Preparation method and application of magnetic hydrogel

Abstract

The invention provides a preparation method and application of magnetic hydrogel, and relates to the technical field of environmental pollution treatment. The embodiment of the invention provides a preparation method and application of magnetic hydrogel. The preparation method comprises the following steps: S1, preparing a magnetotactic bacterium suspension; s2, preparing Schwertmannite powder; s3, the magnetotactic bacterium suspension and the schwertmannite are oscillated and mixed, so that magnetotactic bacteria are attached to the surfaces of schwertmannite powder particles, and a magnetotactic bacterium-schwertmannite compound is obtained; s4, mixing the magnetotactic bacteria-schwertmannite compound in an aqueous solution of polyvinyl alcohol, and stirring to obtain a precursor solution; placing the precursor solution under a circulating freezing-unfreezing condition for crosslinking, so as to obtain the three-dimensional network magnetic hydrogel. According to the preparation method and application of the magnetic hydrogel provided by the embodiment of the invention, a'magnetotactic bacteria-schwertmannite-polyvinyl alcohol 'ternary composite system is constructed, so that a repair material which can be magnetically recycled and can synchronously remove heavy metals and organic pollutants is formed.

Description

Technical Field

[0001] This invention relates to the field of environmental pollution control technology, and in particular to a method for preparing and applying a magnetic hydrogel. Background Technology

[0002] With the acceleration of industrialization and urbanization, water environments and soil systems are facing increasingly severe challenges from combined pollution by heavy metals and organic pollutants. Heavy metals such as lead (Pb), cadmium (Cd), chromium (Cr), and arsenic (As) are persistent, bioaccumulative, and highly toxic, difficult to degrade through natural processes, and can accumulate through the food chain, posing a serious threat to ecosystems and public health. Meanwhile, persistent organic pollutants (POPs) such as polycyclic aromatic hydrocarbons (PAHs), pesticides, and endocrine disruptors are widespread, exhibiting carcinogenic, teratogenic, and mutagenic effects, further exacerbating the risk of environmental pollution. Adding to the complexity, these pollutants often coexist in complex forms, interacting synergistically, additively, or antagonistically, significantly increasing the uncertainty of environmental behavior and the difficulty of remediation. Traditional single remediation technologies, such as adsorption, chemical precipitation, or biodegradation, often fail to simultaneously and efficiently remove multiple pollutants with vastly different properties, and are prone to secondary pollution problems. Therefore, developing efficient remediation technologies and materials that can simultaneously target heavy metals and organic pollutants, are suitable for complex environmental media, and are environmentally friendly has become an urgent need in the current environmental field. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a method for preparing and applying a magnetic hydrogel. The technical solution is as follows:

[0004] This invention provides a method for preparing a magnetic hydrogel, comprising the following steps:

[0005] S1: Preparation of magnetotactic bacterial suspension;

[0006] S2: Preparation of Schiele mineral powder;

[0007] S3: The magnetotactic bacterial suspension is mixed with the Scheringer mineral by oscillation, so that the magnetotactic bacteria attach to the surface of the Scheringer mineral powder particles, and the magnetotactic bacteria-Scheringer mineral complex is obtained by magnetic separation.

[0008] S4: The magnetotactic bacteria-Schönlein mineral complex is mixed in an aqueous solution of polyvinyl alcohol and stirred to obtain a precursor solution; the precursor solution is placed under cyclic freeze-thaw conditions to allow it to crosslink, thereby obtaining a three-dimensional network magnetic hydrogel.

[0009] Magnetotactic bacteria are a class of microorganisms capable of synthesizing chain-like nanoscale magnetic particles (magnetosomes) within their cells through biomineralization. The functional groups on the surface of the bacteria and magnetosomes, including carboxyl, amino, and phosphate groups, can effectively adsorb Pb. 2+ Cd 2+ Cu 2+ This system can remove heavy metal ions and simultaneously degrade polycyclic aromatic hydrocarbons, pesticides, and other organic pollutants through metabolic enzymes and reducing substances. Its inherent magnetic navigation properties allow the bacteria to move and accumulate under magnetic field guidance, providing an efficient pathway for the rapid separation and recovery of remediation materials, thus avoiding the difficulties in recycling traditional remediation materials and the risk of secondary pollution. However, single-cell treatment systems have significant limitations, including insufficient selective adsorption capacity for specific pollutants such as arsenates and chromates; susceptibility to pH, temperature, and nutrient conditions in complex environments leading to unstable metabolic activity and remediation efficiency; the tendency for nanoscale magnetic particles to aggregate, reducing active sites; and high large-scale cultivation costs, all of which severely restrict its practical application.

[0010] To address the aforementioned problems with magnetic microstructures, this invention introduces Schwertmannite (Fe8O8(OH)6(SO4)·nH2O) as a complementary material. This Schwertmannite, with its unique tunnel-like crystal structure and large specific surface area, effectively counteracts the effects of arsenate (AsO4) radicals. 3- ), chromate (CrO4) 2- Anionic pollutants such as ) exhibit specific adsorption advantages, while their surface Fe 2+ / Fe 3 + Redox pairs can activate persulfate to produce strong oxidizing sulfate radicals (SO4·). - This significantly enhances the catalytic degradation capacity of organic pollutants. However, Schiele minerals themselves suffer from drawbacks such as being loosely aggregated at the micron level, lacking magnetism, and being difficult to recycle.

[0011] Research has revealed that biofilms and extracellular polymers produced by magnetotactic bacteria during metabolism provide nucleation sites and stabilizing conditions for the formation of Schehertz minerals, while the presence of minerals provides physical protection and additional adsorption sites for the bacteria, resulting in a significant bio-mineral synergistic effect. Simultaneously, the magnetic response characteristics of magnetotactic bacteria enable the rapid and thorough separation and recovery of magnetic hydrogels under an applied magnetic field, fundamentally solving the problem of Schehertz mineral separation and recovery. This organic combination not only overcomes the practical application limitations of magnetotactic bacteria as a single material but also achieves the dual goals of synergistic removal and material recovery of multiple pollutants through functional complementarity.

[0012] Furthermore, by introducing polyvinyl alcohol (PVA) to construct a three-dimensional network hydrogel framework, this invention can simultaneously and effectively immobilize magnetotactic bacteria and Schiele mineral particles, significantly enhancing the mechanical strength and environmental stability of the composite material. Moreover, the porous nature of PVA provides an efficient channel for pollutant transport and bacterial metabolic processes, while its excellent biocompatibility ensures the maintenance of the metabolic activity of the immobilized magnetotactic bacteria. Ultimately, through multiple mechanisms of carrier stability, functional synergy, and activity protection, the synergistic effect of the magnetotactic bacteria-Schiele mineral-polyvinyl alcohol ternary system in pollution control is achieved.

[0013] Optionally, the volume-to-mass ratio of the magnetotactic bacterial suspension to the Scheres mineral is 1:(1~1.5); the mass ratio of the magnetotactic bacterial-Scheres mineral complex to polyvinyl alcohol is 1:(5~20); wherein the concentration of the magnetotactic bacterial suspension is OD650≥1.5.

[0014] Optionally, the magnetotactic bacteria are of the genus Magnetospira, specifically Magnetospirillum ryphiswaldense MSR-1, with accession number CGMCC 1.5154.

[0015] Optionally, in step S1, the method for preparing the magnetotactic bacterial suspension includes: inoculating magnetotactic bacteria into a magnetic spirochete culture medium, culturing at 25-30°C for 3-7 days, collecting the bacterial cells using an external magnetic field, and dissolving the bacterial cells in a sterile buffer to obtain the magnetotactic bacterial suspension. The magnetic spirochete culture medium is cultured under microaerobic conditions in the dark, and the bacterial cells are collected using a magnetic field after entering the stable growth phase. The magnetic field strength of the external magnetic field is ≥100 mT. For magnetotactic bacteria, a field strength greater than 100 mT can generate a sufficiently large magnetic force to ensure that the bacterial cells can still be captured and separated quickly and efficiently in complex environmental media, achieving rapid recovery. Field strengths below 100 mT result in slow separation and long processing time. The sterile buffer can be HEPES buffer or PIPES buffer with a pH of 6.5-7.5. HEPES and PIPES buffers have good buffering capacity, 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.

[0016] Optionally, in step S2, the method for preparing Schöndorff mineral powder includes: reacting ferrous sulfate with hydrogen peroxide in an acidic environment with a pH of 2.4 to 3.0 to obtain a reaction solution; centrifuging the reaction solution to remove impurities and obtaining a precipitate; and freezing, drying, and pulverizing the precipitate at a temperature of -80°C to -50°C to obtain Schöndorff mineral powder.

[0017] At room temperature, Fe 2+ The reaction with hydrogen peroxide is violent and rapid, which can lead to Fe 3+The concentration rapidly reaches supersaturation, initiating heterogeneous nucleation and generating a mixture of iron hydroxides. Lowering the temperature to -80℃ to -50℃ drastically reduces the molecular thermal energy, significantly slowing down the rate of the entire oxidation and hydrolysis reaction. This promotes the formation of more numerous and more uniformly sized crystal nuclei, resulting in pure and well-crystallized Schiele minerals.

[0018] Schielene mineral is a metastable iron hydroxyl sulfate mineral that readily transforms into more stable iron oxides during synthesis. At higher pH levels, Fe... 3+ The hydrolysis reaction rate will increase dramatically, and the OH- produced by hydrolysis - More will preferentially promote the nucleation and growth of more stable iron hydroxide minerals such as goethite (α-FeOOH) or ferrihydrite, while at extremely low pH, H + Excessive concentration will strongly inhibit Fe 3+ The hydrolysis reaction makes nucleation of Schiele minerals or other iron oxides extremely difficult or slow, resulting in low reaction efficiency. Therefore, the reaction should be carried out in an acidic environment with a pH of 2.4 to 3.0.

[0019] Ferrous sulfate can be ferrous sulfate heptahydrate (FeSO4·7H2O) with a relatively stable structure. The preferred concentration of ferrous sulfate heptahydrate is 0.05M, and the preferred mass concentration of hydrogen peroxide is 30%. For acidic environment, it is preferred to prepare an acidic aqueous solution with a pH of 2.4~3.0 using 98% concentrated sulfuric acid. Sodium hydroxide needs to be added during the synthesis process to maintain the pH of the entire reaction system within the range of 2.4~3.0.

[0020] Optionally, in step S3, the temperature of the oscillation mixing is 25-30°C, the oscillation time is 2-12 hours, and the oscillation speed is 120-180 rpm. Schiele minerals are micron-sized loose aggregates that rapidly settle under static conditions, preventing them from effectively combining with magnetotactic bacteria. The hydrodynamics generated by oscillation ensures that the particles and bacteria remain suspended, and the oscillation creates eddies and shear forces in the liquid, greatly increasing the collision frequency between the magnetotactic bacteria and the Schiele mineral particles. This allows the magnetotactic bacteria to effectively adsorb onto the surface of the Schiele mineral particles, achieving a tight and uniform combination. Too low an oscillation rate is insufficient to overcome the settling of particles and bacteria, while too high an oscillation rate generates excessive shear forces, damaging the cell membranes of the magnetotactic bacteria, causing them to become inactive and lose their magnetic recovery and metabolic functions. Therefore, the oscillation rate is preferably in the range of 120-180 rpm.

[0021] Optionally, in step S4, 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.

[0022] In step S4, the polyvinyl alcohol solution is prepared by adding polyvinyl alcohol powder to ultrapure water at 90-95°C and stirring until the polyvinyl alcohol is completely dissolved. The preferred concentration is 6-12% by mass-volume ratio. The magnetic field strength for magnetic separation is preferably ≥200 mT.

[0023] During the cyclic freeze-thaw process, the polyvinyl alcohol solution undergoes the following changes, forming a cross-linked network: 1) Freezing stage: When the polyvinyl alcohol solution is frozen, pure water ice crystals first form. The growth of the ice crystals repels and concentrates the dissolved polyvinyl alcohol molecular chains into the regions between the ice crystals. In these concentrated regions, the polyvinyl alcohol molecular chains are forced to approach each other, promoting the formation of hydrogen bonds between the molecular chains. At the same time, some polyvinyl alcohol segments will arrange themselves into a regular structure, forming tiny crystalline regions. These crystalline regions and the hydrogen bond network serve as physical cross-linking 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, supported by crystalline regions and hydrogen bond networks, is formed, i.e., the hydrogel; 3) Cycling: Multiple freeze-thaw cycles can increase the number and density of crystalline regions, making the cross-linked network more stable, thereby significantly improving the mechanical strength, elasticity, and stability of the hydrogel. The preferred number of cycles is 2 to 4.

[0024] In the above-mentioned physical crosslinking process, a crosslinking agent can be added to further induce chemical crosslinking, forming a stable covalent bond network between molecular chains, thereby constructing a composite network structure with high mechanical strength, anti-swelling properties, and long-term stability in complex environments. Ferric chloride is preferably used as the crosslinking agent, with a preferred concentration of 0.1~0.5 mol / L. In step S4, before the cyclic freeze-thaw crosslinking, the precursor solution is injected into a specific mold. This specific mold is made of polypropylene, polystyrene, or polytetrafluoroethylene, and its shape is film-like, columnar, or spherical.

[0025] The present invention also provides a magnetic hydrogel prepared by the above preparation method.

[0026] The present invention also provides an application of the above-described magnetic hydrogel in the remediation of heavy metal or organic pollution, including: remediation of water bodies contaminated with heavy metals, in-situ / ex-situ remediation of soil contaminated with heavy metals, remediation of leachate pollution from electronic waste, remediation of acidic wastewater pollution from mines and / or remediation of leachate pollution from metallurgical slag.

[0027] The remediation of water bodies contaminated with heavy metals refers to the treatment of water containing heavy metal ions (such as Pb). 2+ Cd 2+ Cu 2+ Zn 2+ AsO4 3- CrO4 2-The treatment process involves treating industrial wastewater, municipal sewage, or contaminated surface water containing organic pollutants (such as polycyclic aromatic hydrocarbons, pesticides, dyes, and phenols). After treatment, an external magnetic field is used to rapidly separate the magnetic hydrogel from the water, achieving both pollutant removal and material recycling. In-situ remediation of heavy metal-contaminated soil involves directly adding the magnetic hydrogel to the contaminated soil and thoroughly mixing it with the soil through tilling. After remediation, the magnetic hydrogel is separated and recycled from the soil using magnetic separation equipment. Ex-situ remediation of heavy metal-contaminated soil involves mixing the contaminated soil and magnetic hydrogel in a reaction vessel at a specific ratio. After remediation, an external magnetic field is used to separate the magnetic hydrogel from the soil particles, and the purified soil can be backfilled. Furthermore, magnetic hydrogels can rapidly trap, adsorb, and degrade pollutants, and can be used as emergency treatment materials for sudden environmental pollutant leaks.

[0028] Optionally, the heavy metal is one of cadmium, lead, copper, zinc, arsenic or chromium, and the organic pollutant is one of polycyclic aromatic hydrocarbons, pesticides or endocrine disruptors.

[0029] It should be noted that in the remediation of water bodies contaminated with heavy metals, the dosage of magnetic hydrogel accounts for 0.01% to 0.5% of the mass of the water body contaminated with heavy metals, with a preferred mass ratio of 0.02% to 0.2%; in the in-situ / ex-situ remediation of soil contaminated with heavy metals, the dosage of magnetic hydrogel accounts for 0.1% to 5% of the mass of the soil contaminated with heavy metals, with a preferred mass ratio of 0.5% to 2%.

[0030] In the above-mentioned pollutant remediation process, the applicable treatment concentration for heavy metal pollutants is 0.5~500 mg / L, with a preferred concentration of 5~200 mg / L. For pollutants with extremely high concentrations (>500 mg / L), dilution or multi-stage treatment is required. Specifically, the applicable treatment concentration for anionic pollutants such as arsenic and chromium is 0.1~100 mg / L, with a preferred concentration of 1~50 mg / L. The applicable treatment concentration for organic pollutants is 0.1~200 mg / L, with a preferred concentration of 1~100 mg / L.

[0031] Furthermore, the suitable pH range for heavy metals or organic pollutants is 4.0–9.0, within which the magnetic hydrogel can maintain a stable structure and good remediation performance. For highly acidic pollutants, pre-neutralization treatment is necessary. The suitable ambient temperature during the treatment process is 4–40℃. The water remediation cycle is typically 30 minutes to 24 hours, while the soil remediation cycle is typically 14–90 days.

[0032] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0033] This invention constructs a ternary composite system of "magnetotactic bacteria-Schönlein mineral-polyvinyl alcohol," forming a highly efficient and stable environmental remediation material through the complementary and synergistic effects of the three components. Magnetotactic bacteria endow the system with magnetic recovery capabilities, effectively solving the problem of difficult separation of Schönlein mineral. Schönlein mineral significantly enhances the specific adsorption performance of anionic pollutants such as arsenates and chromates, and possesses the ability to activate persulfate to catalytically degrade organic pollutants, compensating for the shortcomings of bacteria in selectivity and catalytic activity. The three-dimensional porous network formed by polyvinyl alcohol acts as a stabilizing carrier, not only fixing the bacteria and mineral particles and preventing their aggregation and loss, but also providing a favorable microenvironment for pollutant mass transfer and maintenance of bacterial metabolic activity due to its good biocompatibility. Under this synergistic mechanism, bacterial metabolism promotes the formation and stabilization of Schönlein mineral, while the mineral provides protection and additional adsorption / reaction sites for the bacteria, and the polyvinyl alcohol network ensures the structural and functional stability of the overall system in complex environments. Ultimately, this composite material achieves multiple functions, including magnetic recovery and simultaneous removal of heavy metals and organic pollutants, providing a novel solution for the treatment of complex pollution. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] The present invention provides a method for preparing a magnetic hydrogel, comprising the following steps:

[0037] S1: Preparation of magnetotactic bacterial suspension:

[0038] Magnetospirillum gryphiswaldense MSR-1 was cultured on magnetic spirochete medium (MSGM) under microaerobic conditions in a constant temperature incubator at 25-30℃ in the dark for 5 days to enter the stable growth phase. The bacterial cells were collected using an external magnetic field (magnetic field strength ≥100mT), washed three times with sterile HEPES or PIPES buffer (pH 7.0), and finally resuspended in the same buffer to prepare a high-concentration bacterial suspension (OD650=1.5), which was stored at 4℃ for later use.

[0039] S2: Preparation of Schiele mineral powder:

[0040] Prepare 1L of acidic aqueous solution with pH 3.0 using 98% concentrated sulfuric acid and place it in a beaker. Weigh 16.45g of FeSO4•7H2O using an electronic balance and add it to the 1L of the above acidic solution, stirring to dissolve. Add 5.3mL of 30% H2O2 solution at a rate of 1mL / 120min while stirring with a mechanical stirrer (140rpm). During the synthesis process, NaOH needs to be added to maintain the pH of the system at 3.0 for 24h. Wash the obtained reaction solution 5 times with a mixture of deionized water and ethanol (1:1), centrifuge at 4500rpm, collect the solid, and then freeze-dry it at -80℃ to obtain the chemically synthesized Schiele mineral. Grind the dried sample into powder using a mortar and pestle and place it in a resealable bag for later use.

[0041] S3: The complex of magnetotactic bacteria and Schiele minerals:

[0042] The magnetotactic bacterial suspension prepared in step S1 and the Scheringer mineral powder prepared in step S2 were mixed at a volume-to-mass ratio of 1:1 and shaken at 180 rpm for 12 hours to allow the magnetotactic bacteria to fully adhere to the surface of the Scheringer mineral powder particles through electrostatic interaction and microbial adhesion characteristics, thus obtaining a magnetotactic bacteria-Scheringer mineral complex. An equal volume of pre-cooled sterile buffer (pH 6.0) was added to the magnetotactic bacteria-Scheringer mineral complex, and the mixture was shaken using a shaker. Magnetic separation was performed again (magnetic field strength ≥ 200 mT), and the supernatant was discarded. This process was repeated 2-3 times to remove unattached, loosely bound Scheringer mineral particles and other soluble impurities. The magnetotactic bacteria-Scheringer mineral complex was collected, washed, and stored at 4°C for short-term use.

[0043] S4: Construction and cross-linking of magnetic hydrogels:

[0044] Preparation of polyvinyl alcohol (PVA) aqueous solution: PVA-124 powder (degree of hydrolysis >98%) was slowly added to ultrapure water at 95°C. The mixture was stirred continuously at 300 rpm while maintaining the temperature until the PVA was completely dissolved and the solution became clear and transparent, thus preparing a 10% (w / v) aqueous solution of PVA. The PVA solution was then cooled to 37°C for later use.

[0045] Crosslinking process: The magnetotactic bacteria-Schönlein mineral complex prepared in step S3 was slowly added to an aqueous solution of polyvinyl alcohol, with a mass ratio of magnetotactic bacteria-Schönlein mineral complex to polyvinyl alcohol of 1:5. The mixture was mechanically stirred at 400 rpm to ensure uniform dispersion, forming a precursor solution, which was then stored at 37°C. The precursor solution was injected into a spherical mold and frozen at -25°C for 16 hours, then thawed at 25°C for 6 hours. This constituted one cycle, and the freeze-thaw cycle was repeated four times. After crosslinking, the resulting hydrogel block was immersed and washed in ultrapure water for 48 hours, with multiple water changes during this period, finally yielding the magnetic hydrogel. This hydrogel can be cut into the desired shape and size and stored in a humid state at 4°C.

[0046] Example 2

[0047] The method for preparing a magnetic hydrogel provided in this embodiment of the invention is the same as that in embodiment 1, except that: in step S4, the magnetotactic bacteria-Schönlein mineral complex prepared in step S3 is slowly added to the polyvinyl alcohol solution, and the mass ratio of the magnetotactic bacteria-Schönlein mineral complex to polyvinyl alcohol is 1:10.

[0048] Example 3

[0049] The method for preparing a magnetic hydrogel provided in this embodiment of the invention is the same as that in embodiment 1, except that: in step S4, the magnetotactic bacteria-Schönlein mineral complex prepared in step S3 is slowly added to the polyvinyl alcohol solution, and the mass ratio of the magnetotactic bacteria-Schönlein mineral complex to polyvinyl alcohol is 1:20.

[0050] Example 4

[0051] The method for preparing a magnetic hydrogel provided in this embodiment of the invention is the same as that in Embodiment 1, except that: in step S3, the magnetotactic bacterial suspension prepared in step S1 is mixed with the Scheres mineral powder prepared in step S2 at a volume-to-mass ratio of 1:1.5; in step S4, the magnetotactic bacteria-Scheres mineral complex prepared in step S3 is slowly added to a polyvinyl alcohol solution, and the mass ratio of the magnetotactic bacteria-Scheres mineral complex to polyvinyl alcohol is 1:5.

[0052] Example 5

[0053] The method for preparing a magnetic hydrogel provided in this embodiment of the invention is the same as that in Embodiment 1, except that: in step S3, the magnetotactic bacterial suspension prepared in step S1 is mixed with the Scheringer mineral powder prepared in step S2 at a volume-to-mass ratio of 1:1.5; in step S4, the magnetotactic bacteria-Scheringer mineral complex prepared in step S3 is slowly added to a polyvinyl alcohol solution, and the mass ratio of the magnetotactic bacteria-Scheringer mineral complex to polyvinyl alcohol is 1:10.

[0054] Example 6

[0055] The method for preparing a magnetic hydrogel provided in this embodiment of the invention is the same as that in embodiment 3, except that: in step S2, the obtained reaction solution is washed 5 times with a mixture of deionized water and ethanol (1:1.5) and then centrifuged at 4500 rpm.

[0056] Test Example 1-1

[0057] The magnetic hydrogels prepared in Examples 1-6 were used to remove mixed contamination of cadmium (Cd=10mg / L) and naphthalene (40mg / kg) from aqueous solutions. 50mL of the mixed cadmium and naphthalene contamination solution was placed in a 250mL Erlenmeyer flask. 0.5g of the magnetic hydrogels prepared in Examples 1-6 was added to the flask, and the mixture was thoroughly mixed and incubated at room temperature for 3 days. Residual cadmium and naphthalene in the contamination solution were extracted, and the cadmium content was quantitatively analyzed by inductively coupled plasma mass spectrometry (ICP-MS), while the naphthalene content was determined by liquid chromatography (LC).

[0058] Comparative Example 1-1

[0059] The effect of using Scheres' minerals to remove mixed cadmium (Cd=10 mg / L) and naphthalene (40 mg / L) contamination from aqueous solution was investigated as follows: 50 mL of the mixed cadmium and naphthalene contamination solution was placed in a 250 mL Erlenmeyer flask, and 0.5 g of Scheres' minerals was added. The mixture was thoroughly mixed and incubated at room temperature for 3 days. Residual cadmium and naphthalene were extracted from the solution, and the cadmium content was quantitatively analyzed by inductively coupled plasma mass spectrometry (ICP-MS), while the naphthalene content was determined by liquid chromatography (LC).

[0060] Comparative Examples 1-2

[0061] The effectiveness of using magnetotactic bacteria in removing mixed contamination of cadmium (Cd=10mg / L) and naphthalene (40mg / kg) from aqueous solution was investigated: 50 mL of the mixed cadmium and naphthalene contamination solution was placed in a 250 mL Erlenmeyer flask, and 0.5 g of magnetotactic bacterial suspension was added. The mixture was thoroughly mixed and incubated at room temperature for 3 days. Residual cadmium and naphthalene were extracted from the solution, and the cadmium content was quantitatively analyzed by inductively coupled plasma mass spectrometry (ICP-MS), while the naphthalene content was determined by liquid chromatography (LC).

[0062] Test Example 1-2

[0063] The magnetic hydrogels prepared in Examples 1-6 were used to remove cadmium (Cd=10mg / L) from aqueous solutions. 50ml of cadmium-contaminated solution was placed in a 250ml Erlenmeyer flask, and 0.5g of the magnetic hydrogels prepared in Examples 1-6 was added to each flask. The mixture was thoroughly mixed and incubated at room temperature for 3 days. Residual cadmium in the solution was extracted and quantitatively analyzed using inductively coupled plasma mass spectrometry.

[0064] Comparative Examples 1-3

[0065] The effect of using Schiele minerals to remove cadmium (Cd=10mg / L) from aqueous solution: 50ml of cadmium-contaminated solution was placed in a 250ml Erlenmeyer flask, 0.5g of Schiele minerals was added, and the mixture was thoroughly mixed and incubated at room temperature for 3 days. The residual cadmium in the solution was extracted and quantitatively analyzed using inductively coupled plasma mass spectrometry.

[0066] Comparative Examples 1-4

[0067] The effect of using magnetotactic bacteria to remove cadmium (Cd=10mg / L) from aqueous solution: 50ml of cadmium-contaminated solution was placed in a 250ml Erlenmeyer flask, and 0.5g of magnetotactic bacterial suspension was added. The mixture was thoroughly mixed and incubated at room temperature for 3 days. Residual cadmium in the solution was extracted and quantitatively analyzed using inductively coupled plasma mass spectrometry.

[0068] Test Example 1-3

[0069] The magnetic hydrogels prepared in Examples 1-6 were used to remove naphthalene (40 mg / L) from an aqueous solution. 50 ml of the naphthalene-contaminated solution was placed in a 250 ml Erlenmeyer flask, and 0.5 g of the magnetic hydrogels prepared in Examples 1-6 was added. The mixture was thoroughly mixed and incubated at room temperature for 3 days. The residual naphthalene in the solution was extracted, and the naphthalene content was determined by liquid chromatography.

[0070] Comparative Examples 1-5

[0071] The effect of using Schiele minerals to remove naphthalene (40 mg / L) from aqueous solution: 50 ml of naphthalene-contaminated solution was placed in a 250 ml Erlenmeyer flask, 0.5 g of Schiele minerals was added, and the mixture was thoroughly mixed and incubated at room temperature for 3 days. The residual naphthalene in the solution was extracted, and the naphthalene content was determined by liquid chromatography.

[0072] Comparative Examples 1-6

[0073] The effect of using magnetotactic bacteria to remove naphthalene (40 mg / L) from aqueous solution: 50 ml of naphthalene-contaminated solution was placed in a 250 ml Erlenmeyer flask, and 0.5 g of the magnetotactic bacterial suspension prepared in Example 1 was added. The mixture was thoroughly mixed and cultured at room temperature for 3 days. The residual naphthalene in the solution was extracted, and the naphthalene content was determined by liquid chromatography.

[0074] The removal rates of cadmium and naphthalene in the aqueous solutions of the above test examples 1-1 to 1-3 and comparative examples 1-1 to 1-6 are shown in Table 1.

[0075] Table 1

[0076]

[0077]

[0078] As shown in Table 1, the magnetic hydrogel of the present invention has a removal rate of 80.7% to 100% for cadmium pollution in solution and a removal rate of 69.8% to 87.2% for naphthalene pollution in solution. Moreover, the addition of the magnetic hydrogel of the present invention (Test Example 1-1) can simultaneously and efficiently remove cadmium and naphthalene from solution, and the removal effect is better than that for solutions with single cadmium or naphthalene pollution.

[0079] Test Example 2-1

[0080] The magnetic hydrogels prepared in Examples 1-6 were used to remove mixed pollution of cadmium (Cd=10mg / kg) and naphthalene (50mg / kg) from soil. 10g of soil contaminated with both cadmium and naphthalene was placed in a petri dish, and 2g of the magnetic hydrogels prepared in Examples 1-6 was added. The moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual cadmium and naphthalene in the soil were extracted and quantitatively analyzed.

[0081] Comparative Example 2-1

[0082] The effect of using Scheres minerals to remove mixed pollution of cadmium (Cd=10mg / kg) and naphthalene (50mg / kg) in soil: 10g of soil contaminated with cadmium and naphthalene was taken, 2g of Scheres minerals was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual cadmium and naphthalene in the soil were extracted and quantitatively analyzed.

[0083] Comparative Example 2-2

[0084] The effect of using magnetotactic bacteria to remove mixed cadmium (Cd=10mg / kg) and naphthalene (50mg / kg) contamination from soil was investigated: 10g of soil contaminated with cadmium and naphthalene was placed in a petri dish, 2g of magnetotactic bacteria was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual cadmium and naphthalene in the soil were extracted and quantitatively analyzed.

[0085] Test Example 2-2

[0086] The magnetic hydrogels prepared in Examples 1-6 were used to remove cadmium (Cd=10mg / kg) from soil. 10g of cadmium-contaminated soil was placed in a petri dish, and 2g of the magnetic hydrogels prepared in Examples 1-6 were added to each dish. The moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual cadmium in the soil was extracted and quantitatively analyzed.

[0087] Comparative Examples 2-3

[0088] The effect of using Scheres' minerals to remove cadmium (Cd=10mg / kg) from soil: 10g of cadmium-contaminated soil was placed in a petri dish, 2g of Scheres' minerals was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. Quantitative analysis was then performed on the extracted cadmium from the soil.

[0089] Comparative Examples 2-4

[0090] The effect of using magnetotactic bacteria to remove cadmium (Cd=10mg / kg) from soil was investigated: 10g of cadmium-contaminated soil was placed in a petri dish, 2g of magnetotactic bacterial suspension was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. Quantitative analysis was then performed on the extracted cadmium from the soil.

[0091] Test Example 2-3

[0092] The magnetic hydrogels prepared in Examples 1-6 were used to remove naphthalene (50 mg / kg) from soil. 10 g of naphthalene-contaminated soil was placed in a petri dish, and 2 g of the magnetic hydrogels prepared in Examples 1-6 were added to each dish. The moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual naphthalene in the soil was extracted and quantitatively analyzed.

[0093] Comparative Examples 2-5

[0094] The effect of using Schiele minerals to remove naphthalene (50 mg / kg) from soil: 10 g of naphthalene-contaminated soil was placed in a petri dish, 2 g of Schiele minerals was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual naphthalene in the soil was extracted and quantitatively analyzed.

[0095] Comparative Examples 2-6

[0096] The effect of using magnetotactic bacteria to remove naphthalene (50 mg / kg) from soil was investigated: 10 g of naphthalene-contaminated soil was placed in a petri dish, 2 g of magnetotactic bacterial suspension was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual naphthalene in the soil was extracted and quantitatively analyzed.

[0097] The removal rates of cadmium and naphthalene in the soil in the above test examples 2-1 to 2-3 and comparative examples 2-1 to 2-6 are shown in Table 2.

[0098] Table 2

[0099]

[0100]

[0101] As shown in Table 2, the magnetic hydrogel of the present invention has a removal rate of 60.7% to 84.9% for cadmium pollution in soil and a removal rate of 38.7% to 76.9% for naphthalene pollution in soil. Moreover, the addition of the magnetic hydrogel of the present invention (Test Example 2-1) can simultaneously and efficiently remove cadmium and naphthalene from soil, which is better than that for soil contaminated with cadmium or naphthalene alone.

[0102] Test Example 3-1

[0103] The recycling effect of the magnetic hydrogels prepared in Examples 1-6 on the removal of cadmium and naphthalene in aqueous solution: Using the magnetic hydrogels prepared in Examples 1-6, the removal rate of cadmium and naphthalene in solution after multiple applications was investigated. After each treatment, the recycled magnetic hydrogel was washed sequentially with 0.3M nitric acid, water, and methanol aqueous solution to desorb the hydrogel. The magnetic hydrogel was then reintroduced into the untreated original cadmium and naphthalene contaminated solution. The degree to which the material's removal capacity was retained after three reuses was tested. Other application methods were the same as in Test Example 1-1.

[0104] Test 3-2

[0105] The magnetic hydrogels prepared in Examples 1-6 were used to investigate the removal rate of cadmium in solution after multiple applications. After each treatment, the magnetic hydrogel was washed with 0.3M nitric acid solution to desorb the recycled hydrogel. The magnetic hydrogel was then reintroduced into the untreated original cadmium-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 1-1.

[0106] Test Example 3-3

[0107] The magnetic hydrogels prepared in Examples 1-6 were used to investigate the removal rate of naphthalene from the solution after multiple applications. After each treatment, the magnetic hydrogel was washed with a methanol-water solution to desorb the recycled hydrogel. The hydrogel was then reintroduced into the untreated original naphthalene-contaminated solution, and the degree to which the material retained its removal capacity after three repeated applications was tested. Other application methods were the same as in Test Example 1-1.

[0108] The removal rates of cadmium and naphthalene in aqueous solution of the recycled magnetic hydrogels in Test Examples 3-1 to 3-3 above are shown in Table 3.

[0109] Table 3

[0110]

[0111]

[0112] As shown in Table 3, the magnetic hydrogel of the present invention still has a high removal rate of cadmium and naphthalene in the solution after multiple adsorption-desorption cycles, indicating that the magnetic hydrogel prepared by the present invention has a stable structure, good mechanical properties, reversible and durable adsorption sites in cadmium and naphthalene contaminated aqueous solution, and is reusable; and the effect of adding the magnetic hydrogel of the present invention (Test Example 3-1) on the cadmium and naphthalene composite contaminated solution after multiple cycles is better than that on the cadmium / naphthalene single contaminated solution.

[0113] Test Example 4-1

[0114] The recycling effect of the magnetic hydrogels prepared in Examples 1-6 on the removal of cadmium and naphthalene in soil was investigated: The magnetic hydrogels prepared in Examples 1-6 were used to explore the removal rate of cadmium and naphthalene in soil after multiple applications. After each treatment, the recycled magnetic hydrogel was washed sequentially with 0.3M nitric acid, water, and methanol aqueous solution to desorb the hydrogel. The magnetic hydrogel was then re-added to the untreated original cadmium and naphthalene-contaminated soil, and the retention of the material's removal capacity was tested after three repeated applications. Other application methods were the same as in Test Example 1-1.

[0115] Test Example 4-2

[0116] The recycling effect of the magnetic hydrogels prepared in Examples 1-6 on cadmium removal from soil: The magnetic hydrogels prepared in Examples 1-6 were used to investigate the removal rate of cadmium from soil after multiple applications. After each treatment, the recycled magnetic hydrogel was washed with 0.3M nitric acid solution to desorb the hydrogel. The magnetic hydrogel was then re-added to the untreated original naphthalene-contaminated soil, and the degree of retention of the material's removal capacity was tested after three reuses. Other application methods were the same as in Test Example 1-1.

[0117] Test Example 4-3

[0118] The recycling effect of the magnetic hydrogels prepared in Examples 1-6 on naphthalene removal from soil: The magnetic hydrogels prepared in Examples 1-6 were used to investigate the removal rate of naphthalene from soil after multiple applications. After each treatment, the recycled magnetic hydrogel was washed with a methanol-water solution to desorb the hydrogel. The magnetic hydrogel was then re-added to the untreated original naphthalene-contaminated soil, and the degree to which the material's removal capacity was retained after three repeated applications was tested. Other application methods were the same as in Test Example 1-1.

[0119] The removal rates of cadmium and naphthalene in soil by the recycled magnetic hydrogels in Test Examples 4-1 to 4-3 above are shown in Table 4.

[0120] Table 4

[0121]

[0122]

[0123] As shown in Table 4, the magnetic hydrogel of the present invention still has a high removal rate of cadmium and naphthalene in soil pollution after multiple adsorption-desorption cycles, indicating that the magnetic hydrogel prepared by the present invention has a stable structure, good mechanical properties, reversible and durable adsorption sites in cadmium and naphthalene contaminated soil, and is reusable; and the effect of adding the magnetic hydrogel of the present invention (Test Example 4-1) on cadmium and naphthalene co-contaminated soil after multiple cycles is better than that on cadmium / naphthalene single contaminated soil.

[0124] Test Example 5-1

[0125] The magnetic hydrogels prepared in Examples 1-6 were used to remove mixed contamination of arsenic (As=2 mg / L) and sulfamethoxazole (200 μg / L) from aqueous solutions. 50 ml of the mixed arsenic and sulfamethoxazole contamination solution was placed in a 250 ml Erlenmeyer flask, and 0.5 g of the magnetic hydrogels prepared in Examples 1-6 was added. The mixture was thoroughly mixed and incubated at room temperature for 3 days. After extraction of residual arsenic and sulfamethoxazole from the solution, the arsenic content was quantitatively analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and the sulfamethoxazole content was determined by liquid chromatography (LC).

[0126] Comparative Example 5-1

[0127] The effect of using Scheres' minerals on removing mixed contamination of arsenic (As=2 mg / L) and sulfamethoxazole (200 μg / L) from aqueous solution was investigated: 50 ml of the mixed arsenic and sulfamethoxazole contamination solution was placed in a 250 ml Erlenmeyer flask, 0.5 g of Scheres' minerals was added, and the mixture was thoroughly mixed and incubated at room temperature for 3 days. After extraction of residual arsenic and sulfamethoxazole from the solution, the arsenic content was quantitatively analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and the sulfamethoxazole content was determined by liquid chromatography (LC).

[0128] Comparative Example 5-2

[0129] The effect of using magnetotactic bacteria to remove mixed contamination of arsenic (As=2 mg / L) and sulfamethoxazole (200 μg / L) in aqueous solution was investigated: 50 ml of the mixed arsenic and sulfamethoxazole contamination solution was placed in a 250 ml Erlenmeyer flask, and 0.5 g of magnetotactic bacterial suspension was added. The mixture was thoroughly mixed and incubated at room temperature for 3 days. After extraction of residual arsenic and sulfamethoxazole from the solution, the arsenic content was quantitatively analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and the sulfamethoxazole content was determined by liquid chromatography (LC).

[0130] Test Example 5-2

[0131] The magnetic hydrogels prepared in Examples 1-6 were used to remove arsenic (As=2 mg / L) from aqueous solutions. 50 ml of arsenic-contaminated solution was placed in a 250 ml Erlenmeyer flask, and 0.5 g of the magnetic hydrogels prepared in Examples 1-6 was added to each flask. The mixture was thoroughly mixed and incubated at room temperature for 3 days. The residual arsenic in the solution was extracted and quantitatively analyzed using inductively coupled plasma mass spectrometry.

[0132] Comparative Example 5-3

[0133] The effect of using Scheres' mineral to remove arsenic (As=2mg / L) from aqueous solution: 50ml of arsenic-contaminated solution was placed in a 250ml Erlenmeyer flask, 0.5g of Scheres' mineral was added, and the mixture was thoroughly mixed and incubated at room temperature for 3 days. The residual arsenic in the solution was extracted and quantitatively analyzed using inductively coupled plasma mass spectrometry.

[0134] Comparative Example 5-4

[0135] The effect of using magnetotactic bacteria to remove arsenic (As=2mg / L) from aqueous solution was investigated as follows: 50ml of arsenic-contaminated solution was placed in a 250ml Erlenmeyer flask, and 0.5g of magnetotactic bacterial suspension was added. The mixture was thoroughly mixed and incubated at room temperature for 3 days. The residual arsenic in the solution was extracted and quantitatively analyzed using inductively coupled plasma mass spectrometry.

[0136] Test Example 5-3

[0137] The magnetic hydrogels prepared in Examples 1-6 were used to remove sulfamethoxazole (200 μg / L) from aqueous solution: 50 ml of sulfamethoxazole-contaminated solution was placed in a 250 ml Erlenmeyer flask, and 0.5 g of the magnetic hydrogels prepared in Examples 1-6 was added. The mixture was thoroughly mixed and incubated at room temperature for 3 days. The residual sulfamethoxazole in the solution was extracted, and the sulfamethoxazole content was determined by liquid chromatography.

[0138] Comparative Example 5-5

[0139] The effect of using Scheres minerals to remove sulfamethoxazole (200 μg / L) from aqueous solution was investigated as follows: 50 ml of sulfamethoxazole-contaminated solution was placed in a 250 ml Erlenmeyer flask, 0.5 g of Scheres minerals was added, and the mixture was thoroughly mixed and incubated at room temperature for 3 days. The residual sulfamethoxazole in the solution was extracted, and the sulfamethoxazole content was determined by liquid chromatography.

[0140] Comparative Examples 5-6

[0141] The effect of using magnetotactic bacteria to remove sulfamethoxazole (200 μg / L) from aqueous solution was investigated as follows: 50 ml of sulfamethoxazole-contaminated solution was placed in a 250 ml Erlenmeyer flask, and 0.5 g of the magnetotactic bacterial suspension prepared in Example 1 was added. The mixture was thoroughly mixed and incubated at room temperature for 3 days. The residual sulfamethoxazole in the solution was extracted, and the sulfamethoxazole content was determined by liquid chromatography.

[0142] The removal rates of arsenic and sulfamethoxazole in aqueous solutions of test examples 5-1 to 5-3 and comparative examples 5-1 to 5-6 are shown in Table 5.

[0143] Table 5

[0144]

[0145]

[0146] As shown in Table 5, the magnetic hydrogel of the present invention has a removal rate of 80.3% to 100% for arsenic contamination in aqueous solution and a removal rate of 63.8% to 80.8% for sulfamethoxazole contamination in aqueous solution. Moreover, the addition of the magnetic hydrogel of the present invention (Test Example 5-1) can simultaneously and efficiently remove arsenic and sulfamethoxazole from the solution, which is better than the effect on solutions contaminated with arsenic or sulfamethoxazole alone.

[0147] Test Example 6-1

[0148] The magnetic hydrogels prepared in Examples 1-6 were used to remove mixed contamination of arsenic (As=70 mg / kg) and sulfamethoxazole (1 mg / kg) from soil. 10 g of soil contaminated with both arsenic and sulfamethoxazole was placed in a petri dish, and 2 g of the magnetic hydrogels prepared in Examples 1-6 were added to each dish. The moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual arsenic and sulfamethoxazole in the soil were extracted and quantitatively analyzed.

[0149] Comparative Example 6-1

[0150] The effect of using Scheres minerals to remove mixed contamination of arsenic (As=70mg / kg) and sulfamethoxazole (1mg / kg) from soil was investigated: 10g of soil contaminated with the combined arsenic and sulfamethoxazole was placed in a petri dish, 2g of Scheres minerals was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual arsenic and sulfamethoxazole in the soil were extracted and quantitatively analyzed.

[0151] Comparative Example 6-2

[0152] The effect of using magnetotactic bacteria to remove mixed contamination of arsenic (As=70mg / kg) and sulfamethoxazole (1mg / kg) from soil was investigated. 10g of soil contaminated with both arsenic and sulfamethoxazole was placed in a petri dish, 2g of magnetotactic bacteria was added, and the moisture content was adjusted to 30%. The mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual arsenic and sulfamethoxazole in the soil were extracted and quantitatively analyzed.

[0153] Test Example 6-2

[0154] The magnetic hydrogels prepared in Examples 1-6 were used to remove arsenic (As=70mg / kg) from soil. 10g of arsenic-contaminated soil was placed in a petri dish, and 2g of the magnetic hydrogels prepared in Examples 1-6 were added to each dish. The moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual arsenic in the soil was extracted and quantitatively analyzed.

[0155] Comparative Example 6-3

[0156] The effect of using Scheres' mineral to remove arsenic (As=70mg / kg) from soil: 10g of arsenic-contaminated soil was placed in a petri dish, 2g of Scheres' mineral was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual arsenic in the soil was extracted and quantitatively analyzed.

[0157] Comparative Example 6-4

[0158] The effect of using magnetotactic bacteria to remove arsenic (As=70mg / kg) from soil was investigated: 10g of arsenic-contaminated soil was placed in a petri dish, 2g of magnetotactic bacterial suspension was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual arsenic in the soil was extracted and quantitatively analyzed.

[0159] Test Example 6-3

[0160] The magnetic hydrogels prepared in Examples 1-6 were used to investigate their effectiveness in removing sulfamethoxazole (1 mg / kg) from soil. 10 g of sulfamethoxazole-contaminated soil was placed in a petri dish, and 2 g of the magnetic hydrogels prepared in Examples 1-6 were added to each dish. The moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual sulfamethoxazole in the soil was extracted and quantitatively analyzed.

[0161] Comparative Example 6-5

[0162] The effect of using Scheres minerals to remove sulfamethoxazole (1 mg / kg) from soil was investigated: 10 g of sulfamethoxazole-contaminated soil was placed in a petri dish, 2 g of Scheres minerals was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual sulfamethoxazole in the soil was extracted and quantitatively analyzed.

[0163] Comparative Example 6-6

[0164] The effect of using magnetotactic bacteria to remove sulfamethoxazole (1 mg / kg) from soil was investigated: 10 g of sulfamethoxazole-contaminated soil was placed in a petri dish, 2 g of magnetotactic bacterial suspension was added, the moisture content was adjusted to 30%, and the mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual sulfamethoxazole in the soil was extracted and quantitatively analyzed.

[0165] The removal rates of arsenic and sulfamethoxazole in the soil of the above test examples 6-1 to 6-3 and comparative examples 6-1 to 6-6 are shown in Table 6.

[0166] Table 6

[0167]

[0168]

[0169] As shown in Table 6, the magnetic hydrogel of the present invention has a removal rate of 57.6% to 78.9% for arsenic pollution in soil and a removal rate of 40.8% to 60.3% for sulfamethoxazole pollution in soil. Moreover, the addition of the magnetic hydrogel of the present invention (Test Example 6-1) can simultaneously and efficiently remove arsenic and sulfamethoxazole from soil, which is better than the effect on soil contaminated with arsenic or sulfamethoxazole alone.

[0170] Test Example 7-1

[0171] The recycling effect of the magnetic hydrogels prepared in Examples 1-6 on the removal of arsenic and sulfamethoxazole in aqueous solution was investigated: The magnetic hydrogels prepared in Examples 1-6 were used to explore the removal rate of arsenic and sulfamethoxazole in solution after multiple applications. After each treatment, the recycled magnetic hydrogel was washed sequentially with 0.3M nitric acid, water, and methanol aqueous solution to desorb the arsenic and sulfamethoxazole contaminated solution. The magnetic hydrogel was then re-added to the untreated original arsenic and sulfamethoxazole contaminated solution, and the degree of retention of the material's removal capacity after three reuses was tested. Other application methods were the same as in Test Example 1-1.

[0172] Test Example 7-2

[0173] The magnetic hydrogels prepared in Examples 1-6 were used to investigate the removal rate of arsenic from the solution after multiple applications. After each treatment, the magnetic hydrogel was washed with 0.3M nitric acid solution to desorb the recycled hydrogel. The magnetic hydrogel was then reintroduced into the untreated original arsenic-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 1-1.

[0174] Test Example 7-3

[0175] The magnetic hydrogels prepared in Examples 1-6 were used to investigate the removal rate of sulfamethoxazole in solution after multiple applications. After each treatment, the circulating magnetic hydrogel was washed with a methanol-water solution to desorb the hydrogel. The magnetic hydrogel was then reintroduced into the untreated original sulfamethoxazole-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 1-1.

[0176] The removal rates of arsenic and sulfamethoxazole in aqueous solution of the recycled magnetic hydrogels in Test Examples 7-1 to 7-3 above are shown in Table 7.

[0177] Table 7

[0178]

[0179] As shown in Table 7, the magnetic hydrogel of the present invention still has a high removal rate of arsenic and sulfamethoxazole in the solution after multiple adsorption-desorption cycles. This indicates that the magnetic hydrogel prepared by the present invention has a stable structure, good mechanical properties, reversible and durable adsorption sites, and is reusable in aqueous solutions contaminated with arsenic and sulfamethoxazole. Furthermore, the effect of adding the magnetic hydrogel of the present invention (Test Example 7-1) on the multiple cycles of arsenic and sulfamethoxazole combined contaminated solution is better than that on arsenic / sulfamethoxazole single contaminated solution.

[0180] Test Example 8-1

[0181] The recycling effect of the magnetic hydrogels prepared in Examples 1-6 on the removal of arsenic and sulfamethoxazole from soil was investigated: The magnetic hydrogels prepared in Examples 1-6 were used to explore the removal rate of arsenic and sulfamethoxazole from soil after multiple applications. After each treatment, the recycled magnetic hydrogel was washed sequentially with 0.3M nitric acid, water, and methanol aqueous solution to desorb the hydrogel. The magnetic hydrogel was then re-added to the untreated original arsenic and sulfamethoxazole-contaminated soil, and the retention of the material's removal capacity was tested after three repeated uses. Other application methods were the same as in Test Example 1-1.

[0182] Test Example 8-2

[0183] The recycling effect of the magnetic hydrogels prepared in Examples 1-6 on arsenic removal from soil was investigated: The magnetic hydrogels prepared in Examples 1-6 were used to explore the arsenic removal rate in soil after multiple applications. After each treatment, the recycled magnetic hydrogel was washed with 0.3M nitric acid solution to desorb the hydrogel. The magnetic hydrogel was then re-added to the untreated original arsenic-contaminated soil, and the retention of the material's removal capacity was tested after three repeated applications. Other application methods were the same as in Test Example 1-1.

[0184] Test Example 8-3

[0185] The recycling effect of the magnetic hydrogels prepared in Examples 1-6 on the removal of sulfamethoxazole from soil was investigated: Magnetic hydrogels prepared in Examples 1-6 were used to explore the removal rate of sulfamethoxazole from soil after multiple applications. After each treatment, the recycled magnetic hydrogel was washed with a methanol-water solution to desorb the hydrogel. The magnetic hydrogel was then re-added to the untreated, original sulfamethoxazole-contaminated soil. The retention of the material's removal capacity after three repeated applications was tested. Other application methods were the same as in Test Example 1-1.

[0186] The removal rates of arsenic and sulfamethoxazole in soil by the recycled magnetic hydrogels in Test Examples 8-1 to 8-3 above are shown in Table 8.

[0187] Table 8

[0188]

[0189]

[0190] As shown in Table 8, the magnetic hydrogel of the present invention still has a high removal rate of arsenic and sulfamethoxazole in soil pollution after multiple adsorption-desorption cycles. This indicates that the magnetic hydrogel prepared by the present invention has a stable structure, good mechanical properties, reversible and durable adsorption sites in arsenic and sulfamethoxazole contaminated soil, and is reusable. Moreover, the effect of adding the magnetic hydrogel of the present invention (Test Example 8-1) on the combined arsenic and sulfamethoxazole contaminated soil after multiple cycles is better than that on arsenic / sulfamethoxazole contaminated soil.

[0191] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a magnetic hydrogel, characterized in that, Includes the following steps: S1: Preparation of magnetotactic bacterial suspension; S2: Preparation of Schiele mineral powder; S3: The magnetotactic bacterial suspension is mixed with the Scheringer mineral by oscillation, so that the magnetotactic bacteria attach to the surface of the Scheringer mineral powder particles, and the magnetotactic bacteria-Scheringer mineral complex is obtained by magnetic separation. S4: The magnetotactic bacteria-Schönlein mineral complex is mixed in an aqueous solution of polyvinyl alcohol and stirred to obtain a precursor solution; the precursor solution is placed under cyclic freeze-thaw conditions to allow it to crosslink, thereby obtaining a three-dimensional network magnetic hydrogel.

2. The preparation method according to claim 1, characterized in that, The volume-to-mass ratio of the magnetotactic bacterial suspension to the Scheres mineral is 1:(1~1.5); the mass ratio of the magnetotactic bacterial-Scheres mineral complex to polyvinyl alcohol is 1:(5~20); 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 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.

5. The preparation method according to claim 1, characterized in that, In step S2, the method for preparing Schöndorff mineral powder includes: reacting ferrous sulfate with hydrogen peroxide in an acidic environment with a pH of 2.4 to 3.0 to obtain a reaction solution; centrifuging the reaction solution to remove the supernatant to obtain a precipitate; and freezing, drying, and pulverizing the precipitate at a temperature of -80°C to -50°C to obtain Schöndorff mineral powder.

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 S4, 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.

8. A magnetic hydrogel, characterized in that, It is prepared using the preparation method described in any one of claims 1 to 7.

9. The application of the magnetic hydrogel according to claim 8 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, and / or remediation of leachate contamination from metallurgical slag.

10. The application according to claim 9, characterized in that, The heavy metal is one of cadmium, lead, copper, zinc, arsenic or chromium, and the organic pollutant is one of polycyclic aromatic hydrocarbons, pesticides or endocrine disruptors.

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