and diverse scenario requirements.

[0025] (2) The technology and materials provided by this invention can achieve synergistic enhancement of catalytic adsorption dual functions in the field of low-concentration nuclide recycling in seawater. The zirconium metal cluster sites and oxygen-containing functional groups in the UiO series zirconium-based metal-organic framework have both nuclide coordination adsorption and valence state conversion activities. The high specific surface area of ​​GO can quickly capture nuclides and anchor them to the active sites in the UiO series zirconium-based metal-organic framework. The interlayer pores of MMT accelerate mass transfer and diffusion. The synergy of the three greatly improves the uranium adsorption capacity. Compared with the single UiO series zirconium-based metal-organic framework and the traditional GO / MMT gel, the adsorption capacity can be increased by 30% and 120%, respectively, and the nuclide catalytic conversion efficiency is ≥88%. Among them, the conversion efficiency of U(VI) to the recyclable form (low-solubility U(IV) complex) exceeds 90%, which solves the core pain point of existing materials that "only adsorb but do not convert".

[0026] (3) During the preparation of the gel material, a multi-level network of "micropore-mesopore-macropore" was successfully constructed through MMT ultrasonic exfoliation, GO ultrasonic dispersion, and "liquid nitrogen directional freezing + vacuum freeze drying" processes. The porosity and pore connectivity were significantly improved, effectively shortening the time required for nuclide adsorption equilibrium. Zr 4+ With Al 3+ By combining with organic crosslinking agents to strengthen the interfacial bonding, the material has a compressive strength ≥2.2MPa, a swelling rate ≤220% after immersion in artificial seawater for 96 hours, and an adsorption capacity retention rate ≥90% in environments with pH=3-10, thus solving the problems of easy pulverization and gel collapse of the UiO series zirconium-based metal-organic framework.

[0027] (4) "Ethanol-water mixed solvent + polyvinylpyrrolidone / sodium dodecylbenzenesulfonate dispersion" stabilizes the particle size of UiO series zirconium-based metal-organic frameworks at 50-500 nm. Polytetrafluoroethylene molds ensure molding precision and are suitable for batch filling of adsorption columns. The process does not require high temperature and high pressure. Ultrasonic and freeze-drying are both mature industrial technologies and can be mass-produced through continuous equipment. The preparation cost is reduced by 20-30% compared with the existing UiO series zirconium-based metal-organic frameworks, providing core support for technology transformation. The present invention proposes a catalytic adsorption bifunctional synergistic porous gel material for the utilization of low-concentration radionuclide resources in seawater. Its adsorption capacity for uranium, thorium, and neptunium is superior to that of traditional adsorption materials. It can efficiently enrich low-concentration radionuclides in nearshore and nuclear power plant warm wastewater to achieve resource recovery. Moreover, no toxic components are leached out, and it is resistant to seawater salt spray corrosion, taking into account the dual value of nuclear energy security and marine environmental safety.

[0028] (5) The porous gel material based on bovine collagen mentioned in this invention exhibits significantly improved adsorption capacity, cycle stability, and mechanical strength (compressive strength, tensile strength, and elastic modulus) compared to single-component and traditional adsorption materials under the same conditions. The adsorption capacity reaches 403.4 mg / g, the selective adsorption rate for uranium complexes is 78.6%, and the removal efficiency decreases by only 2.9% after 5 adsorption cycles. The mechanical strength (compressive strength, tensile strength, and elastic modulus) are 1.2, 0.22, and 13.2 MPa, respectively. Furthermore, XPS analysis and peak fitting of the gel material after catalytic adsorption saturation equilibrium revealed that tetravalent uranium accounted for 50.62% and hexavalent uranium accounted for 49.38%, confirming that the porous gel material of this invention has considerable catalytic conversion and reduction efficiency for hexavalent uranium, achieving a conversion efficiency of over 50% with only 0.2 g / L of adsorbent.

[0029] Table 1 compares the adsorption capacity, cycle stability, mechanical strength, and other properties of the porous gel material of this invention with those of single-component and traditional adsorbent materials under the same conditions.

[0030] Adsorbent materials Adsorption capacity (mg / g) Selectivity (%) Performance degradation rate after 5 cycles (%) Compressive strength (MPa) Tensile strength (MPa) Elastic modulus (MPa) GO / MMT 2.4 <50 30.2 0.25 0.08 3.5 BHC / GO / MMT 4.5 <30 54.3 0.50 0.14 6.5 UIO 221.3 <55 10.2 0.55 - 11.8 Activated carbon 12.5 <15 54.3 0.25 - 5.0 Ion exchange resin 25.1 <10 45.6 0.60 0.12 10.2 UiO / BHC / GO / MMT 403.4 78.6 2.9 1.20 0.22 13.2 Attached Figure Description

[0031] Figure 1 This is a performance graph showing the effect of the amount of adsorbent used in this invention on the uranium adsorption capacity and removal efficiency of the material.

[0032] Figure 2 This is a performance graph showing the effect of the initial pollutant concentration on the uranium adsorption capacity and removal efficiency of the material.

[0033] Figure 3 This is a performance graph showing the effect of adsorption temperature on the uranium adsorption capacity and removal efficiency of the material according to the present invention.

[0034] Figure 4 This is a performance graph showing the effect of the number of cycles on the uranium adsorption capacity of the material according to the present invention.

[0035] Figure 5 This is a performance diagram showing the effect of the present invention on uranium adsorption capacity and removal efficiency under actual environmental simulation conditions of low-concentration uranium.

[0036] Figure 6 This is a high-resolution XPS spectrum of uranium elemental composition, representing the catalytic conversion efficiency of this invention after catalytic adsorption saturation. Detailed Implementation

[0037] The present invention will now be described in detail through specific embodiments. These embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art. As used throughout the specification and claims, the terms "comprising" or "including" are open-ended and are interpreted as "comprising but not limited to". The following description is a preferred embodiment for carrying out the invention; however, this description is intended to illustrate the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the invention is determined by the appended claims. Unless otherwise specified, all reagents and materials used in the present invention are commercially available.

[0038] All raw materials used in this invention are designated as conventional in the field, and each designation and abbreviation is clearly defined within its relevant application. Those skilled in the art can obtain them from commercially available sources or prepare them using conventional methods based on the designation, abbreviation, and corresponding application. There are no particular limitations on the purity of any raw materials used in this invention; however, industrial purity or conventional purity used in composite material preparation techniques is preferred. All processes used in this invention are also designated as conventional abbreviations in the field, and each abbreviation is clearly defined within its relevant application. Those skilled in the art can understand the conventional process steps based on the abbreviation. In this invention and its embodiments, the liquid ratios involved in each step, and the percentages of each chemical used, are based on the mass of the gel matrix material used in the process. The embodiments of this invention are only used to more clearly illustrate the technical solutions of this patent and are therefore only examples, not intended to limit the scope of protection of this patent. It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning understood by those skilled in the art to which this patent pertains. In the process described in this invention, the range of values ​​for each parameter (such as temperature, time, etc.) can be appropriately adjusted according to actual production needs and material types. The adjustment method is a conventional technical means for those skilled in the art.

[0039] This invention relates to a catalytic adsorption bifunctional bovine collagen-based porous gel material, which is composed of a catalytically responsive zirconium-based metal-organic framework and a three-dimensional helical BHC introduced into a GO / MMT gel system. Through the synergistic effect of adsorption and catalysis, it achieves resource utilization of low-concentration radionuclides in the Bohai Sea. The porous gel material consists of a composite matrix framework and catalytic adsorption functional units loaded therein. The composite matrix framework is a BHC / GO / MMT gel system with a three-dimensional porous network structure formed by cross-linking BHC, GO, and MMT with a cross-linking agent. The catalytic adsorption functional units are UiO series zirconium-based metal-organic frameworks, which are stably bound to the BHC / GO / MMT gel system under the action of a dispersant stabilizer. Through the enhanced adsorption of high specific surface area of ​​GO, the interlayer pore regulation of MMT, the three-dimensional helical stabilizing structure of BHC, and the synergistic effect of the dual catalytic adsorption of the UiO series zirconium-based metal-organic framework, efficient capture and conversion of low-concentration radionuclides in seawater is achieved.

[0040] The dispersion can be selected from polyvinylpyrrolidone or sodium dodecylbenzenesulfonate, and the amount used is 1 to 3% of the mass of the UiO series zirconium-based metal-organic framework, which is used to improve its dispersion uniformity in the three-dimensional porous network structure.

[0041] A method for preparing a catalytically adsorbed bifunctional bovine collagen-based porous gel material includes the following steps: (1) Component pretreatment: MMT was added to deionized water and ultrasonically dissected for 40-120 min to obtain an MMT dispersion with a concentration of 0.5-2 wt%; GO was added to deionized water and ultrasonically dispersed for 30-60 min to obtain a GO dispersion with a concentration of 0.1-0.5 wt%; BHC was added to deionized water and ultrasonically dispersed for 30-60 min to obtain a BHC dispersion with a concentration of 0.2-0.5 wt%; UiO series zirconium-based metal-organic frameworks were added to an ethanol-water mixed solvent (volume ratio 1:1-3) and ultrasonically dispersed for 20-40 min to obtain a UiO series zirconium-based metal-organic framework dispersion with a concentration of 1-5 wt%. (2) Preparation of precursor solution: MMT dispersion, GO dispersion and BHC dispersion are mixed at a mass ratio of 6-16:2:1 and stirred at 55-70 °C for 40-80 min. Crosslinking agent is added and stirred for 15-30 min. At the same time, dispersant is added and stirred to dissolve. Then, UiO series zirconium-based metal-organic framework dispersion is added dropwise and stirred continuously at 45-60 °C for 30-60 min to obtain composite precursor solution. (3) Initial cross-linking gel formation: The composite precursor solution is injected into the mold and cross-linked at a constant temperature of 30-50 °C for 4-10 h to form the initial gel; (4) Freeze-thaw cycle shaping: The initial gel is subjected to freeze-thaw cycle treatment 4-6 times, the freezing temperature is -30 to -15℃, the freezing time is 2 to 4 h, the thawing temperature is 25 to 35℃, and the thawing time is 1 to 2 h; then it is vacuum freeze-dried at -60 to -40℃ for 16 to 30 h to remove the solvent and retain the porous structure, so as to obtain the catalytic adsorption bifunctional bovine collagen-based porous gel material.

[0042] Example 1

[0043] A catalytic adsorption bifunctional bovine collagen-based porous gel material for utilizing low-concentration radionuclide resources in seawater includes the following steps: (1) Component pretreatment: 1 g MMT was added to 100 mL of deionized water and ultrasonically dissected for 60 min to obtain an MMT dispersion with a concentration of 1 wt%; 0.5 g GO was added to 100 mL of deionized water and ultrasonically dispersed for 60 min to obtain a GO dispersion with a concentration of 0.5 wt%; 0.5 g BHC was added to 100 mL of deionized water and ultrasonically dispersed for 30 min to obtain a BHC dispersion with a concentration of 0.5 wt%; UiO series zirconium-based metal-organic frameworks were added to an ethanol-water mixed solvent (volume ratio 1:2, 90 mL) and ultrasonically dispersed for 30 min to obtain a UiO series zirconium-based metal-organic framework dispersion with a concentration of 2 wt%. (2) Preparation of precursor solution: MMT dispersion, GO dispersion and BHC dispersion were mixed at a mass ratio of 6:2:1 and stirred at 60°C for 60 min. Crosslinking agent was added and stirred for 30 min. At the same time, dispersant was added and stirred to dissolve. Then, UiO series zirconium-based metal-organic framework dispersion was added dropwise and stirred continuously at 60°C for 45 min to obtain composite precursor solution. (3) Initial cross-linking gel formation: The composite precursor solution is injected into the mold and cross-linked at 40°C for 8 hours to form the initial gel. (4) Freeze-thaw cycle shaping: The initial gel was subjected to freeze-thaw cycle treatment 4 times, with a freezing temperature of -30℃ and a freezing time of 4h, and a thawing temperature of 25℃ and a thawing time of 2h; then it was vacuum freeze-dried at -60℃ for 24h to remove the solvent and retain the porous structure, thus obtaining the catalytic adsorption bifunctional bovine collagen-based porous gel material.

[0044] (5) Material application parameters: The granular or blocky porous gel material prepared by the above method is filled into the adsorption column and treated with seawater at a flow rate of 3BV / h, or used for the enrichment and recovery of nuclides in the warm wastewater of nuclear power plants, radioactive contaminated seawater in the nearshore area, and deep removal of low concentration nuclides in the pretreatment of seawater desalination.

[0045] Example 2

[0046] A catalytic adsorption bifunctional bovine collagen-based porous gel material for utilizing low-concentration radionuclide resources in seawater includes the following steps: (1) Component pretreatment: 2g MMT was added to 100mL deionized water and ultrasonically dissected for 120min to obtain a 2wt% MMT dispersion; 0.2g GO was added to 100mL deionized water and ultrasonically dispersed for 50min to obtain a 0.2wt% GO dispersion; 0.2g BHC was added to 100mL deionized water and ultrasonically dispersed for 50min to obtain a 0.2wt% BHC dispersion; UiO series zirconium-based metal-organic frameworks were added to ethanol-water mixed solvent (volume ratio 1:3, 100mL) and ultrasonically dispersed for 40min to obtain a 5wt% UiO series zirconium-based metal-organic framework dispersion. (2) Preparation of precursor solution: MMT dispersion, GO dispersion and BHC dispersion were mixed at a mass ratio of 10:2:1 and stirred at 70°C for 80 min. Crosslinking agent was added and stirred for 30 min. At the same time, dispersant was added and stirred to dissolve. Then, UiO series zirconium-based metal-organic framework dispersion was added dropwise and stirred continuously at 60°C for 60 min to obtain composite precursor solution. (3) Initial cross-linking gel formation: The composite precursor solution is injected into the mold and cross-linked at 50°C for 10 hours to form the initial gel. (4) Freeze-thaw cycle shaping: The initial gel was subjected to a freeze-thaw cycle treatment 6 times. The freezing temperature was -20℃ and the freezing time was 3h. The thawing temperature was 30℃ and the thawing time was 1.5h. Then, it was vacuum freeze-dried at -50℃ for 30h to remove the solvent and retain the porous structure, thus obtaining the catalytic adsorption bifunctional bovine collagen-based porous gel material.

[0047] (5) Material application parameters: The granular or blocky porous gel material prepared by the above method is filled into the adsorption column and treated with seawater at a flow rate of 5 BV / h, or used for the enrichment and recovery of nuclides in the warm wastewater of nuclear power plants, radioactive contaminated seawater in the nearshore area, and deep removal of low concentration nuclides in the pretreatment of seawater desalination.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications and substitutions should all fall within the protection scope defined by the claims of the present invention.

Claims

1. A porous gel material based on bovine collagen that catalytically adsorbs collagen, characterized in that, It is composed of the following components: bovine collagen powder, graphene oxide, montmorillonite, and zirconium-based metal-organic framework material; the material has a three-dimensional porous network structure with a pore size distribution of 80–800 nm and a specific surface area ≥300 m². 2 / g, porosity ≥75%.

2. The porous gel material based on bovine collagen for catalytic adsorption according to claim 1, characterized in that, The zirconium-based metal-organic framework material is at least one of UiO-66, UiO-67, or UiO-68.

3. The porous gel material based on bovine collagen for catalytic adsorption according to claim 1, characterized in that, The bovine collagen powder is derived from at least one of the following: bovine leather scraps, shaved bovine hide shavings, or trimming waste.

4. The porous gel material based on bovine collagen for catalytic adsorption according to claim 1, characterized in that, The montmorillonite is sodium-based montmorillonite or calcium-based montmorillonite.

5. The porous gel material based on bovine collagen for catalytic adsorption according to claim 1, characterized in that, The graphene oxide has a sheet size of 0.5–5 μm and an oxygen-containing functional group content of 18–25%.

6. A method for preparing the material according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Prepare montmorillonite dispersion, graphene oxide dispersion, bovine collagen dispersion and zirconium-based metal-organic framework material dispersion respectively; (2) Mix the above dispersions in proportion, add crosslinking agent and dispersant, and stir to obtain composite precursor solution; (3) The precursor solution is injected into the mold and cross-linked to form the initial gel; (4) The initial gel is subjected to freeze-thaw cycle treatment and then vacuum freeze-drying to obtain the target product, a catalytic adsorption bifunctional bovine collagen-based porous gel material for the utilization of low-concentration radionuclide resources in seawater.

7. The preparation method according to claim 6, characterized in that, The crosslinking agent is Zr. 4+ Al 3+ At least one of glutaraldehyde or epichlorohydrin is used, in an amount of 5 to 20% of the total mass of graphene oxide and montmorillonite.

8. The preparation method according to claim 6, characterized in that, The freeze-thaw cycle is performed 4 to 6 times, with a freezing temperature of -30 to -15°C and a freezing time of 2 to 4 hours, and a thawing temperature of 25 to 35°C and a thawing time of 1 to 2 hours; then, the product is vacuum freeze-dried at -60 to -40°C for 16 to 30 hours.

9. An application of the material as described in any one of claims 1 to 5 in the adsorption and recovery of radionuclides in seawater or radionuclide-containing water bodies.

10. The application according to claim 9, characterized in that, The nuclide includes at least one of uranium, thorium, and neptunium.

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