Composite repairing material for removing halogenated hydrocarbon in underground water as well as preparation method and application of composite repairing material

Abstract

The invention belongs to the technical field of environmental governance, and relates to a composite repair material for removing halogenated hydrocarbon in underground water and a preparation method and application thereof. The invention provides a composite repair material. The composite repair material is mainly prepared from enteromorpha biochar. The invention also provides a method for removing halogenated hydrocarbon in underground water, and the method comprises the following steps: adjusting halogenated hydrocarbon polluted underground water to weak acidity, then adding a certain amount of the composite repairing material into sewage to be treated, and stirring for a period of time at normal temperature. The adsorption capacity and the reduction capacity of the nano zero-valent iron particles are improved through biochar and vulcanization modification treatment, and organic compounds containing halogen can be effectively removed. Compared with a chemical method and a physical method, the method does not need to add a large amount of chemical reagents or carry out high-temperature treatment, and does not cause a new pollution problem.

Description

Technical Field

[0001] This invention belongs to the field of environmental remediation technology, and relates to a composite remediation material for removing halogenated hydrocarbons from groundwater, its preparation method, and its applications. Background Technology

[0002] Halogenated hydrocarbons (HHHs) are a common class of organic pollutants, including chlorinated hydrocarbons, brominated hydrocarbons, and fluorinated hydrocarbons. They are widely used in industrial production and agricultural activities, but due to their high toxicity and persistent degradation, they easily pollute groundwater. Groundwater remediation technologies for these pollutants mainly include physical methods, chemical methods, biological methods, and integrated remediation technologies. Physical methods utilize physical processes such as adsorption, volatilization, distillation, and ion exchange to separate and remove HHH pollutants. Chemical methods transform and degrade HHHs through chemical reactions. Biological methods utilize the metabolic capabilities of microorganisms for decomposition and degradation. Integrated remediation technologies combine multiple methods to improve remediation effectiveness. By selecting appropriate remediation technologies based on the specific circumstances and combining them with monitoring and assessment measures, HHH pollution in groundwater can be effectively remediated, protecting water resources and environmental health.

[0003] Ulva prolifera, also known as "seaweed" or "marshland," is widely distributed in the world's oceans. Due to its massive proliferation, it frequently causes large-scale green tides. For example, in the summer of 2008, an unprecedented Ulva prolifera outbreak occurred in Qingdao, China. It was estimated that there were one billion tons of Ulva prolifera in the Yellow Sea, with a total harvest of 100 million tons. Ulva prolifera outbreaks have caused a series of environmental problems. The rapid growth and explosive expansion of Ulva prolifera means that unutilized resources still need to be disposed of through incineration and landfill, easily causing secondary pollution. Using high-temperature pyrolysis technology to prepare biochar from Ulva prolifera can not only solve marine pollution problems to some extent but also produce carbon adsorbents with good adsorption properties, while effectively reducing carbon dioxide emissions. The technical background for Ulva prolifera biochar production includes raw material selection and processing, pyrolysis process, control parameters, and application areas. By rationally selecting and controlling these aspects, biochar products with good properties and broad application potential can be obtained, which can be used in agriculture, environmental management, energy utilization, and other fields, achieving the sustainable utilization of Ulva prolifera resources and solving environmental problems.

[0004] Modified nano-zero-valent iron technology is a promising groundwater remediation technology that can effectively remove halogenated organic compounds, such as polychlorinated biphenyls (PCBs), hexachlorocyclohexane (HCH), and chlorinated hydrocarbons. This technology utilizes nano-zero-valent iron particles as a carrier, enhancing their adsorption and reduction capabilities through surface modification to achieve the degradation and purification of halogenated hydrocarbons. It boasts advantages such as high efficiency, controllability, renewability, and environmental friendliness, making it a promising method for halogenated hydrocarbon removal.

[0005] Catalytic reduction is an effective treatment method that utilizes catalysts to convert halogenated hydrocarbons into non-toxic or less toxic compounds, thereby achieving the degradation and removal of pollutants. Silicotungstic acid catalysts possess excellent catalytic activity, stability, and adsorption characteristics, enabling them to participate in reduction reactions by generating surface acid sites and providing activated hydrogen to catalyze the dehalogenation reduction of halogenated hydrocarbons. This technology can be widely applied in environments containing halogenated hydrocarbons, such as wastewater and waste gas, offering high efficiency and economy. Furthermore, silicotungstic acid catalysts can be combined with other catalysts to further enhance the catalytic reduction effect. Based on these advantages and application prospects, silicotungstic acid-modified materials play a crucial role in environmental remediation and waste treatment.

[0006] Surfactant-modified hydrophobic composites enhance the affinity and adsorption capacity of materials for halogenated hydrocarbons by introducing hydrophobic functionality, exhibiting synergistic effects and excellent performance. These composites not only possess hydrophobicity but also other properties such as high specific surface area and porous structure, thereby improving the adsorption capacity and removal efficiency of halogenated hydrocarbons. They can efficiently adsorb and remove halogenated hydrocarbon pollutants from water as adsorbents and can also act as catalysts in the dehalogenation reduction process of halogenated hydrocarbons, achieving the transformation and degradation of pollutants. Therefore, surfactant-modified hydrophobic composites provide an effective technical solution for addressing the problem of halogenated hydrocarbon pollution. Summary of the Invention

[0007] The purpose of this invention is to provide a composite remediation material and method for removing halogenated hydrocarbon pollutants from groundwater. By preparing the composite remediation material and adjusting the pH value of the groundwater, halogenated hydrocarbon pollutants in groundwater can be effectively removed. This invention utilizes *Ulva prolifera* biochar as an adsorbent and modifier, which, together with carbon polysulfide, is used to modify nano-zero-valent iron to prepare the composite remediation material. Furthermore, silicotungstic acid catalyst and methylchlorosilane are used to modify the material, improving its affinity for halogenated hydrocarbons and its catalytic reduction efficiency. This comprehensive remediation technology can effectively solve the problem of halogenated hydrocarbon pollution in groundwater, protecting water resources and environmental health.

[0008] The technical solution adopted by this invention to solve its technical problem is: a method for preparing a composite remediation material for removing halogenated hydrocarbons from groundwater, comprising the following steps: Wash the seaweed, dry it, and grind it into powder. Powdered seaweed was placed in a tube furnace for pyrolysis. During the pyrolysis process, N2 was continuously introduced to isolate the air. After the pyrolysis was completed and the temperature dropped to room temperature, the seaweed biochar was obtained. FeSO4·7H2O was dissolved in an ethanol-water solution. Ulva prolifera biochar, calcium polysulfide, and polyethylene glycol-4000 were added to the solution, with a mass ratio of FeSO4·7H2O, Ulva prolifera biochar, calcium polysulfide, and polyethylene glycol-4000 of 10:(0.5~1.5):(5~15):1. The solution was stirred under nitrogen protection for a period of time, and the pH was adjusted. Then, freshly prepared NaBH4 was added dropwise to the solution. After the NaBH4 solution was added, the mixture was stirred for a period of time. The resulting material was separated from the solution using a magnet, washed several times alternately with deionized water and anhydrous ethanol, and then freeze-dried to obtain material a. Add material a to anhydrous ethanol and stir; fully dissolve silicotungstic acid in anhydrous ethanol and slowly add it dropwise to the above mixture. The mass ratio of material a to silicotungstic acid is 1:0.5~2; stir at room temperature for a period of time, then evaporate to dryness in a water bath. Calcine the obtained solid material at 330-360℃ for several hours to obtain material b. Material b was weighed and added to anhydrous ethanol, and the mixture was sonicated for a period of time. Trimethylchlorosilane was added to the sonicated suspension, with a mass ratio of material b to trimethylchlorosilane of 1:0.05~0.2. The mixture was stirred at a constant temperature of 45~65℃ for a period of time, and the surface-modified composite material was collected by centrifugation. After washing several times with anhydrous ethanol, the material c was dried, which is the final composite repair material.

[0009] Preferably, the concentration of NaBH4 is 0.5~1.5 mol / L, and the molar ratio of the added amount is NaBH4: FeSO4·7H2O=1:4~8.

[0010] The present invention also provides a composite repair material prepared using the above method.

[0011] The present invention further provides a method for removing halogenated hydrocarbons from groundwater using the aforementioned composite remediation material, comprising: adjusting the groundwater contaminated with halogenated hydrocarbons to a weakly acidic or weakly alkaline state, then adding a certain amount of composite remediation material to the wastewater to be treated, and stirring at room temperature for a period of time.

[0012] The advantages of this invention compared to the prior art mainly include the following: 1. Highly efficient removal capacity: By enhancing the adsorption and reduction capabilities of the nano-zero-valent iron particles through biochar and sulfide modification, it can effectively remove halogen-containing organic compounds. Compared to traditional remediation technologies, it boasts higher removal efficiency and degradation rate.

[0013] 2. Controllability and Renewability: The modification technology is controllable, and the remediation effect can be optimized by adjusting the properties of the catalyst and reaction conditions. Furthermore, nano-zero-valent iron particles can be regenerated, achieving a degree of recycling and reducing resource consumption and costs.

[0014] 3. Environmental friendliness: Compared to chemical and physical methods, it does not require the addition of large amounts of chemical reagents or high-temperature treatment, and will not cause new pollution problems. The use of green catalysts such as silicotungstic acid to modify the material further enhances its environmental friendliness.

[0015] 4. By introducing hydrophobic functionality, the modified material can enhance its affinity and adsorption capacity for halogenated hydrocarbons. Secondly, the composite material possesses a high specific surface area and porous structure, which improves adsorption capacity and removal efficiency. This enables them to efficiently adsorb and remove halogenated hydrocarbon pollutants from water. Furthermore, the surfactant-modified hydrophobic composite material can also act as a catalyst in the dehalogenation reduction process of halogenated hydrocarbons, achieving the transformation and degradation of pollutants. Its hydrophobicity and other properties give it a synergistic effect in the removal of halogenated hydrocarbons and can improve the catalytic reduction effect. Therefore, this composite material can not only adsorb halogenated hydrocarbons but also participate in their dehalogenation reduction process, thereby achieving more thorough pollutant removal.

[0016] 5. By combining physical, chemical, biological, and integrated remediation technologies, the remediation effect can be improved, and the problem of groundwater remediation of halogenated hydrocarbon pollutants can be solved. Detailed Implementation

[0017] The present invention will now be described more completely and clearly with reference to specific embodiments. These embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0018] Example 1 The composite remediation material for removing halogenated hydrocarbons from groundwater provided in this example is prepared by the following method: After washing the seaweed with deionized water, place it in an oven and dry it at 110℃ for 24 hours. Then grind it into powder with a diameter of 0.10~0.20mm and put it into a sealed bag for later use. Take 5g of seaweed powder and put it into a tube furnace. Pyrolyze it at 500℃ for 2 hours. During the pyrolysis process, N2 needs to be continuously introduced to isolate the air. After the pyrolysis is completed, take it out when the temperature drops to room temperature to obtain seaweed biochar. Dissolve 5g of FeSO4·7H2O in 100ml of an ethanol-water solution (ethanol:water = 3:7, volume ratio). Add 0.5g of *Ulva prolifera* biochar and 5g of calcium polysulfide to the solution, then add 0.5g of polyethylene glycol-4000. Stir in a four-necked flask for 45min. Adjust the pH of the solution to 6 with 0.1mol / L NaOH solution. Then, add 50ml of freshly prepared 1mol / L NaBH4 solution dropwise to the above solution at a rate of 1-2 drops / second. After the NaBH4 solution is added, continue stirring for 30min. Separate the obtained material from the solution using a magnet. Wash three times alternately with deionized water and anhydrous ethanol. After freeze-drying, store in a nitrogen-filled brown glass bottle for later use. The obtained material is denoted as material a.

[0019] Weigh 1g of material a and add it to 30ml of anhydrous ethanol and stir. Weigh 1g of silicotungstic acid and add it to 30ml of anhydrous ethanol. Stir thoroughly to dissolve it completely. Then slowly add it dropwise to the mixture of material a and ethanol. Stir at room temperature for 24 hours and then evaporate to dryness in a 70℃ water bath. Wash the obtained solid material three times with deionized water and calcine it at 350℃ for 5 hours. The resulting material is denoted as material b.

[0020] Weigh 1.5g of material b and add it to 35ml of anhydrous ethanol. Sonicate the mixture for a period of time. Add 0.15g of trimethylchlorosilane (TMCS) to the sonicated suspension. Stir the mixture at 50°C for 12 hours, then centrifuge to collect the surface-modified composite material. Wash several times with anhydrous ethanol, and dry at 60°C for 24 hours to obtain the final composite repair material, denoted as material c.

[0021] Experiments on the removal of halohydrocarbons from water using the composite remediation material prepared in this embodiment: A 500ml sample of simulated contaminated groundwater with a trichloroethylene concentration of 60mg / L was prepared using deionized water in a 1000ml Erlenmeyer flask. The pH of the water sample was adjusted to 5 using hydrochloric acid. 1g of material c was added to the water sample. After incubating the sample at 25℃ with shaking for 48 hours, the trichloroethylene concentration in the sample was analyzed using gas chromatography. The trichloroethylene removal rate was calculated using the formula P=(C0-CT)*100% / C0, where C0 represents the initial concentration of the pollutant and CT represents the concentration of the pollutant at the time of sampling.

[0022] In this embodiment, material c achieved a trichloroethylene removal rate of 99.8% in simulated contaminated groundwater samples.

[0023] Example 2 The composite remediation material for removing halogenated hydrocarbons from groundwater provided in this example is prepared by the following method: Dissolve 5g of FeSO4·7H2O in 100ml of an ethanol-water solution (ethanol:water = 3:7, volume ratio). Add 0.25g of *Ulva prolifera* biochar and 5g of calcium polysulfide to the solution, then add 0.5g of polyethylene glycol-4000. Stir in a four-necked flask for 45 min. Adjust the pH of the solution to 6 with 0.1mol / L NaOH solution. Then, add 50ml of freshly prepared 1mol / L NaBH4 solution dropwise to the above solution at a rate of 1-2 drops / second. After the NaBH4 solution is added, continue stirring for 30 min. Separate the obtained material from the solution using a magnet. Wash three times alternately with deionized water and anhydrous ethanol. After freeze-drying, store in a nitrogen-filled brown glass bottle for later use. The obtained material is designated as material a. Other steps are the same as in Example 1.

[0024] The experiment on removing halohydrocarbons from water using the composite remediation material prepared in this embodiment follows the same steps as in Example 1.

[0025] In this embodiment, material c achieved a trichloroethylene removal rate of 95.6% in simulated contaminated groundwater samples.

[0026] Example 3 The composite remediation material for removing halogenated hydrocarbons from groundwater provided in this example is prepared by the following method: Dissolve 5g of FeSO4·7H2O in 100ml of an ethanol-water solution (ethanol:water = 3:7, volume ratio). Add 0.75g of *Ulva prolifera* biochar and 5g of calcium polysulfide to the solution, then add 0.5g of polyethylene glycol-4000. Stir in a four-necked flask for 45 min. Adjust the pH of the solution to 6 with 0.1mol / L NaOH solution. Then, add 50ml of freshly prepared 1mol / L NaBH4 solution dropwise to the above solution at a rate of 1-2 drops / second. After the NaBH4 solution is added, continue stirring for 30 min. Separate the obtained material from the solution using a magnet. Wash three times alternately with deionized water and anhydrous ethanol. After freeze-drying, store in a nitrogen-filled brown glass bottle for later use. The obtained material is designated as material a. Other steps are the same as in Example 1.

[0027] Experiments on the removal of halohydrocarbons from water using the composite remediation material prepared in this embodiment: In this embodiment, material c achieved a trichloroethylene removal rate of 97.1% in simulated contaminated groundwater samples.

[0028] Example 4 The composite remediation material for removing halogenated hydrocarbons from groundwater provided in this example is prepared by the following method: Dissolve 5g of FeSO4·7H2O in 100ml of an ethanol-water solution (ethanol:water = 3:7, volume ratio). Add 0.5g of *Ulva prolifera* biochar and 2.5g of calcium polysulfide to the solution, then add 0.5g of polyethylene glycol-4000. Stir in a four-necked flask for 45 min. Adjust the pH of the solution to 6 with 0.1mol / L NaOH solution. Then, add 50ml of freshly prepared 1mol / L NaBH4 solution dropwise to the above solution at a rate of 1-2 drops / second. After the NaBH4 solution is added, continue stirring for 30 min. Separate the obtained material from the solution using a magnet. Wash three times alternately with deionized water and anhydrous ethanol. After freeze-drying, store in a nitrogen-filled brown glass bottle for later use. The obtained material is designated as material a. Other steps are the same as in Example 1.

[0029] The experiment on removing halohydrocarbons from water using the composite remediation material prepared in this embodiment follows the same steps as in Example 1.

[0030] In this embodiment, material c achieved a trichloroethylene removal rate of 93.9% in simulated contaminated groundwater samples.

[0031] Example 5 The composite remediation material for removing halogenated hydrocarbons from groundwater provided in this example is prepared by the following method: The steps are the same as in Example 1.

[0032] Dissolve 5g of FeSO4·7H2O in 100ml of an ethanol-water solution (ethanol:water = 3:7, volume ratio). Add 0.5g of *Ulva prolifera* biochar and 7.5g of calcium polysulfide to the solution, then add 0.5g of polyethylene glycol-4000. Stir in a four-necked flask for 45 min. Adjust the pH of the solution to 6 with 0.1mol / L NaOH solution. Then, add 50ml of freshly prepared 1mol / L NaBH4 solution dropwise to the above solution at a rate of 1-2 drops / second. After the NaBH4 solution is added, continue stirring for 30 min. Separate the obtained material from the solution using a magnet. Wash three times alternately with deionized water and anhydrous ethanol. After freeze-drying, store in a nitrogen-filled brown glass bottle for later use. The obtained material is designated as material a. Other steps are the same as in Example 1.

[0033] The experiment on removing halohydrocarbons from water using the composite remediation material prepared in this embodiment follows the same steps as in Example 1.

[0034] In this embodiment, material c achieved a trichloroethylene removal rate of 96.3% in simulated contaminated groundwater samples.

[0035] Example 6 The composite remediation material for removing halogenated hydrocarbons from groundwater provided in this example is prepared by the following method: The other steps are the same as in Example 1.

[0036] Weigh 1g of material a and add it to 30ml of anhydrous ethanol and stir. Weigh 0.5g of silicotungstic acid and add it to 30ml of anhydrous ethanol. Stir thoroughly to dissolve it completely. Then slowly add it dropwise to the mixture of material a and ethanol. Stir at room temperature for 24 hours and then evaporate to dryness in a 70℃ water bath. Wash the obtained solid material three times with deionized water and calcine it at 350℃ for 5 hours. The resulting material is denoted as material b.

[0037] The experiment on removing halohydrocarbons from water using the composite remediation material prepared in this embodiment follows the same steps as in Example 1.

[0038] In this embodiment, material c achieved a trichloroethylene removal rate of 92.2% in simulated contaminated groundwater samples.

[0039] Example 7 The composite remediation material for removing halogenated hydrocarbons from groundwater provided in this example is prepared by the following method: The other steps are the same as in Example 1.

[0040] Weigh 1g of material a and add it to 30ml of anhydrous ethanol and stir. Weigh 1.5g of silicotungstic acid and add it to 30ml of anhydrous ethanol. Stir thoroughly to dissolve it completely. Then slowly add it dropwise to the mixture of material a and ethanol. Stir at room temperature for 24 hours and then evaporate to dryness in a 70℃ water bath. Wash the obtained solid material three times with deionized water and calcine it at 350℃ for 5 hours. The resulting material is denoted as material b.

[0041] The experiment on removing halohydrocarbons from water using the composite remediation material prepared in this embodiment follows the same steps as in Example 1.

[0042] In this embodiment, material c achieved a trichloroethylene removal rate of 96.7% in simulated contaminated groundwater samples.

[0043] Example 8 The composite remediation material for removing halogenated hydrocarbons from groundwater provided in this example is prepared by the following method: The other steps are the same as in Example 1.

[0044] Weigh 1.5g of material b and add it to 35ml of anhydrous ethanol. Sonicate the mixture for a period of time. Add 0.10g of trimethylchlorosilane (TMCS) to the sonicated suspension. Stir the mixture at 50°C for 12 hours, then centrifuge to collect the surface-modified composite material. Wash several times with anhydrous ethanol, and dry at 60°C for 24 hours to obtain the final composite repair material, denoted as material c.

[0045] The experiment on removing halohydrocarbons from water using the composite remediation material prepared in this embodiment follows the same steps as in Example 1.

[0046] In this embodiment, material c achieved a trichloroethylene removal rate of 94.6% in simulated contaminated groundwater samples.

[0047] Example 9 The composite remediation material for removing halogenated hydrocarbons from groundwater provided in this example is prepared by the following method: The other steps are the same as in Example 1.

[0048] Weigh 1.5g of material b and add it to 35ml of anhydrous ethanol. Sonicate the mixture for a period of time. Add 0.20g of trimethylchlorosilane (TMCS) to the sonicated suspension. Stir the mixture at 50°C for 12 hours, then centrifuge to collect the surface-modified composite material. Wash several times with anhydrous ethanol, and dry at 60°C for 24 hours to obtain the final composite repair material, denoted as material c.

[0049] The experiment on removing halohydrocarbons from water using the composite remediation material prepared in this embodiment follows the same steps as in Example 1.

[0050] In this embodiment, material c achieved a trichloroethylene removal rate of 97.7% in simulated contaminated groundwater samples.

[0051] Example 10: Experiment on the removal of haloalkanes from water using the composite remediation material prepared in Example 1: A 500ml sample of simulated contaminated groundwater with a trichloroethylene concentration of 60mg / L was prepared using deionized water in a 1000ml conical flask. The pH of the water sample was adjusted to 5 using hydrochloric acid. 0.5g of material c was added to the water sample. After shaking the sample at 25℃ for 48 hours, the trichloroethylene concentration in the sample was analyzed by gas chromatography.

[0052] In this embodiment, the removal rate of trichloroethylene in the simulated contaminated groundwater sample was 89.5%.

[0053] Example 11: Experiment on the removal of haloalkanes from water using the composite remediation material prepared in Example 1: A 500ml sample of simulated contaminated groundwater with a trichloroethylene concentration of 60mg / L was prepared using deionized water in a 1000ml conical flask. The pH of the water sample was adjusted to 5 using hydrochloric acid. 2g of material c was added to the water sample. After the sample was kept at 25℃ and shaken for 48 hours, the trichloroethylene concentration in the sample was analyzed by gas chromatography.

[0054] In this embodiment, material c achieved a trichloroethylene removal rate of 99.8% in simulated contaminated groundwater samples.

[0055] Example 12: Experiment on the removal of haloalkanes from water using the composite remediation material prepared in Example 1: A 500ml sample of simulated contaminated groundwater with a trichloroethylene concentration of 60mg / L was prepared using deionized water in a 1000ml conical flask. The pH of the water sample was adjusted to 3 using hydrochloric acid. 1g of material c was added to the water sample. After the sample was kept at 25℃ and shaken for 48 hours, the trichloroethylene concentration in the sample was analyzed by gas chromatography.

[0056] In this embodiment, material c achieved a trichloroethylene removal rate of 98.9% in simulated contaminated groundwater samples.

[0057] Example 13: Experiment on the removal of haloalkanes from water using the composite remediation material prepared in Example 1: A 500ml sample of simulated contaminated groundwater with a trichloroethylene concentration of 60mg / L was prepared using deionized water in a 1000ml conical flask. The pH of the water sample was adjusted to 8 using sodium hydroxide. 1g of material c was added to the water sample. After shaking the sample at 25℃ for 48 hours, the trichloroethylene concentration in the sample was analyzed by gas chromatography.

[0058] In this embodiment, material c achieved a trichloroethylene removal rate of 83.3% in simulated contaminated groundwater samples.

Claims

1. A method for preparing a composite remediation material for removing halogenated hydrocarbons from groundwater, comprising the following steps: Wash the seaweed, dry it, and grind it into powder. Powdered seaweed was placed in a tube furnace for pyrolysis. During the pyrolysis process, N2 was continuously introduced to isolate the air. After the pyrolysis was completed and the temperature dropped to room temperature, the seaweed biochar was obtained. FeSO4·7H2O was dissolved in an ethanol-water solution. Ulva prolifera biochar, calcium polysulfide, and polyethylene glycol-4000 were added to the solution, with a mass ratio of FeSO4·7H2O, Ulva prolifera biochar, calcium polysulfide, and polyethylene glycol-4000 of 10:(0.5~1.5):(5~15):

1. The solution was stirred under nitrogen protection for a period of time, and the pH was adjusted. Then, freshly prepared NaBH4 was added dropwise to the solution. After the NaBH4 solution was added, the mixture was stirred for a period of time. The resulting material was separated from the solution using a magnet, washed several times alternately with deionized water and anhydrous ethanol, and then freeze-dried to obtain material a. Add material a to anhydrous ethanol and stir; fully dissolve silicotungstic acid in anhydrous ethanol and slowly add it dropwise to the above mixture. The mass ratio of material a to silicotungstic acid is 1:0.5~2; stir at room temperature for a period of time, then evaporate to dryness in a water bath. Calcine the obtained solid material at 330-360℃ for several hours to obtain material b. Material b was weighed and added to anhydrous ethanol, and the mixture was sonicated for a period of time. Trimethylchlorosilane was added to the sonicated suspension, with a mass ratio of material b to trimethylchlorosilane of 1:0.05~0.

2. The mixture was stirred at a constant temperature of 45~65℃ for a period of time, and the surface-modified composite material was collected by centrifugation. After washing several times with anhydrous ethanol, the material c was dried, which is the final composite repair material.

2. The method for preparing the composite remediation material for removing halogenated hydrocarbons from groundwater according to claim 1, characterized in that: The concentration of NaBH4 is 0.5~1.5 mol / L, and the molar ratio of NaBH4: FeSO4·7H2O is 1:4~8.

3. A composite repair material prepared using the method of claim 1.

4. The use of the composite remediation material as described in claim 3 in the treatment of sewage pollution.

5. A method for removing halogenated hydrocarbons from groundwater using the composite remediation material according to claim 3, characterized in that, include: Adjust the groundwater contaminated with halogenated hydrocarbons to a weakly acidic or weakly alkaline state, then add 1-3 g / L of composite remediation material to the wastewater to be treated, and stir at room temperature for a period of time.