Soil remediation compositions, contaminated soil leaching agents, and methods for remediating contaminated soil

Abstract

This invention relates to the field of soil remediation technology, and discloses a soil remediation composition, a contaminated soil leaching agent, and a method for remediating contaminated soil. The composition comprises a modified cyclodextrin derivative and an anionic nonionic surfactant; the modified cyclodextrin derivative has the structure shown in formula (I), where R1 is selected from C8-C9. 22 The composition comprises alkyl groups; R3 and R4 are each independently selected from H, -PO3M2, -PO3HM, -SO3M, or -COOM, and at least one of R3 and R4 is not H; M is selected from any one of Li, Na, K, and NH4; each R2 is independently selected from hydrogen or a C1-C4 alkyl group; m is selected from any integer from 1 to 10, n is selected from any integer from 1 to 10, z is selected from any integer from 0 to 9, and the sum of m, n, and z is any integer from 5 to 11. This composition, as a leaching agent, can effectively remove benzene-based pollutants from soil, is environmentally friendly, and pollution-free.

Description

Technical Field

[0001] This invention relates to the field of soil remediation technology, specifically to a soil remediation composition, a contaminated soil leaching agent, and a method for remediating contaminated soil. Background Technology

[0002] Industrial wastewater from the petrochemical, coking, pesticide, and pharmaceutical industries often contains high levels of benzene compounds, causing severe pollution to the soil near these factories. Benzene compounds have a high octanol-water partition coefficient, making them typical hydrophobic organic pollutants. Due to their lipophilic, persistent, and recalcitrant nature, they easily accumulate in the environment. Furthermore, benzene compounds are highly toxic pollutants, exhibiting carcinogenic, mutagenic, and teratogenic effects, and also strongly inhibit microbial growth, posing a serious threat to human health and the ecological environment.

[0003] CN106269820A discloses a method for remediating benzene-contaminated soil. The method involves pretreating the contaminated soil with a ferric sulfate heptahydrate solution, then placing the pretreated soil into a thermal desorption device. Humic acid and polyoxyethylene sorbitan monolaurate are mixed with the soil in a solution, electrodes are inserted, and a constant voltage is applied for several hours. This method achieves a high removal rate of benzene compounds from the soil. However, the added humic acid has a complex chemical structure, which can cause secondary pollution to the soil environment. Furthermore, the method is complex and not easily applicable to industrial applications.

[0004] CN111534462A discloses a composite microbial agent for the treatment of petroleum hydrocarbons and benzene series compounds. Contaminated soil treated with this composite microbial agent can maintain a high degradation efficiency for a long period, ultimately achieving complete remediation of the contaminated soil, with a removal rate of over 98% for benzene series compounds and petroleum hydrocarbons. However, the degradation efficiency of microorganisms for pollutants is limited by environmental conditions and pollutant concentration, and the treatment cycle is relatively long.

[0005] In addition, existing leaching agents for remediating benzene-contaminated soil have problems such as large dosage, low pollutant removal efficiency, and poor removal effect. Therefore, it is necessary to develop a new type of leaching agent that has a significant effect on the removal of benzene series compounds, is environmentally friendly, and is easily degradable, in order to remediate soil contaminated by benzene series compounds. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of poor removal effect and low removal efficiency of benzene series compounds in benzene-contaminated soil in the prior art, and to provide a soil remediation composition, a soil leaching agent for contaminated soil, and a method for remediating contaminated soil. The composition used as a soil leaching agent can efficiently remove aromatic pollutants from contaminated soil.

[0007] To achieve the above objectives, a first aspect of the present invention provides a soil remediation composition comprising a modified cyclodextrin derivative and an anionic nonionic surfactant;

[0008] The modified cyclodextrin derivative has the structure shown in formula (I).

[0009]

[0010] Among them, R1 is selected from C8-C 22 Alkyl groups;

[0011] R3 and R4 are each independently selected from H, -PO3M2, -PO3HM, -SO3M or -COOM, and at least one of R3 and R4 is not H; M is selected from any one of Li, Na, K, NH4;

[0012] Each R2 is independently selected from hydrogen or C1-C4 alkyl groups;

[0013] m is selected from any integer from 1 to 10, n is selected from any integer from 1 to 10, z is selected from any integer from 0 to 9, and the sum of m, n, and z is any integer from 5 to 11.

[0014] A second aspect of the present invention provides a soil leaching agent for contaminated soil, the leaching agent comprising the soil remediation composition and solvent described in the first aspect.

[0015] A third aspect of the present invention provides a method for remediating contaminated soil, the method comprising: mixing a leaching agent with contaminated soil, and then performing solid-liquid separation;

[0016] The leaching agent is the soil leaching agent described in the second aspect.

[0017] Preferably, the pollutants in the contaminated soil include substituted or unsubstituted aromatic hydrocarbons.

[0018] The soil remediation composition provided by this invention comprises a modified cyclodextrin derivative and an anionic nonionic surfactant. The unique cavity of the cyclodextrin molecule can combine with aromatic pollutants in benzene-contaminated soil to form a host-guest complex, thereby effectively removing benzene pollutants from the soil. The combination of the modified cyclodextrin derivative and the anionic nonionic surfactant effectively improves the removal efficiency of benzene compounds in contaminated soil. Compared with existing leaching agents, at comparable dosages, the leaching agent provided by this invention exhibits a higher removal rate for aromatic pollutants in contaminated soil, especially for contaminated soil with pollutant concentrations exceeding 1500 mg / kg, demonstrating excellent pollutant removal performance.

[0019] In addition, compared with existing soil leaching agents, the modified cyclodextrin derivatives and anionic nonionic surfactants used in this invention are both environmentally friendly materials, non-toxic and biodegradable, and will not cause secondary pollution to the soil. Based on the above-mentioned main advantages, the method for remediating benzene-contaminated soil provided by this invention can be mass-produced and is easy to promote and use. Attached Figure Description

[0020] Figure 1 It is the modified cyclodextrin derivative A1 obtained in Preparation Example 1 of this invention. 1 H NMR spectrum;

[0021] Figure 2 It is the modified cyclodextrin derivative A2 obtained in Preparation Example 2 of this invention. 1 H NMR spectrum. Detailed Implementation

[0022] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] The first aspect of this invention provides a soil remediation composition comprising a modified cyclodextrin derivative and an anionic nonionic surfactant;

[0024] The modified cyclodextrin derivative has the structure shown in formula (I).

[0025]

[0026] Among them, R1 is selected from C8-C 22 Alkyl groups;

[0027] R3 and R4 are each independently selected from H, -PO3M2, -PO3HM, -SO3M or -COOM, and at least one of R3 and R4 is not H; M is selected from any one of Li, Na, K, NH4;

[0028] Each R2 is independently selected from hydrogen or C1-C4 alkyl groups;

[0029] m is selected from any integer from 1 to 10, n is selected from any integer from 1 to 10, z is selected from any integer from 0 to 9, and the sum of m, n, and z is any integer from 5 to 11.

[0030] The soil remediation composition provided by this invention comprises a modified cyclodextrin derivative and an anionic nonionic surfactant, which can effectively enhance the solubility of benzene compounds in solution, enabling the migration and removal of pollutants from soil to the aqueous phase. This is due, on the one hand, to the unique cavity environment of the modified cyclodextrin derivative, which allows it to combine with hydrophobic molecules of suitable size to form host-guest complexes; and on the other hand, the combination of the modified cyclodextrin derivative and the anionic nonionic surfactant helps to further reduce the surface tension of the aqueous solution, thereby improving the solubilization effect on benzene compounds.

[0031] In this invention, "C8-C" 22 "alkyl" refers to an alkyl group with a total number of carbon atoms of 8-22, including C8-C6. 22 Straight-chain alkyl, C8-C 22 Branched alkyl groups can be, for example, straight-chain or branched alkyl groups with a total number of carbon atoms of 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, or 22. Examples include n-octyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, and n-hexadecyl. (For C8-C...) 16 Alkyl groups and C1-C4 alkyl groups have similar interpretations, the difference being the number of carbon atoms. C1-C4 alkyl groups can be, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, etc.

[0032] According to some preferred embodiments of the present invention, R1 is selected from C8-C 16 The alkyl group is preferably n-octyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, or n-hexadecyl.

[0033] According to the present invention, each R2 in formula (I) may be the same or different, and preferably, each R2 is independently selected from H, methyl or ethyl.

[0034] According to the present invention, preferably, M is selected from Na or K.

[0035] According to the present invention, preferably, m is selected from any integer from 1 to 7, n is selected from any integer from 1 to 7, z is selected from any integer from 0 to 6, and the sum of m, n, and z is any integer from 6 to 8.

[0036] When R3 and R4 are each independently selected from H, -PO3M2 or -PO3HM, and at least one of R3 and R4 is not H, the modified cyclodextrin derivative can be prepared by the preparation method of cyclodextrin-based phosphate salt surfactant provided in Chinese Patent Application 202310007991.5. The entire contents of the above patent application are incorporated herein by reference.

[0037] When R3 and R4 are each independently selected from H or -SO3M, and at least one of R3 and R4 is not H, the modified cyclodextrin derivative can be prepared by the preparation method of anionic sulfate surfactant provided in Chinese Patent Application 202310010247.0. The entire contents of the above patent application are incorporated herein by reference.

[0038] When R3 and R4 are each independently selected from H or -COOM, and at least one of R3 and R4 is not H, the preparation method of the modified cyclodextrin derivative includes:

[0039] (1) In the presence of solvent I and catalyst, the 1,2-epoxide compound shown in formula (I-1) is reacted with the cyclodextrin compound shown in formula (I-2) to obtain an intermediate;

[0040] (2) In the presence of solvent II, the intermediate, the oxidant and the alkaline substance containing element M are mixed to carry out an oxidation reaction;

[0041]

[0042] Among them, in formula (I-1), formula (I-2), and alkaline substances,

[0043] The definitions of R1, R2, m, n, z, and M are the same as those in the previous text.

[0044] According to a preferred embodiment, in step (1), the cyclodextrin compound is provided by at least one of cyclodextrin, methylcyclodextrin, hydroxyethylcyclodextrin, and hydroxypropylcyclodextrin.

[0045] Preferably, the cyclodextrin is selected from at least one of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

[0046] More preferably, the cyclodextrin compound is selected from at least one of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, and hydroxypropyl-β-cyclodextrin.

[0047] It should be noted that the cyclodextrin compounds, the 1,2-epoxide compounds, and the sulfonating agents mentioned in this invention can be commercially available chemical reagents or can be prepared by those skilled in the art using methods known in the art.

[0048] According to a preferred embodiment, the method further includes: in step (1), filtering and drying the product obtained after the contact reaction of the 1,2-epoxide compound and the cyclodextrin compound. The present invention does not particularly limit the specific method of filtration and drying; those skilled in the art can perform the process according to known methods; as long as an intermediate that has been dried to constant weight after solvent removal can be obtained.

[0049] Preferably, the molar ratio of the cyclodextrin compound to the 1,2-epoxide compound is 1:(1-40). More preferably, the molar ratio of the cyclodextrin compound to the 1,2-epoxide compound is 1:(1-32).

[0050] In a preferred embodiment, in step (1), the solvent I is water, and the catalyst is an alkali metal hydroxide or 4-dimethylaminopyridine.

[0051] Preferably, the alkali metal hydroxide is selected from at least one of NaOH, KOH, and LiOH.

[0052] Preferably, in step (1), the conditions for the contact reaction are at least: a temperature of 30-100°C and a time of 1-10 hours. More preferably, the conditions for the contact reaction are at least: a temperature of 60-90°C and a time of 3-8 hours.

[0053] Preferably, in step (1), the amount of solvent I used is 0.1-50 mL relative to 1 mmol of the cyclodextrin compound, and the amount of catalyst used is 0.001-0.1 mmol. More preferably, the amount of solvent I used is 1-10 mL relative to 1 mmol of the cyclodextrin compound, and the amount of catalyst used is 0.005-0.1 mmol.

[0054] In the above preparation method, some alkyl hydroxyl groups are oxidized to carboxyl groups through the oxidation reaction described in step (2). The present invention does not have any particular limitation on the selection of the oxidant, and conventional oxidants in the art can be used, such as potassium permanganate.

[0055] Preferably, the mass ratio of the intermediate to the oxidant is 1:(1-5), more preferably 1:(1.5-2.5).

[0056] Preferably, the amount of solvent II is 5-20 mL relative to 1 g of the intermediate.

[0057] In a preferred embodiment, in step (2), solvent II is selected from at least one of tetrahydrofuran, 1,4-dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and pyridine.

[0058] Preferably, in step (2), the conditions for the oxidation reaction are at least: temperature of 0-90°C and time of 1-24h.

[0059] Preferably, in step (3), the alkaline substance is selected from at least one of lithium hydroxide, sodium hydroxide, potassium hydroxide, and ammonia water.

[0060] Preferably, the mass ratio of the alkaline substance containing element M to the intermediate is (1-5):1.

[0061] In this invention, the term "anionic nonionic surfactant" has the conventional definition in the art, referring to a surfactant composed of two hydrophilic groups and possessing both nonionic and anionic surface chemical properties. Surfactants with the above characteristics can be applied to this invention. For example, the anionic nonionic surfactant can be an alkylphenol or a fatty alcohol polyoxyethylene ether derivative.

[0062] According to some preferred embodiments of the present invention, the anionic nonionic surfactant is a fatty alcohol polyoxyethylene ether derivative, which is preferably any one of fatty alcohol polyoxyethylene ether carboxylate, fatty alcohol polyoxyethylene ether sulfonate, fatty alcohol polyoxyethylene ether sulfate, and fatty alcohol polyoxyethylene ether phosphate, wherein the metal cation in the above salts can be sodium or potassium.

[0063] Preferably, the anionic nonionic surfactant is selected from at least one of sodium fatty alcohol polyoxyethylene ether carboxylate, sodium fatty alcohol polyoxyethylene ether sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, and sodium fatty alcohol polyoxyethylene ether phosphate. When the above-mentioned preferred anionic nonionic surfactant is compounded with a modified cyclodextrin derivative, the resulting soil remediation composition exhibits a higher pollutant removal rate when used for contaminated soil leaching.

[0064] In this invention, preferably, the fatty alcohol polyoxyethylene ether derivative has an alkyl group with 6-14 carbon atoms. For example, the fatty alcohol can be an isomer of hexanol, heptanol, octanol, nonanol, decanol, dodecanol, tetradecanol, or more. Preferably, the fatty alcohol has an alkyl group with 6-12 carbon atoms.

[0065] Preferably, in the fatty alcohol polyoxyethylene ether derivative, the degree of polymerization of ethylene oxide is 3-80, more preferably 6-50.

[0066] In this invention, the modified cyclodextrin derivative and the anionic nonionic surfactant in the soil remediation composition can be compounded in any proportion. The presence of both components is sufficient to improve the removal efficiency of benzene series compounds in contaminated soil. To further improve the removal rate of benzene series compounds, preferably, the mass ratio of the modified cyclodextrin derivative to the anionic nonionic surfactant in the composition is 60-95:5-40, more preferably 75-95:5-25. For example, the mass ratio of the modified cyclodextrin derivative to the anionic nonionic surfactant can be typical but not limiting, such as 75:25, 78:22, 80:20, 82:28, 85:15, 88:12, 90:10, 92:8, 95:5, etc. Under the above preferred composition, it is beneficial to promote the formation of host-guest complexes between the modified cyclodextrin derivative and benzene series compounds in the contaminated soil, thereby improving the removal efficiency of the compounded system for benzene series compounds. A second aspect of this invention provides a contaminated soil leaching agent, which includes the soil remediation composition described in the first aspect and a solvent.

[0067] This invention allows for a wide range of solvent choices; conventional inorganic or organic solvents in the art can be used. Preferably, the solvent is water. Using water as a solvent in the leaching agent not only improves the solubility of benzene compounds in the leaching agent but is also non-toxic, environmentally friendly, and avoids secondary pollution to the soil.

[0068] According to the present invention, preferably, the concentration of the composition in the leaching agent is 50-200 mg / L, for example, typical but not limiting concentration values ​​such as 50 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, 90 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, or a range between the two. Preferably, the concentration of the composition in the leaching agent is 50-180 mg / L. Within the above-mentioned preferred concentration range, it is beneficial to further enhance the leaching effect of the composition formed by the modified cyclodextrin derivative and the fatty alcohol polyoxyethylene ether derivative on benzene series pollutants in the soil.

[0069] According to some preferred embodiments of the present invention, the preparation method of the contaminated soil leaching agent includes: mixing a modified cyclodextrin derivative, an anionic nonionic surfactant, and a solvent. The mixing can be carried out in a manner conventional in the art, and the present invention does not particularly limit this process.

[0070] A third aspect of the present invention provides a method for remediating contaminated soil, the method comprising: mixing a leaching agent with contaminated soil, and then performing solid-liquid separation;

[0071] The leaching agent is the soil leaching agent described in the second aspect.

[0072] The method for remediating contaminated soil provided by this invention has a wide applicability to contaminated soils with varying levels of pollutants. In particular, compared to existing technologies, the method for remediating contaminated soils provided by this invention has a better remediation effect on contaminated soils with high levels of benzene series pollutants.

[0073] According to some preferred embodiments of the present invention, based on the total amount of contaminated soil, the total content of the pollutants is 800-8000 mg / kg, preferably 1000-8000 mg / kg. For contaminated soil with the aforementioned high pollutant content, the existing leaching methods have poor removal efficiency and are limited by solubility, typically requiring the introduction of large amounts of leaching agent. However, with comparable dosages, the method for remediating contaminated soil provided by the present invention has a higher pollutant removal rate and greater efficiency for contaminated soil with high pollutant content.

[0074] According to some preferred embodiments of the present invention, the mass ratio of the leaching agent to the contaminated soil is (2-10):1, for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, preferably (3-9):1.

[0075] The method for remediating contaminated soil provided by this invention is particularly applicable to contaminated soil containing substituted or unsubstituted aromatic hydrocarbons (benzene compounds), such as soil contaminated by industrial wastewater discharged from organic chemical industries such as petrochemicals, coking, pesticides, and pharmaceuticals. The substituted or unsubstituted aromatic hydrocarbons have 6-10 carbon atoms. At least one H atom on a carbon atom in the substituted aromatic hydrocarbon can be substituted, for example, with alkyl, alkenyl, or hydroxyl groups. For example, the pollutants in the contaminated soil may include at least one of benzene, toluene, o-xylene, m-xylene, p-xylene, styrene, and phenol.

[0076] According to some preferred embodiments of the present invention, based on the total amount of the contaminated soil, the content of benzene is 100-1500 mg / kg, the content of toluene is 0-1500 mg / kg, the content of o-xylene is 30-1000 mg / kg, the content of m / p-xylene is 0-1000 mg / kg, the content of styrene is 0-1500 mg / kg, and the content of phenol is 0-1500 mg / kg.

[0077] In particular, the method for remediating contaminated soil provided by this invention is especially suitable for contaminated soil containing high levels of phenol, especially contaminated soil with a phenol content exceeding 1000 mg / kg. Under the same leaching agent dosage conditions, conventional leaching agents in the prior art generally achieve a phenol removal rate of less than 60 wt% for contaminated soil containing high phenol content, while the phenol removal rate in this invention is above 90 wt%.

[0078] The present invention does not have any particular limitation on the mixing method of the leaching agent and the contaminated soil, and conventional soil leaching operation methods and conditions in the field can be used.

[0079] According to some preferred embodiments of the present invention, the mixing is carried out under conditions of oscillation and / or stirring, preferably at a rotation speed of 100-250 rpm. Using the above-mentioned preferred mixing method facilitates uniform mixing of the leaching agent and contaminated soil, thereby fully exerting the removal effect on benzene compounds.

[0080] In this invention, the mixing can be carried out at room temperature or under heating conditions. Preferably, the mixing conditions include a temperature of 20-70°C and a time of 5-10 hours.

[0081] According to the present invention, leached soil and supernatant are obtained through solid-liquid separation. The solid-liquid separation can be performed using conventional methods in the art, and the present invention is not particularly limited in this regard. For example, filtration, vacuum filtration, centrifugation, etc., can be used.

[0082] The present invention will be described in detail below through embodiments.

[0083] The following preparation examples illustrate the preparation of modified cyclodextrin derivatives.

[0084] Preparation Example 1

[0085] Weigh 10 mmol of β-cyclodextrin and 70 mmol of 1,2-epoxytetradecane into a reaction flask, then add 20 mL of water, 0.05 mmol of 4-dimethylaminopyridine, and a magnetic stir bar. Stir the reaction at 85 °C for 7 hours, then stop the reaction, filter, and dry to obtain intermediate I, which is a white solid.

[0086] 1 g of intermediate I and 10 mL of N,N-dimethylformamide were added to a three-necked flask. At the same time, 2 g of sulfur trioxide pyridine complex (50 wt% active SO3 content) was weighed and dissolved in 5 mL of N,N-dimethylformamide. This solution was then added to the three-necked flask. The mixture was stirred at 50 °C for 2 h. After cooling to room temperature, a 10 wt% sodium hydroxide aqueous solution was added to adjust the pH to 7. The solvent was removed by rotary evaporation and the product was dried to obtain the modified cyclodextrin derivative A1, with a yield of 81%.

[0087]

[0088] The structures shown in equations (1) and (2) are those of intermediate I and modified cyclodextrin derivative A1, respectively. In equations (1) and (2), m is 2, n+z is 5, the sum of m, n, and z is 7, and -C 12 H 25 It indicates n-dodecyl.

[0089] Modified cyclodextrin derivative A1 was subjected to... 1 ¹H NMR characterization (using deuterated water as the deuterated solvent) yielded the following results: Figure 1 As shown, 1 H NMR (D2O): δ=0.78(-C) 11 H 22 CH3), 1.20-1.65(-C 11 H 22 CH3),3.28-3.85(-CH2OH,-CH-CH2-O-CH2-CHOH-C 12 H 25 ,-O-CH-CH-CH2-O-,-CHOH,),4.06(-CH-CH2-OSO3Na),4.18-4.49(-CH-CH2-OSO3Na,-CH-CH2-O-CH2-CHOH-C 12 H 25 ).

[0090] Depend on Figure 1 It can be seen that there are two broad peaks in the proton chemical shift at 4.06 ppm and 4.18-4.49 ppm. Specifically, 4.06 ppm corresponds to -CH-CH2OSO3Na, and the peaks at 4.18-4.49 ppm correspond to -CH-CH2-OSO3Na and -CH-CH2-O-CH2-CHOH-C, respectively. 12 H 25 This proves the successful conduct of the sulfonation reaction and the existence of the sulfonation products.

[0091] Preparation Example 2

[0092] Weigh 10 mmol of α-cyclodextrin and 90 mmol of 1,2-epoxytetradecane into a reaction flask, then add 10 mL of distilled water, 0.30 mmol of 4-dimethylaminopyridine, and a magnetic stir bar. Stir the reaction mixture at 60 °C for 8 hours, then stop the reaction, filter, and dry to obtain a white solid intermediate II.

[0093] 1 g of intermediate II, 10 mL of N,N-dimethylformamide, and 2 g of polyphosphoric acid were added to a three-necked flask and stirred at 60 °C for 4 h. Then, 0.15 g of water was added, and the reaction was continued at 60 °C for another 1 h. Subsequently, 10 wt% potassium hydroxide was added to adjust the pH to 7. The solvent was removed by rotary evaporation, and the mixture was dried to obtain the modified cyclodextrin derivative A2, with a yield of 78%.

[0094]

[0095] The structures shown in equations (3) and (4) are those of intermediate II and modified cyclodextrin derivative A2, respectively. In equations (3) and (4), m is 2, n+z is 4, the sum of m, n and z is 6, and -C 12 H 25 It represents n-dodecyl.

[0096] Modified cyclodextrin derivative A2 was subjected to... 1 H NMR characterization, results as follows Figure 2 As shown. Figure 2 The affiliations of the various peaks are as follows:

[0097] 1 H NMR (DMSO-d6): δ=0.97(-C 11 H 22 CH3), 1.35-1.48(-C 11 H 22 CH3),3.31-3.53(-CH2OH,-CH-CH2-O-CH2-CHOH-C 12 H 25 ,-O-CH-CH-CH2-O-),3.62-3.87(-CH2OH,-CH-CH-OH,-CH-CH2-O-CH2-CHOH-C 12 H 25 ,-CH-CH2-OPO3K2),4.79-4.90(-O-CH-O-).

[0098] Preparation Example 3

[0099] Weigh 10 mmol of β-cyclodextrin and 80 mmol of 1,2-epoxyoctadecane into a reaction flask, add 20 mL of deionized water and 0.2 mmol of 4-dimethylaminopyridine, stir the reaction at 80 °C for 10 hours, stop the reaction, filter, dry, and obtain white intermediate III.

[0100] 1 g of intermediate III, 10 mL of N,N-dimethylformamide, and 2 g of chlorosulfonic acid were added to a three-necked flask and reacted at 45 °C for 3 h. After the reaction was completed, the mixture was cooled to room temperature, and 10 wt% sodium hydroxide aqueous solution was added to adjust the pH to 7. After drying, the modified cyclodextrin derivative A3 was obtained with a yield of 74%.

[0101]

[0102] The structures shown in equations (5) and (6) are those of intermediate III and modified cyclodextrin derivative A3, respectively. In equations (5) and (6), m is 3, n+z is 4, the sum of m, n and z is 7, and -C 16 H 33 It indicates a hexadecyl group.

[0103] Preparation Example 4

[0104] Weigh 10 mmol of β-cyclodextrin and 50 mmol of 1,2-epoxydodecane into a reaction flask, add 20 mL of deionized water and 0.1 mmol of 4-dimethylaminopyridine, react at 70 °C for 9 hours, stop the reaction, filter, dry, and obtain white intermediate IV.

[0105] 1 g of intermediate IV, 10 mL of N,N-dimethylformamide, 2 g of potassium permanganate and 1 g of potassium hydroxide were added to a three-necked flask. The mixture was reacted at 70 °C for 2 h, cooled to room temperature, filtered, and the solvent was removed by rotary evaporation of the filtrate. A large amount of acetone was added for recrystallization to obtain the modified cyclodextrin derivative A4 with a yield of 65%.

[0106]

[0107] The structures shown in equations (7) and (8) are those of intermediate IV and modified cyclodextrin derivative A4, respectively. In equations (7) and (8), m is 2, n+z is 5, the sum of m, n and z is 7, and -C 10 H 21 It indicates n-decyl group.

[0108] The following examples illustrate the preparation of soil leaching agents and methods for remediating contaminated soil.

[0109] Example 1

[0110] Weigh 90 mg of modified cyclodextrin derivative A1 and 10 mg of sodium n-octanol polyoxyethylene ether (80) phosphate (purchased from Beijing Xingpu New Product Development Center), and prepare an aqueous solution with a concentration of 100 mg / L using distilled water to obtain the rinsing agent.

[0111] Contaminated soil from a dye chemical plant was used. The main pollutants were benzene (384 mg / kg), toluene (798 mg / kg), o-xylene (243 mg / kg), and m / p-xylene (98 mg / kg). 50 g of contaminated soil was taken and 150 g of prepared leaching agent was added. The mixture was stirred at 50°C for 10 hours at 110 rpm to ensure thorough mixing. After the stirring, solid-liquid separation was performed, and the content of each pollutant in the supernatant was measured. The removal rate was calculated, and the specific results are shown in Table 1.

[0112] Removal rate (wt%) = (Total contaminants - Content of each contaminant in the supernatant) / Total contaminants × 100%

[0113] Example 2

[0114] Weigh 95 mg of modified cyclodextrin derivative A2 and 5 mg of sodium tetradecyl alcohol polyoxyethylene ether (30) sulfate (purchased from Beijing Xingpu New Product Development Center), and prepare an aqueous solution with a concentration of 100 mg / L using distilled water to obtain the rinsing agent.

[0115] At a petroleum refining site, the main pollutants were toluene (1200 mg / kg), o-xylene (640 mg / kg), m / p-xylene (570 mg / kg), and styrene (1290 mg / kg). 50 g of contaminated soil was taken and 350 g of prepared leaching agent was added. The mixture was stirred at 30°C for 6 hours at 150 rpm to ensure thorough mixing. After the mixture was stirred, the solid and liquid phases were separated, and the content of each pollutant in the supernatant was determined. The removal rate was also calculated. The specific results are shown in Table 1.

[0116] Example 3

[0117] Weigh 85 mg of modified cyclodextrin derivative A3 and 15 mg of sodium dodecyl alcohol polyoxyethylene ether (3) carboxylate (purchased from Beijing Xingpu New Product Development Center), and prepare an aqueous solution with a concentration of 100 mg / L using distilled water to obtain the rinsing agent.

[0118] Soil contaminated at a chemical storage site was used. The main pollutants were benzene (1040 mg / kg), o-xylene (32.7 mg / kg), and styrene (2.5 mg / kg). 50 g of contaminated soil was taken and 450 g of prepared leaching agent was added. The mixture was stirred at 65℃ for 8 hours at 250 rpm to ensure thorough mixing. After stirring, solid-liquid separation was performed, and the content of each pollutant in the supernatant was determined. The removal rate was calculated, and the specific results are shown in Table 1.

[0119] Example 4

[0120] Weigh 80 mg of modified cyclodextrin derivative A4 and 20 mg of sodium hexyl alcohol polyoxyethylene ether (50) sulfonate (purchased from Beijing Xingpu New Product Development Center), and prepare a 100 mg / L aqueous solution with distilled water to obtain the rinsing agent.

[0121] Contaminated soil from a coking plant site was used. The main pollutants were benzene (228.8 mg / kg), phenol (1330 mg / kg), and toluene (2.8 mg / kg). 50 g of contaminated soil was taken and 250 g of prepared leaching agent was added. The mixture was stirred at 20°C for 5 hours at 180 rpm to ensure thorough mixing. After stirring, solid-liquid separation was performed, and the content of each pollutant in the supernatant was measured. The removal rate was calculated, and the specific results are shown in Table 1.

[0122] Example 5

[0123] The method of Example 4 is followed, except that the amount of modified cyclodextrin derivative A4 is 30 mg and the amount of sodium hexanol polyoxyethylene ether (50) sulfonate is 70 mg. The mixture is prepared into a 100 mg / L aqueous solution with distilled water to obtain the rinsing agent.

[0124] The contaminated soil was leached according to the method in Example 4, and the results are shown in Table 1.

[0125] Example 6

[0126] The method was followed in Example 1, except that an equal mass of sodium octyl polyoxyethylene ether (120) phosphate was used instead of sodium octyl polyoxyethylene ether (80) phosphate. The solution was prepared into a 100 mg / L aqueous solution using distilled water to obtain the eluent.

[0127] The contaminated soil was leached according to the method in Example 1, and the results are shown in Table 1.

[0128] Comparative Example 1

[0129] Weigh 100 mg of α-cyclodextrin and prepare it into a 100 mg / L aqueous solution with distilled water to obtain the rinsing agent.

[0130] Take 50g of the contaminated soil from Example 3, add 450g of the prepared leaching agent, and mix thoroughly at 65℃. Stir at 250 rpm for 8 hours. After the mixture is dissolved in liquid, determine the content of each pollutant in the supernatant, and calculate the removal rate. The specific results are shown in Table 1.

[0131] Comparative Example 2

[0132] Weigh 95 mg of β-cyclodextrin and 5 mg of sodium tetradecyl alcohol polyoxyethylene ether (30) sulfate (purchased from Beijing Xingpu New Product Development Center), and prepare a 100 mg / L aqueous solution with distilled water to obtain the rinsing agent.

[0133] Take 50g of the contaminated soil from Example 2, add 350g of the prepared leaching agent, and mix thoroughly at 30℃. Stir at 150 rpm for 6 hours. After the mixture is dissolved in liquid, the content of each pollutant in the supernatant is measured, and the removal rate is calculated. The specific results are shown in Table 1.

[0134] Comparative Example 3

[0135] Weigh 100 mg of sodium tetradecyl alcohol polyoxyethylene ether (30) sulfate and prepare it into a 100 mg / L aqueous solution with distilled water to obtain the rinsing agent.

[0136] Take 50g of the contaminated soil from Example 2, add 350g of the prepared leaching agent, and mix thoroughly at 30℃. Stir at 150 rpm for 6 hours. After the mixture is dissolved in liquid, the content of each pollutant in the supernatant is measured, and the removal rate is calculated. The specific results are shown in Table 1.

[0137] Comparative Example 4

[0138] Weigh 100 mg of sodium dodecyl sulfate (SDS) and prepare it into a 100 mg / L aqueous solution with distilled water to obtain the rinsing agent.

[0139] Take 50g of the contaminated soil from Example 4, add 250g of the prepared leaching agent, and mix thoroughly at 20℃. Stir at 180 rpm for 5 hours. After the mixture is dissolved, separate the solid and liquid components, determine the content of each pollutant in the supernatant, and calculate the removal rate. The specific results are shown in Table 1.

[0140] Table 1

[0141]

[0142] The results in Table 1 show that the method provided by this invention can effectively remove benzene series pollutants, such as benzene, toluene, xylene, phenol, and styrene, from soil. In particular, a comparison of the examples and comparative examples demonstrates that the soil remediation composition or leaching agent provided by this invention is more effective in removing benzene series pollutants, especially exhibiting excellent removal efficiency for high concentrations of phenol.

[0143] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A soil remediation composition, characterized in that, The composition comprises a modified cyclodextrin derivative and an anionic nonionic surfactant; The modified cyclodextrin derivative has the structure shown in formula (I). Formula (I), Among them, R1 is selected from C8-C 22 Alkyl groups; R3 and R4 are each independently selected from H, -PO3M2, -PO3HM, -SO3M or -COOM, and at least one of R3 and R4 is not H; M is selected from any one of Li, Na, K, NH4; Each R2 is independently selected from hydrogen or C1-C4 alkyl groups; m is selected from any integer from 1 to 10, n is selected from any integer from 1 to 10, z is selected from any integer from 0 to 9, and the sum of m, n, and z is any integer from 5 to 11.

2. The composition according to claim 1, wherein, R1 is selected from C8-C 16 Alkyl groups; And / or, each R2 is independently selected from H, methyl, or ethyl; And / or, M is selected from Na or K; And / or, m is any integer from 1 to 7, n is any integer from 1 to 7, z is any integer from 0 to 6, and the sum of m, n, and z is any integer from 6 to 8.

3. The composition according to claim 2, wherein, R1 is selected from C 10 -C 14 Alkyl groups.

4. The composition according to any one of claims 1-3, wherein, The anionic nonionic surfactant is a fatty alcohol polyoxyethylene ether derivative.

5. The composition according to claim 4, wherein, The fatty alcohol polyoxyethylene ether derivative is at least one of sodium fatty alcohol polyoxyethylene ether carboxylate, sodium fatty alcohol polyoxyethylene ether sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, and sodium fatty alcohol polyoxyethylene ether phosphate.

6. The composition according to claim 4, wherein, In the fatty alcohol polyoxyethylene ether derivative, the fatty alcohol has 6-14 alkyl carbons and the degree of polymerization of ethylene oxide is 3-80.

7. The composition according to claim 6, wherein, In the fatty alcohol polyoxyethylene ether derivative, the fatty alcohol has 6-12 alkyl carbons and the degree of polymerization of ethylene oxide is 6-50.

8. The composition according to any one of claims 1-3, wherein, In the composition, the mass ratio of the modified cyclodextrin derivative to the anionic nonionic surfactant is 60-95:5-40.

9. The composition according to claim 8, wherein, In the composition, the mass ratio of the modified cyclodextrin derivative to the anionic nonionic surfactant is 75-95:5-25.

10. A soil leaching agent for contaminated soil, characterized in that, The leaching agent comprises the soil remediation composition and solvent according to any one of claims 1-9.

11. The soil leaching agent according to claim 10, wherein, The solvent is water.

12. The soil leaching agent according to claim 10, wherein, In the rinsing agent, the concentration of the composition is 50-200 mg / L.

13. A method for remediating contaminated soil, characterized in that, The method includes: mixing a leaching agent with contaminated soil, and then performing solid-liquid separation; Wherein, the leaching agent is the soil leaching agent according to any one of claims 10-12; The pollutants in the contaminated soil include substituted or unsubstituted aromatic hydrocarbons.

14. The method according to claim 13, wherein, Based on the total amount of the contaminated soil, the total content of the pollutants is 800-8000 mg / kg.

15. The method according to claim 14, wherein, Based on the total amount of the contaminated soil, the total content of the pollutants is 1000-8000 mg / kg.

16. The method according to claim 13, wherein, The mass ratio of the leaching agent to the contaminated soil is (2-10):

1.

17. The method according to claim 16, wherein, The mass ratio of the leaching agent to the contaminated soil is (3-9):

1.

18. The method according to claim 13, wherein, The substituted or unsubstituted aromatic hydrocarbons have 6-10 carbon atoms.

19. The method according to claim 18, wherein, The pollutants in the contaminated soil include at least one of benzene, toluene, o-xylene, m-xylene, p-xylene, styrene, and phenol.

20. The method according to claim 19, wherein, Based on the total amount of the contaminated soil, the content of benzene is 100-1500 mg / kg, the content of toluene is 0-1500 mg / kg, the content of o-xylene is 30-1000 mg / kg, the content of m / p-xylene is 0-1000 mg / kg, the content of styrene is 0-1500 mg / kg, and the content of phenol is 0-1500 mg / kg.

21. The method according to claim 13, wherein, The mixing is carried out under conditions of oscillation and / or stirring.

22. The method according to claim 21, wherein, The oscillation and / or stirring speed is 100-250 rpm.

23. The method according to claim 21, wherein, The mixing conditions include a temperature of 20-70°C and a time of 5-10 hours.

Images