Oil washing composition suitable for repairing thick oil contaminated soil, preparation method and application thereof, and method for repairing thick oil contaminated soil

Abstract

This invention relates to the field of contaminated soil remediation, and discloses an oil washing composition suitable for remediating heavy oil-contaminated soil, its preparation method, and its application. The oil washing composition contains the following components: based on the total weight of the composition, the content of oligomeric cationic quaternary ammonium salt surfactant is 0.01wt%-0.15wt%, the content of anionic nonionic surfactant is 0.015wt%-1.0wt%, the content of cyclodextrin is 0.05wt%-0.25wt%, and the content of water is 98.6wt%-99.7wt%. This oil washing composition has a good oil washing effect on heavy oil-contaminated soil, and its adsorption on the soil surface is low. Simultaneously, the composition is readily biodegradable, does not produce secondary pollution, and does not undergo association precipitation within the ratio range where the positive / negative charge ratio of the cationic and anionic nonionic surfactants is close to the charge neutrality point.

Description

Technical Field

[0001] This invention relates to the field of contaminated soil remediation, specifically to an oil washing composition suitable for remediating heavy oil contaminated soil, its preparation method and application, and a method for remediating heavy oil contaminated soil. Background Technology

[0002] In recent years, soil pollution in the oil and petrochemical industry has attracted significant attention. Due to factors such as pipeline leaks, storage tank leaks, illegal discharges, and sudden environmental accidents, soil at various enterprise sites suffers from varying degrees of petroleum-related pollution. Furthermore, the remediation of aging oil-contaminated soil inherited from oilfields, as well as the disposal of oil sludge, polymer-containing sludge, and tank bottom sludge collected by oilfield joint stations, have become critical and challenging issues. Guided by the concept of "ecological priority and green development," how to remediate contaminated sites and achieve green development is a key issue that urgently needs to be addressed.

[0003] Ex-situ soil leaching is a relatively mature soil remediation technology with advantages such as rapid effectiveness and simple process. However, soil pollutants from the petroleum and petrochemical industry contain high levels of polycyclic aromatic hydrocarbons (PAHs), which have poor water solubility and strong adhesion to the soil surface, making them difficult to remove effectively with traditional leaching agents. Therefore, there is an urgent need to develop highly efficient soil leaching agents that can effectively desorb PAHs from the soil.

[0004] Current research indicates that the desorption of PAHs depends on the solubilizing effect of surfactant aggregates on PAHs. Studies have shown that the solubilizing ability of different aggregate morphologies on PAHs follows the order: vesicles > rod-shaped micelles > spherical micelles. Compared to the other two aggregate morphologies, vesicles possess larger hydrophobic microdomains, thus accommodating more PAHs. Based on this idea, further increasing the hydrophobic microdomains of the aggregates beyond vesicles should enhance their solubilizing ability on PAHs, thereby enabling the construction of an ultra-efficient oil washing system.

[0005] Fingerprint-like aggregates are a special type of aggregate structure composed of multiple layers of vesicles arranged in a regular pattern. Their hydrophobic microdomains can be dozens of times larger than those of a single vesicle, thus possessing the potential for ultra-efficient solubilization of PAHs. However, conventional surfactant complex systems rarely form fingerprint-like aggregate structures in water, and related reports are scarce.

[0006] The literature has successfully constructed fingerprint-like aggregates using star-shaped hexacationic quaternary ammonium salt surfactants and single-chain anionic surfactants. However, the star-shaped hexacationic quaternary ammonium salt surfactants used in this system are difficult to synthesize, have low yields, and poor biodegradability. Furthermore, the system is in a precipitation zone near the isoelectric point, which is not conducive to practical applications.

[0007] Therefore, there is a need to develop simpler and more readily available surfactant systems to construct fingerprint-like aggregates, enabling them to possess highly efficient PAH solubilization capabilities and thus exhibit excellent oil-washing performance. Simultaneously, it is necessary to improve the stability of the fingerprint-like aggregates formed by the system to prevent precipitation. Summary of the Invention

[0008] The purpose of this invention is to provide a highly efficient oil washing composition capable of forming multi-layered fingerprint-like aggregates, thereby improving the oil washing efficiency for heavy oil contaminants, and the system forms a precipitate within a ratio range where the positive / negative charge ratio of the cationic and anionic nonionic surfactants is close to the charge neutrality point.

[0009] To achieve the above objectives, a first aspect of the present invention provides an oil washing composition suitable for remediating heavy oil-contaminated soil, the oil washing composition containing the following components, each stored independently or in combination:

[0010] Oligomeric cationic quaternary ammonium salt surfactants, anionic nonionic surfactants, cyclodextrins, and water;

[0011] Based on the total weight of the wash oil composition, the content of the oligomeric cationic quaternary ammonium salt surfactant is 0.01wt%-0.15wt%, the content of the anionic nonionic surfactant is 0.015wt%-1.0wt%, the content of the cyclodextrin is 0.05wt%-0.25wt%, and the content of water is 98.6wt%-99.7wt%.

[0012] The mass ratio of the anionic nonionic surfactant to the oligomeric cationic quaternary ammonium salt surfactant is 1.1-7.0:1;

[0013] The oligomeric cationic quaternary ammonium salt surfactant has the structure shown in formula (I).

[0014]

[0015] In equation (I),

[0016] All three X's are identical and are Cl, Br, or I; all R's are identical and selected from C8-C. 16 Alkyl groups.

[0017] A second aspect of the present invention provides a method for preparing the wash oil composition of the first aspect, the method comprising: mixing the components of the wash oil composition of the first aspect.

[0018] A third aspect of the invention provides the use of the wash oil composition described in the first aspect in the remediation of heavy oil-contaminated soil.

[0019] A fourth aspect of the present invention provides a method for remediating oil-contaminated soil, the method comprising:

[0020] (1) Contacting heavy oil-contaminated soil with the washing oil composition described in the first aspect to obtain mixture I;

[0021] (2) Perform solid-liquid separation on the mixture I.

[0022] The high-efficiency oil washing composition provided by this invention has good applicability to heavy oil contaminated soil with a hydrocarbon oil content of 5wt%-25wt%, and its oil washing efficiency is as high as 90% or more.

[0023] The high-efficiency oil washing composition provided by this invention can form multilayer fingerprint-like aggregates. Compared with traditional vesicles, rod-shaped micelles, or spherical micelles, these aggregates have a stronger ability to solubilize polycyclic aromatic hydrocarbon pollutants. Furthermore, the cyclodextrin in this oil washing composition can synergistically solubilize pollutants through host-guest interactions at the molecular level, further improving the oil leaching efficiency in heavy oil-contaminated soil.

[0024] Meanwhile, the fingerprint-like aggregates formed by the wash oil composition provided by this invention have a strong negative charge on their surface, resulting in low adsorption on the soil surface and high stability. They do not associate or precipitate within a ratio range where the positive / negative charge ratio of the cationic and anionic nonionic surfactants is close to the charge neutrality point, facilitating on-site preparation and use. Furthermore, the presence of anionic nonionic surfactants and cyclodextrins makes the wash oil composition readily biodegradable, preventing secondary pollution and enabling the green remediation and utilization of petroleum-contaminated soil. Attached Figure Description

[0025] Figure 1 This is a cryogenic transmission electron microscope image of the wash oil composition A1 prepared in Example 1 of the present invention.

[0026] Figure 2 The image shows the zeta potential diagram of the wash oil composition A1 prepared in Example 1 of this invention.

[0027] Figure 3 This is an appearance diagram of the wash oil composition A4 prepared in Test Example 1 of the present invention.

[0028] Figure 4 The image shows the appearance of the wash oil composition DA5 prepared in Test Example 1 of this invention. Detailed Implementation

[0029] 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.

[0030] The terminology used in this invention is explained as follows:

[0031] C8-C 16 Alkyl groups refer to alkyl groups with a total number of carbon atoms of 8-16, including C8-C6. 16 Straight-chain alkyl, C8-C 16 Branched alkyl groups, such as straight-chain or branched alkyl groups with a total number of carbon atoms of 8, 9, 10, 11, 12, 13, 14, 15, or 16, for example, n-octyl, isooctyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, etc. (Regarding "C8-C") 12 "alkyl" has a similar interpretation, except that the number of carbon atoms is different.

[0032] As previously described, a first aspect of the present invention provides an oil washing composition suitable for remediating heavy oil-contaminated soil, the oil washing composition containing the following components, which may be stored individually or in combination:

[0033] Oligomeric cationic quaternary ammonium salt surfactants, anionic nonionic surfactants, cyclodextrins, and water;

[0034] Based on the total weight of the wash oil composition, the content of the oligomeric cationic quaternary ammonium salt surfactant is 0.01wt%-0.15wt%, the content of the anionic nonionic surfactant is 0.015wt%-1.0wt%, the content of the cyclodextrin is 0.05wt%-0.25wt%, and the content of water is 98.6wt%-99.7wt%.

[0035] The mass ratio of the anionic nonionic surfactant to the oligomeric cationic quaternary ammonium salt surfactant is 1.1-7.0:1;

[0036] The oligomeric cationic quaternary ammonium salt surfactant has the structure shown in formula (I).

[0037]

[0038] In equation (I),

[0039] All three X's are identical and are Cl, Br, or I; all R's are identical and selected from C8-C. 16 Alkyl groups.

[0040] Preferably, in formula (I), the three X's are the same and are either Cl or Br; all R's are the same and are selected from C8-C. 12 Alkyl groups.

[0041] More preferably, in formula (I), the three X's are the same and are Br; each R's is the same and is selected from -C. 12 H 25 More preferably, in formula (I), the three X's are the same and are Br; and the three R's are the same and are n-dodecyl.

[0042] In a preferred embodiment, the anionic nonionic surfactant is selected from at least one of alkyl alcohol polyoxyethylene ether sulfate, alkyl alcohol polyoxyethylene ether carboxylate, alkylphenol polyoxyethylene ether sulfate, alkylphenol polyoxyethylene ether carboxylate, and alkylphenol polyoxyethylene ether phosphate.

[0043] Preferably, the degree of polymerization of the alkyl alcohol polyoxyethylene ether sulfate, alkyl alcohol polyoxyethylene ether carboxylate, alkylphenol polyoxyethylene ether sulfate, alkylphenol polyoxyethylene ether carboxylate, and alkylphenol polyoxyethylene ether phosphate is 2-10, and the alkyl chain length is 8-16.

[0044] Preferably, the degree of polymerization of the alkyl alcohol polyoxyethylene ether sulfate, alkyl alcohol polyoxyethylene ether carboxylate, alkylphenol polyoxyethylene ether sulfate, alkylphenol polyoxyethylene ether carboxylate, and alkylphenol polyoxyethylene ether phosphate is 2-7, and the alkyl chain length is 12-16.

[0045] Preferably, the anionic nonionic surfactant is alkyl alcohol polyoxyethylene ether sulfate. More preferably, the anionic nonionic surfactant is sodium alkyl alcohol polyoxyethylene ether sulfate. The inventors of this invention have found that, under this preferred condition, the washing composition provided by this invention has a better washing effect on heavy oil contaminants.

[0046] In a preferred embodiment, the cyclodextrin is selected from at least one of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, methyl-α-cyclodextrin, methyl-β-cyclodextrin, methyl-γ-cyclodextrin, hydroxypropyl-α-cyclodextrin, hydroxypropyl-β-cyclodextrin, and hydroxypropyl-γ-cyclodextrin.

[0047] Preferably, the cyclodextrin is selected from at least one of β-cyclodextrin, α-cyclodextrin, and γ-cyclodextrin.

[0048] More preferably, the cyclodextrin is β-cyclodextrin. The inventors of this invention have discovered that, in this preferred embodiment, the washing composition provided by this invention has a better washing effect on heavy oil contaminants.

[0049] The oligomeric cationic quaternary ammonium salt surfactants, anionic nonionic surfactants, and cyclodextrins described in this invention can be purchased or prepared according to known methods in the art.

[0050] The present invention does not impose any particular limitation on the method for preparing the oligomeric cationic quaternary ammonium salt surfactant. However, in order to obtain better oil washing effect, the present invention preferably provides the method described below for preparing the oligomeric cationic quaternary ammonium salt surfactant.

[0051] According to a preferred embodiment, the present invention provides a method for preparing the oligomeric cationic quaternary ammonium salt surfactant, the method comprising:

[0052] Add 9-11g of N,N-dimethylethylenediamine to 1-3g of trimethyl citrate and react at 90-110℃ for 2.5-3.5h. After the reaction is complete, remove excess raw material using a rotary evaporator to obtain the intermediate.

[0053] Take 3-5g of intermediate and 15-17g of compound RX (in compound RX, the definitions of R and X are the same as those in formula (I) of the first aspect) and dissolve them in 20-50mL of methanol / acetone mixed solvent (the volume ratio of methanol to acetone is 2-5:1). React at 35-45℃ for 70-75h, remove the solvent by rotary evaporation, and recrystallize the crude product in a methanol / ethyl acetate mixed solution to obtain oligomeric cationic quaternary ammonium salt surfactant.

[0054] The water mentioned in this invention can be deionized water, ultrapure water, etc., and this invention does not have any special requirements for it.

[0055] Preferably, based on the total weight of the wash oil composition, the content of the oligomeric cationic quaternary ammonium salt surfactant is 0.1wt%-0.15wt%, the content of the anionic nonionic surfactant is 0.15wt%-0.45wt%, the content of the cyclodextrin is 0.1wt%-0.2wt%, and the content of water is 99.2wt%-99.65wt%.

[0056] Preferably, the mass ratio of the anionic nonionic surfactant to the oligomeric cationic quaternary ammonium salt surfactant is (1.5-3.0):1.

[0057] As previously stated, a second aspect of the present invention provides a method for preparing the wash oil composition of the first aspect, the method comprising: mixing the components of the wash oil composition of the first aspect.

[0058] Preferably, the mixing conditions at least satisfy the following: stirring speed of 200-1000 rpm and stirring time of 30-200 min.

[0059] In this invention, unless otherwise specified, the reaction temperature refers to the reaction being carried out at room temperature, which is 25±5℃.

[0060] As previously stated, a third aspect of the present invention provides the use of the wash oil composition described in the first aspect in the remediation of heavy oil-contaminated soil.

[0061] As previously described, a fourth aspect of the present invention provides a method for remediating heavy oil-contaminated soil, the method comprising:

[0062] (1) Contacting heavy oil-contaminated soil with the washing oil composition described in the first aspect to obtain mixture I;

[0063] (2) Perform solid-liquid separation on the mixture I.

[0064] Preferably, the contact conditions at least satisfy the following: temperature of 25-80℃, time of 1-6h, and shaking frequency of 60-200rpm.

[0065] More preferably, the contact conditions shall at least satisfy the following: temperature of 40-60°C, time of 2-4 hours, and shaking rate of 60-200 rpm.

[0066] According to a preferred embodiment, the weight ratio of the wash oil composition to the heavy oil-contaminated soil is 3:1 to 9:1.

[0067] More preferably, the weight ratio of the wash oil composition to the heavy oil-contaminated soil is 3:1 to 6:1.

[0068] The present invention does not have any particular requirements on the specific method of solid-liquid separation in step (2), and those skilled in the art can use methods known in the art as needed.

[0069] The aforementioned method for remediating heavy oil-contaminated soil of the present invention may also involve various post-processing operations known in the art, such as filtration and drying. The present invention does not impose any particular limitation on these operations, and those skilled in the art should not interpret them as limitations on the present invention.

[0070] Preferably, the hydrocarbon oil content in the heavy oil contaminated soil is 5 wt%-25 wt%. More preferably, the hydrocarbon oil content in the heavy oil contaminated soil is 5 wt%-10 wt%.

[0071] Unless otherwise specified, the hydrocarbon content in the heavy oil contaminated soil described in this invention is calculated by gravimetric method.

[0072] Compared with the prior art, the present invention has the following advantages:

[0073] (1) The washing composition provided by the present invention can form multilayer fingerprint-like aggregates in a mass ratio of anionic nonionic surfactant to oligomeric cationic quaternary ammonium salt surfactant of 1.1-7:1. The hydrophobic volume of the aggregates is more than 10 times that of monolayer vesicles, which can significantly enhance the solubilization and removal effect on crude oil contaminants. Through the multilayer hydrophobic cavities of the fingerprint-like aggregates and the host-guest effect of cyclodextrin, the solubilization efficiency of PAHs contaminants can be improved, thereby achieving the desorption and migration of petroleum contaminants and achieving the purpose of efficient oil washing.

[0074] (2) The fingerprint-like aggregates formed by the washing oil composition provided by the present invention have low adsorption on the soil surface, strong stability, and are easy to biodegrade. They will not precipitate within the ratio range of positive / negative charge ratio of cationic and anionic nonionic surfactants that is close to the charge neutrality point, and will not cause secondary pollution.

[0075] (3) The method for remediating heavy oil-contaminated soil provided by the present invention is applicable to heavy oil-contaminated soil with a hydrocarbon content of 5wt%-25wt%, and its oil washing efficiency is as high as 90% or more.

[0076] Unless otherwise specified, the instruments, reagents, and materials used in the following examples are all conventional instruments, reagents, and materials already available in the prior art and can be obtained through legitimate commercial channels. Unless otherwise specified, the experimental methods and detection methods used in the following examples are all conventional experimental methods and detection methods already available in the prior art. The water used in the following examples is deionized water.

[0077] The main raw materials used in the embodiments are shown in Table 1:

[0078] Table 1.

[0079]

[0080] Preparation Example 1: Citric-3C, an oligomeric cationic quaternary ammonium salt surfactant 12 Preparation

[0081] In formula (I), when all three X's are the same and are Br, and all R's are n-dodecyl, the structure shown in formula (I) is the oligomeric cationic quaternary ammonium salt surfactant Citric-3C. 12 .

[0082]

[0083] 10g of N,N-dimethylethylenediamine was added to 2g of trimethyl citrate, and the mixture was reacted at 100℃ for 3 hours. After the reaction was completed, excess raw materials were removed by rotary evaporation to obtain the intermediate.

[0084] 4 g of the intermediate and 16 g of 1-bromododecane were dissolved in 30 mL of a methanol / acetone mixed solvent (methanol to acetone volume ratio of 3:1) and reacted at 40 °C for 72 h. The solvent was removed by rotary evaporation, and the crude product was recrystallized in a methanol / ethyl acetate mixed solution to obtain an oligomeric cationic quaternary ammonium salt surfactant.

[0085] Preparation Example 2: Preparation of Heavy Oil Contaminated Soil

[0086] Uncontaminated soil (from the CN block of Shengli Oilfield) was pulverized and dried in a 150℃ constant temperature oven for 6 hours. The dried soil was then sieved through a 100-mesh sieve. The sieved soil and crude oil (Shengli Oilfield heavy oil, density 0.90 g / mL) were placed in an 80℃ constant temperature oven for 8 hours. 95 g of the dried soil was mixed with 5 g of dried Shengli Oilfield heavy oil and thoroughly mixed at 80℃. The soil mixed with heavy oil was aged in a 50℃ constant temperature oven for 7 days to prepare a sample of heavy oil-contaminated soil with an oil content of 5 wt% (i.e., oil-bearing soil).

[0087] Example 1

[0088] Add 0.15g of the oligomeric cationic quaternary ammonium salt surfactant Citric-3C 12 0.45 g of AES, 0.2 g of β-cyclodextrin and 99.2 g of water were mixed and stirred at 600 rpm for 100 min at room temperature to prepare wash oil composition A1.

[0089] The wash oil composition was characterized by cryo-transmission electron microscopy. The specific test method is as follows:

[0090] The prepared wash oil composition sample was placed on a newly carbon-coated porous copper mesh to form a thin sample film. The copper mesh containing the wash oil composition sample was then placed in liquid ethane frozen by liquid nitrogen to freeze the sample. The morphology of the sample was then observed using a FEI Tecnai 20 transmission electron microscope (LaB6). The transmission electron microscope images were taken at 200 kV, in low-dose mode (approximately 2000 e / nm). 2 The experiment was conducted under the conditions of a magnification of 50,000 and a resolution of 50,000, and finally, the results were obtained using a Nikon 9000 at the corresponding resolution. Digital imaging is achieved at a scanning speed of 2000 dpi per pixel.

[0091] The results of transmission electron microscopy are as follows Figure 1 As shown, the aggregate morphology formed by the washing oil composition A1 is a multilayered fingerprint-like spherical aggregate, and the volume of its hydrophobic microdomains can reach more than 10 times that of traditional monolayer vesicles, indicating that the washing oil composition A1 has a strong solubilizing ability. The surface Zeta potential of the multilayered fingerprint-like aggregates formed by the washing oil composition A1 is a negative value with a large absolute value (e.g., Figure 2As shown in the figure, this indicates that the aggregates formed by the wash oil composition are not easily adsorbed on the negatively charged soil surface, thus reducing the amount of surfactant adsorbed.

[0092] Then, weigh 10g of oily soil and add 60g of wash oil composition A1 into an Erlenmeyer flask. Place the flask in a shaker and heat it to 60℃, maintaining a constant frequency (120rpm) for 4 hours. Allow it to settle and separate. Take out the upper solution and transfer it to a graduated centrifuge tube for centrifugation. Read the volume of the separated crude oil V1. Dry the lower solid and weigh it as m1.

[0093] The oil removal rate (oil washing efficiency) and the residual oil content in the soil after washing are calculated using the following formulas:

[0094] Oil removal rate from oily soil = ρV / (0.5g) * 100%

[0095] Residual oil content in the cleaned soil = (0.5g - ρV) / m * 100%

[0096] In the above calculation formula:

[0097] ρ is the density of crude oil, with a value of 0.90 g / mL;

[0098] V represents the volume of crude oil read after liquid-solid separation, in mL;

[0099] m is the mass of the oil-containing soil dried after liquid-solid separation, in grams;

[0100] Calculation results show that after the crude oil contaminated soil is treated with the high-efficiency oil washing composition of this embodiment, the residual oil content is 0.30% and the oil washing efficiency is 95.5%.

[0101] Example 2

[0102] Add 0.1g of the oligomeric cationic quaternary ammonium salt surfactant Citric-3C 12 0.15 g of AES, 0.1 g of γ-cyclodextrin, and 99.65 g of water were mixed and stirred at 1000 rpm for 30 min at room temperature to prepare wash oil composition A2. Wash oil composition A2 was characterized by transmission electron microscopy, and the results showed that wash oil composition A2 also formed a multilayer fingerprint-like aggregate structure similar to that in Example 1.

[0103] Then, weigh 10g of oily soil, add 30g of washing oil composition A2 into an Erlenmeyer flask, place it in a shaker and heat to 60℃, shaking at a constant frequency (60rpm) for 4 hours. Allow it to settle and separate, take out the upper solution and transfer it to a graduated centrifuge tube for centrifugation, and read the volume of the separated oil V2; dry the lower solid and weigh it as m2.

[0104] Finally, the washing efficiency of this embodiment was calculated to be 90.7% and the residual oil content was 0.52% using the formula in Example 1.

[0105] Example 3

[0106] Weigh 0.12g of the oligomeric cationic quaternary ammonium salt surfactant Citric-3C. 12 0.25 g of AES, 0.15 g of α-cyclodextrin, and 99.48 g of water were mixed and stirred at room temperature and 200 rpm for 200 min to prepare wash oil composition A3. Wash oil composition A3 was characterized by cryo-transmission electron microscopy, and the results showed that wash oil composition A3 also formed a multilayer fingerprint-like aggregate structure similar to that of Example 1.

[0107] Then, weigh 10g of oil-containing soil and add 60g of high-efficiency oil washing system into an Erlenmeyer flask. Place the flask in a shaker and heat it to 40℃, maintaining a constant frequency (200rpm) for 2 hours. Allow it to settle and separate. Take out the upper solution and transfer it to a graduated centrifuge tube for centrifugation. Read the volume of the separated oil, V3. Dry the lower solid and weigh it, m3.

[0108] Finally, the washing efficiency of this embodiment was calculated to be 94.2% and the residual oil content was 0.40% using the formula in Example 1.

[0109] Comparative Example 1

[0110] 0.15 g of single-chain cationic quaternary ammonium salt surfactant DTAB, 0.45 g of AES, 0.2 g of β-cyclodextrin, and 99.2 g of water were mixed and stirred at room temperature and 600 rpm for 100 min to prepare wash oil composition DA1. Wash oil composition DA1 was characterized by cryo-transmission electron microscopy, and the results showed that the system formed monolayer vesicles.

[0111] Then, weigh 10g of oily soil, add 60g of the washing oil composition DA1 into an Erlenmeyer flask, place it in a shaker and heat to 60℃, shaking at a constant frequency (120rpm) for 4 hours. Allow it to settle and separate, take out the upper solution and transfer it to a graduated centrifuge tube for centrifugation, and read the volume of the separated oil V4; dry the lower solid and weigh it as m4.

[0112] Finally, the washing efficiency of this comparative example was calculated to be 51.8% and the residual oil content was 10.26% using the formula in Example 1.

[0113] Comparative Example 2

[0114] Add 0.15g of the oligomeric cationic quaternary ammonium salt surfactant Citric-3C12 0.2 g of β-cyclodextrin and 99.65 g of water were mixed and stirred at 600 rpm for 100 min at room temperature to prepare wash oil composition DA2. Wash oil composition DA2 was characterized by cryo-transmission electron microscopy, and the results showed that the system formed small-sized spherical micelles.

[0115] Then, weigh 10g of oily soil, add 60g of the washing oil composition DA2 into an Erlenmeyer flask, place it in a shaker and heat to 60℃, shaking at a constant frequency (120rpm) for 4 hours. Allow it to settle and separate, take out the upper solution and transfer it to a graduated centrifuge tube for centrifugation, and read the volume of the separated oil V5; dry the lower solid and weigh it as m5.

[0116] Finally, the washing efficiency of this comparative example was calculated to be 60.5% and the residual oil content was 8.33% using the formula in Example 1.

[0117] Comparative Example 3

[0118] Add 0.15g of the oligomeric cationic quaternary ammonium salt surfactant Citric-3C 12 0.45 g of AES and 99.4 g of water were mixed and stirred at 600 rpm for 100 min at room temperature to prepare the wash oil composition DA3. The wash oil composition DA3 was characterized by cryo-transmission electron microscopy, and the results showed that the system formed monolayer vesicles.

[0119] Then, weigh 10g of oil-containing soil, add 60g of the washing oil composition DA3 into an Erlenmeyer flask, place it in a shaker and heat to 60℃, shaking at a constant frequency (120rpm) for 4 hours. Allow it to settle and separate, take out the upper solution and transfer it to a graduated centrifuge tube for centrifugation, and read the volume of the separated oil as V6; dry the lower solid and weigh it as m6.

[0120] Finally, the washing efficiency of this comparative example was calculated to be 45.0% and the residual oil content was 2.70% using the formula in Example 1.

[0121] Comparative Example 4

[0122] The wash oil composition was prepared using the raw materials from Example 2 in CN110129020A.

[0123] Add 0.15g of the oligomeric cationic quaternary ammonium salt surfactant Citric-3C 120.45g of anionic nonionic surfactant alkyl alcohol polyoxyethylene ether ammonium sulfate (DNS-18), 0.2g of ethanol-diethanolamine mixed solvent (ethanol to diethanolamine in a mass ratio of 1:1) and 99.2g of water were mixed and stirred at room temperature and 600 rpm for 100 min to prepare the wash oil composition DA4.

[0124] Then, weigh 10g of oily soil, add 60g of the washing oil composition DA4 into an Erlenmeyer flask, place it in a shaker and heat to 60℃, shaking at a constant frequency (120rpm) for 4 hours. Allow it to settle and separate, take out the upper solution and transfer it to a graduated centrifuge tube for centrifugation, and read the volume of the separated oil V7; dry the lower solid and weigh it as m7.

[0125] Finally, the washing efficiency of this comparative example was calculated to be 62.7% and the residual oil content was 7.39% using the formula in Example 1.

[0126] The results of the above embodiments show that the highly efficient oil washing system formed by the combination of oligomeric cationic quaternary ammonium salt surfactants, anionic nonionic surfactants, and cyclodextrins all form unique multilayer fingerprint-like aggregates in aqueous solutions. Because the hydrophobic space volume is more than 10 times that of a single-layer vesicle, the solubility and removal efficiency of pollutants is significantly improved. The oil washing efficiency of all three embodiments reached over 90%, and the residual oil content in the soil could be reduced to 0.30%, demonstrating excellent leaching effects on heavy oil pollutants.

[0127] The comparison between Example 1 and Comparative Example 1 shows that, compared with traditional single-chain cationic quaternary ammonium salt surfactants, oligomeric cationic quaternary ammonium salt surfactants can make the washing composition have a better washing effect. This is because oligomeric cationic quaternary ammonium salt surfactants can interact with anionic nonionic surfactants to form multilayer fingerprint-like aggregates with larger hydrophobic volumes, while single-chain cationic quaternary ammonium salt surfactants form monolayer vesicles after being compounded with anionic nonionic surfactants.

[0128] A comparison of Example 1 with Comparative Examples 1, 2, and 3 shows that the oligomeric cationic quaternary ammonium salt surfactant, the anionic nonionic surfactant, and the cyclodextrin are all indispensable components in the washing oil composition provided by the present invention. This washing oil composition achieves the formation of multilayer fingerprint-like aggregates through the synergistic effect of these three components, thereby giving the system a stronger solubilizing ability and effectively enhancing its washing oil performance.

[0129] A comparison of Example 1 and Comparative Example 4 shows that when β-cyclodextrin is replaced with an ethanol-diethanolamine mixed solvent, the system fails to form fingerprint-like aggregates and instead forms a viscoelastic fluid with an aggregation morphology of worm-like micelles. Compared to the worm-like micelles formed in Comparative Example 4, the washing composition provided by this invention significantly improves the cleaning ability of heavy oil contaminants.

[0130] Test Example 1

[0131] Add 0.15g of the oligomeric cationic quaternary ammonium salt surfactant Citric-3C 12 0.165 g of AES, 0.1 g of β-cyclodextrin, and 99.585 g of water were mixed and stirred at 600 rpm for 100 min at room temperature to prepare a wash oil composition A4, in which the cationic surfactant and the anionic nonionic surfactant both have an electrically neutral charge. Figure 3 (As shown). By Figure 3 It can be seen that no precipitate was formed in the wash oil composition A4 in the beaker.

[0132] Add 0.15g of the oligomeric cationic quaternary ammonium salt surfactant Citric-3C 12 0.165 g of AES and 99.685 g of water were mixed and stirred at room temperature and 600 rpm for 100 min to prepare a wash oil composition DA5 (e.g., a cationic surfactant and anionic nonionic surfactant with an electrically neutral charge). Figure 4 As shown), by Figure 4 It can be seen that a large amount of precipitate was formed at the bottom of the beaker from the washing oil composition DA5.

[0133] Comparing the morphology of wash oil compositions A4 and DA5 reveals that the presence of cyclodextrin is crucial for the formation of fingerprint-like aggregates and for preventing precipitation in this system. In the absence of cyclodextrin, when the positive and negative charges of the cationic and anionic nonionic surfactants are equal, precipitation is easily caused by insufficient net charge.

[0134] Experimental group: 0.15g of oligomeric cationic quaternary ammonium salt surfactant Citric-3C was added. 12 Add 0.1g of β-cyclodextrin, and change the amount of AES and water to adjust the charge ratio of negative to positive charges in the system, and observe the state of the system.

[0135] Control group: No β-cyclodextrin was added to this system; the types and amounts of other substances were the same as in the experimental group. The state of the system was observed after mixing. The apparent state results of the experimental group and the control group are shown in Table 2.

[0136] Table 2

[0137] Charge ratio (negative charge : positive charge) experimental group control group 1.05 Pale blue milky luster, no sediment. precipitation 1.10 Pale blue milky luster, no sediment. precipitation 1.15 Pale blue milky luster, no sediment. precipitation 1.20 Pale blue milky luster, no sediment. precipitation 1.25 Pale blue milky luster, no sediment. precipitation 1.30 Pale blue milky luster, no sediment. precipitation 1.35 Pale blue milky luster, no sediment. precipitation 1.40 Pale blue milky luster, no sediment. precipitation 1.45 Pale blue milky luster, no sediment. Pale blue milky luster, no sediment. 1.50 Pale blue milky luster, no sediment. Pale blue milky luster, no sediment.

[0138] In the wash oil composition, no precipitation occurred in the experimental groups when the charge ratio of negative to positive charges was in the range of 1-1.5. However, in the control group without β-cyclodextrin, precipitates formed in the system with a charge ratio ranging from 1-1.4. Therefore, the results in Table 2 indicate that the presence of β-cyclodextrin effectively inhibited the formation of precipitates near the charge neutral point.

[0139] Test Example 2: Biodegradability Test

[0140] The biodegradability of chemical agents is evaluated by the ratio of their biochemical oxygen demand (BOD) to chemical oxygen demand (COD) (B / C ratio). A higher B / C ratio indicates better biodegradability of the surfactant. A B / C ratio of 0.3 is typically used as a baseline parameter; if the B / C ratio of an agent is greater than or equal to 0.3, it indicates that the agent is readily biodegradable. The BOD and COD ratios were determined according to the methods described in national standards HJ 505-2009 and HJ 828-2017, respectively. The measurement results of BOD, COD, and B / C ratios for the above examples and comparative examples are shown in Table 3.

[0141] Table 3: BOD, COD, and B / C ratio of different compositions with surfactant functions

[0142] Case BOD / (mg / L) COD / (mg / L) B / C ratio Example 1 149.22 403.3 0.37 Example 2 135.86 399.6 0.34 Example 3 127.32 410.7 0.31 Comparative Example 1 163.56 408.9 0.40 Comparative Example 2 162 450.0 0.36 Comparative Example 3 27.12 630.7 0.043 Comparative Example 4 1.16 580.1 0.002

[0143] Examples 1-3 and Comparative Examples 1 and 2 all contain cyclodextrin, and the B / C ratios of the corresponding systems are all higher than 0.3, indicating a high degree of biodegradability. However, Comparative Examples 3 and 4 do not contain cyclodextrin, and their B / C ratios are very low, making them difficult to biodegrade. Therefore, the addition of cyclodextrin can reduce the biotoxicity of the washing oil composition system and improve its biodegradability, which meets the requirements of green soil leaching agents and will not cause secondary pollution to the soil.

[0144] 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 washing composition suitable for remediating oil-contaminated soil, characterized in that, The wash oil composition contains the following components, which may be stored individually or in combination: Oligomeric cationic quaternary ammonium salt surfactants, anionic nonionic surfactants, cyclodextrins, and water; Based on the total weight of the wash oil composition, the content of the oligomeric cationic quaternary ammonium salt surfactant is 0.01wt%-0.15wt%, the content of the anionic nonionic surfactant is 0.015wt%-1.0wt%, the content of the cyclodextrin is 0.05wt%-0.25wt%, and the content of water is 98.6wt%-99.7wt%. The mass ratio of the anionic nonionic surfactant to the oligomeric cationic quaternary ammonium salt surfactant is 1.1-7.0:1; The anionic nonionic surfactant is selected from at least one of alkyl alcohol polyoxyethylene ether sulfate, alkyl alcohol polyoxyethylene ether carboxylate, alkylphenol polyoxyethylene ether sulfate, alkylphenol polyoxyethylene ether carboxylate, and alkylphenol polyoxyethylene ether phosphate. The oligomeric cationic quaternary ammonium salt surfactant has the structure shown in formula (I). Equation (I) In equation (I), All three X's are identical and are Cl, Br, or I; all R's are identical and selected from C8-C. 16 Alkyl groups.

2. The wash oil composition according to claim 1, wherein, In equation (I), All three X's are identical and are either Cl or Br; all R's are identical and selected from C8-C. 12 Alkyl groups.

3. The washing oil composition according to claim 2, wherein, In equation (I), the three X's are identical and are Br; all R's are identical and selected from -C. 12 H 25 .

4. The wash oil composition according to claim 1 or 2, wherein, The anionic nonionic surfactant is alkyl alcohol polyoxyethylene ether sulfate.

5. The washing oil composition according to claim 1, wherein, The degree of polymerization of the alkyl alcohol polyoxyethylene ether sulfate, alkyl alcohol polyoxyethylene ether carboxylate, alkylphenol polyoxyethylene ether sulfate, alkylphenol polyoxyethylene ether carboxylate, and alkylphenol polyoxyethylene ether phosphate is 2-10, and the alkyl chain length is 8-16.

6. The wash oil composition according to any one of claims 1-3, wherein, The cyclic paste is selected from... α -Cyclodextrin, β -Cyclodextrin, γ -Cyclodextrin, methyl- α -Cyclodextrin, methyl- β -Cyclodextrin, methyl- γ -Cyclodextrin, hydroxypropyl- α -Cyclodextrin, hydroxypropyl- β -Cyclodextrin, hydroxypropyl- γ - At least one of the cyclodextrins.

7. The wash oil composition according to claim 6, wherein, The cyclic paste is selected from... β -Cyclodextrin, α -Cyclodextrin, γ - At least one of the cyclodextrins.

8. The wash oil composition according to any one of claims 1-3, wherein, Based on the total weight of the wash oil composition, the content of the oligomeric cationic quaternary ammonium salt surfactant is 0.1wt%-0.15wt%, the content of the anionic nonionic surfactant is 0.15wt%-0.45wt%, the content of the cyclodextrin is 0.1wt%-0.2wt%, and the content of water is 99.2wt%-99.65wt%.

9. The wash oil composition according to any one of claims 1-3, wherein, The mass ratio of the anionic nonionic surfactant to the oligomeric cationic quaternary ammonium salt surfactant is (1.5-3.0):

1.

10. A method for preparing the wash oil composition according to any one of claims 1-9, characterized in that, The method includes mixing the components of the wash oil composition according to any one of claims 1-9.

11. The method according to claim 10, wherein, The mixing conditions must at least meet the following requirements: stirring speed of 200-1000 rpm and stirring time of 30-200 min.

12. The use of the wash oil composition according to any one of claims 1-9 in the remediation of heavy oil contaminated soil.

13. A method for remediating oil-contaminated soil, characterized in that, The method includes: (1) Contacting the oil-contaminated soil with the washing oil composition according to any one of claims 1-9 to obtain mixture I; (2) Perform solid-liquid separation on the mixture I.

14. The method according to claim 13, wherein, The contact conditions must at least meet the following: temperature 25-80℃, time 1-6h, and shaking frequency 60-200rpm.

15. The method according to claim 14, wherein, The contact conditions must at least meet the following: temperature of 40-60℃, time of 2-4h, and shaking frequency of 60-200rpm.

16. The method according to any one of claims 13-15, wherein, The weight ratio of the wash oil composition to the heavy oil-contaminated soil is 3:1 to 9:

1.

17. The method according to claim 16, wherein, The weight ratio of the wash oil composition to the heavy oil-contaminated soil is 3:1 to 6:

1.

18. The method according to any one of claims 13-15, wherein, The hydrocarbon oil content in the heavy oil contaminated soil is 5wt%-25wt%.

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