Preparation method and application of multifunctional magnetic hydrogel

Abstract

The invention provides a preparation method and application of multifunctional magnetic hydrogel, and relates to the technical field of environmental pollution treatment. The embodiment of the invention provides a preparation method and application of multifunctional magnetic hydrogel. The method comprises the following steps: S1, preparing Schwertmannite powder; s2, preparing a magnetotactic bacterium suspension; s3, compounding of Schwertmannite and magnetotactic bacteria; s4, preparing a polyvinyl alcohol solution; s5, preparing an MOF colloidal solution; s6, preparation of the multifunctional magnetic hydrogel: mixing the Schwertmannite-magnetotactic bacterium compound and the MOF colloidal solution in a polyvinyl alcohol solution, and stirring to obtain a precursor solution; and placing the precursor solution under a circulating freezing-unfreezing condition for crosslinking to obtain the three-dimensional network multifunctional magnetic hydrogel. The multifunctional magnetic hydrogel provided by the embodiment of the invention integrates'efficient repair, real-time monitoring and convenient recovery ', and has the characteristics of greenness, intelligence and sustainability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental pollution treatment, in particular to a preparation method and application of a multifunctional magnetic hydrogel. BACKGROUND

[0002] With the rapid development of industrialization and urbanization, the problem of combined pollution in soil and water environment is increasingly prominent. Various pollutants, especially heavy metals (such as lead, chromium, arsenic, mercury) and organic pollutants (such as polycyclic aromatic hydrocarbons, petroleum hydrocarbons, pesticides) often coexist in the same environmental medium, forming a complex composition and significant interaction of combined pollution system. Due to the synergistic or antagonistic effect between pollutants, the migration and transformation behavior is more complex, and the traditional single-function repair material is difficult to achieve simultaneous and efficient removal of multiple types of pollutants. The widely used repair materials such as biochar, zero-valent iron nanoparticles or clay minerals have certain effect in removing specific pollutants, but they generally have single function, lack of response ability to the repair process, and are difficult to recycle after use. The residue of the material not only may cause secondary pollution, but also limits its reuse and increases the treatment cost. More importantly, the existing technology cannot realize real-time monitoring and feedback of the repair process, which makes it difficult to accurately control the repair period and easily causes under-repair or over-repair. SUMMARY

[0003] In order to solve the above technical problems, the present application provides a preparation method and application of a multifunctional magnetic hydrogel, which is an intelligent environmental remediation material with multifunctional synergistic repair ability, real-time sensing of pollutant removal state and convenient recycling and reuse. The technical solution is as follows:

[0004] The present application provides a preparation method of a multifunctional magnetic hydrogel, comprising the following steps:

[0005] S1: preparing a schulteite powder;

[0006] S2: preparing a magnetotactic bacteria suspension;

[0007] S3: magnetotactic bacteria-schulteite composite: mixing the magnetotactic bacteria suspension and the schulteite by oscillation, so that the magnetotactic bacteria adhere to the surface of the schulteite powder particles, and the schulteite-magnetotactic bacteria composite is collected by magnetic separation;

[0008] S4: preparation of polyvinyl alcohol solution: adding polyvinyl alcohol powder into deionized water to prepare a polyvinyl alcohol solution;

[0009] S5: preparation of MOF colloidal solution: adding an organic ligand solution into a metal salt solution, centrifuging to remove the supernatant and obtain the precipitate phase, dissolving the precipitate phase in deionized water and ultrasonic treatment to obtain the MOF colloidal solution;

[0010] S6: Preparation of multifunctional magnetic hydrogel:

[0011] The schwertmannite-magnetotactic bacteria complex is mixed with a MOF colloidal solution in a polyvinyl alcohol solution to obtain a precursor solution; the precursor solution is subjected to a cyclic freezing-thawing condition to cause crosslinking, thereby obtaining a three-dimensional network multifunctional magnetic hydrogel.

[0012] Schwertmannite, as a natural secondary iron-hydroxyl sulfate mineral, has a large specific surface area, abundant surface active sites, good ion exchange capacity, and certain catalytic activity, and thus has broad application prospects in environmental remediation. It can not only efficiently adsorb various heavy metal ions (such as Pb 2+ , Cr 3+ , AsO4 3- , etc.) in water and soil, but also degrade organic pollutants such as pesticides and polycyclic aromatic hydrocarbons (PAHs) through surface-mediated redox reactions or Fenton-like reactions. However, schwertmannite usually exists in the form of micron-sized loose particles and is not magnetic itself. Once added to complex environmental media, it is difficult to achieve effective separation and recovery, which can cause material waste and potential secondary pollution, and seriously limits its large-scale application in practical engineering.

[0013] To solve the problem of material recovery, magnetotactic bacteria are introduced as biological carriers. These microorganisms can synthesize nanoscale magnetosomes (mainly composed of Fe3O4 or Fe3S4) with superparamagnetic properties in cells, which can be moved and collected efficiently under the action of a weak external magnetic field, thereby providing a biological path for the convenient recovery of functional materials. At the same time, magnetotactic bacteria and their magnetosomes are rich in functional groups such as carboxyl and amino groups on their surfaces, and have certain heavy metal adsorption capacity, and can participate in the degradation of organic pollutants through the reductase system or extracellular electron transfer mechanism produced by metabolism. However, the selective recognition ability of magnetotactic bacteria for different pollutants is weak, and their physiological activity is easily inhibited by environmental pH, temperature, and toxic substances, resulting in unstable remediation efficiency; in addition, free magnetosomes are easily aggregated in complex environments and lose activity, and their separate use cannot meet the dual demands of high efficiency and stability for the treatment of complex pollution.

[0014] Non-heavy metal-organic framework (MOF) materials have high sensitivity and selectivity in pollutant identification and sensing detection due to their highly adjustable pore structure, rich ligand design space, and excellent fluorescence / colorimetric response characteristics. Through rational design, MOFs can specifically recognize heavy metal ions or specific organic pollutants and convert the recognition event into visual optical signal output, making real-time monitoring of the remediation process possible. However, MOFs themselves lack active remediation function and cannot effectively adsorb or degrade pollutants, and their stability in aqueous environments is poor, which limits their direct application in dynamic remediation systems.

[0015] Although the Shengshi mineral, magnetotactic bacteria and MOF have significant complementarity in function, respectively assuming the roles of "repair", "recycling" and "perception", the integration between the three faces severe challenges. Due to the significant differences in physical form, surface properties and action mechanism, simple physical mixing not only is difficult to achieve synergistic effect, but also may lead to functional interference: for example, Shengshi mineral particles may shield the magnetic response performance of magnetosomes, affecting the directional migration under the driving of magnetic field; the biological activity of magnetotactic bacteria may destroy the crystal structure of MOF; and the MOF channels are easy to be blocked by microorganisms or mineral particles, resulting in the failure of recognition function.

[0016] In view of this, the present application provides an intelligent composite hydrogel material based on a functional integration strategy, aiming to realize the synergistic and efficient repair of heavy metals and organic pollutants in complex environment, real-time process monitoring and convenient recycling and reuse.

[0017] The hydrogel takes Shengshi mineral as the core functional unit, fully utilizes the advantages of high specific surface area and surface active sites, and serves as an efficient adsorption center for heavy metal ions (such as Pb 2+ , Cr 3+ , As(V) and the like), and simultaneously utilizes the iron-based catalytic properties to activate hydrogen peroxide or persulfate, generates strong oxidizing free radicals, realizes in-situ catalytic degradation of pesticides, polycyclic aromatic hydrocarbons and other refractory organic pollutants, and thus constructs a repair platform for simultaneous removal of multiple pollutants.

[0018] In order to solve the problem of difficult recycling of Shengshi mineral, the present application introduces magnetotactic bacteria as an embedded magnetic response carrier. The magnetosomes synthesized in the cells of magnetotactic bacteria have excellent superparamagnetic properties, and can realize rapid directional separation and recycling of the entire hydrogel system under the action of an applied weak magnetic field, significantly reduces the risk of material residue, and avoids secondary pollution. At the same time, the biological adsorption ability of magnetotactic bacteria itself and the degradation effect of its metabolites on part of the organic pollutants further enhance the comprehensive repair performance of the system, forming a biological-mineral synergistic mechanism.

[0019] In order to further improve the intelligent level of the system, the present application integrates a non-heavy metal metal-organic framework (MOF) material with specific recognition ability into the hydrogel network. The MOF selectively recognizes target pollutants through its designable channel structure, and produces optical signal outputs such as fluorescence quenching or color change after binding, realizing real-time and visual monitoring of the removal process of pollutants. This function makes the repair process change from "blind treatment" to "visual and controllable", and provides technical support for precise control of the repair period and prevention of repair deficiency or resource waste.

[0020] The above-mentioned multiple components are collectively encapsulated in a three-dimensional hydrogel matrix formed by a polyvinyl alcohol (PVA) crosslinked network. PVA not only provides good mechanical stability and environmental tolerance, but also forms a dense but permeable network structure through freeze-thaw cycling or chemical crosslinking, effectively preventing mutual shielding or inactivation between the functional units, ensuring the ordered distribution and functional independence of the schwertmannite, magnetotactic bacteria and MOF in space. By optimizing the component ratio and crosslinking process parameters, the hydrogel can maintain high repair efficiency while having excellent magnetic responsiveness and signal response sensitivity. This integrated design realizes the multifunctional integration of "adsorption / catalysis - identification / monitoring - directional recovery", achieving green, efficient and sustainable management of complex and complex pollution.

[0021] Optionally, the mass-volume ratio of the schwertmannite to the magnetotactic bacteria suspension is (1-3):1; the mass ratio of the schwertmannite-magnetotactic bacteria complex, the MOF colloidal solution and the polyvinyl alcohol solution is (10-25):(1-5):(70-85); wherein the concentration OD650 of the magnetotactic bacteria suspension is ≥1.5.

[0022] Optionally, in step S1, the method for preparing the schwertmannite powder comprises: reacting ferrous sulfate and hydrogen peroxide in an acidic environment to obtain a reaction solution, centrifuging the reaction solution to remove the supernatant to obtain a precipitate, and then freezing, drying and crushing the precipitate to obtain the schwertmannite powder. The pH value of the acidic environment is preferably 2.4-3.0; the centrifugal speed is preferably 4000-4500 rpm; and the freezing temperature is preferably -80℃ to -50℃.

[0023] At room temperature, Fe 2+ reacts violently and rapidly with hydrogen peroxide, which can cause Fe 3+ to rapidly reach supersaturation, thereby triggering uneven nucleation and generating a mixture of iron hydroxides. By reducing the temperature to -80℃ to -50℃, the molecular thermal motion energy can be sharply reduced, greatly slowing down the entire oxidation and hydrolysis reaction rate, which is conducive to the formation of a larger number of crystal nuclei with more uniform size, thereby generating pure and well-crystallized schwertmannite.

[0024] Schwertmannite is a metastable iron hydroxyl sulfate mineral. During the synthesis process, it is easy to transform into more stable iron oxides. At a higher pH, the hydrolysis reaction rate of Fe 3+ will sharply accelerate, and the OH - generated by hydrolysis will preferentially promote the nucleation and growth of more stable iron hydroxide minerals such as goethite (α-FeOOH) or ferrihydrite. At very low pH, the H + concentration is too high, which will strongly inhibit the nucleation and growth of Fe 3+The hydrolysis reaction of the iron oxide is extremely difficult or slow, and the reaction efficiency is low, so the reaction is preferably carried out in an acidic environment with a pH of 2.4-3.0.

[0025] The ferrous sulfate can be seven hydrated ferrous sulfate (FeSO4·7H2O) with stable structure, and the concentration of the seven hydrated ferrous sulfate is preferably 0.05M, and the mass concentration of the hydrogen peroxide is preferably 30%; the acidic environment preferably uses 98% concentrated sulfuric acid to prepare an acidic aqueous solution with a pH of 2.4-3.0, and sodium hydroxide is added during the synthesis process to maintain the pH of the entire reaction system in the range of 2.4-3.0.

[0026] Alternatively, the magnetotactic bacteria are Magnetospirillum, and specifically can be Magnetospirillum gryphiswaldense MSR-1 with a preservation number of CGMCC 1.5154.

[0027] Alternatively, in the step S2, the method for preparing the magnetotactic bacteria suspension includes inoculating the magnetotactic bacteria into a Magnetospirillum culture medium, culturing at a temperature of 25-30℃ for 3-7 days, collecting the bacterial bodies by using an external magnetic field, and dissolving the bacterial bodies in sterile buffer to obtain the magnetotactic bacteria suspension.

[0028] The Magnetospirillum culture medium is cultured in a micro-aerobic condition in the dark, and the bacterial bodies are collected by using a magnetic field after entering the stable growth phase. The magnetic field strength of the external magnetic field is ≥100 mT. For the magnetotactic bacteria, a field strength greater than 100 mT can generate a large enough magnetic force to ensure that the bacterial bodies can be quickly and efficiently captured and separated in a complex environmental medium, achieving rapid recovery, while a field strength lower than 100 mT is slow and time-consuming. The sterile buffer can be HEPES buffer or PIPES buffer with a pH of 6.5-7.5. The HEPES buffer and the PIPES buffer have good buffering capacity, and do not participate in most biochemical reactions, do not form complexes with metal ions, and do not interfere with enzyme activity, cell metabolism or electrophysiological processes.

[0029] Optionally, in the step S3, the temperature of the oscillation mixing is 25-30℃, the oscillation time is 2-12 hours, and the oscillation speed is 120-180 rpm. The Schleringerite is a micron-sized loose aggregate, which will quickly settle under static conditions, resulting in its ineffective compounding with the magnetotactic bacteria. The fluid dynamics generated by the oscillation can ensure that the particles and bacteria are always in a suspended state, and the oscillation causes the liquid to generate vortex and shear force, greatly increasing the collision frequency between the magnetotactic bacteria and the Schleringerite particles, so that the magnetotactic bacteria are fully attached to the surface of the Schleringerite powder particles through electrostatic action and microbial adhesion characteristics, realizing the close and uniform compounding of the two. Too low oscillation speed is not enough to overcome the sedimentation of particles and bacteria, and too high oscillation speed will generate too high shear force, which will damage the cell membrane of the magnetotactic bacteria, making it inactivated, losing the functions of magnetic recovery and metabolism, so the oscillation speed is preferably in the range of 120-180 rpm.

[0030] Optionally, in the step S5, the metal salt solution is a zinc acetate dihydrate solution; the organic ligand solution is a 2-methylimidazole solution; and the mixing molar ratio of zinc acetate dihydrate and 2-methylimidazole is (4-8):1. The concentration of the zinc acetate dihydrate solution is preferably 0.1-0.5 M, and the concentration of the 2-methylimidazole solution is preferably 0.4-2.0 M. In a preferred embodiment, the centrifugal speed is 6000-10000 rpm, and the centrifugal time is 5-10 min; the ultrasonic treatment conditions are ice bath, and the time is 30-60 s.

[0031] Optionally, in the step S6, the freezing temperature is -15 to -25℃, and the freezing time is 10-16 hours; the thawing temperature is 15-25℃, and the thawing time is 4-8 hours.

[0032] In step S4, the preparation process of the polyvinyl alcohol solution is as follows: polyvinyl alcohol powder is added to ultrapure water at 90-95℃, and stirred until the polyvinyl alcohol is completely dissolved, and the concentration is preferably 6-12% (mass / volume). The magnetic field strength of the magnetic separation collection is preferably ≥200 mT.

[0033] In step S6, the polyvinyl alcohol solution undergoes the following changes during the cyclic freezing-thawing process, thereby forming a crosslinked network: 1) freezing stage: when the polyvinyl alcohol solution is frozen, pure water ice crystals are first formed, and the growth of the ice crystals repels and concentrates the dissolved polyvinyl alcohol molecular chains to the areas between the ice crystals. In these concentrated areas, the polyvinyl alcohol molecular chains are forced to come close to each other, promoting the formation of hydrogen bonds between the molecular chains, and at the same time, some polyvinyl alcohol segments arrange into regular structures to form tiny crystal regions. These crystal regions and the hydrogen bond network act as physical crosslinking points, giving the hydrogel good elasticity and biocompatibility; 2) thawing stage: after the ice crystals melt, a three-dimensional porous network structure rich in water, i.e., a hydrogel, is formed, which is supported by the crystal regions and the hydrogen bond network; 3) cycle: multiple cycles of freezing-thawing can increase the number and density of crystal regions, making the crosslinked network more stable, thereby significantly improving the mechanical strength, elasticity, and stability of the hydrogel. Preferably, the number of cycles is 2-4 times.

[0034] In the above-mentioned physical crosslinking process, a crosslinking agent can also be added to further undergo chemical crosslinking, forming a stable covalent bond network between molecular chains, thereby constructing a composite network structure with high mechanical strength, anti-swelling property, and long-term stability in complex environments. The crosslinking agent preferably uses ferric chloride, and the concentration is preferably 0.1-0.5 mol / L. In step S4, before the cyclic freezing-thawing crosslinking, the precursor solution is injected into a specific mold, which is made of polypropylene, polystyrene, or polytetrafluoroethylene, and has a shape such as a film, a column, or a sphere.

[0035] The application also provides a multifunctional magnetic hydrogel prepared by the above preparation method.

[0036] The application also provides an application of the above-mentioned multifunctional magnetic hydrogel in repairing heavy metal or organic pollution, including: repairing of heavy metal contaminated water bodies, in-situ / ex-situ repair of heavy metal contaminated soil, repair of electronic waste leaching solution pollution, repair of mine acid wastewater pollution, and / or repair of metallurgical waste leachate pollution.

[0037] The repair treatment of heavy metal contaminated water bodies refers to the treatment of industrial wastewater, municipal sewage, or contaminated surface water containing heavy metal ions (such as Pb 2+ , Cd 2+ , Cu 2+ , Zn 2+ , AsO4 3- , CrO4 2- ) and / or organic pollutants (such as polycyclic aromatic hydrocarbons, pesticides, dyes, and phenols); after the treatment is completed, the multifunctional magnetic hydrogel is quickly separated from the water body by using an external magnetic field, achieving the removal of pollutants and the recycling of the material.

[0038] The in-situ remediation of heavy metal contaminated soil refers to directly adding the multifunctional magnetic hydrogel into the contaminated soil, mixing it with the soil through ploughing, and separating and recycling the multifunctional magnetic hydrogel from the soil through a magnetic separation device after the remediation is completed.

[0039] The ex-situ remediation of heavy metal contaminated soil refers to mixing the contaminated soil with the multifunctional magnetic hydrogel in a reaction container according to a certain proportion, separating the multifunctional magnetic hydrogel from the soil particles by using an external magnetic field after the remediation is completed, and backfilling the purified soil. In addition, the multifunctional magnetic hydrogel can quickly intercept, adsorb and degrade pollutants, and can be used as an emergency treatment material for emergency treatment of sudden environmental pollutant leakage accidents.

[0040] The monitoring of pollutants in contaminated media refers to using the fluorescence or colorimetric response of the multifunctional magnetic hydrogel to qualitatively detect the pollutants in the environmental media.

[0041] It should be noted that in the remediation of heavy metal contaminated water, the mass ratio of the dosage of the multifunctional magnetic hydrogel to the target pollutant is (10-1000):1, and the mass ratio is preferably (50-200):1. The specific dosage needs to be determined through experiments according to the initial concentration of the pollutant, the water quality composition (such as the content of coexisting ions and organic matter), and the target effluent requirements. In the in-situ / ex-situ remediation of heavy metal contaminated soil, the mass ratio of the dosage of the multifunctional magnetic hydrogel to the heavy metal contaminated soil is 0.1%-5%, and the mass ratio is preferably 0.5%-2%.

[0042] In the above pollutant remediation and treatment process, the applicable treatment concentration of heavy metal pollutants is 0.5-500 mg / L, and the preferred treatment concentration is 5-200 mg / L. For pollutants with extremely high concentration (>500 mg / L), dilution or multi-stage treatment is required. The applicable treatment concentration of anion pollutants such as arsenic and chromium is 0.1-100 mg / L, and the preferred treatment concentration is 1-50 mg / L. The applicable treatment concentration of organic pollutants is 0.1-200 mg / L, and the preferred treatment concentration is 1-100 mg / L.

[0043] Further, the suitable pH of heavy metal or organic pollutants is 4.0-9.0, and within this range, the multifunctional magnetic hydrogel can maintain a stable structure and good remediation performance. For extremely acidic pollutants, neutralization treatment is required in advance. The environmental temperature during the treatment process is preferably 4-40°C. The water remediation period is usually 30 minutes-24 hours, and the soil remediation period is usually 14-90 days.

[0044] In the above applications, the multifunctional magnetic hydrogel can be quickly and completely separated and recovered under the action of an external magnetic field. After recovery, the hydrogel can be repeatedly used in the pollution treatment process after proper desorption, washing and regeneration treatment. The separation and recovery mode is specifically as follows: the saturated multifunctional magnetic hydrogel is removed from the external magnetic field and immersed in a desorption agent. The desorption is carried out at 25-30°C under the condition of 50-150 rpm oscillation for 1-4 hours. After the desorption is completed, the hydrogel is separated by a magnetic field, and is repeatedly washed with deionized water until it is neutral. The hydrogel is stored under a wet condition at 4°C for standby use. The selection of the desorption agent: for the hydrogel adsorbing heavy metals, 0.1-0.5M nitric acid or hydrochloric acid solution is selected; for the hydrogel adsorbing organic pollutants, 50%-80% (v / v) ethanol or methanol aqueous solution is selected; for the hydrogel adsorbing heavy metal and organic composite pollution, the continuous steps of acid washing-water washing-organic solvent washing can be adopted to achieve complete desorption and recovery of different types of pollutants.

[0045] The technical scheme provided by the embodiment of the present application has at least the following beneficial effects:

[0046] The multifunctional magnetic hydrogel material provided by the embodiment of the present application combines the Schiff mineral, the magnetotactic bacteria and the functionalized metal organic framework (MOF) material, constructs an intelligent system integrating efficient repair, real-time monitoring and convenient recovery, and effectively solves the problem that the traditional environmental repair material has single function and is difficult to cope with the composite pollution of heavy metals and organic pollutants. In the material, the Schiff mineral and the magnetotactic bacteria synergistically act to significantly improve the adsorption and degradation efficiency of various pollutants. The magnetosome endogenously synthesized by the magnetotactic bacteria endows the material with excellent magnetic response performance, and the material can be quickly and directionally recovered under a weak magnetic field, avoids secondary pollution and supports reuse, and reduces the treatment cost. The functionalized MOF serves as a specific recognition unit to construct a visual monitoring module, and real-time feedback of the pollutant removal process enables the repair process to change from “experience-driven” to “signal-oriented”, realizes precise control, and avoids resource waste. In addition, the polyvinyl alcohol crosslinked network not only provides a stable and permeable three-dimensional carrier environment for each functional component, guarantees the spatial independence and biological / chemical activity thereof, but also significantly enhances the mechanical strength and environmental adaptability of the material. Overall, the material integrates “efficient repair, real-time monitoring and convenient recovery”, has the characteristics of greenness, intelligence and sustainability, and provides an efficient, precise and low-cost treatment technical solution for the comprehensive treatment of composite pollution in complex environments. DETAILED DESCRIPTION

[0047] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without any inventive effort fall within the protection scope of the present application.

[0048] Embodiment 1

[0049] The preparation method of the multifunctional magnetic hydrogel provided by the embodiments of the present application comprises the following steps:

[0050] S1: Preparation of a schlenkite powder

[0051] A 1L acidic aqueous solution with a pH of 3.0 is prepared by using 98% concentrated sulfuric acid, and 16.45g of FeSO4•7H2O is weighed by using an electronic balance and added to the 1L acidic solution above for stirring and dissolution. Under the condition of mechanical stirring (140rpm), 5.3mL of 30% H2O2 solution is added at a speed of 1mL / 120min, and NaOH is added to maintain the pH of the system at 3.0 for 24h during the synthesis process. The obtained reaction solution is centrifuged at a speed of 4500rpm, and the solid is collected, washed with deionized water for 3 times, and then freeze-dried at-80℃ to obtain the chemically synthesized schlenkite. After the dried sample is finely ground into a powder by using a mortar, it is placed in a self-sealing bag for use.

[0052] S2: Preparation of a magnetotactic bacteria suspension

[0053] Magnetospirillum gryphiswaldense MSR-1 is selected, and under micro-aerobic conditions, the magnetospirillum culture medium (MSGM) is used to culture the bacteria in a constant-temperature incubator at 28℃ in the dark for 5 days to enter the stable growth phase. The bacteria are collected by using an external magnetic field (magnetic field strength: 150mT), washed with a sterile buffer of HEPES or PIPES with a pH of 7.0 for 3 times, and finally resuspended in the same buffer to prepare a high-concentration bacterial suspension (OD650=1.5), which is stored at 4℃ for standby use.

[0054] S3: Compound of schlenkite-magnetotactic bacteria

[0055] The magnetotactic bacteria suspension prepared in step S2 and the schlenkite powder prepared in step S1 were mixed at a ratio of 1:1 by volume and mass, and oscillated at 180 rpm for 12 hours to allow the magnetotactic bacteria to adhere to the surface of the schlenkite powder particles by electrostatic attraction and the adhesion properties of the microorganisms, thereby obtaining a schlenkite-magnetotactic bacteria composite; an equal volume of pre-cooled sterile buffer (pH 6.0) was added to the schlenkite-magnetotactic bacteria composite, which was oscillated using a shaker, and then subjected to magnetic separation again (magnetic field strength: 300 mT), and the supernatant was discarded, and this process was repeated 2-3 times to remove unattached schlenkite particles, loosely combined schlenkite particles, and other soluble impurities, and the schlenkite-magnetotactic bacteria composite was collected and stored at 4°C for short-term preservation.

[0056] S4: Preparation of polyvinyl alcohol solution

[0057] Polyvinyl alcohol (type PVA-124, alcoholysis degree > 98%) powder was slowly added to ultrapure water at 95°C to prepare a PVA solution with a concentration of 10% (w / v) at 300 rpm. The temperature was maintained under continuous mechanical stirring until the PVA was completely dissolved and the solution became clear and transparent. The PVA solution was then cooled to 37°C for use.

[0058] S5: Preparation of MOF colloidal solution

[0059] A 0.3M zinc acetate dihydrate solution was quickly poured into a 1.5M zinc acetate dihydrate solution at a mixing ratio of 5:1, and stirred at 25°C for 50 min at 300 rpm. The synthesized solution was centrifuged to remove unreacted precursor molecules and byproducts, and the washed precipitate was dispersed in ultrapure water in an ice bath and ultrasonicated for 40 s to form a uniform and stable colloidal sol, which was stored at 4°C for use.

[0060] S6: Preparation of multifunctional magnetic hydrogel

[0061] The schlenkite-magnetotactic bacteria composite prepared in step S3 and the MOF colloidal solution synthesized in step S5 were added to the polyvinyl alcohol solution prepared in step S4 (mixing ratio of schlenkite-magnetotactic bacteria composite, MOF colloidal solution, and hydrogel matrix: 10:1:89). The mixture was uniformly dispersed by mechanical stirring at 300 rpm to form a mixed precursor solution, which was stored at 37°C. The mixed precursor solution was injected into spherical molds with a diameter of 0.2 mm, and subjected to a freeze-thaw cycle of 12 h freezing at -25°C and 4 h thawing. This cycle was repeated 4 times. After crosslinking was completed, the obtained hydrogel spheres were soaked and washed with ultrapure water for 24 h, with water being changed several times during the period, and finally the multifunctional magnetic hydrogel was obtained, which was stored in a humid state at 4°C.

[0062] Example 2

[0063] The preparation method of the multifunctional magnetic hydrogel provided in the embodiment of the present application is the same as that in Embodiment 1, except that in step S3, the Schleren mineral powder and the magnetotactic bacteria suspension are mixed in a volume-mass ratio of 2:1; and in step S6, the Schleren mineral-magnetotactic bacteria compound, the MOF colloidal solution and the hydrogel matrix are mixed in a mass ratio of 10:1:89.

[0064] Embodiment 3

[0065] The preparation method of the multifunctional magnetic hydrogel provided in the embodiment of the present application is the same as that in Embodiment 1, except that in step S3, the Schleren mineral powder and the magnetotactic bacteria suspension are mixed in a volume-mass ratio of 1:2; and in step S6, the Schleren mineral-magnetotactic bacteria compound, the MOF colloidal solution and the hydrogel matrix are mixed in a mass ratio of 10:1:89.

[0066] Embodiment 4

[0067] The preparation method of the multifunctional magnetic hydrogel provided in the embodiment of the present application is the same as that in Embodiment 1, except that in step S6, the Schleren mineral-magnetotactic bacteria compound, the MOF colloidal solution and the hydrogel matrix are mixed in a mass ratio of 10:1:89.

[0068] Embodiment 5

[0069] The preparation method of the multifunctional magnetic hydrogel provided in the embodiment of the present application is the same as that in Embodiment 1, except that in step S3, the Schleren mineral powder and the magnetotactic bacteria suspension are mixed in a volume-mass ratio of 2:1; and in step S6, the Schleren mineral-magnetotactic bacteria compound, the MOF colloidal solution and the hydrogel matrix are mixed in a mass ratio of 20:4:76.

[0070] Embodiment 6

[0071] The preparation method of the multifunctional magnetic hydrogel provided in the embodiment of the present application is the same as that in Embodiment 3, except that in step S3, the Schleren mineral powder and the magnetotactic bacteria suspension are mixed in a volume-mass ratio of 1:2; and in step S6, the Schleren mineral-magnetotactic bacteria compound, the MOF colloidal solution and the hydrogel matrix are mixed in a mass ratio of 30:6:64.

[0072] Test Example 7-1

[0073] The effects of removing the mixed pollution of chromium (Cr=10mg / L) and phenanthrene (30mg / L) in the aqueous solution by the multifunctional magnetic hydrogel prepared in Embodiments 1-6 are as follows:

[0074] Take 50 mL of chromium-phenanthrene mixed pollution solution into a 250 mL conical flask, add 0.5 g of the multifunctional magnetic hydrogel prepared in Examples 1-6 to the conical flask, mix thoroughly, and cultivate at room temperature. Observe the change in fluorescence color and intensity in the solution under ultraviolet light. After extracting the residual chromium and phenanthrene in the pollution solution, quantitatively detect and analyze the chromium content by inductively coupled plasma mass spectrometry, and determine the phenanthrene content by liquid chromatography.

[0075] Comparative Example 7-1

[0076] The test method is the same as that of Test Example 7-1, except that 0.5 g of schultes mineral is added to remove chromium (Cr=10 mg / L) and phenanthrene (30 mg / L) mixed pollution in the aqueous solution.

[0077] Comparative Example 7-2

[0078] The test method is the same as that of Test Example 7-1, except that 0.5 g of magnetotactic bacteria suspension is added to remove chromium (Cr=10 mg / L) and phenanthrene (30 mg / L) mixed pollution in the aqueous solution.

[0079] Comparative Example 7-3

[0080] The test method is the same as that of Test Example 7-1, except that 0.01 g of MOF colloidal solution is added to remove chromium (Cr=10 mg / L) and phenanthrene (30 mg / L) mixed pollution in the aqueous solution.

[0081] Comparative Example 7-4

[0082] The test method is the same as that of Test Example 7-1, except that 0.5 g of schultes mineral-magnetotactic bacteria composite solution is added to remove chromium (Cr=10 mg / L) and phenanthrene (30 mg / L) mixed pollution in the aqueous solution.

[0083] Test Example 7-2

[0084] The effect of the multifunctional magnetic hydrogel prepared in Examples 1-6 on removing chromium (Cr=10 mg / L) in the aqueous solution is as follows:

[0085] Take 50 ml of chromium pollution solution into a 250 ml conical flask, and add 0.5 g of the multifunctional magnetic hydrogel prepared in Examples 1-6, mix thoroughly, and cultivate at room temperature. Observe the change in fluorescence color and intensity in the solution under ultraviolet light. After extracting the residual chromium in the solution, quantitatively detect and analyze it by inductively coupled plasma mass spectrometry.

[0086] Comparative Example 7-5

[0087] The test method is the same as that of Test Example 7-2, except that 0.5 g of schultes mineral is added to remove chromium (Cr=10 mg / L) in the aqueous solution.

[0088] Comparative Example 7-6

[0089] The test method is the same as in Test Example 7-2, except that 0.5g of magnetotactic bacterial suspension is added to remove chromium (Cr=10mg / L) from the aqueous solution.

[0090] Comparative Example 7-7

[0091] The test method is the same as in Test Example 7-2, except that 0.01g of MOF colloidal solution is added to remove chromium (Cr=10mg / L) from the aqueous solution.

[0092] Comparative Examples 7-8

[0093] The test method is the same as in Test Example 7-2, except that 0.5g of Schiele mineral-magnetotactic bacteria complex solution is added to remove chromium (Cr=10mg / L) from the aqueous solution.

[0094] Test Example 7-3

[0095] The effect of the multifunctional magnetic hydrogels prepared in Examples 1-6 on removing phenanthrene (30 mg / L) from aqueous solution:

[0096] Take 50 ml of phenanthrene-contaminated solution and place it into a 250 ml Erlenmeyer flask. Add 0.5 g of the multifunctional magnetic hydrogel prepared in Examples 1-6, mix thoroughly, and incubate at room temperature. Observe the changes in fluorescence color and intensity in the solution using ultraviolet light. After extracting the residual phenanthrene in the solution, determine the phenanthrene content by liquid chromatography.

[0097] Comparative Examples 7-9

[0098] The test method is the same as in Test Example 7-3, except that 0.5g of Schiele mineral is added to remove phenanthrene (30mg / L) from the aqueous solution.

[0099] Comparative Examples 7-10

[0100] The test method is the same as in test example 7-3, except that 0.5g of magnetotactic bacterial suspension is added to remove phenanthrene (30mg / L) from the aqueous solution.

[0101] Comparative Examples 7-11

[0102] The test method is the same as in Test Example 7-3, except that 0.01g of MOF colloidal solution is added to remove phenanthrene (30mg / L) from the aqueous solution.

[0103] Comparative Examples 7-12

[0104] The test method is the same as in Test Example 7-3, except that 0.5g of Scheres mineral-magnetotactic bacteria complex solution is added to remove phenanthrene (30mg / L) from the aqueous solution.

[0105] The removal rates of chromium and phenanthrene in the aqueous solution in test examples 7-1 to 7-3 and comparative examples 7-1 to 7-12 are shown in Table 1.

[0106] Table 1

[0107]

[0108]

[0109] As can be seen from Table 1, the multifunctional magnetic hydrogel of the present application can simultaneously and efficiently remove chromium and phenanthrene in the solution, and the removal rate of the multifunctional magnetic hydrogel of the present application for chromium pollution in the solution is as high as 92.1% to 100%, and the removal rate for phenanthrene pollution in the solution is as high as 89.7% to 94.0%.

[0110] Test example 8-1

[0111] The effects of the multifunctional magnetic hydrogel prepared in examples 1 to 6 on the removal of chromium (Cr=10 mg / kg) and phenanthrene (30 mg / kg) mixed pollution in soil are as follows:

[0112] 10 g of chromium and phenanthrene mixed pollution soil was taken into a culture dish, 2 g of the multifunctional magnetic hydrogel prepared in examples 1 to 6 was added respectively, the water content was adjusted to 30%, and the mixture was thoroughly mixed and cultured at room temperature. The multifunctional magnetic hydrogel was periodically taken out and observed for the change of fluorescence color and intensity under ultraviolet light. The residual chromium and phenanthrene in the soil was extracted and quantitatively detected and analyzed.

[0113] Comparative example 8-1

[0114] The test method was the same as that in test example 8-1, except that 1 g of schlenk mineral was added to remove chromium (Cr=10 mg / kg) and phenanthrene (30 mg / kg) mixed pollution in soil.

[0115] Comparative example 8-2

[0116] The test method was the same as that in test example 8-1, except that 1 g of magnetotactic bacteria suspension was added to remove chromium (Cr=10 mg / kg) and phenanthrene (30 mg / kg) mixed pollution in soil.

[0117] Comparative example 8-3

[0118] The test method was the same as that in test example 8-1, except that 0.04 g of MOF colloidal solution was added to remove chromium (Cr=10 mg / kg) and phenanthrene (30 mg / kg) mixed pollution in soil.

[0119] Comparative example 8-4

[0120] The test method is the same as that of Test Example 8-1, except that 1 g of the Schleromix - magnetotactic bacteria composite solution is added to remove chromium (Cr = 10 mg / kg) and phenanthrene (30 mg / kg) mixed pollution from the soil.

[0121] Test Example 8-2

[0122] Effect of the multifunctional magnetic hydrogel prepared in Examples 1 to 6 on the removal of chromium (Cr = 10 mg / kg) from soil:

[0123] 10 g of chromium-contaminated soil was taken into a culture dish, 2 g of the multifunctional magnetic hydrogel prepared in Examples 1 to 6 was added, the water content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature. The multifunctional magnetic hydrogel was periodically taken out and observed for changes in fluorescence color and intensity under ultraviolet light. The residual chromium in the soil was extracted and quantitatively detected and analyzed.

[0124] Comparative Example 8-5

[0125] The test method is the same as that of Test Example 8-2, except that 1 g of Schleromix is added to remove chromium (Cr = 10 mg / kg) from the soil.

[0126] Comparative Example 8-6

[0127] The test method is the same as that of Test Example 8-2, except that 1 g of a magnetotactic bacteria suspension is added to remove chromium (Cr = 10 mg / kg) from the soil.

[0128] Comparative Example 8-7

[0129] The test method is the same as that of Test Example 8-2, except that 0.04 g of a MOF colloidal solution is added to remove chromium (Cr = 10 mg / gk) from the soil.

[0130] Comparative Example 8-8

[0131] The test method is the same as that of Test Example 8-2, except that 1 g of the Schleromix - magnetotactic bacteria composite solution is added to remove chromium (Cr = 10 mg / kg) and phenanthrene (30 mg / kg) mixed pollution from the soil.

[0132] Test Example 8-3

[0133] Effect of the multifunctional magnetic hydrogel prepared in Examples 1 to 6 on the removal of phenanthrene (30 mg / kg) from soil:

[0134] 10 g of phenanthrene-contaminated soil was taken into a culture dish, 2 g of the multifunctional magnetic hydrogel prepared in Examples 1 to 6 was added, the water content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature. The multifunctional magnetic hydrogel was periodically taken out and observed for changes in fluorescence color and intensity under ultraviolet light. The residual phenanthrene in the soil was extracted and quantitatively detected and analyzed.

[0135] Comparative Examples 8-9

[0136] The test method is the same as in test example 8-3, except that 1g of Scheres mineral is added to remove phenanthrene (30mg / kg) from the soil.

[0137] Comparative Examples 8-10

[0138] The test method is the same as in test example 8-3, except that 1g of magnetotactic bacterial suspension is added to remove phenanthrene (30mg / kg) from the soil.

[0139] Comparative Examples 8-11

[0140] The test method is the same as in Test Example 8-3, except that 0.04g of MOF colloidal solution was added to remove phenanthrene (30mg / kg) from the soil.

[0141] Comparative Examples 8-12

[0142] The test method is the same as in test example 8-3, except that 1g of Scheres mineral-magnetotactic bacteria complex solution is added to remove phenanthrene (30mg / kg) from the soil.

[0143] The removal rates of chromium and phenanthrene in the soil of the above test examples 8-1 to 8-3 and comparative examples 8-1 to 8-12 are shown in Table 2.

[0144] Table 2

[0145]

[0146]

[0147] As shown in Table 2, the addition of the multifunctional magnetic hydrogel of the present invention can simultaneously and efficiently remove chromium and phenanthrene from the soil. The multifunctional magnetic hydrogel of the present invention has a removal rate of 80.5% to 89.8% for chromium pollution in soil and a removal rate of 67.8% to 78.3% for phenanthrene pollution in soil.

[0148] Test Example 9

[0149] The recycling effect of the multifunctional magnetic hydrogels prepared in Examples 1-6 on the removal of chromium and phenanthrene in aqueous solution:

[0150] The multifunctional magnetic hydrogels prepared in Examples 1-6 were used to investigate the removal rates of chromium and phenanthrene in solutions after repeated applications. After each treatment, the multifunctional magnetic hydrogel was desorbed and recycled by sequentially washing with 0.3M nitric acid, water, and methanol aqueous solution. The multifunctional magnetic hydrogel was then reintroduced into the untreated original chromium and phenanthrene contaminated solution, and the degree to which the material retained its removal capacity after three repeated uses was tested. Other application methods were the same as in Test Example 7.

[0151] Comparative Example 9-1

[0152] The same as Test Example 9, except that the multifunctional magnetic hydrogel was re- introduced into the untreated original chromium contaminated solution.

[0153] Comparative Example 9-2

[0154] The same as Test Example 9, except that the multifunctional magnetic hydrogel was re- introduced into the untreated original phenanthrene contaminated solution.

[0155] The removal rates of chromium and phenanthrene in the solutions in Test Example 9, Comparative Examples 9-1 and 9-2 are shown in Table 3.

[0156] Table 3

[0157]

[0158]

[0159] As can be seen from Table 3, the multifunctional magnetic hydrogel of the present application still has a high removal rate for chromium and phenanthrene in solution after multiple adsorption-desorption cycles, indicating that the multifunctional magnetic hydrogel prepared in the present application has a stable structure, good mechanical properties, reversible adsorption sites and durability in chromium and phenanthrene contaminated solutions, and is reusable.

[0160] Test Example 10

[0161] Circulation effect of the recyclable multifunctional magnetic hydrogel prepared by using the multifunctional magnetic hydrogel prepared in Example 1 to remove chromium and phenanthrene in soil:

[0162] The multifunctional magnetic hydrogel prepared in Example 1 was selected to investigate the removal rate of chromium and phenanthrene in soil after multiple applications. After each treatment, 0.3M nitric acid, water and methanol solution were used in sequence to desorb the multifunctional magnetic hydrogel, and the multifunctional magnetic hydrogel was re-introduced into the untreated original chromium and phenanthrene contaminated soil, and the retention degree of the removal capacity of the material itself after 3 times of reuse of the multifunctional magnetic hydrogel was tested. Other application modes were the same as in Example 8.

[0163] Comparative Example 10-1

[0164] The same as Test Example 10, except that the multifunctional magnetic hydrogel was re- introduced into the untreated original chromium contaminated soil.

[0165] Comparative Example 10-2

[0166] The same as Test Example 10, except that the multifunctional magnetic hydrogel was re- introduced into the untreated original phenanthrene contaminated soil.

[0167] The removal rates of chromium and phenanthrene in the soil in the above test example 10, comparative examples 10-1 and 10-2 are shown in Table 4.

[0168] Table 4

[0169]

[0170]

[0171] As can be seen from Table 4, the multifunctional magnetic hydrogel of the present application still has a high removal rate for chromium and phenanthrene in soil pollution after multiple adsorption-desorption cycles, indicating that the multifunctional magnetic hydrogel prepared in the present application has a stable structure, good mechanical properties, reversible adsorption sites and durability in chromium and phenanthrene contaminated soil, and has reusability.

[0172] Test Example 11-1

[0173] The effect of removing mixed pollution of arsenic (As = 2 mg / L) and sulfamethoxazole (200 μg / L) in aqueous solution by the multifunctional magnetic hydrogel prepared in Examples 1-6 is as follows:

[0174] 50 ml of arsenic and sulfamethoxazole mixed pollution solution was taken into a 250 ml conical flask, 0.5 g of multifunctional magnetic hydrogel prepared in Examples 1-6 was added, and the solution was mixed and incubated at room temperature. The change in fluorescence color and intensity in the solution was observed under ultraviolet light. After extracting the residual arsenic and sulfamethoxazole in the solution, the arsenic content was quantitatively detected and analyzed by inductively coupled plasma mass spectrometry, and the sulfamethoxazole content was determined by liquid chromatography.

[0175] Comparative Example 11-1

[0176] The test method is the same as that in Test Example 11-1, except that 0.5 g of schultes mineral is added to remove mixed pollution of arsenic (As = 2 mg / L) and sulfamethoxazole (200 μg / L) in aqueous solution.

[0177] Comparative Example 11-2

[0178] The test method is the same as that in Test Example 11-1, except that 0.5 g of magnetotactic bacteria suspension is added to remove mixed pollution of arsenic (As = 2 mg / L) and sulfamethoxazole (200 μg / L) in aqueous solution.

[0179] Comparative Example 11-3

[0180] The test method is the same as that in Test Example 11-1, except that 0.01 g of MOF colloidal solution is added to remove mixed pollution of arsenic (As = 2 mg / L) and sulfamethoxazole (200 μg / L) in aqueous solution.

[0181] Comparative Example 11-4

[0182] The test method is the same as that in Test Example 11-1, except that 0.5 g of the Sheng's mineral-magnetic bacteria composite solution is added to remove arsenic (As = 2 mg / L) and sulfamethoxazole (200 μg / L) mixed pollution in the aqueous solution.

[0183] Test Example 11-2

[0184] Effect of the multifunctional magnetic hydrogel prepared in Examples 1-6 on removal of arsenic (As = 2 mg / L) in an aqueous solution:

[0185] 50 ml of an arsenic contaminated solution was taken in a 250 ml conical flask, 0.5 g of the multifunctional magnetic hydrogel prepared in Examples 1-6 was added, and the solution was mixed thoroughly and incubated at room temperature. The change in fluorescence color and intensity of the solution was observed under ultraviolet light. The arsenic content was quantitatively detected and analyzed by inductively coupled plasma mass spectrometry.

[0186] Comparative Example 11-5

[0187] The test method is the same as that in Test Example 11-2, except that 0.5 g of Sheng's mineral is added to remove arsenic (As = 2 mg / L) in the aqueous solution.

[0188] Comparative Example 11-6

[0189] The test method is the same as that in Test Example 11-2, except that 0.5 g of a magnetic bacteria suspension is added to remove arsenic (As = 2 mg / L) in the aqueous solution.

[0190] Comparative Example 11-7

[0191] The test method is the same as that in Test Example 11-2, except that 0.01 g of a MOF colloidal solution is added to remove arsenic (As = 2 mg / L) in the aqueous solution.

[0192] Comparative Example 11-8

[0193] The test method is the same as that in Test Example 11-2, except that 0.5 g of the Sheng's mineral-magnetic bacteria composite solution is added to remove arsenic (As = 2 mg / L) in the aqueous solution.

[0194] Test Example 11-3

[0195] Effect of the multifunctional magnetic hydrogel prepared in Examples 1-6 on removal of sulfamethoxazole (200 μg / L) in an aqueous solution:

[0196] Take 50 ml sulfamethoxazole contaminated solution into 250 ml conical flask, add 0.5 g of multifunctional magnetic hydrogel prepared in examples 1-6, mix well, cultivate at room temperature, observe the change of fluorescence color and intensity in solution with ultraviolet light. After extracting the residual sulfamethoxazole in solution, determine the content of sulfamethoxazole by liquid chromatography.

[0197] Comparative example 11-9

[0198] The test method is the same as test example 11-3, except that 0.5 g of schultes mineral is added to remove sulfamethoxazole (200 μg / L) in aqueous solution.

[0199] Comparative example 11-10

[0200] The test method is the same as test example 11-3, except that 0.5 g of magnetotactic bacteria suspension is added to remove sulfamethoxazole (200 μg / L) in aqueous solution.

[0201] Comparative example 11-11

[0202] The test method is the same as test example 11-3, except that 0.01 g of MOF colloidal solution is added to remove sulfamethoxazole (200 μg / L) in aqueous solution.

[0203] Comparative example 11-12

[0204] The test method is the same as test example 11-3, except that 0.5 g of schultes mineral-magnetotactic bacteria composite solution is added to remove sulfamethoxazole (200 μg / L) in aqueous solution.

[0205] The removal rates of arsenic and sulfamethoxazole in the above test examples 11-1 to 11-3 and comparative examples 11-1 to 11-12 are shown in Table 5.

[0206] Table 5

[0207]

[0208]

[0209]

[0210] As can be seen from Table 5, the addition of multifunctional magnetic hydrogel of the application can simultaneously and efficiently remove arsenic and sulfamethoxazole in solution, the removal rate of multifunctional magnetic hydrogel of the application for arsenic pollution in solution is as high as 87.5% to 100%, and the removal rate for sulfamethoxazole pollution in solution is as high as 82.1% to 96.3%.

[0211] Test example 12-1

[0212] The effect of removing arsenic (As = 70 mg / kg) and sulfamethoxazole (1 mg / kg) mixed pollution from soil by using the multifunctional magnetic hydrogel prepared in Examples 1-6:

[0213] 10 g of soil mixedly polluted by arsenic and sulfamethoxazole was taken into a culture dish, 2 g of multifunctional magnetic hydrogel prepared in Examples 1-6 was added respectively, the water content was adjusted to 30%, and then it was mixed thoroughly and cultured at room temperature. The multifunctional magnetic hydrogel was taken out regularly to observe the change of fluorescence color and intensity under ultraviolet light. The residual arsenic and sulfamethoxazole in the soil were extracted and then quantitatively detected and analyzed.

[0214] Comparative Example 12-1

[0215] The test method was the same as that in Test Example 12-1, except that 1 g of schlenk mineral was added to remove arsenic (As = 70 mg / kg) and sulfamethoxazole (1 mg / kg) mixed pollution from soil.

[0216] Comparative Example 12-2

[0217] The test method was the same as that in Test Example 12-1, except that 1 g of magnetotactic bacteria suspension was added to remove arsenic (As = 70 mg / kg) and sulfamethoxazole (1 mg / kg) mixed pollution from soil.

[0218] Comparative Example 12-3

[0219] The test method was the same as that in Test Example 12-1, except that 0.04 g of MOF colloidal solution was added to remove arsenic (As = 70 mg / kg) and sulfamethoxazole (1 mg / kg) mixed pollution from soil.

[0220] Comparative Example 12-4

[0221] The test method was the same as that in Test Example 12-1, except that 1 g of schlenk mineral-magnetotactic bacteria composite solution was added to remove arsenic (As = 70 mg / kg) and sulfamethoxazole (1 mg / kg) mixed pollution from soil.

[0222] Test Example 12-2

[0223] The effect of removing arsenic (As = 70 mg / kg) from soil by using the multifunctional magnetic hydrogel prepared in Examples 1-6:

[0224] 10 g of arsenic contaminated soil was taken into a culture dish, 2 g of multifunctional magnetic hydrogel prepared in Examples 1-6 was added respectively, the water content was adjusted to 30%, and then it was mixed thoroughly and cultured at room temperature. The multifunctional magnetic hydrogel was taken out regularly to observe the change of fluorescence color and intensity under ultraviolet light. The residual arsenic in the soil was extracted and then quantitatively detected and analyzed.

[0225] Comparative Example 12-5

[0226] The test method is the same as that of Test Example 12-2, except that 1 g of Schlegel's mineral is added, and arsenic in the soil is removed (As = 70 mg / kg).

[0227] Comparative Example 12-6

[0228] The test method is the same as that of Test Example 12-2, except that 1 g of Schlegel's mineral is added, and arsenic in the soil is removed (As = 70 mg / kg).

[0229] Comparative Example 12-7

[0230] The test method is the same as that of Test Example 12-2, except that 1 g of Schlegel's mineral is added, and arsenic in the soil is removed (As = 70 mg / kg).

[0231] Comparative Example 12-8

[0232] The test method is the same as that of Test Example 12-2, except that 1 g of Schlegel's mineral is added, and arsenic in the soil is removed (As = 70 mg / kg).

[0233] Test Example 12-3

[0234] The effect of removing sulfamethoxazole (1 mg / kg) in soil using the multifunctional magnetic hydrogel prepared in Examples 1 to 6:

[0235] 10 g of sulfamethoxazole-contaminated soil was taken into a culture dish, 2 g of multifunctional magnetic hydrogel prepared in Examples 1 to 6 was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature. The multifunctional magnetic hydrogel was periodically removed and observed for changes in fluorescence color and intensity under ultraviolet light. The residual sulfamethoxazole in the soil was extracted and quantitatively analyzed.

[0236] Comparative Example 12-9

[0237] The test method is the same as that of Test Example 12-3, except that 1 g of Schlegel's mineral is added, and sulfamethoxazole in the soil is removed (1 mg / kg).

[0238] Comparative Example 12-10

[0239] The test method is the same as that of Test Example 12-3, except that 1 g of Schlegel's mineral is added, and sulfamethoxazole in the soil is removed (1 mg / kg).

[0240] Comparative Example 12-11

[0241] The test method is the same as that of Test Example 12-3, except that 1 g of Schlegel's mineral is added, and sulfamethoxazole in the soil is removed (1 mg / kg).

[0242] Comparative Example 12-12

[0243] The test method is the same as that of Test Example 12-3, except that 1 g of the Shewanella-Bacillus magnetotactic bacteria composite solution is added, and sulfamethoxazole (1 mg / kg) is removed from the soil.

[0244] The removal rates of arsenic and sulfamethoxazole in the soil in Test Examples 12-1 to 12-3 and Comparative Examples 12-1 to 12-12 above are shown in Table 6.

[0245] Table 6

[0246]

[0247]

[0248]

[0249] As can be seen from Table 6, the multifunctional magnetic hydrogel of the present application can simultaneously and efficiently remove arsenic and sulfamethoxazole from the soil. The removal rate of the multifunctional magnetic hydrogel of the present application for arsenic pollution in the soil is as high as 51.4% to 71.5%, and the removal rate for sulfamethoxazole pollution in the soil is as high as 48.9% to 65.8%.

[0250] Test Example 13

[0251] Cyclic effect of the recyclable multifunctional magnetic hydrogel prepared by using Examples 1 to 6 on removal of arsenic and sulfamethoxazole in an aqueous solution:

[0252] The multifunctional magnetic hydrogel prepared by using Examples 1 to 6 is selected to explore the removal rate of chromium and phenanthrene in the solution after multiple applications. After each treatment, 0.3 M nitric acid, water, and methanol solution are used in sequence to desorb the recycled multifunctional magnetic hydrogel, and the multifunctional magnetic hydrogel is re-disposed into the untreated original arsenic and sulfamethoxazole contaminated solution. The degree of retention of the removal capacity of the material itself after the multifunctional magnetic hydrogel is tested for 3 times of repeated use. Other application modes are the same as those of Test Example 7.

[0253] Comparative Example 13-1

[0254] The same as Test Example 13, except that the multifunctional magnetic hydrogel is re-disposed into the untreated original arsenic contaminated solution.

[0255] Comparative Example 13-2

[0256] The same as Test Example 13, except that the multifunctional magnetic hydrogel is re-disposed into the untreated original sulfamethoxazole contaminated solution.

[0257] The removal rates of arsenic and sulfamethoxazole in the solution in Test Example 13, Comparative Examples 13-1 and 13-2 are shown in Table 7.

[0258] Table 7

[0259]

[0260]

[0261] As can be seen from Table 7, the multifunctional magnetic hydrogel of the present application still has a high removal rate for arsenic and sulfamethoxazole in the solution after multiple adsorption-desorption cycles, indicating that the multifunctional magnetic hydrogel prepared in the present application has a stable structure, good mechanical properties, reversible adsorption sites and durability in the arsenic and sulfamethoxazole contaminated solution, and has reusability.

[0262] Test Example 14

[0263] Circulation effect of the recyclable multifunctional magnetic hydrogel prepared by using the multifunctional magnetic hydrogel prepared in Example 1 to remove arsenic and sulfamethoxazole in soil:

[0264] The multifunctional magnetic hydrogel prepared in Example 1 was selected to investigate the removal rate of arsenic and sulfamethoxazole in soil after multiple applications. After each treatment, 0.3M nitric acid, water and methanol solution were used in sequence to desorb the multifunctional magnetic hydrogel, and the multifunctional magnetic hydrogel was re-disposed into untreated original arsenic and sulfamethoxazole contaminated soil, and the retention degree of the removal capacity of the material itself after 3 times of reuse of the multifunctional magnetic hydrogel was tested. Other application methods were the same as in Example 8.

[0265] Comparative Example 14-1

[0266] The same as Test Example 14, except that the multifunctional magnetic hydrogel was re-disposed into untreated original arsenic contaminated soil.

[0267] Comparative Example 14-2

[0268] The same as Test Example 14, except that the multifunctional magnetic hydrogel was re-disposed into untreated original sulfamethoxazole contaminated soil.

[0269] The removal rates of arsenic and sulfamethoxazole in the soil in Test Example 14, Comparative Examples 14-1 and 14-2 are shown in Table 8.

[0270] Table 8

[0271]

[0272]

[0273] As shown in Table 8, the multifunctional magnetic hydrogel has high removal rates of arsenic and sulfamethoxazole in soil after multiple adsorption-desorption cycles, indicating that the multifunctional magnetic hydrogel prepared in the application has stable structure, good mechanical properties, reversible adsorption sites and durability in arsenic and sulfamethoxazole contaminated soil, and has reusability.

[0274] The above merely provides a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for preparing a multifunctional magnetic hydrogel, characterized in that, Includes the following steps: S1: Preparation of Schiele mineral powder; S2: Preparation of magnetotactic bacterial suspension; S3: Schiele mineral-magnetotactic bacteria complex: The magnetic bacteria suspension is mixed with the Schiele mineral by shaking, so that the magnetic bacteria attach to the surface of the Schiele mineral powder particles, and the Schiele mineral-magnetotactic bacteria complex is obtained by magnetic separation. S4: Preparation of polyvinyl alcohol solution: Add polyvinyl alcohol powder to deionized water to prepare polyvinyl alcohol solution; S5: Preparation of MOF colloidal solution: Add the organic ligand solution to the metal salt solution, centrifuge to remove the precipitate, dissolve the precipitate in deionized water and sonicate to obtain MOF colloidal solution; S6: Preparation of multifunctional magnetic hydrogel: The Scheres mineral-magnetotactic bacteria complex was mixed with MOF colloidal solution in polyvinyl alcohol solution and stirred to obtain a precursor solution; the precursor solution was placed under cyclic freeze-thaw conditions to allow it to crosslink, thereby obtaining a three-dimensional network multifunctional magnetic hydrogel.

2. The preparation method according to claim 1, characterized in that, The mass-to-volume ratio of the Scheres mineral to the magnetotactic bacterial suspension is (3~1):1; the mass ratio of the Scheres mineral-magnetotactic bacterial complex, MOF colloidal solution, and polyvinyl alcohol solution is (10~25):(1~5):(70~85); wherein the concentration of the magnetotactic bacterial suspension is OD650≥1.

5.

3. The preparation method according to claim 1, characterized in that, Magnetotactic bacteria belong to the genus *Magnetic Spirulina*.

4. The preparation method according to claim 1, characterized in that, In step S1, the method for preparing Schöndorff mineral powder includes: Ferrous sulfate and hydrogen peroxide are reacted in an acidic environment with a pH of 2.4 to 3.0 to obtain a reaction solution. The reaction solution is centrifuged to remove the supernatant and obtain a precipitate. The precipitate is then frozen, dried, and pulverized to obtain Schiele mineral powder.

5. The preparation method according to claim 1, characterized in that, In step S2, the method for preparing the magnetotactic bacterial suspension includes: Magnetotactic bacteria were inoculated into a magnetic spirochete culture medium and cultured at 25-30°C for 3-7 days. The bacterial cells were collected using an external magnetic field and dissolved in a sterile buffer to obtain a magnetic tactic bacterial suspension.

6. The preparation method according to claim 1, characterized in that, In step S3, the temperature of the oscillation mixing is 25~30℃, the oscillation time is 2~12 hours, and the oscillation speed is 120~180rpm.

7. The preparation method according to claim 1, characterized in that, In step S5, the metal salt solution is zinc acetate dihydrate; the organic ligand solution is 2-methylimidazole; wherein the molar ratio of zinc acetate dihydrate to 2-methylimidazole is (4~8):

1.

8. The preparation method according to claim 1, characterized in that, In step S6, the freezing temperature is -15 to -25°C and the freezing time is 10 to 16 hours; the thawing temperature is 15 to 25°C and the thawing time is 4 to 8 hours.

9. A multifunctional magnetic hydrogel, characterized in that, It is prepared using the preparation method described in any one of claims 1 to 8.

10. The application of the multifunctional magnetic hydrogel of claim 9 in the remediation of heavy metal or organic pollution, characterized in that, include: Remediation of water bodies contaminated with heavy metals, in-situ / ex-situ remediation of soil contaminated with heavy metals, remediation of leachate contamination from electronic waste, remediation of acidic wastewater contamination from mines, remediation of leachate contamination from metallurgical slag, and / or monitoring of pollutants in contaminated media.

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