Chlorinated hydrocarbon remediation material, method of making and in situ remediation of chlorinated hydrocarbons from aquifers

Abstract

The present application relates to the technical field of biological stimulation remediation of chlorinated organic pollutants in aquifer, and discloses a chlorinated hydrocarbon remediation material, a preparation method thereof and a method for in-situ remediation of chlorinated hydrocarbon in aquifer. The chlorinated hydrocarbon remediation material contains organic matter A, organic matter B and organic matter C, the organic matter A wraps the organic matter B and the organic matter C; the molecular weight of the organic matter A is 1000-30000, the molecular weight of the organic matter B is 200-2000, and the molecular weight of the organic matter C is 100-400. The method for preparing the chlorinated hydrocarbon remediation material comprises the following steps: S1, under the protection of inert atmosphere, first mixing the organic matter A with an organic solvent, and then second mixing the obtained first mixed solution with the organic matter B and the organic matter C; S2, drying the second mixed solution obtained in step S1. The chlorinated hydrocarbon remediation material can maintain solid-phase reduction dechlorination components for a long period of operation, and the effective slow-release period thereof can be significantly increased.

Description

Technical Field

[0001] The invention relates to the technical field of biostimulation remediation of chlorinated organic pollutants in aquifers, and in particular to a chlorinated hydrocarbon remediation material and a preparation method thereof, and a method for in-situ remediation of chlorinated hydrocarbons in aquifers. Background Art

[0002] Among the halogenated hydrocarbon organic pollutants in my country's aquifers, trichloroethylene (TCE), carbon tetrachloride (CT), and tetrachloroethylene (PCE) are the most common. Similarly, TCE and PCE are also the most common organic pollutants in aquifers in countries and regions such as Europe, the United States, and Japan.

[0003] Chlorinated organic solvents are widely used in industrial manufacturing processes such as degreasing, electronic parts cleaning, and dry cleaning. Due to improper management and disposal, these solvents often leak into aquifers as dense non-aqueous phase liquids (DNAPLs), a common contaminant. Because DNAPLs are denser than water and are immiscible or only slightly soluble in water, they form a separate liquid phase upon entering an aquifer. Once a chlorinated hydrocarbon leak occurs, it could potentially be exposed to the environment through various pathways, including drinking water, posing a serious health risk to nearby residents.

[0004] Traditional remediation technologies include aquifer extraction and treatment, in-situ thermal desorption, surfactant leaching, and zero-valent iron chemical reduction. However, these technologies all present various problems, the most common of which are tailing and rebound during the remediation process. To address these pollution issues, many studies have developed in-situ biostimulation remediation technology for DNAPL-contaminated aquifers, targeting chlorinated hydrocarbons. This technology is environmentally friendly, safe, and economical. Its application in the in-situ degradation of environmental pollutants primarily involves providing biodegradable organic matrix components to promote the growth of indigenous dechlorinating microorganisms, which assist in the microbial decomposition of pollutants. Therefore, compared with physical and chemical remediation methods, it can reduce remediation costs, is easy to operate, and is more widely accepted by the public. Furthermore, in-situ biostimulation remediation technology is an in-situ remediation technology with minimal site disturbance. Since the process does not require ex-situ disposal, it avoids the generation of wastewater and solid waste, and eliminates concerns about secondary environmental damage such as chemical precipitation and the production of large amounts of hazardous sludge.

[0005] Chinese patent application CN114477474A discloses a kind of in-situ remediation agent for aquifer chlorinated hydrocarbon pollution, manufacturing method and application, remediation agent includes zero-valent iron powder, biochar, biological carbon source, emulsifier, stabilizer and water, biological carbon source includes short-acting, medium-acting and long-acting carbon source, each component is percentage by weight: zero-valent iron powder 20~45%, biochar 8~15%, biological carbon source 15~35%, emulsifier 1~3%, stabilizer 0.1~0.5%, water 15~30%.By adding reusable oil and emulsifier in water, make reusable oil and emulsifier fully emulsified by low-speed stirring;Zero-valent iron powder, biochar and stabilizer are sequentially added, and stirred to mix evenly;Industrial syrup and straw powder are added, and mixed at 2000r / min stirring speed for 10~20min to prepare remediation agent slurry, and the remediation agent is high-pressure injected into aquifer halogenated hydrocarbon pollution water layer.

[0006] Chinese patent application CN108675435A discloses a nano-emulsified carbon source with low aquifer permeability loss in aquifer remediation and a preparation method thereof, specifically discloses that the nano-emulsified carbon source is composed of water, edible vegetable oil and food-grade emulsifier; the mass ratio of the food-grade emulsifier to the edible vegetable oil is 1:(1-2); the food-grade emulsifier is a mixture of Tween-80 and Span-80, and the mass ratio of Tween-80 to Span-80 is 1:(0.2-0.5); the internal phase content is 5-35%.The preparation method is as follows: mix the components in proportion, stir for 5-15 minutes, then ultrasonic for 15-25 minutes, heat to 55-70℃ for 5-10 minutes, and cool naturally.

[0007] Chinese patent application CN109534517A discloses an emulsified vegetable oil, a preparation method and application thereof, specifically discloses that the emulsified vegetable oil includes the following components by weight percentage: edible vegetable oil 45%-75%, surfactant 2%-12% and water 20%-45%; and further includes optional co-substrate and / or pH regulator.The preparation method of the emulsified vegetable oil includes soluble substrate mixing and dissolving, oil-water mixing and stirring, etc.The application method of the emulsified vegetable oil includes well construction, emulsified oil use liquid preparation, indigenous microorganism activity evaluation, emulsified oil use liquid injection, etc., to realize standard remediation of chlorinated organic matter pollution aquifer.

[0008] The prior art often uses vegetable oil and surfactant as raw materials to prepare liquid emulsified oil by ultrasonic or mechanical stirring, which has good treatment effect and is widely used abroad. However, the inner phase particle size of the emulsified oil is less than 10 μm or in nanometer level, and in the high permeability site, such as the site with permeability coefficient greater than 1 m / d, the groundwater flow in the aquifer is fast, which causes part of the emulsified oil agent to flow away with the groundwater, and it is difficult to play the role of continuous supply of electron donors. Moreover, when used in the permeable reactive wall, especially when the permeable reactive wall needs to maintain high permeability to facilitate the groundwater flow, the conventional emulsified oil agent will flow away from the permeable reactive wall with the aquifer, which shortens the effective period of the permeable reactive wall and causes the failure of the permeable reactive wall. SUMMARY

[0009] The present application aims to overcome the problems that in the high permeability site, the groundwater flow in the aquifer is fast, which causes part of the emulsified oil agent to flow away with the groundwater, and when used in the permeable reactive wall, the chlorinated hydrocarbon remediation material will flow away from the permeable reactive wall with the aquifer, which causes the failure of the permeable reactive wall. At the same time, the effective period of the chlorinated hydrocarbon remediation material is improved, and a chlorinated hydrocarbon remediation material, a preparation method thereof and a method for in-situ remediation of chlorinated hydrocarbon in the aquifer are provided. At the same time, the solid material can be made into granular or block shape to meet the requirements of different forms, and can maintain long-period operation of the solid-phase reduction dechlorination component, and the effective slow-release period can be significantly increased.

[0010] In order to achieve the above-mentioned purpose, the present application provides a chlorinated hydrocarbon remediation material, which contains organic matter A, organic matter B and organic matter C, and the organic matter A wraps the organic matter B and the organic matter C; wherein the molecular weight of the organic matter A is 1000-30000, the molecular weight of the organic matter B is 200-2000, and the molecular weight of the organic matter C is 100-400.

[0011] Preferably, the weight ratio of the organic matter A, the organic matter B and the organic matter C is 30:0.5-20:0.1-3, preferably 30:1-15:1-2.

[0012] Preferably, the molecular weight of the organic matter A is 5000-20000.

[0013] Preferably, the organic matter A is a polymer; more preferably, the organic matter A is selected from one or more than two of polylactide, polyvinyl alcohol and polyalginic acid.

[0014] Preferably, the molecular weight of the organic matter B is 200-1500.

[0015] Preferably, the organic matter B is selected from one or more than two of vegetable oil, higher fatty acid and higher fatty acid ester.

[0016] Preferably, the molecular weight of the vegetable oil is 500-1500, preferably 700-1100.

[0017] Preferably, the vegetable oil is selected from one or more of soybean oil, peanut oil, rapeseed oil and sesame oil.

[0018] Preferably, the higher fatty acid is a C16~C18 fatty acid.

[0019] Preferably, the molecular weight of the higher fatty acid is 200-400, preferably 250-350.

[0020] Preferably, the higher fatty acid is selected from one or more of palmitic acid, stearic acid, palmitic acid and oleic acid.

[0021] Preferably, the higher fatty acid ester is a C16~C18 fatty acid ester.

[0022] Preferably, the molecular weight of the higher fatty acid ester is 600-1200, preferably 750-1000.

[0023] Preferably, the higher fatty acid ester is glyceryl stearate and / or glyceryl palmitate.

[0024] Preferably, the molecular weight of the organic matter C is 100-350.

[0025] Preferably, the organic matter C is low molecular weight polylactide.

[0026] Preferably, the chlorinated hydrocarbon repair material is a solid material.

[0027] Preferably, the chlorinated hydrocarbon repair material is in powder, granular or block form.

[0028] A second aspect of the present invention provides a method for preparing the chlorinated hydrocarbon repair material described above, the method comprising the following steps:

[0029] S1. Under an inert atmosphere, organic matter A is first mixed with an organic solvent, and then the obtained first mixed solution is secondly mixed with organic matter B and organic matter C;

[0030] S2. Drying the second mixed solution obtained in step S1.

[0031] Preferably, in step S1, the weight ratio of the organic matter A, the organic matter B and the organic matter C is 30:0.5-20:0.1-3.

[0032] Preferably, in step S1, the ratio of the organic matter A to the organic solvent is 5-50 g:100 mL, preferably 10-30 g:100 mL.

[0033] Preferably, in step S1, the organic solvent is one or more of ethanol, ethyl acetate and dichloromethane.

[0034] In step S1, the first mixing conditions include: a temperature of 35-85°C, preferably 50-65°C.

[0035] Preferably, in step S1, the second mixing conditions include: a temperature of 35-85°C, preferably 65-70°C.

[0036] In step S2, the drying conditions include: a temperature of 40-100°C, preferably 50-70°C.

[0037] Preferably, step S2 further comprises: drying the solid block product obtained in step S2, and then optionally crushing the solid block product to obtain a powdered material.

[0038] Preferably, the particle size of the powdery material is 10-1000 μm.

[0039] Preferably, step S2 further comprises: drying the step S2 to obtain a gel-like product, then shaping the gel-like product into spherical particles, freeze-drying the spherical particles to obtain a granular material, and then optionally crushing the granular material to obtain a powdery material;

[0040] Preferably, the freeze-drying conditions include: a temperature of -30 to -40°C and a time of 2 to 8 hours.

[0041] Preferably, the particle size of the powdery material is 10-1000 μm.

[0042] The third aspect of the present invention provides a chlorinated hydrocarbon repair material prepared by the method described above.

[0043] Preferably, the chlorinated hydrocarbon repair material is suitable for high permeability sites with a permeability coefficient greater than 1 m / d and special sites with high permeability in fractured aquifers.

[0044] A fourth aspect of the present invention provides a method for in-situ remediation of chlorinated hydrocarbons in an aquifer, the method comprising: mixing a chlorinated hydrocarbon remediation material, water, and a rapid start agent, and then injecting the resulting mixed solution into a chlorinated hydrocarbon-contaminated water layer in the aquifer;

[0045] The chlorinated hydrocarbon repair material is the chlorinated hydrocarbon repair material described above;

[0046] The fast-acting agent is selected from one or more of lactic acid, alginate, ethanol, ascorbic acid, citric acid, and glucose.

[0047] Preferably, the weight ratio of the amount of the chlorinated hydrocarbon remediation material to the amount of water is 1:2 to 20, preferably 1:2 to 15.

[0048] Preferably, the weight ratio of the amount of the chlorinated hydrocarbon remediation material to the amount of the fast-acting agent is 10 to 50:1, preferably 10 to 30:1.

[0049] Preferably, the method further comprises adding a pH adjusting agent during the mixing of the chlorinated hydrocarbon remediation material, water, and fast-acting agent.

[0050] Preferably, the pH adjusting agent is selected from one or more of Ca(OH)2, Mg(OH)2, CaCO3, MgCO3, Na2CO3, and NaHCO3, preferably CaCO3 and / or MgCO3.

[0051] Preferably, the chlorinated hydrocarbon is selected from one or more of carbon tetrachloride, tetrachloroethylene, trichloroethylene, dichloroethylene, tetrachloropropane, trichloropropane, dichloropropane, trichlorobenzene, dichlorobenzene, and chloroethane.

[0052] The fifth aspect of the present application provides a method for in-situ remediation of chlorinated hydrocarbons in an aquifer, the method comprising: mixing a chlorinated hydrocarbon remediation material and a fast-acting agent, and then placing the mixture in a permeable reactive wall in a chlorinated hydrocarbon-contaminated zone of the aquifer;

[0053] The chlorinated hydrocarbon remediation material is as described above;

[0054] The fast-acting agent is selected from one or more of lactic acid, alginate, ethanol, ascorbic acid, citric acid, and glucose.

[0055] Preferably, the weight ratio of the amount of the chlorinated hydrocarbon remediation material to the amount of the fast-acting agent is 10 to 50:1, preferably 10 to 30:1.

[0056] Preferably, the chlorinated hydrocarbon is selected from one or more of carbon tetrachloride, tetrachloroethylene, trichloroethylene, dichloroethylene, tetrachloropropane, trichloropropane, dichloropropane, trichlorobenzene, dichlorobenzene, and chloroethane.

[0057] The present invention provides a controlled-release, long-life reduction and dechlorination composite repair material, which includes a medium-release agent and a slow-release agent, and the medium-release agent and the slow-release agent are wrapped by macromolecular degradable organic matter. The solid-phase agent in the material can maintain the long-term operation of the solid-phase reduction and dechlorination component, and its effective sustained-release period can be significantly increased. At the same time, when the agent is used, an agent with a rapid start-up reduction and dechlorination function can be added, thereby quickly starting the agent to carry out the reduction and dechlorination process of chlorinated hydrocarbons; at the same time, the material can be in the form of solid particles or powder particles, and can be mixed with other materials of the permeable reaction wall in a high-permeability site or directly filled into the permeable reaction wall to ensure that the agent is not lost with the groundwater, thereby achieving the purpose of long-term reduction and dechlorination, and can meet the needs of reduction and dechlorination at different stages. The preparation method is simple; preferably, all the agent components are biodegradable components, and there is no secondary pollution problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a morphology image of the solid spherical particles prepared in step (2) of Example 1;

[0059] Figure 2 Schematic diagram of the structure of the test device used in Test Example 8.

[0060] Reference numerals

[0061] 1. Blender 2. Water container

[0062] 3 Peristaltic pump 4 Reaction soil column

[0063] 5 Water outlet storage tank 41 Sample injection port DETAILED DESCRIPTION

[0064] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0065] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0066] In one aspect, the present invention provides a chlorinated hydrocarbon repair material, which contains organic matter A, organic matter B and organic matter C, wherein the organic matter A encapsulates the organic matter B and the organic matter C; wherein the molecular weight of the organic matter A is 1000-30000, the molecular weight of the organic matter B is 200-2000, and the molecular weight of the organic matter C is 100-400.

[0067] In the chlorinated hydrocarbon remediation material described herein, the organic compound A physically encapsulates the organic compounds B and C, which are then mixed together. When the chlorinated hydrocarbon remediation material is used to repair chlorinated hydrocarbons in an aquifer, the organic compounds A, B, and C slowly (anaerobic) ferment and degrade within the underground aquifer, gradually releasing the organic compounds B and C. During use, the organic compound B is released at a slower rate (referred to as a slow-release agent), while the organic compound C is released at a faster rate (referred to as a moderate-release agent). The specific combination of organic compounds B and C achieves controlled release, achieving the effect of a long-lasting, sustained-release electron donor, thereby increasing the operating cycle of the reduction and dechlorination component. In the present invention, the terms "slow-release agent" and "moderate-release agent" have no specific meanings; they are simply used to illustrate their relative release rates during use, i.e., the slow-release agent has a lower release rate than the moderate-release agent.

[0068] In a preferred embodiment, the chlorinated hydrocarbon repair material described in the present application can be a solid material, which can prevent it from flowing with the flow of the aquifer during use, causing part of the material to flow away with the aquifer without playing the role of a corresponding electron donor; it can also prevent the material from being lost from the permeable reaction wall as the aquifer flows when used in the permeable reaction wall, causing the permeable reaction wall to fail.

[0069] Specifically, the chlorinated hydrocarbon repair material can be in any form, including powder, granules, or blocks, as long as it is solid and can be released normally during use. Different forms can be selected based on different usage scenarios. For example, if a permeable reactive wall is used, granules or blocks can be used; if direct injection is used, a powder can be used.

[0070] In the chlorinated hydrocarbon repair material described herein, the weight ratio of organic compounds A, B, and C must be within an appropriate range to ensure that organic compounds A, B, and C exert their effects rapidly during use, while simultaneously allowing organic compounds B and C to exert their respective slow and moderate release effects, achieving controlled release. Furthermore, the chlorinated hydrocarbon repair material can release the compound continuously for an extended period of time, preventing the moderate-release component from being fully released while the slow-release component has not yet begun to release. In the present invention, the terms "slow" and "moderate" have no specific meanings and are merely used to illustrate the relative rates of the two.

[0071] Specifically, the weight ratio of the organic matter A, the organic matter B and the organic matter C is 30:0.5~20:0.1~3, preferably 30:1~15:1~2, for example, 30:12:1.2, 30:1.5:0.3, 30:5:1.2, 30:9:1.2 and 30:10:1.2.

[0072] In the chlorinated hydrocarbon repair material described herein, the organic compound A can be a biodegradable organic compound with a molecular weight of 1,000 to 30,000, preferably a polymer with a molecular weight of 1,000 to 30,000. In a preferred embodiment, the molecular weight of the organic compound A is 5,000 to 20,000. In a more preferred embodiment, the organic compound A is a polymer; more preferably, the organic compound A is selected from one or more of polylactide, polyvinyl alcohol, and polyalginic acid.

[0073] In a specific embodiment, the organic matter B can be a biodegradable organic matter with a molecular weight of 200 to 2000. In a preferred embodiment, the molecular weight of the organic matter B is 200 to 1500.

[0074] In a specific embodiment, the organic matter B is selected from one or more of vegetable oils, higher fatty acids and higher fatty acid esters.

[0075] In the present invention, the vegetable oil can be a common biodegradable vegetable oil in the art. Specifically, the molecular weight of the vegetable oil can be 500-1500, preferably 700-1100, for example, 700, 800, 900, 1000 or 1100.

[0076] Preferably, the vegetable oil is selected from one or more of soybean oil, peanut oil, rapeseed oil and sesame oil.

[0077] In the chlorinated hydrocarbon repair material of the present invention, the higher fatty acid can be a biodegradable higher fatty acid commonly found in the art. Specifically, the higher fatty acid can be a C16-C18 fatty acid. More specifically, the molecular weight of the higher fatty acid can be 200-400, preferably 250-350, such as 250, 256, 282, 284, 300, 312, 330, or 350. In a preferred embodiment, the higher fatty acid is selected from one or more of palmitoleic acid, stearic acid, palmitic acid, and oleic acid.

[0078] In the chlorinated hydrocarbon repair material of the present invention, the higher fatty acid ester can be a biodegradable higher fatty acid ester commonly found in the art. Specifically, the higher fatty acid ester can be a C16-C18 fatty acid ester. Specifically, the molecular weight of the higher fatty acid ester can be 600-1200, preferably 750-1000, for example, 750, 760, 770, 880, 890, 900, 910, 920, 930, 940, 950, or 1000. Preferably, the higher fatty acid ester is glyceryl stearate and / or glyceryl palmitate.

[0079] In the chlorinated hydrocarbon repair material of the present invention, to better cooperate with the organic compound B, achieve controlled release, achieve the effect of long-term sustained release of electron donors, and increase the operating cycle of the reduction and dechlorination component, the molecular weight of the organic compound C can be 50 to 400, preferably 100 to 350. In a preferred embodiment, the organic compound C can be a low-molecular-weight polylactide.

[0080] In order to obtain a long-lasting slow-release electron donor in-situ repair material, the second aspect of the present invention provides a method for preparing the above-mentioned chlorinated hydrocarbon repair material, which comprises the following steps:

[0081] S1. Under an inert atmosphere, organic matter A is first mixed with an organic solvent, and then the obtained first mixed solution is secondly mixed with organic matter B and organic matter C;

[0082] S2. Drying the second mixed solution obtained in step S1.

[0083] In the method described in the present invention, organic matter A is dissolved in an organic solvent under the protection of an inert atmosphere, and then organic matter B and organic matter C are completely dissolved in the first mixed liquid, and then the second mixed liquid is dried. During the drying process, the degree of drying can be controlled according to the morphology of the material to be obtained. If a block material is required, the obtained mixture can be completely dried; if a granular material is required, the obtained mixture can be dried to a semi-solid state, and then formed into balls manually or mechanically. In this method, after organic matter A is dissolved in an organic solvent, organic matter B and organic matter C are completely dissolved or evenly dispersed in the above system. During the drying process, the organic solvent evaporates, and organic matter A returns to its original polymerization state, thereby encapsulating organic matter B and organic matter C.

[0084] In the method of the present application, in order to make the organic matter A, the organic matter B and the organic matter C in the obtained chlorinated hydrocarbon remediation material quickly function in use, while making the organic matter B and the organic matter C each function in slow and medium speed release, realize controlled release, and the chlorinated hydrocarbon remediation material can be continuously released for a long time, prevent the situation that the medium speed release component has been released while the low speed release component has not started to release, the weight of the organic matter A, the organic matter B and the organic matter C can be limited within an appropriate range.

[0085] Specifically, the weight ratio of the organic matter A, the organic matter B and the organic matter C is 30:0.5~20:0.1~3, preferably 30:1~15:1~2, for example, can be 30:12:1.2, 30:1.5:0.3, 30:5:1.2, 30:9:1.2 and 30:10:1.2.

[0086] In the present application, in step S1, the use amount ratio of the organic matter A to the organic solvent is not particularly limited, as long as the organic solvent is sufficient to dissolve the organic matter A, the organic matter B and the organic matter C, and facilitate the drying degree of the obtained second mixed solution according to the morphology control of the obtained material in the subsequent steps.

[0087] In the preferred embodiment, the use amount ratio of the organic matter A to the organic solvent can be 5~50g:100mL, preferably 10~30g:100mL.

[0088] In the present application, the organic solvent can be an organic matter well known in the art which can dissolve the organic matter A, the organic matter B and the organic matter C and is volatile.

[0089] Specifically, in step S1, the organic solvent is one or two or more of ethanol, ethyl acetate and dichloromethane. Preferably, in step S1, the organic solvent is ethanol, which is biodegradable and does not cause secondary pollution.

[0090] In the specific embodiment, the first mixing and the second mixing in step S1 are both carried out under the protection of inert atmosphere. Preferably, the inert atmosphere can be provided by nitrogen or inert gas.

[0091] In the preferred embodiment, in step S1, the temperature of the first mixing can be 35~85℃, preferably 50~65℃. In step S1, the time of the first mixing is not particularly limited, as long as the organic matter A and the organic solvent can be mixed to obtain a milky white solution or a clear solution.

[0092] In the specific embodiment, in step S1, the order of mixing the first mixed solution with the organic matter B and the organic matter C is not particularly limited, as long as the organic matter B and the organic matter C can be dissolved to obtain a uniform solution.

[0093] In the preferred embodiment, in step S2, the temperature of the second mixing can be 35-85°C, preferably 65-70°C. In step S2, the time of the second mixing is not particularly limited, as long as the first mixed solution can be mixed with the organic matter B and the organic matter C to obtain a uniform solution. Preferably, in order to improve the mixing rate and mixing effect, in step S1, the first mixing and the second mixing are both mixed under stirring, i.e., the first mixing and the second mixing are in the form of stirring mixing. Specifically, the stirring mixing rate can be 100-1000 rpm.

[0094] In the present application, in step S2, the drying method is not limited, and can be a conventional drying method in the art, as long as the organic solvent can be evaporated. In the specific embodiment, in step S2, the drying method is natural evaporation drying or heating drying.

[0095] Specifically, the temperature of the heating drying is not limited, as long as the organic solvent can be evaporated and the macromolecular organic matter and the low-molecular organic matter are not damaged.

[0096] In the specific embodiment, in step S2, the drying temperature can be 40-100°C, preferably 50-70°C.

[0097] In the present application, for the drying process of step S2, the drying degree, drying time and whether subsequent crushing is needed can be selected according to the morphology of the material required for subsequent use.

[0098] In the specific embodiment, step S2 further comprises: drying the second mixed solution obtained in step S1 to directly obtain a solid block product. Subsequently, no crushing is performed, and the block material can be directly mixed with a rapid-starting agent for use, and then the mixed material is placed in a permeable reaction wall of a water-bearing layer chlorinated hydrocarbon contaminated water layer; or the block material and the rapid-starting agent are prepared into a mixed solution and injected into the water-bearing layer chlorinated hydrocarbon contaminated water layer. The drying time of the solid block product obtained by the heating drying method is not limited, as long as the mixed solution obtained in step S1 can be completely dried at the aforementioned heating drying temperature to obtain a solid block product; preferably, the drying time is 30 min-6 h.

[0099] In the specific embodiment, the step S2 further comprises: obtaining the solid block product after the drying of step S2, and then optionally crushing the solid block product to obtain the powder material. In use, the powder material and the fast-starting reagent can be formulated into a mixed solution and injected into the chlorinated hydrocarbon contaminated water layer. The drying time for obtaining the solid block product by heating and drying is not limited, as long as the mixed solution obtained in step S1 can be completely dried at the temperature of the aforementioned heating and drying to obtain the solid block product; preferably, the drying time is 30 min to 6 h. Specifically, the particle size of the powder material can be 10-1000 μm.

[0100] In the specific embodiment, the step S2 further comprises: obtaining the gel product after the drying of step S2, then shaping the gel product into spherical particles, and freeze-drying the spherical particles to obtain the granular material, and then optionally crushing the granular material to obtain the powder material. In order to obtain the gel semi-solid product, the drying time at the temperature of the aforementioned heating and drying is 20 min to 5 h. The spherical particles can be centimeter-sized pellets.

[0101] In the present application, after obtaining the solid spherical particles, the solid spherical particles can be directly mixed with the fast-starting reagent without crushing, and then the mixture is placed in the permeable reaction wall of the chlorinated hydrocarbon contaminated water layer in the aquifer; or the solid spherical particles and the fast-starting reagent can be formulated into a mixed solution and injected into the chlorinated hydrocarbon contaminated water layer in the aquifer; or the powder material obtained by crushing the solid spherical particles and the fast-starting reagent can be formulated into a mixed solution and injected into the chlorinated hydrocarbon contaminated water layer in the aquifer. Specifically, the particle size of the powder material can be 10-1000 μm.

[0102] Specifically, in order to obtain the solid spherical particles, the conditions of the freeze-drying can include: the temperature is -30 to -40℃; and the time can be 2-8 h.

[0103] In the present application, the crushing of the aforementioned solid block product or solid spherical particles can be performed in a ball mill; and the ball milling rate can be 1000-3000 r / min.

[0104] The third aspect of the present application provides a chlorinated hydrocarbon remediation material prepared by the method described above. The chlorinated hydrocarbon remediation material is a controlled-release, long-life reductive dechlorination composite remediation material, which contains a medium-speed release agent and a slow-speed release agent. The agent is a solid-phase component, which can maintain the solid-phase reductive dechlorination component for a long period of operation, and the effective slow-release period can be significantly increased. At the same time, a fast-start reductive dechlorination agent can be added to the agent during use, so that the chlorinated hydrocarbon reductive dechlorination process can be quickly started. At the same time, since the material can be solid, it can be directly mixed and filled with other materials permeable to the reaction wall into the permeable reaction wall to achieve the purpose of long-acting reductive dechlorination, and can meet the needs of reductive dechlorination at different stages.

[0105] Under preferred conditions, the chlorinated hydrocarbon remediation material prepared by the method described above is suitable for high-permeability sites with a permeability coefficient greater than 1 m / d and fractured aquifer high-permeability special sites. The permeability coefficient is determined by the steady flow pumping test method GB50027-2001 of the pumping well and the monitoring well.

[0106] The fourth aspect of the present application provides a method for in-situ remediation of chlorinated hydrocarbons in an aquifer, which comprises: mixing a chlorinated hydrocarbon remediation material, water and a fast-starting agent, and then injecting the obtained mixed solution into the chlorinated hydrocarbon contaminated aquifer of the aquifer; the chlorinated hydrocarbon remediation material is the chlorinated hydrocarbon remediation material described above; and the fast-starting agent is selected from one or more of lactic acid, alginate, ethanol, ascorbic acid, citric acid and glucose.

[0107] Specifically, the weight ratio of the amount of the chlorinated hydrocarbon remediation material to water is 1:2-20, preferably 1:2-15, for example, it can be 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14 or 1:15.

[0108] Specifically, the weight ratio of the amount of the chlorinated hydrocarbon remediation material to the fast-starting agent can be 10-50:1, preferably 10-30:1, for example, it can be 10:1, 15:1, 20:1, 25:1, 30:1.

[0109] In the present application, specifically, the preparation process of the mixed solution of the fourth aspect comprises: uniformly mixing the chlorinated hydrocarbon remediation material and water, and then adding the fast-starting agent and stirring to obtain a uniform mixed solution.

[0110] Specifically, various acidic substances may be generated during the aforementioned chlorinated hydrocarbon repair materials, quick-start agents, and chlorinated hydrocarbon reduction and dechlorination processes. A small amount of pH regulator may be added to adjust the pH value when preparing the mixed solution to avoid the pH value of the water being lowered due to chloride ions generated during the chlorinated hydrocarbon reduction and dechlorination process after the mixed solution is injected into the aquifer to contaminate the chlorinated hydrocarbon-contaminated water layer, thereby affecting the water layer environment.

[0111] Preferably, the method described in the fourth aspect further comprises: adding a pH regulator during the mixing process of the chlorinated hydrocarbon repair material, water and the quick-start agent.

[0112] Specifically, the pH adjuster can be various alkaline substances well known in the art. Preferably, the pH adjuster is selected from one or more of Ca(OH)2, Mg(OH)2, CaCO3, MgCO3, Na2CO3, and NaHCO3, more preferably CaCO3 and / or MgCO3.

[0113] In a specific embodiment, the chlorinated hydrocarbon is selected from one or more of carbon tetrachloride, tetrachloroethylene, trichloroethylene, dichloroethylene, tetrachloropropane, trichloropropane, dichloropropane, trichlorobenzene, dichlorobenzene, and ethyl chloride.

[0114] A fifth aspect of the present invention provides a method for in-situ remediation of chlorinated hydrocarbons in an aquifer, the method comprising: mixing a chlorinated hydrocarbon remediation material and a quick-start agent, and then placing the mixture in a permeable reaction wall of a chlorinated hydrocarbon-contaminated water layer in the aquifer; the chlorinated hydrocarbon remediation material is the chlorinated hydrocarbon remediation material described above; and the quick-start agent is selected from one or more of lactic acid, alginate, ethanol, ascorbic acid, citric acid and glucose.

[0115] Specifically, the weight ratio of the chlorinated hydrocarbon repair material to the rapid start agent is 10-50:1, preferably 10-30:1, for example, 10:1, 15:1, 20:1, 25:1, or 30:1.

[0116] In a specific embodiment, the chlorinated hydrocarbon is selected from one or more of carbon tetrachloride, tetrachloroethylene, trichloroethylene, dichloroethylene, tetrachloropropane, trichloropropane, dichloropropane, trichlorobenzene, dichlorobenzene, and ethyl chloride.

[0117] Specifically, various acidic substances may be generated during the aforementioned chlorinated hydrocarbon repair materials, quick-start agents, and chlorinated hydrocarbon reduction and dechlorination processes. When the chlorinated hydrocarbon repair materials and quick-start agents are mixed, a small amount of pH regulator may be added to adjust the pH to avoid placing the mixture behind a permeable reaction wall in the chlorinated hydrocarbon-contaminated water layer of the aquifer and conducting the chlorinated hydrocarbon reduction and dechlorination process. Chloride ions generated may cause the pH value in the water to decrease, thereby affecting the water layer environment.

[0118] Preferably, the method of the fifth aspect comprises mixing the chlorinated hydrocarbon remediation material, the rapid-starting agent and the pH adjusting agent, and then placing the mixture into a permeable reactive wall in the chlorinated hydrocarbon-contaminated aquifer.

[0119] In particular, the pH adjusting agent can be any of the various alkaline substances known in the art. Preferably, the pH adjusting agent is selected from one or more of Ca(OH)2, Mg(OH)2, CaCO3, MgCO3, Na2CO3 and NaHCO3, more preferably CaCO3 and / or MgCO3.

[0120] The chlorinated hydrocarbon remediation material of the present application is suitable for use in sites where the aquifer has a relatively high flow rate, and is preferably used in sandy and silty soils.

[0121] The present application will now be described in detail by way of examples, but the scope of the present application is not limited to the examples. Unless otherwise specified, the reagents used in the examples and comparative examples are commercially available.

[0122] Examples 1-5 and Comparative Example -2 are used to illustrate the preparation of the chlorinated hydrocarbon remediation material.

[0123] Example 1

[0124] (1) Under the protection of a nitrogen atmosphere and with heating and magnetic stirring, 10 g of polylactide having a molecular weight of 5000 and 100 mL of an ethanol solution having a concentration of 99% were added to a three-necked flask, and the solution was heated and stirred at 65°C for 20 minutes until the polylactide was completely dissolved, to obtain a milky white or clear solution. Then 4 g of stearic acid having a molecular weight of 284 was added to the solution, and the solution was heated and stirred at 65°C for 10 minutes to obtain a uniform solution. Then 0.4 g of low-molecular polylactide having a degree of polymerization of 4 and a molecular weight of 306 was added to the solution, and the solution was heated and stirred at 65°C for 10 minutes to obtain a uniform solution. The stirring speed of the heating and magnetic stirrer was 1000 r / min.

[0125] (2) The mixture obtained in step S1 was heated at 65°C for 3 hours until the ethanol was completely volatilized, to obtain a gel-like semi-solid. Then the semi-solid was manually formed into a ball to obtain a centimeter-level (about 1 cm in diameter) spherical particle. Then the spherical particle was freeze-dried at a temperature of -40°C for 2 hours to obtain a solid spherical particle (as shown in Figure 1 ).

[0126] (3) The solid spherical particle was placed in a high-energy ball mill, and was ball-milled at a speed of 2000 r / min for 15 minutes to obtain a powder-like chlorinated hydrocarbon remediation material A1 having a particle size distribution of 20-200 μm.

[0127] Example 2

[0128] (1) Under the protection of nitrogen atmosphere and heating magnetic stirrer stirring, 20 g, molecular weight of 10000 polylactide and 100 mL, concentration of 99% ethyl acetate solution into a three-necked flask, 50 ℃ constant temperature stirring heating 20 minutes to polylactide completely dissolved, get milky white or clear solution, then to the solution 1 g of soybean oil, continue to 50 ℃ constant temperature stirring heating 20 minutes, get uniform solution, then to the solution 0.2 g, molecular weight of 306 low molecular weight polylactide, continue to 70 ℃ constant temperature stirring heating 10 minutes, get uniform solution, wherein, the stirring speed of the heating magnetic stirrer is 500 r / min;

[0129] (2) the mixed solution obtained in step S1 is heated at 50 ℃ for 30 minutes until the ethyl acetate volatilizes completely, obtaining a gel-like semi-solid, then manually balling, forming centimeter level (diameter about 1 cm) spherical particles, then the spherical particles are freeze-dried, the temperature of freeze-drying is-30 ℃, the time of freeze-drying is 4 h, obtaining solid spherical particles;

[0130] (3) the solid spherical particles are placed in a high-energy ball mill, and ball milling is carried out at a rotating speed of 2000 r / min for 3 min, obtaining powder-like chlorinated hydrocarbon repair material A2 with a particle size distribution of 50-600 μm.

[0131] Example 3

[0132] (1) Under the protection of nitrogen atmosphere and heating magnetic stirrer stirring, 30 g, molecular weight of 2000 polylactide and 100 mL, concentration of 99% ethanol solution into a three-necked flask, 65 ℃ constant temperature stirring heating 20 minutes to polylactide completely dissolved, get milky white or clear solution, then to the solution 5 g, molecular weight of 891 triglyceride stearate, continue to 65 ℃ constant temperature stirring heating 20 minutes, get uniform solution, then to the solution 1.2 g, molecular weight of 234 low molecular weight polylactide, continue to 65 ℃ constant temperature stirring heating 10 minutes, get uniform solution, wherein, the stirring speed of the heating magnetic stirrer is 500 r / min;

[0133] (2) the mixed solution obtained in step S1 is heated at 70 ℃ for 2 h until the ethanol volatilizes completely, obtaining a gel-like semi-solid, then manually balling, forming spherical particles with a diameter of 2 cm, then the spherical particles are freeze-dried, the temperature of freeze-drying is-40 ℃, the time of freeze-drying is 4 h, obtaining solid spherical particles;

[0134] (3) The solid spherical particles are placed in a high-energy ball mill, and ball milling is performed at a rotation speed of 2000 r / min for 5 min to obtain a powdered chlorinated hydrocarbon repair material A3 with a particle size distribution of 30-400 μm.

[0135] Example 4

[0136] (1) Under the protection of a nitrogen atmosphere and stirring of a heated magnetic stirrer, 5 g of polylactide with a molecular weight of 20,000 and 100 mL of an ethanol solution with a concentration of 99% are added to a three-necked flask, and constant temperature stirring and heating are performed at 70°C for 20 min until the polylactide is completely dissolved, to obtain a milky white or clear solution. Then, 1.5 g of soft stearic acid with a molecular weight of 256 is added to the solution, and constant temperature stirring and heating are continued at 65°C for 10 min to obtain a uniform solution. Then, 0.2 g of low-molecular polylactide with a degree of polymerization of 4 and a molecular weight of 306 is added to the solution, and constant temperature stirring and heating are continued at 65°C for 15 min to obtain a uniform solution. The stirring rotation speed of the heated magnetic stirrer is 500 r / min;

[0137] (2) The mixed solution obtained in step S1 is heated at 65°C for 2 h until the ethanol is completely volatilized, to obtain a gel-like semi-solid. Then, the semi-solid is manually formed into spherical particles with a centimeter level (about 2 cm in diameter). Then, the spherical particles are freeze-dried at a temperature of -40°C for 4 h to obtain solid spherical particles;

[0138] (3) The solid spherical particles are placed in a high-energy ball mill, and ball milling is performed at a rotation speed of 1000 r / min for 5 min to obtain a powdered chlorinated hydrocarbon repair material A4 with a particle size distribution of 40-500 μm.

[0139] Example 5

[0140] (1) Under the protection of a nitrogen atmosphere and stirring of a heated magnetic stirrer, 15 g of polylactide with a molecular weight of 1000 and 100 mL of a dichloromethane solution with a concentration of 99% are added to a three-necked flask, and constant temperature stirring and heating are performed at 70°C for 10 min until the polylactide is completely dissolved, to obtain a milky white or clear solution. Then, 5 g of rapeseed oil is added to the solution, and constant temperature stirring and heating are continued at 65°C for 20 min to obtain a uniform solution. Then, 0.6 g of low-molecular polylactide with a molecular weight of less than 200 is added to the solution, and constant temperature stirring and heating are continued at 65°C for 10 min to obtain a uniform solution. The stirring rotation speed of the heated magnetic stirrer is 500 r / min;

[0141] (2) The mixed solution obtained in step S1 is heated at 65°C for 10 minutes until the dichloromethane is completely volatilized, obtaining a gel-like semi-solid, which is then manually formed into a ball to form a centimeter-level (about 0.5 cm in diameter) spherical particle, and then the spherical particle is freeze-dried at a temperature of -40°C for 4 hours to obtain a solid spherical particle;

[0142] (3) The solid spherical particle is placed in a high-energy ball mill and ball-milled at a speed of 2000 r / min for 5 minutes to obtain a powder-like chlorinated hydrocarbon repair material A5 with a particle size distribution of 30-500 μm.

[0143] Comparative Example 1

[0144] The method of Example 1 is implemented, except that in step (1), no low-molecular poly-lactide is added. The specific method includes:

[0145] (1) Under the protection of nitrogen atmosphere and heating magnetic stirrer stirring, 10 g of poly-lactide with a molecular weight of 5000 and 100 mL of ethanol solution with a concentration of 99% are added to a three-necked flask, and the solution is heated and stirred at 65°C for 20 minutes until the poly-lactide is completely dissolved, obtaining a milky white or clear solution, and then 4 g of stearic acid with a molecular weight of 284 is added to the solution, and the solution is continuously heated and stirred at 65°C for 10 minutes to obtain a uniform solution, wherein the stirring speed of the heating magnetic stirrer is 1000 r / min;

[0146] (2) The mixed solution obtained in step S1 is heated at 65°C for 3 hours until the ethanol is completely volatilized, obtaining a gel-like semi-solid, which is then manually formed into a ball to form a centimeter-level (about 1 cm in diameter) spherical particle, and then the spherical particle is freeze-dried at a temperature of -40°C for 2 hours to obtain a solid spherical particle;

[0147] (3) The solid spherical particle is placed in a high-energy ball mill and ball-milled at a speed of 2000 r / min for 15 minutes to obtain a powder-like chlorinated hydrocarbon repair material B1 with a particle size distribution of 20-200 μm.

[0148] Comparative Example 2

[0149] The method of Example 1 is implemented, except that in step (1), no stearic acid is added. The specific method includes:

[0150] (1) Under nitrogen atmosphere protection and stirring with a heating magnetic stirrer, 10 g of polylactide with a molecular weight of 5000 and 100 mL of 99% ethanol solution were added to a three-necked flask, and the mixture was stirred and heated at 65°C for 20 minutes until the polylactide was completely dissolved to obtain a milky white or clear solution; then 0.4 g of low molecular weight polylactide with a degree of polymerization of 4 and a molecular weight of 306 was added to the solution, and the mixture was stirred and heated at 65°C for 10 minutes to obtain a uniform solution, wherein the stirring speed of the heating magnetic stirrer was 1000 r / min;

[0151] (2) The mixed solution obtained in step S1 was heated at a constant temperature of 65°C for 3 h until the ethanol was almost completely evaporated to obtain a gel-like semi-solid, which was then manually sphericalized to form centimeter-sized (approximately 1 cm in diameter) spherical particles. The spherical particles were then freeze-dried at a temperature of -40°C for 4 h to obtain solid spherical particles.

[0152] (3) The solid spherical particles are placed in a high-energy ball mill and ball-milled at a rotation speed of 2000 r / min for 15 minutes to obtain a powdered chlorinated hydrocarbon repair material B2 with a particle size distribution of 20-200 μm.

[0153] Test Case

[0154] The release of dissolved COD in the aqueous phase was determined by the potassium dichromate method to detect the effective action period of the powdered chlorinated hydrocarbon repair materials A1-A5 and B1-B2 prepared in Examples 1-5 and Comparative Examples 1-2. Figure 2 As shown, the device includes: a water storage container 2, a stirrer 1, a peristaltic pump 3, a reaction soil column 4 (length 30 cm), and a water outlet water reservoir 5; wherein the stirrer 1, water storage container 2, peristaltic pump 3, reaction soil column 4 and water outlet water reservoir 5 are connected in sequence; the reaction soil column 4 is provided with a sample injection port 41, a water inlet and a water outlet, the water inlet is connected to the peristaltic pump 3, and the water outlet is connected to the water outlet water reservoir 5.

[0155] During the test, the powdered chlorinated hydrocarbon repair materials A1-A5 and B1-B2 to be tested samples are injected from the sample injection port 41, and then both sides of the to-be-tested samples are filled with quartz sand. The lower part of the water storage container 2 is filled with deionized water, and the upper part is filled with nitrogen to remove oxygen from the headspace above the aqueous solution; the deionized water in the water storage container 2 is continuously injected into the reaction soil column 4 at a certain rate through the peristaltic pump 3, and the dissolved COD content data at the outlet of the reaction soil column 4 are regularly measured. The data are shown in Table 1-2.

[0156] As can be seen from Tables 1 and 2, the powdered chlorinated hydrocarbon repair materials prepared in Examples 1-5 maintained a relatively stable concentration of dissolved COD from about 20 days to 300 days during the entire action cycle, indicating that the entire sustained-release repair material maintained a continuous and stable release within the 300-day period, which is beneficial for providing a continuous carbon source for microorganisms and a good environment for the biostimulation and degradation of chlorinated hydrocarbons.

[0157] However, the concentration of dissolved COD in the powdered chlorinated hydrocarbon repair materials prepared in Comparative Examples 1 and 2 was not stable within the entire action cycle of 300 days, indicating that the chlorinated hydrocarbon repair materials could not be released continuously and stably within the 300-day period.

[0158] Table 1 Dissolved COD test results

[0159]

[0160] Table 2 Dissolved COD test results

[0161]

[0162] Examples 6-10 and Comparative Examples 3-4 are used to simulate the process of in-situ remediation of chlorinated hydrocarbons in aquifers using chlorinated hydrocarbon remediation materials.

[0163] Example 6

[0164] Sediments from a 1,1,2-trichloroethane-contaminated aquifer were obtained from contaminated soil at a corporate site. GS-MS analysis revealed an initial concentration of 50 mg / kg of trichloroethane and a water content of 32%. The contaminated aquifer sediment was placed in a tube and transported to the laboratory, where it was placed directly in a glove box, shielded from air throughout the entire process.

[0165] Accurately weigh 5 g of the powdered chlorinated hydrocarbon repair material A1 prepared in Example 1 and place it in 10 g of deionized water. Mix thoroughly. Then, add 0.2 g of lactic acid and 0.3 g of glucose and continue stirring to obtain a mixed solution. Add the mixed solution to 2 kg of contaminated aquifer sediment and continue stirring until the entire system forms a slurry.

[0166] 10 g of the above slurry sample was weighed and placed in multiple headspace bottles, which were then placed in a constant temperature incubator for cultivation. The dissolved oxygen, redox potential and trichloroethane pollutant concentration were measured regularly. The data are shown in Table 3-8.

[0167] It can be seen from Tables 3 and 4 that the dissolved oxygen content decreased rapidly from the initial 0.6 ppm to below 0.3 ppm within 10 days, and from the 10th day to the 300th day, the dissolved oxygen content remained in a very low and relatively stable range.

[0168] As can be seen from Table 5 and Table 6, the redox potential rapidly decreases from the initial 120 mV to -50 mV on the 10th day, then slowly decreases to -176 mV on the 50th day, and remains stable from the 50th day to the 300th day, indicating that the environment has been converted from an oxidizing environment to a reducing environment due to the addition of the electron donor, which provides good reducing conditions for the reductive dechlorination of chlorinated hydrocarbons, and the reductive dechlorination process is relatively stable.

[0169] As can be seen from Table 7 and Table 8, the pollutant concentration changes little from the initial 56 ppm in the first 10 days, basically maintaining at about 50 ppm, which may be due to the heterogeneity during the mixing of the sediment with the reagent and the system error existing during the test. However, from the 30th day, the pollutant concentration changes greatly, rapidly decreasing, indicating that after several days of microbial growth, the dechlorination bacterial population has become the main colony structure, thereby rapidly degrading the chlorinated hydrocarbons, resulting in a rapid decrease in the concentration of chlorinated hydrocarbons.

[0170] Example 7

[0171] Polluted soil was obtained from a site of a certain enterprise, and the initial concentration of 1,1,2-trichloroethane in the water-containing sediment was determined by GS-MS to be 76 mg / kg, and the moisture content of the sediment was 28%. The contaminated water-containing sediment was placed in a tube and sent to the laboratory, and was directly placed in a glove box during the whole process to avoid air contact.

[0172] 5 g of the powder chlorinated hydrocarbon remediation material A2 prepared in Example 2 was accurately weighed and placed in 50 g of deionized water, mixed uniformly, then 0.3 g of ethanol was added, and 2 g of Ca(OH)2 solid powder was added, and the mixture was continuously stirred and mixed uniformly to obtain a mixed solution. The mixed solution was added to 2 kg of contaminated water-containing sediment, and the whole system was continuously stirred and mixed uniformly to form a slurry state.

[0173] 10 g of the above-mentioned sample in a slurry state was weighed and placed in multiple headspace bottles, then placed in a constant temperature incubator for incubation, and the dissolved oxygen, redox potential and trichloropropane pollutant concentration were determined periodically, and the data are shown in Table 3-8.

[0174] As can be seen from Table 3 and Table 4, the dissolved oxygen content rapidly decreases from the initial 0.7 ppm to below 0.2 ppm within 10 days, and remains in a very low and relatively stable range from the 10th day to the 300th day.

[0175] As can be seen from Table 5 and Table 6, the redox potential rapidly decreases from the initial 204 mV to -40 mV on the 10th day, then slowly decreases to -143 mV on the 50th day, and is relatively stable from the 80th day to the 300th day, indicating that the environment has been converted from an oxidizing environment to a reducing environment due to the addition of the electron donor, which provides good reducing conditions for the reductive dechlorination of chlorinated hydrocarbons, and the reductive dechlorination process is relatively stable.

[0176] As can be seen from Table 7 and Table 8, the pollutant concentration changes little from the initial 76 ppm in the first 10 days, basically maintaining at about 70 ppm, which may be due to the heterogeneity during the mixing of the sediment with the reagent and the system error existing during the test. However, the pollutant concentration changes greatly from the 30th day, rapidly decreasing, indicating that after the growth of microorganisms for several tens of days, the dechlorination bacterial population has become the main colony structure, thereby rapidly degrading the chlorinated hydrocarbons, resulting in a rapid decrease in the concentration of chlorinated hydrocarbons.

[0177] Example 8

[0178] From the contaminated soil of a certain enterprise site, tetrachloroethylene-contaminated aquifer sediment was obtained, and the initial concentration of tetrachloroethylene in the aquifer sediment was determined by GS-MS to be 135 mg / kg, and the moisture content of the sediment was 30%. The contaminated aquifer sediment was placed in a tube and sent to the laboratory, and directly placed in a glove box during the whole process to avoid air contact.

[0179] Accurately weigh 5 g of the powder chlorinated hydrocarbon remediation material A3 prepared in Example 3, 0.2 g of ascorbic acid, and 5 g of NaHCO3 solid powder, mix uniformly, and place in Figure 2 the material filling position.

[0180] A soil column test was used to simulate the permeable reactive wall technology, and tetrachloroethylene-contaminated aquifer sediment was filled in the soil column. The simulation test is shown in Figure 2 , the influent pollutant concentration was 100 ppm, and the dissolved oxygen, redox potential, and tetrachloroethylene pollutant concentration of the effluent were determined, and the results are shown in Tables 3-8.

[0181] As can be seen from Table 3 and Table 4, the dissolved oxygen content rapidly decreases from the initial 1.0 ppm to below 0.4 ppm within 15 days, and the dissolved oxygen content is maintained in a very low range within the subsequent 200 days.

[0182] As can be seen from Table 5 and Table 6, the redox potential rapidly decreases from the initial 106 mV to -80 mV within 30 days, then slowly decreases to -172 mV at the 80th day, and remains stable from the 80th day to the 300th day, indicating that the environment has been converted from an oxidizing environment to a reducing environment due to the addition of the electron donor, which provides good reducing conditions for the reductive dechlorination of chlorinated hydrocarbons.

[0183] As can be seen from Table 7 and Table 8, the initial effluent concentration of the pollutant is 106 ppm, which changes little within the first 15 days and basically remains at about 100 ppm, which may be due to the heterogeneity during the mixing of the sediment and the reagent and the system error existing during the test, but it can be seen that the pollutant concentration does not change greatly within this short period of time. However, from the 30th day, the pollutant concentration changes greatly, rapidly decreasing, indicating that after the growth of microorganisms for several tens of days, the dechlorination bacterial population has become the main colony structure, thereby rapidly degrading chlorinated hydrocarbons, resulting in a rapid decrease in the concentration of chlorinated hydrocarbons.

[0184] Example 9

[0185] From the contaminated soil of a certain enterprise site, trichloropropane-contaminated aquifer sediment was obtained, and the initial concentration of trichloropropane in the aquifer sediment was determined by GS-MS to be 100 mg / kg, and the moisture content of the sediment was 32%. The contaminated aquifer sediment was placed in a tube and sent to the laboratory, and was directly placed in a glove box during the entire process to avoid air contact.

[0186] 5 g of the powder chlorinated hydrocarbon remediation material A4 prepared in Example 4 was accurately weighed and placed in 50 g of deionized water, mixed uniformly, then 0.5 g of lactic acid was added, and the mixture was continuously stirred and mixed uniformly to obtain a mixed solution. The mixed solution was added to 2 kg of contaminated aquifer sediment, and continuously stirred and mixed uniformly to make the entire system present a slurry state.

[0187] 10 g of the above-mentioned sample in a slurry state was weighed and placed in multiple headspace bottles, then placed in a constant-temperature incubator for incubation, and the dissolved oxygen, redox potential, and trichloropropane pollutant concentration were determined periodically, and the results are shown in Table 3-8.

[0188] As can be seen from Table 3 and Table 4, the dissolved oxygen content rapidly decreases from the initial 0.9 ppm to below 0.3 ppm within 10 days, and remains in a very low range within the subsequent 300 days.

[0189] It can be seen from Tables 5 and 6 that the redox potential decreased rapidly from the initial 89 mV to -86 mV within 20 days, and then slowly decreased to -140 mV on the 50th day. The redox potential was relatively stable from the 140th day to the 300th day, indicating that due to the addition of electron donors in this process, the entire environment has been transformed from an oxidizing environment to a reducing environment, which provides better reducing conditions for the reductive dechlorination of chlorinated hydrocarbons.

[0190] As can be seen from Tables 7 and 8, the pollutant concentration did not change much from the initial 100 ppm during the first 15 days, remaining essentially around 100 ppm. This may be due to the heterogeneity of the sediment and reagent during the initial mixing process and the systematic errors in the testing process, but it also indicates that the pollutant concentration did not change significantly during this short period of time. However, starting from the 30th day, the pollutant concentration changed significantly, and the pollutant concentration decreased rapidly. This indicates that after dozens of days of microbial growth, the dechlorinating bacteria have become the most dominant bacterial colony structure, thereby rapidly degrading the chlorinated hydrocarbons, resulting in a rapid decrease in the chlorinated hydrocarbon concentration.

[0191] Comparative Example 3

[0192] A tetrachloroethylene-contaminated aquifer sediment was obtained from contaminated soil at a certain enterprise site. GS-MS analysis revealed an initial tetrachloroethylene concentration of 135 mg / kg and a water content of 30%. The contaminated aquifer sediment was placed in a tube and transported to the laboratory, where it was placed directly in a glove box, shielded from air throughout the entire process.

[0193] Accurately weigh 5g of triglycerol stearate, 0.2g of ascorbic acid, and 5g of NaHCO3 solid powder, mix them evenly, and place them in a Figure 2 Material filling position.

[0194] A soil column test was used to simulate the permeable reactive wall technology. The soil column was filled with tetrachloroethylene contaminated aquifer sediments. Figure 2 As shown, the influent pollutant concentration is 100 ppm, and the effluent dissolved oxygen, redox potential and tetrachloroethylene pollutant concentration are measured. The results are detailed in Table 3-8.

[0195] As can be seen from Tables 3 and 4, the dissolved oxygen content rapidly decreased from the initial 1.0 ppm to below 0.4 ppm within 3 days, and remained in a very low range for the subsequent 80 days. However, the concentration increased significantly from 140 to 300 days in the later period. This may be due to the loss of triglycerol stearate as it dissolved in the aqueous phase, thus losing its degradation effect.

[0196] As shown in Tables 5 and 6, the redox potential rapidly decreased from an initial 109 mV to -79 mV within 20 days, then slowly decreased to -162 mV on day 30. This indicates that the addition of the electron donor transformed the overall environment from an oxidizing one to a reducing one, providing favorable conditions for the reductive dechlorination of chlorinated hydrocarbons. However, the redox potential increased significantly from day 140 to day 300, and the overall environment returned to an oxidizing one. This is likely due to the loss of triglycerol stearate as it dissolved in the aqueous phase, resulting in a loss of degradation.

[0197] As can be seen from Tables 7 and 8, the pollutant concentration changed little from an initial 106 ppm over the first seven days, remaining essentially around 100 ppm. This may be due to heterogeneity in the initial mixing of the sediment and the reagent and systematic errors in the testing process, but it also indicates that the pollutant concentration did not change significantly during this short period. Starting from the 20th day, the pollutant concentration changed significantly, decreasing rapidly. This indicates that after dozens of days of microbial growth, the dechlorinating bacteria have become the dominant colony structure, rapidly degrading chlorinated hydrocarbons and causing a rapid decrease in chlorinated hydrocarbon concentrations. However, the concentration gradually increased from the 80th to the 300th day, likely due to the loss of triglycerol stearate as it dissolved in the aqueous phase, losing its degradation function.

[0198] Comparative Example 4

[0199] A tetrachloroethylene-contaminated aquifer sediment was obtained from contaminated soil at a certain enterprise site. GS-MS analysis revealed an initial tetrachloroethylene concentration of 135 mg / kg and a water content of 30%. The contaminated aquifer sediment was placed in a tube and transported to the laboratory, where it was placed directly in a glove box, shielded from air throughout the entire process.

[0200] Accurately weigh 5g of the powdered chlorinated hydrocarbon repair material B2 prepared in Comparative Example 2, 0.2g of ascorbic acid, and 5g of NaHCO3 solid powder, mix them evenly, and place them in a Figure 2 Material filling position.

[0201] A soil column test was used to simulate the permeable reactive wall technology. The soil column was filled with tetrachloroethylene-contaminated aquifer sediments. The soil column simulation test is shown in the figure. The influent pollutant concentration was 100 ppm. The dissolved oxygen, redox potential and tetrachloroethylene pollutant concentration of the effluent were measured regularly. The results are detailed in Table 3-8.

[0202] From Table 3 and Table 4, it can be seen that the dissolved oxygen content is rapidly reduced from the initial 1.0 ppm to below 0.4 ppm within 10 days, and within the subsequent 30 days, the dissolved oxygen content is maintained in a very low range, but the concentration gradually increases from 50 days to 300 days, which may be due to the fact that the powder chlorinated hydrocarbon repair material B2 does not add organic matter B, and the degradation is rapid, which leads to the loss of degradation effect.

[0203] From Table 5 and Table 6, it can be seen that the oxidation-reduction potential is rapidly reduced from the initial 106 mV to -104 mV within 20 days, and then slowly reduced to -162 mV at 50 days, indicating that the environment has been converted from an oxidation environment to a reduction environment due to the addition of an electron donor during the process, which provides good reduction conditions for the reductive dechlorination of chlorinated hydrocarbons. However, the concentration significantly increases from 50 days to 300 days, which may be due to the fact that the powder chlorinated hydrocarbon repair material B2 does not add organic matter B, and the degradation is rapid, which leads to the loss of degradation effect.

[0204] From Table 7 and Table 8, it can be seen that the pollutant concentration changes little from the initial 106 ppm within the first 7 days, basically maintaining at around 100 ppm, which may be due to the fact that during the early sediment mixing process, there is a system error due to heterogeneity and testing process, which can indicate that the pollutant concentration does not change much within this short period of time. At 20 days, the pollutant concentration changes, and the pollutant concentration decreases, indicating that after several decades of microbial growth, the dechlorination bacterial population has become the main colony structure, thereby rapidly degrading chlorinated hydrocarbons, resulting in a rapid decrease in chlorinated hydrocarbon concentration. However, the concentration significantly increases after 50 days, which may be due to the fact that the powder chlorinated hydrocarbon repair material B2 does not add organic matter B, and the degradation is rapid, which leads to the loss of degradation effect.

[0205] Table 3 Dissolved oxygen test results

[0206]

[0207] Table 4 Dissolved oxygen test results

[0208]

[0209] Table 5 Oxidation-reduction potential test results

[0210]

[0211] Table 6 Oxidation-reduction potential test results

[0212]

[0213] Table 7 Pollutant concentration data

[0214]

[0215] Table 8 Contaminant concentration data

[0216]

[0217] The preferred embodiments of the present application have been described in detail above, but the present application is not limited thereto. Various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A chlorinated hydrocarbon repair material, characterized in that: The chlorinated hydrocarbon repair material is composed of organic matter A, organic matter B and organic matter C, wherein the organic matter A encapsulates the organic matter B and the organic matter C; wherein the organic matter A is a polymer, the molecular weight of the organic matter A is 1000-30000, the organic matter B is selected from one or more of plant oils, higher fatty acids and higher fatty acid esters, the molecular weight of the organic matter B is 200-2000, the molecular weight of the organic matter C is 100-400, the weight ratio of the organic matter A, the organic matter B and the organic matter C is 30:0.5-20:0.1-3, and the organic matter A, organic matter B and organic matter C can be gradually degraded in the underground aquifer.

2. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The weight ratio of the organic matter A, the organic matter B and the organic matter C is 30:1-15:1-2.

3. The chlorinated hydrocarbon repair material according to claim 1 or 2, characterized in that The molecular weight of the organic matter A is 5000-20000.

4. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The organic matter A is selected from one or more of polylactide, polyvinyl alcohol and polyalginic acid.

5. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The molecular weight of the organic matter B is 200-1500.

6. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The molecular weight of the vegetable oil is 500-1500.

7. The chlorinated hydrocarbon repair material according to claim 6, characterized in that The molecular weight of the vegetable oil is 700-1100.

8. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The vegetable oil is selected from one or more of soybean oil, peanut oil, rapeseed oil and sesame oil.

9. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The higher fatty acids are C16~C18 fatty acids.

10. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The molecular weight of the higher fatty acid is 200-400.

11. The chlorinated hydrocarbon repair material according to claim 10, characterized in that The molecular weight of the higher fatty acid is 250-350.

12. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The higher fatty acid is selected from one or more of palmitic acid, stearic acid, palmitic acid and oleic acid.

13. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The higher fatty acid ester is a C16~C18 fatty acid ester.

14. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The molecular weight of the higher fatty acid ester is 600-1200.

15. The chlorinated hydrocarbon repair material according to claim 14, characterized in that The molecular weight of the higher fatty acid ester is 750-1000.

16. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The higher fatty acid ester is glyceryl stearate and / or glyceryl palmitate.

17. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The molecular weight of the organic matter C is 100-350.

18. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The organic matter C is low molecular weight polylactide.

19. The chlorinated hydrocarbon repair material according to claim 1, characterized in that The chlorinated hydrocarbon repair material is a solid material.

20. The chlorinated hydrocarbon repair material according to claim 19, characterized in that The chlorinated hydrocarbon repair material is in powder form.

21. The chlorinated hydrocarbon repair material according to claim 19, characterized in that The chlorinated hydrocarbon repair material is in granular form.

22. The chlorinated hydrocarbon repair material according to claim 19, characterized in that The chlorinated hydrocarbon repair material is in block shape.

23. A method for preparing the chlorinated hydrocarbon repair material according to any one of claims 1 to 22, characterized in that: The method comprises the following steps: S1. Under an inert atmosphere, organic matter A is first mixed with an organic solvent, and then the obtained first mixed solution is secondly mixed with organic matter B and organic matter C; S2. Drying the second mixed solution obtained in step S1.

24. The method according to claim 23, wherein In step S1 , the weight ratio of the organic matter A, the organic matter B, and the organic matter C is 30:0.5-20:0.1-3.

25. The method according to claim 23 or 24, characterized in that In step S1, the ratio of the organic matter A to the organic solvent is 5-50 g:100 mL.

26. The method according to claim 25, characterized in that In step S1, the ratio of the organic matter A to the organic solvent is 10-30 g:100 mL.

27. The method according to claim 26, characterized in that In step S1, the organic solvent is one or more of ethanol, ethyl acetate and dichloromethane.

28. The method according to claim 23, wherein In step S1, the first mixing condition includes: a temperature of 35-85°C.

29. The method according to claim 28, characterized in that In step S1, the temperature of the first mixing is 50-65°C.

30. The method according to claim 23, wherein In step S1, the second mixing condition includes: a temperature of 35-85°C.

31. The method according to claim 30, wherein In step S1, the temperature of the second mixing is 65-70°C.

32. The method according to claim 23, wherein In step S2, the drying conditions include: a temperature of 40-100°C.

33. The method according to claim 32, characterized in that In step S2, the drying temperature is 50-70°C.

34. The method according to claim 23, wherein Step S2 further includes: drying the solid block product obtained in step S2, and then optionally crushing the solid block product to obtain a powdered material.

35. The method according to claim 34, wherein The particle size of the powdered material is 10-1000 μm.

36. The method according to claim 23, wherein Step S2 further includes: drying step S2 to obtain a gel-like product, then shaping the gel-like product into spherical particles, freeze-drying the spherical particles to obtain a granular material, and then optionally crushing the granular material to obtain a powdery material.

37. The method according to claim 36, wherein The freeze-drying conditions include: a temperature of -30 to -40°C and a time of 2 to 8 hours.

38. The method according to claim 36, characterized in that The particle size of the powdery material is 10-1000 μm.

39. A chlorinated hydrocarbon repair material prepared by the method of any one of claims 23 to 38.

40. The chlorinated hydrocarbon repair material according to claim 39, characterized in that The chlorinated hydrocarbon repair material is suitable for high-permeability sites with a permeability coefficient greater than 1 m / d and special sites with high permeability in fractured aquifers.

41. A method for in situ remediation of chlorinated hydrocarbons in an aquifer, characterized in that: The method comprises: mixing chlorinated hydrocarbon remediation materials, water and a quick-start agent, and then injecting the obtained mixed solution into a chlorinated hydrocarbon-contaminated water layer in an aquifer; The chlorinated hydrocarbon repair material is the chlorinated hydrocarbon repair material according to any one of claims 1 to 22, or the chlorinated hydrocarbon repair material according to claim 39 or 40; The rapid start agent is selected from one or more of lactic acid, alginate, ethanol, ascorbic acid, citric acid and glucose.

42. The method according to claim 41, wherein The weight ratio of the chlorinated hydrocarbon repair material to water is 1:2-20.

43. The method according to claim 42, characterized in that The weight ratio of the chlorinated hydrocarbon repair material to water is 1:2-15.

44. The method according to claim 41, wherein The weight ratio of the chlorinated hydrocarbon repair material to the quick-start agent is 10-50:

1.

45. The method according to claim 44, wherein The weight ratio of the chlorinated hydrocarbon repair material to the quick-start agent is 10-30:

1.

46. ​​The method according to claim 41 or 42, characterized in that The method further comprises: adding a pH value regulator during the mixing process of the chlorinated hydrocarbon repair material, water and the quick-start agent.

47. The method according to claim 46, wherein The pH regulator is selected from one or more of Ca(OH)2, Mg(OH)2, CaCO3, MgCO3, Na2CO3 and NaHCO3.

48. The method according to claim 41, wherein The chlorinated hydrocarbon is selected from one or more of carbon tetrachloride, tetrachloroethylene, trichloroethylene, dichloroethylene, tetrachloropropane, trichloropropane, dichloropropane, trichlorobenzene, dichlorobenzene and ethyl chloride.

49. A method for in situ remediation of chlorinated hydrocarbons in an aquifer, characterized in that: The method comprises: mixing a chlorinated hydrocarbon remediation material and a quick-start agent, and then placing the resulting mixture in a permeable reactive wall in a chlorinated hydrocarbon-contaminated water layer of an aquifer; The chlorinated hydrocarbon repair material is the chlorinated hydrocarbon repair material according to any one of claims 1 to 22, or the chlorinated hydrocarbon repair material according to claim 39 or 40; The rapid start agent is selected from one or more of lactic acid, alginate, ethanol, ascorbic acid, citric acid and glucose.

50. The method according to claim 49, wherein The weight ratio of the chlorinated hydrocarbon repair material to the quick-start agent is 10-50:

1.

51. The method according to claim 50, characterized in that The weight ratio of the chlorinated hydrocarbon repair material to the quick-start agent is 10-30:

1.

52. The method according to claim 49, wherein The chlorinated hydrocarbon is selected from one or more of carbon tetrachloride, tetrachloroethylene, trichloroethylene, dichloroethylene, tetrachloropropane, trichloropropane, dichloropropane, trichlorobenzene, dichlorobenzene and ethyl chloride.

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