Modified rhamnolipid as well as preparation method and application thereof
By sulfonating and modifying rhamnolipids to optimize their structure, the problems of low efficiency and environmental toxicity of existing chemical flooding agents are solved. This achieves efficient reduction of oil-water interfacial tension and dispersion of heavy oil, thus improving the cleaning effect of oily solids in oil fields.
Patent Information
- Application Number
- CN202410641362.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-22
- Publication Date
- 2025-11-25
AI Technical Summary
Existing chemical flooding agents have problems such as large dosage, low oil washing efficiency and environmental toxicity in improving the recovery rate of low-permeability reservoirs. Natural rhamnolipids have low yield and high cost, which limits their large-scale application.
Modified rhamnolipin was prepared by sulfonating it to introduce sulfonic acid groups and optimize its structure, thereby giving it better hydrophilicity and lower oil-water interfacial tension.
Modified rhamnolipids can reverse the lipophilic surface to a hydrophilic surface, improving dispersion stability and oil washing efficiency, reducing oil-water interfacial tension, and are suitable for cleaning oily solids in oil fields to improve heavy oil recovery.
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Figure CN121005752A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of oil extraction technology, specifically to a modified rhamnolipin, its preparation method, and its application. Background Technology
[0002] Petroleum, known as the "lifeblood of industry," is a vital non-renewable resource. Currently, low-permeability reservoirs (<50mD) account for approximately 11% of China's total petroleum geological reserves, and over 60% of proven but untapped petroleum geological reserves. With ongoing extraction, most of my country's oilfields have entered a high water-cut stage, increasing the difficulty of extraction. Therefore, improving the recovery rate of low-permeability reservoirs is of great significance.
[0003] Due to the oleophilic nature of the reservoir bed, a large amount of residual oil is adsorbed in the pores of the reservoir rock. To improve reservoir recovery, it is necessary to improve the oil washing efficiency of waterflooding. Surfactant systems alter reservoir wettability, making the oleophilic bed hydrophilic and reducing the oil-water interfacial tension, thereby stripping residual oil from the oleophilic surface of the bed. Currently used chemical flooding methods generally suffer from problems such as large dosage, low oil washing efficiency, poor degradation, and environmental toxicity. Rhamnose lipolipid surfactants are a class of bio-based surfactants that can reduce the oil-water interfacial tension to 10. -2 With a concentration of mN / m, it exhibits good interfacial activity. However, the low yield and high cost of natural rhamnolipids prevent them from competing commercially with synthetic surfactants, limiting their large-scale application. This necessitates researchers to develop more innovative methods to enhance their functionality and expand their application scenarios. Summary of the Invention
[0004] The purpose of this disclosure is to provide a modified rhamnolipid, its preparation method and application. The modified rhamnolipid has an optimized structure, has better hydrophilicity and lower oil-water interfacial tension, can reverse the lipophilic surface to a hydrophilic surface, and has high surface activity and dispersion stability.
[0005] To achieve the above objectives, a first aspect of this disclosure provides a modified rhamnolipid comprising compounds having the structures shown in formula (1) and / or formula (2):
[0006]
[0007] In formula (1) and / or formula (2), X1 to X6 may be the same or different, and each independently represents H, SO3H or SO3Na, and at least one is SO3H or SO3Na;
[0008] R1 and R2 may be the same or different, and each is independently selected from alkyl groups having 5 to 10 carbon atoms, where m represents... The number of elements, where m is 0 or 1.
[0009] Optionally, R1 and R2 may be the same or different, and each is independently selected from one or more of n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; preferably, R1 and R2 are the same and are both selected from n-pentyl, n-hexyl, n-heptyl, or n-octyl; more preferably, R1 and R2 are both selected from n-heptyl.
[0010] Optionally, the modified rhamnolipid is selected from one or more compounds having the structures shown in formulas (I) to (IX):
[0011]
[0012] A second aspect of this disclosure provides a method for preparing modified rhamnolipids, the method comprising: contacting the rhamnolipids with a sulfonating agent in an organic solvent to carry out a sulfonation reaction; wherein the rhamnolipids comprise compounds having the structures shown in formula (3) and / or formula (4) as follows:
[0013]
[0014] In formula (3) and / or formula (4), R1 and R2 may be the same or different, and each is independently selected from alkyl groups having 5 to 10 carbon atoms, where m represents The number of elements, where m is 0 or 1.
[0015] Optionally, the contact conditions include: dissolving the rhamnolipin in the organic solvent to obtain a rhamnolipin solution; then mixing the rhamnolipin solution with a sulfonating agent; the concentration of the rhamnolipin solution is 50-100 g / L, preferably 50-80 g / L; the organic solvent is selected from one or more of dichloromethane, methanol, chloroform, ethyl acetate, ethanol and dimethylacetamide, preferably dichloromethane.
[0016] Optionally, the weight ratio of the rhamnolipid to the sulfonating agent is 1:(0.1-1.0), preferably 1:(0.2-0.6); the sulfonation reaction temperature is -20 to 20°C, preferably -10 to 10°C; the time is 1 to 15 hours, preferably 4 to 6 hours; the sulfonating agent is selected from one or more of chlorosulfonic acid, aminosulfonic acid and sulfur trioxide, preferably chlorosulfonic acid.
[0017] Optionally, the method further includes neutralizing the sulfonation reaction product with an alkali, wherein the weight ratio of the alkali to the rhamnolipid is (0.01-0.1):1, preferably (0.05-0.08):1; the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate, preferably sodium hydroxide.
[0018] A third aspect of this disclosure provides a modified rhamnolipid prepared using the method described in the second aspect of this disclosure.
[0019] This fourth aspect of the disclosure provides the application of the modified rhamnolipids described in the first and third aspects of the disclosure in oilfield oil solids cleaning, pesticides, and daily chemical products.
[0020] Optionally, the application of the modified rhamnolipin in the cleaning of oily solids in oilfields includes: contacting an aqueous solution containing the modified rhamnolipin with the oily solids, wherein the contact temperature is 40–60°C and the contact time is 1–3 hours; wherein the concentration of the modified rhamnolipin in the aqueous solution is 500–3000 mg / L, preferably 500–1000 mg / L; the oil content of the oily solids is 5–20% by weight, and the weight ratio of the oily solids to the aqueous solution is 1:(2–6), preferably 1:(3–5); preferably, the oily solids are selected from one or more of oily soil, oily sludge, oily stainless steel, and oily ceramics.
[0021] Through the above technical solution, this disclosure provides a modified rhamnolipin, its preparation method, and its application. This modified rhamnolipin is sulfonated using a sulfonating agent, modifying the hydroxyl groups at the highly reactive sites of the rhamnolipin with sulfonic acid groups. Compared to unmodified rhamnolipin, the structure of the modified rhamnolipin disclosed in this disclosure is optimized, exhibiting superior hydrophilicity and lower oil-water interfacial tension. It can reverse the oleophilic surface to a hydrophilic surface and possesses high surface activity and dispersion stability. The preparation method of this disclosure has the advantages of simple process, mild reaction conditions, and readily available green raw materials, making it easy to achieve industrial-scale modified production and possessing industrial scale-up value. Applying the modified rhamnolipin of this disclosure to oilfield heavy oil-contaminated soil can reduce the oil-water interfacial tension, allowing the heavy oil to disperse in the aqueous solution and emulsify into a homogeneous dispersion system. Simultaneously, it can transform the oleophilic sublayer into a hydrophilic sublayer, thereby stripping residual oil from the surface of the oleophilic sublayer, improving the oil washing efficiency and heavy oil recovery rate of the contaminated soil.
[0022] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description
[0023] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:
[0024] Figure 1 The infrared spectra of the modified rhamnolipin and the unmodified rhamnolipin prepared in Example 1 of this disclosure are shown.
[0025] Figure 2This is a comparison diagram of the oil-washing effects of the modified rhamnolipin and the unmodified rhamnolipin prepared in Example 1 of this disclosure. Detailed Implementation
[0026] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.
[0027] The first aspect of this disclosure provides a modified rhamnolipid having the structure shown in formula (1) and / or formula (2):
[0028]
[0029] In formula (1) and / or formula (2), X1 to X6 may be the same or different, and each independently represents H, SO3H or SO3Na, and at least one is SO3H or SO3Na; R1 and R2 may be the same or different, and each independently selected from alkyl groups having 5 to 10 carbon atoms, and m represents The number of elements, where m is 0 or 1.
[0030] The modified rhamnolipin disclosed herein is modified by sulfonating rhamnolipin with a sulfonating agent, thereby modifying the hydroxyl groups at the highly reactive sites of the rhamnolipin with sulfonic acid groups. Compared with unmodified rhamnolipin, the modified rhamnolipin of this disclosure has an optimized structure, exhibiting superior hydrophilicity and lower oil-water interfacial tension. It can reverse the lipophilic surface to a hydrophilic surface and possesses high surface activity and dispersion stability.
[0031] In one embodiment of this disclosure, R1 and R2 may be the same or different, and each is independently selected from one or more of n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl. In a specific embodiment, R1 and R2 are the same and are both selected from n-pentyl, n-hexyl, n-heptyl, or n-octyl; in a preferred embodiment, R1 and R2 are both selected from n-heptyl.
[0032] In this disclosure, there are no limitations on the number and position of sulfonic acid groups on the modified rhamnolipid. Preferably, the number of sulfonic acid groups is not limited to one or two. In one embodiment, the modified rhamnolipid is selected from one or more compounds having the structures shown in formulas (I) to (IX):
[0033]
[0034] In the above embodiments, the modified rhamnolipid has a hydrophilic sodium sulfonate group, which can reduce the interfacial tension between oil and water, and transform the lipophilic bottom layer into a hydrophilic bottom layer.
[0035] A second aspect of this disclosure provides a method for preparing modified rhamnolipids, the method comprising: contacting the rhamnolipids with a sulfonating agent in an organic solvent to carry out a sulfonation reaction; the rhamnolipids having the structure shown in formula (3) and / or formula (4):
[0036]
[0037] In formulas (3) to (4), R1 and R2 may be the same or different, and each is independently selected from alkyl groups having 5 to 10 carbon atoms, where m represents The number of elements, where m is 0 or 1.
[0038] The rhamnolipid disclosed herein is obtained by drying fermentation broth and is a mixed system of disaccharide diesters, monosaccharide diesters, disaccharide monoesters, and monosaccharide monoesters. Its specific structural formula is shown in formula (3) and / or formula (4) above, where m is 0 or 1. The preparation method disclosed herein has the advantages of simple process, mild reaction conditions, and readily available green raw materials, making it easy to achieve industrial-scale modified production and possessing industrial scale-up value.
[0039] In one embodiment of this disclosure, the contact conditions include: first dissolving the rhamnolipin in the organic solvent to obtain a rhamnolipin solution; then mixing the rhamnolipin solution with a sulfonating agent; the concentration of the rhamnolipin solution is 50–100 g / L, preferably 50–80 g / L; the organic solvent is selected from one or more of dichloromethane, methanol, chloroform, ethyl acetate, ethanol, and dimethylacetamide, preferably dichloromethane. In the above embodiment, first dissolving the rhamnolipin in the organic solvent is beneficial to increasing the solubility of the rhamnolipin; mixing the rhamnolipin solution with the sulfonating agent is beneficial to the effective contact between the highly reactive hydroxyl groups of the rhamnolipin and the sulfonating agent, thereby improving the effect of the sulfonation reaction.
[0040] In one embodiment of this disclosure, the weight ratio of the rhamnolipid to the sulfonating agent is 1:(0.1-1.0), preferably 1:(0.2-0.6); the sulfonation reaction temperature is -20 to 20°C, preferably -10 to 10°C; the reaction time is 1 to 15 hours, preferably 4 to 6 hours; the sulfonating agent is selected from one or more of chlorosulfonic acid, aminosulfonic acid, and sulfur trioxide, preferably chlorosulfonic acid. In the above embodiments, selecting the preferred raw material molar ratio and sulfonation conditions is beneficial for synthesizing modified rhamnolipids with a suitable sulfonic acid group content.
[0041] In one embodiment of this disclosure, the method further includes neutralizing the sulfonation reaction product with an alkali, wherein the weight ratio of the alkali to the rhamnolipid is (0.01–0.1):1, preferably (0.05–0.08):1; the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate, preferably sodium hydroxide. In the above embodiment, neutralizing the sulfonation reaction product with an alkali is beneficial to further improve the hydrophilicity of the modified rhamnolipid, thereby improving its oil washing efficiency.
[0042] A third aspect of this disclosure provides a modified rhamnolipid prepared using the method described in the second aspect of this disclosure.
[0043] This fourth aspect of the disclosure provides the application of the modified rhamnolipids described in the first and third aspects of the disclosure in oilfield oil solids cleaning, pesticides, and daily chemical products.
[0044] In one embodiment of this disclosure, the application of the modified rhamnolipin in oilfield oil solids cleaning includes: contacting an aqueous solution containing the modified rhamnolipin with the oil solids, wherein the contact temperature is 40–60°C and the contact time is 1–3 hours; wherein the concentration of the modified rhamnolipin in the aqueous solution is 500–3000 mg / L, preferably 500–1000 mg / L; the oil content of the oil solids is 5–20% by weight, and the weight ratio of the oil solids to the aqueous solution is 1:(2–6), preferably 1:(3–5). In a preferred embodiment, the oil solids are selected from one or more of oily soil, oily sludge, oily stainless steel, and oily ceramics. The modified rhamnolipin of this disclosure, when used in oilfield oil solids cleaning, has high oil washing efficiency and can remove residual oil from the surface of the oleophilic substrate, thereby improving the recovery rate of heavy oil.
[0045] The present disclosure is further illustrated by the following examples, but the present disclosure is not limited thereto. Unless otherwise specified, all raw materials used in the examples and comparative examples of the present disclosure are commercially available and are pure reagents.
[0046] Example 1
[0047] 1 g of rhamnolipin was weighed into a 50 ml flask and dissolved in 20 ml of dichloromethane (an organic solvent) to obtain a rhamnolipin solution with a concentration of 50 g / L. The reaction system was cooled to 0 °C, and 0.2 g of chlorosulfonic acid (a sulfonating agent) was added dropwise to carry out the sulfonation reaction. After 4 hours of reaction (i.e., the sulfonation reaction temperature was 0 °C and the time was 4 hours), 0.07 g of sodium hydroxide was added for neutralization. After drying, modified rhamnolipin was obtained. The weight ratio of rhamnolipin to sulfonating agent was 1:0.2, and the weight ratio of sodium hydroxide to rhamnolipin was 0.07:1.
[0048] Rhamnose lipids have the structures shown in formula (3) and / or formula (4):
[0049]
[0050] In equations (3) and / or (4), R1 and R2 are the same and are both selected from the n-heptyl group, where m represents... The number of elements, where m is 0 or 1;
[0051] The obtained modified rhamnolipids are selected from one or more compounds having the structures shown in formulas (I) to (IX):
[0052]
[0053] The modified and unmodified rhamnolipids were analyzed using Fourier transform infrared spectroscopy. The infrared spectra are shown below. Figure 1 As shown, the modified rhamnolipid has a concentration of 900–1350 cm⁻¹ -1 The modified rhamnolipid exhibits an infrared absorption peak with sulfonic acid groups, while the unmodified rhamnolipid does not, indicating that it does not contain sulfonic acid groups.
[0054] Example 2
[0055] The method of Example 1 was used, except that sodium hydroxide was not added for neutralization after the sulfonation reaction was completed, and the modified rhamnolipid was obtained after drying.
[0056] Example 3
[0057] The method of Example 1 was used, except that the sulfonating agent chlorosulfonic acid was replaced with the same amount of aminosulfonic acid, and the modified rhamnolipid was finally obtained.
[0058] Example 4
[0059] The method of Example 1 was adopted, except that the content of the sulfonating agent chlorosulfonic acid was adjusted from 0.2g to 0.4g, so that the weight ratio of rhamnolipid to sulfonating agent was 1:0.4, and the modified rhamnolipid was finally obtained.
[0060] Example 5
[0061] The method of Example 1 was used, with the only difference being that the sulfonation reaction temperature was 20°C and the time was 1 hour, ultimately yielding modified rhamnolipid.
[0062] Test Example 1
[0063] The wetting ability of the modified rhamnolipids and unmodified rhamnolipids prepared in Examples 1-5 was evaluated:
[0064] First, Victory SDS21×11 heavy oil or paraffin was uniformly coated onto a clean glass slide at high temperature and allowed to cool naturally. Then, the modified rhamnolipin and unmodified rhamnolipin prepared in Examples 1-5 were mixed with deionized water to prepare a 1000 mg / L aqueous solution of the test sample. This aqueous solution was then dropped onto the glass slide surface, and the contact angle was measured using a KRUSSDSA100 contact angle meter via the seated drop method. The contact angle experiment temperature was controlled at 25℃. Timing began when the droplet reached the oily interface, and after equilibration for 1 minute, the contact angle was obtained by photographing and fitting the image. The measurement results are shown in Table 1.
[0065] Table 1
[0066]
[0067]
[0068] The data in Table 1 show that, at a concentration of 1000 mg / L, the contact angle of unmodified rhamnolipin aqueous solution droplets on an oily surface is 42.5°. However, after sulfonation modification, the contact angle of the prepared modified rhamnolipin aqueous solution at the oily interface ranges from 20.5° to 37.8°, a decrease of up to 22° compared to the unmodified solution. This indicates that the modified rhamnolipin of this disclosure possesses superior hydrophilicity, lower oil-water interfacial tension, and better wettability, enabling the conversion of oleophilic surfaces into hydrophilic surfaces.
[0069] Test Example 2
[0070] The emulsifying and dispersing abilities of the modified rhamnolipids and unmodified rhamnolipids prepared in Examples 1-5 were evaluated:
[0071] SDS21×11 heavy oil from Shengli Oilfield was selected as the test oil to determine its emulsification performance. The specific steps are as follows: 25g of the aqueous solution of the sample prepared in Test Example 1 was added to 50g of the test oil. The beaker was placed in a 70℃ water bath and allowed to stand for 1 hour. A biological shaker was used to simulate the emulsification process under weak shear conditions. The shaking level was set to level 1, the mixing rate was 6 rpm, and the shaking time was 30 minutes. The emulsion morphology of the heavy oil was observed using an optical microscope. The results are shown in Table 2.
[0072] Table 2
[0073] Emulsification effect Example 1 Non-layered, heavy oil is dispersed in a uniform fine-particle emulsion. Example 2 Non-layered, heavy oil is dispersed in coarse particles as an emulsion Example 3 Non-layered, heavy oil is dispersed in a uniform fine-particle emulsion. Example 4 Non-layered, heavy oil is dispersed in a uniform fine-particle emulsion. Example 5 Non-layered, heavy oil is dispersed in a uniform fine-particle emulsion. Unmodified rhamnolipid In a layered state, heavy oil exhibits an aggregated state.
[0074] As shown in Table 2, the modified rhamnolipin provided in this disclosure can disperse heavy oil in an aqueous solution and emulsify Shengli heavy oil into a low-viscosity state with uniform particle dispersion. In contrast, the unmodified rhamnolipin in Comparative Example 1 could not disperse heavy oil in an aqueous solution, and the heavy oil exhibited a layered aggregated state. This indicates that the modified rhamnolipin of this disclosure has better dispersibility for heavy oil and a significant advantage in emulsification effect.
[0075] Test Example 3
[0076] The oil-washing ability of the modified rhamnolipids and unmodified rhamnolipids prepared in Examples 1-5 was evaluated:
[0077] Take 100-mesh quartz sand, wash it, and dry it in a constant temperature oven at 150℃ for 6 hours. Place the quartz sand and SDS21×11 heavy oil in a constant temperature oven at 80℃ for 8 hours. Take 85g of dried quartz sand, add 15g of Shengli Oilfield SDS21×11 heavy oil (density 0.903g / mL), and mix them evenly at 80℃. Place the quartz sand mixed with crude oil in a constant temperature oven at 80℃ for one week of aging to prepare oil sand with an oil content of 15% by weight. Prepare a 1000mg / L wash oil system by mixing the modified rhamnolipin obtained in Examples 1-5 and the unmodified rhamnolipin with tap water.
[0078] 10g of oil sand with an oil content of 15% by weight was weighed into an Erlenmeyer flask, and 40mL of washing oil system was added. After sealing, the flask was placed in a Jinyi SHZ-88 water bath constant temperature shaker and heated to 50℃, and shaken at a constant rate of 30rpm for 3 hours. After cooling to room temperature, the flask was allowed to settle and separate. The solution and the washed crude oil were separated from the solid phase. The separated solid was dried at 100℃ to constant weight and weighed. The comparison of the washing effect of the modified rhamnolipin and the unmodified rhamnolipin prepared in Example 1 is shown in the figure below. Figure 2 As shown, from left to right, the images depict the washing effect of unmodified rhamnolipin (left) and the washing effect of modified rhamnolipin obtained in Example 1 (right). In the left image, the lower layer is deposited black oil sand, and the upper layer of floating black aggregates is the washed crude oil. As can be seen from the left image, unmodified rhamnolipin cannot wash all the oil from the oil sand; some crude oil remains adsorbed on the surface of the oil sand, giving it a black color. In contrast, the lower layer in the right image is deposited white quartz sand, and the upper layer of floating black aggregates is the washed crude oil. As can be seen from the right image, modified rhamnolipin can wash the oil sand into white quartz sand, indicating a better washing effect. Finally, the washing efficiency of this washing system is calculated using the following formula:
[0079] Washing efficiency = (10g – m) / (1.5g) × 100%; the calculation results are shown in Table 3:
[0080] Table 3
[0081] serial number Oil washing efficiency (%) Example 1 95 Example 2 82 Example 3 92 Example 4 93 Example 5 94 Unmodified rhamnolipid 79
[0082] The results in Table 3 show that the modified rhamnolipid of this disclosure has a higher oil washing efficiency, which can reach more than 82%, and is 3% higher than that of unmodified rhamnolipid. This indicates that the performance of sulfonated rhamnolipid in terms of oil washing efficiency is significantly improved.
[0083] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.
[0084] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.
[0085] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.
Claims
1. A modified rhamnolipid, characterized in that, The modified rhamnolipid has the structure shown in formula (1) and / or formula (2): In formula (1) and / or formula (2), X1 to X6 may be the same or different, and each independently represents H, SO3H or SO3Na, and at least one is SO3H or SO3Na; R1 and R2 may be the same or different, and each is independently selected from alkyl groups having 5 to 10 carbon atoms, where m represents... The number of elements, where m is 0 or 1.
2. The modified rhamnolipid according to claim 1, characterized in that, R1 and R2 may be the same or different, and each is independently selected from one or more of n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; preferably, R1 and R2 are the same and are both selected from n-pentyl, n-hexyl, n-heptyl, or n-octyl; more preferably, R1 and R2 are both selected from n-heptyl.
3. The modified rhamnolipid according to claim 1, characterized in that, The modified rhamnolipid is selected from one or more compounds having the structures shown in formulas (I) to (IX):
4. A method for preparing modified rhamnolipids, characterized in that, The method includes: contacting rhamnolipid with a sulfonating agent in an organic solvent to carry out a sulfonation reaction; The rhamnolipid has the structure shown in formula (3) and / or formula (4): In formula (3) and / or formula (4), R1 and R2 may be the same or different, and each is independently selected from alkyl groups having 5 to 10 carbon atoms, where m represents The number of elements, where m is 0 or 1.
5. The method according to claim 4, characterized in that, The contact conditions include: first dissolving the rhamnolipin in the organic solvent to obtain a rhamnolipin solution; then mixing the rhamnolipin solution with a sulfonating agent; The concentration of the rhamnolipid solution is 50-100 g / L, preferably 50-80 g / L; the organic solvent is selected from one or more of dichloromethane, methanol, chloroform, ethyl acetate, ethanol and dimethylacetamide, preferably dichloromethane.
6. The method according to claim 4, characterized in that, The weight ratio of the rhamnolipid to the sulfonating agent is 1:(0.1-1.0), preferably 1:(0.2-0.6); the sulfonation reaction temperature is -20 to 20°C, preferably -10 to 10°C; the reaction time is 1 to 15 hours, preferably 4 to 6 hours. The sulfonating agent is selected from one or more of chlorosulfonic acid, aminosulfonic acid and sulfur trioxide, preferably chlorosulfonic acid.
7. The method according to claim 4, characterized in that, The method further includes neutralizing the sulfonation reaction product with an alkali, wherein the weight ratio of the alkali to the rhamnolipid is (0.01-0.1):1, preferably (0.05-0.08):1; The alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate, preferably sodium hydroxide.
8. Modified rhamnolipid prepared by the method according to any one of claims 4 to 7.
9. The application of the modified rhamnolipid according to any one of claims 1 to 3 and claim 8 in oilfield oil solids cleaning, pesticides and daily chemical products.
10. The application according to claim 9, characterized in that, The application of the modified rhamnolipin in the cleaning of oily solids in oil fields includes: contacting an aqueous solution containing the modified rhamnolipin with oily solids, wherein the contact temperature is 40-60°C and the contact time is 1-3 hours; The concentration of modified rhamnolipid in the aqueous solution is 500–3000 mg / L, preferably 500–1000 mg / L; the oil content of the oil-containing solid is 5–20% by weight; and the weight ratio of the oil-containing solid to the aqueous solution is 1:(2–6), preferably 1:(3–5). Preferably, the oily solid is selected from one or more of oily soil, oily sludge, oily stainless steel, and oily ceramics.