Bio-based surfactant, preparation method therefor and use thereof

Abstract

The present disclosure relates to compounds of the structure shown in Formula 1 and Formula 2, an oligomeric bio-based surfactant composition containing the compounds of Formula 1 and / or Formula 2, a preparation method therefor and a use thereof. In Formula 1 and Formula 2, X1-X2 are selected from -(CH2)n- or -(CH2)m1-U-(CH2)m2- having 4-10 carbon atoms, U representing a substituted or unsubstituted thienylene group, m1 and m2 representing the number of CH2 and each independently being 0 or 1, and n representing the number of CH2, n being selected from any integer from 0-12; Z1-Z5 are each independently selected from a disaccharide group, R1-R5 are each independently selected from a linear or branched, saturated or unsaturated fatty acid group having 12-22 carbon atoms or a salt thereof, preferably -CH(CH3)-Y-COOM, Y being selected from a saturated or unsaturated linear hydrocarbon group having 9-19 carbon atoms, and M representing H, a monovalent metal cation or a monovalent non-metal cation. Compared with unmodified sophorolipids, the compounds of the structures shown in Formula 1 and Formula 2 disclosed in the present invention have lower contact angles and higher wettability; in addition, the molecules have a branching spatial structure and intramolecular sugar ring steric hindrance, which can promote fusion between bubbles and exhibit low-foam characteristics. As green, efficient, low-foam bio-based cleaning agents, they have good industrial application prospects.

Description

A bio-based surfactant and its preparation method and application Technical Field

[0001] The present disclosure relates to surfactants, and in particular, to a bio-based surfactant, a composition comprising the bio-based surfactant, and a preparation method and application thereof. Background Art

[0002] Surfactants are a class of amphiphilic compounds containing both a hydrophilic head group and a hydrophobic tail. They possess unique functions such as foaming, wetting, solubilization, and emulsification. Traditional surfactant preparation processes rely on raw materials derived from petroleum refining products, resulting in poor biodegradability and a difficult-to-treat environmental pollutant. In recent years, bio-based surfactants such as sophorolipids and rhamnolipids, derived from biofermentation, have been considered as alternatives to traditional petroleum-based synthetic surfactants due to their environmental friendliness, non-toxicity, biodegradability, and high efficacy. They are also gaining application in industrial cleaning, household chemicals, oil recovery, environmental protection (especially soil washing), and pharmaceuticals. While the cost of bio-fermentation products is currently manageable, their price remains high, ranging from two to five times that of petroleum-based synthetic surfactants. Improving the efficiency of bio-based surfactants and reducing the amount of chemicals used are crucial for their industrial application.

[0003] The Stevens group reported a series of new dimeric sophorolipids (ACS Sustainable Chemistry & Engineering, 2018, 6, 7, 8992-9005.) and evaluated the antibacterial and transfection properties of this type of new dimeric sophorolipids. The synthesis steps of dimeric sophorolipids reported in the literature require at least 4 to 6 steps, including ester exchange ring opening of sophorolipids, esterification protection of sugar ring hydroxyl groups, conversion of tail chain ester groups to aldehyde groups, condensation of aldehyde groups with alkylamines to form Schiff bases, and subsequent reduction, deprotection of sugar ring hydroxyl groups of the reduced products, and quaternization reaction of tertiary amine linking groups. Obviously, this method has many reaction steps, resulting in a low overall yield, and industrial amplification is difficult to achieve. At the same time, the application performance of dimeric sophorolipid products in water, such as foaming and cleaning, has not been evaluated, and the advantages of low consumption and high efficiency of dimer products have not been presented, so its potential applications still need to be further explored.

[0004] In addition, in the field of industrial cleaning or soil washing, the large amount of foam generated by surfactants is difficult to handle, which will greatly increase the difficulty of post-processing of the cleaning or leaching process. Therefore, low-foaming surfactants are preferred as cleaning agents or leaching agents. However, to date, there is a lack of comprehensive evaluation of the foaming and cleaning capabilities of biosurfactants (sophorolipids, rhamnolipids, lipopeptides) or their modified products, making it impossible to optimize the relevant products.

[0005] Summary of the Invention

[0006] The purpose of the present disclosure is to provide a bio-based surfactant and its preparation method and application. The bio-based surfactant should be able to be easily prepared with the help of biological source compounds, have high surface activity, and be easily biodegradable.

[0007] In order to achieve the above objectives, the present disclosure provides a compound represented by Formula 1 or Formula 2 in a first aspect:

[0008] X1~X2 are selected from -(CH2) n - or -(CH2) with 4 to 10 carbon atoms m1 -U-(CH2) m2 -, wherein U represents a substituted or unsubstituted thienylene group, m1 and m2 represent the number of CH2, and are each independently 0 or 1;

[0009] Wherein n represents the number of CH2, and n is selected from any integer between 0 and 12;

[0010] Z1 to Z5 are each independently selected from a disaccharide group, R1 to R5 are each independently selected from a linear or branched, saturated or unsaturated fatty acid group having 12 to 22 carbon atoms or a salt thereof, preferably -CH(CH3)-Y-COOM, wherein Y is selected from a saturated or unsaturated linear hydrocarbon group having 9 to 19 carbon atoms, preferably a linear alkyl group or a mono- or poly-unsaturated alkenyl group, and M represents H, a monovalent metal cation or a monovalent non-metallic cation, preferably Na + , K + 、Li + NH4 + .

[0011] Optionally, Z1 to Z4 are each independently selected from the following groups: in Indicates the chemical bond connecting Z1~Z4 and R1~R4; —* indicates that Z1~Z4 and or Chemical bonds connecting.

[0012] Optionally, Z5 is selected from in Indicates the chemical bond connecting Z5 and R5; —* indicates that Z5 and Chemical bonds connecting.

[0013] Optionally, the compound represented by Formula 1 or Formula 2 has a structure represented by the following formulas (I) to (VI):

[0014] wherein X1 and X2 have the meanings as described above.

[0015] Optionally, X1 to X2 are selected from -(CH2) n -, n is selected from any integer in the range of 0 to 10, preferably, n is selected from any integer in the range of 0 to 3; X1 to X2 are selected from -(CH2) having 4 to 10 carbon atoms m1 - U-(CH2) m2 -, -(CH2) m1 -U-(CH2) m2 - is selected from a substituted or unsubstituted group W, wherein the unsubstituted group W is selected from the group consisting of: in represents a chemical bond; the substituted group W has one or more substituents, each of which is independently selected from deuterium, fluorine, cyano, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl; preferably, X1 to X2 are selected from The Y is selected from -(CH2)9-, -(CH2)6CH=CH(CH2)7- or -(CH2)3CH=CHCH2CH=CH(CH2)7-.

[0016] Optionally, the compound described in Formula 1 or Formula 2 has a foaming height of less than 10 mL; a foaming stabilization time of less than 60 s; and a contact angle of less than 20°.

[0017] A second aspect of the present disclosure provides a method for preparing a bio-based surfactant composition, the method comprising:

[0018] S1. Prepare a solution of sophorolipid in water, and adjust the pH of the sophorolipid aqueous solution to 1.0-5.0 with acid to obtain a first solution;

[0019] S2, adding an aldehyde cross-linking agent to the first solution and reacting to obtain a second solution;

[0020] S3, adjusting the pH of the second solution to 6 to 8.5 with a base to obtain a bio-based surfactant composition;

[0021] The sophorolipids include acid-type sophorolipids and / or lactone-type sophorolipids, and the acid-type sophorolipids have a structure as shown in Formula 3 below:

[0022] The lactone-type sophorolipid has a structure as shown in Formula 4 below:

[0023] wherein RZ- is selected from R1-Z1-, R2-Z2-, R3-Z3-, R4-Z4- or R5-Z5-, Z' and Z1 to Z5 are each independently selected from a disaccharide group; R1 to R5 are each independently selected from a linear or branched, saturated or unsaturated fatty acid group having 12 to 22 carbon atoms, preferably -CH(CH3)-Y-COOH, wherein Y is selected from a saturated or unsaturated linear hydrocarbon group having 9 to 19 carbon atoms, preferably a linear alkyl group or a mono- or polyunsaturated alkenyl group;

[0024] The aldehyde crosslinking agent is selected from CHO-X1-CHO or CHO-X2-CHO, wherein X1 to X2 are selected from -(CH2) n - or -(CH2) with 4 to 10 carbon atoms m1 -U-(CH2) m2 -, wherein U represents a substituted or unsubstituted thienylene group, m1 and m2 represent the number of CH2 and are each independently 0 or 1; n represents the number of CH2 and n is selected from any integer between 0 and 12.

[0025] Optionally, in step S1, the acid-type sophorolipid is selected from one or more of the structures shown in the following formulas 5-7:

[0026] The lactone-type sophorolipid is selected from one or more of the structures shown in the following formulas 8-10:

[0027] Preferably, the content of sophorolipid in the sophorolipid aqueous solution is 5 to 30 weight % based on the total weight of the sophorolipid aqueous solution.

[0028] Preferably, the water used to prepare the sophorolipid aqueous solution is selected from one or more of deionized water, distilled water and ultrapure water.

[0029] The acid is selected from one or more of hydrochloric acid, sulfuric acid and phosphoric acid.

[0030] Step S1 is carried out under stirring at a temperature of 10 to 40° C. for 20 to 120 minutes.

[0031] In step S2, preferably, the molar ratio of the aldehyde cross-linking agent to the sophorolipid in the first solution is 1: (2 to 4), preferably 1: (2 to 3); the aldehyde cross-linking agent is selected from glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, adipaldehyde or heptaldehyde, preferably glyoxal, succinaldehyde or glutaraldehyde; thiophene-2,3-dicarboxaldehyde, thiophene-2,3-diacetaldehyde, thiophene-2,4-dicarboxaldehyde, thiophene-2,4-diacetaldehyde, thiophene-2,5-dicarboxaldehyde or thiophene-2,5-diacetaldehyde, preferably thiophene-2,3-dicarboxaldehyde;

[0032] In step S2, preferably, the temperature is 10-40°C and the time is 3-6 hours.

[0033] In step S3, preferably, the base is selected from one or more of sodium hydroxide, potassium hydroxide, aqueous ammonia, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate.

[0034] Preferably, step S3 is carried out with stirring at a temperature of 10 to 40° C. for a time of 5 to 120 minutes.

[0035] Optionally, the method includes step S4: separating and purifying the compound represented by Formula 1 and / or Formula 2 from the biosurfactant composition. Methods for separating or purifying specific compounds are well known to those skilled in the art. Methods for separation and purification include, but are not limited to, distillation, extraction, crystallization, recrystallization, and combinations thereof. The purified compound represented by Formula 1 and / or Formula 2 can be beneficial to conventional application areas of surfactants. Based on the advantageous surface active properties, renewability, and biodegradability of the compound represented by Formula 1 and / or Formula 2 of the present invention, it can be advantageously used in a wide range of fields, including but not limited to cleaning of oil-containing solids in oil fields, cleaning of oily contaminants, pesticides, pharmaceuticals, or daily chemicals.

[0036] A third aspect of the present disclosure provides a bio-based surfactant composition prepared by the method described in the second aspect of the present disclosure.

[0037] Alternatively, the third aspect of the present disclosure provides a bio-based surfactant composition comprising an effective amount of the compound of Formula 1 and / or Formula 2 provided by the first aspect of the present disclosure for exerting a surface active function.

[0038] Optionally, the bio-based surfactant composition has a foaming height of less than 10 mL; a foam stabilization time of less than 60 s; and a contact angle of less than 20°.

[0039] The fourth aspect of the present disclosure provides an application of the compound of the first aspect of the present disclosure and the bio-based surfactant composition of the third aspect in oilfield oil-containing solid cleaning, oil pollution cleaning, pesticides, medicines and daily chemicals.

[0040] According to one embodiment of the present invention, the bio-based surfactant composition prepared according to the method described in the second aspect of the present disclosure is directly used for cleaning oil-containing solids and oil pollution in oil fields without further treatment.

[0041] Optionally, the use of the bio-based surfactant composition in cleaning oil-containing solids in oil fields comprises: mixing an aqueous solution obtained by diluting the bio-based surfactant composition with oil-containing solids, the mixing temperature being 50-80°C for 2-8 hours; wherein the concentration of the bio-based surfactant composition in the aqueous solution is 10-30,000 mg / L, and the weight ratio of the oil-containing solids to the aqueous solution is 1:(3-10), preferably 1:(5-10). Alternatively, the sum of the concentrations of the compounds represented by Formula 1 and Formula 2 in the aqueous solution is 1-3,000 mg / L, and the weight ratio of the oil-containing solids to the aqueous solution is 1:(3-10), preferably 1:(5-10).

[0042] The bio-based surfactant provided by the present disclosure has a branched spatial structure and has a stronger ability to strip the oil phase. When used to clean oily soil, it has a good cleaning effect with a cleaning efficiency of more than 85%, and almost no foaming, reducing the difficulty of subsequent leaching.

[0043] Through the above technical solution, the present disclosure provides a bio-based surfactant and its preparation method and application, wherein the oligomeric bio-based surfactant is a biosurfactant in which the hydroxyl group of a biosurfactant is chemically linked to the aldehyde group of an aldehyde cross-linking agent to form a modified biosurfactant dimer or trimer. Compared with unmodified biosurfactants, the oligomeric bio-based surfactant disclosed herein has a lower contact angle and higher wettability, and has a branched spatial structure and intramolecular sugar ring steric hindrance, which can reduce the generation of foam and promote the fusion between foams. The preparation method disclosed herein can use low-cost industrial biosurfactants as raw materials, has mild reaction conditions, is simple and easy to operate, has high conversion rate and yield, does not produce three wastes, and can produce oligomeric bio-based surfactants with lower critical micelle concentration and better surface activity. When the bio-based surfactant is used to clean heavy oil-contaminated soil, the contact angle is less than 18°, and the heavy oil-covered surface can be turned into a strong water-wet surface, has excellent oil phase stripping ability, and is almost non-foaming, reducing the difficulty of subsequent elution. Compared with unmodified sophorolipids, the oligomeric bio-based surfactant disclosed herein has a cleaning efficiency of more than 85% for heavy oil-contaminated soil, and the critical micelle concentration is reduced by 1 to 2 orders of magnitude, is more resistant to dilution, and has a lower dosage. Compared with surfactants of chemical origin, the bio-based surfactant of the present invention does not consume fossil raw materials and is renewable. In addition, the bio-based surface active agent of the present invention has good biological metabolism and does not pollute the environment.

[0044] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The accompanying drawings are provided to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following detailed description, they are used to explain the present disclosure but are not intended to limit the present disclosure. In the accompanying drawings: FIG1 is a mass spectrometry diagram of the oligomeric bio-based surfactant prepared in Example 1 of the present disclosure. DETAILED DESCRIPTION

[0046] The following describes the specific embodiments of the present disclosure in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0047] In a first aspect, the present disclosure provides a compound represented by Formula 1 or Formula 2:

[0048] X1~X2 are selected from -(CH2) n - or -(CH2) with 4 to 10 carbon atoms m1 -U-(CH2) m2 -, wherein U represents a substituted or unsubstituted thienylene group, m1 and m2 represent the number of CH2, and are each independently 0 or 1;

[0049] Wherein n represents the number of CH2, and n is selected from any integer between 0 and 12;

[0050] Z1 to Z5 are each independently selected from a disaccharide group, R1 to R5 are each independently selected from a linear or branched, saturated or unsaturated fatty acid group having 12 to 22 carbon atoms or a salt thereof, preferably -CH(CH3)-Y-COOM, wherein Y is selected from a saturated or unsaturated linear hydrocarbon group having 9 to 19 carbon atoms, preferably a linear alkyl group or a mono- or poly-unsaturated alkenyl group, and M represents H, a monovalent metal cation or a monovalent non-metallic cation, preferably Na + , K + 、Li + , Rb + NH4 + The polyunsaturated olefin group herein refers to more than one unsaturated olefinic bond, preferably 2 to 5, such as 2, 3, 4 or 5. Preferably, the cation is derived from the cation contained in the acid or base used in the preparation of the compound.

[0051] A disaccharide group is a disaccharide group that is linked to other groups via two attachment sites. Disaccharides are formed by the condensation reaction of two monosaccharide molecules with the removal of one water molecule. Disaccharides include sucrose, lactose, maltose, trehalose, cellobiose, chitobiose, kojibiose, nigerose, isomaltose, isotrehalose, neotrehalose, sophorose, laminaribiose, gentiobiose, trehalulose, turanose, maltulose, leucrose, isomaltulose, gentiodiulose, mannobiose, melibiose, allolactose, plantagobiose, lactulose, neohesperidose, rutinose, rutinulose, xylobiose, elderose, and sabose, with sophorose being preferred.

[0052] The bio-based surfactant provided by the present disclosure is to connect the hydroxyl group of the sophorolipid with the aldehyde group of the aldehyde cross-linking agent through a chemical bond to form a modified sophorolipid dimer or trimer. Compared to unmodified sophorolipids, the oligomeric bio-based surfactants disclosed in the present disclosure have a lower contact angle and higher wettability, and have a branched spatial structure and intramolecular sugar ring steric hindrance, which can reduce the generation of foam and promote the fusion between foams. Wherein the sophorolipid is generally composed of a hydrophilic sophorose (two glucose molecules are bound by a β-1,2 glycosidic bond) and a hydrophobic saturated or unsaturated long-chain ω- (or ω-1) hydroxy fatty acid.

[0053] Depending on the different fatty acid chains to which the sophorolipids are connected, the types of R1 to R5 are not limited. In one embodiment, R1 to R5 represent a straight or branched, saturated or unsaturated fatty acid group or a salt form thereof having 12 to 22 carbon atoms. Preferably, the number of carbon atoms is 16 to 20. The fatty acid group is preferably a straight chain. In the case of a branched fatty acid group, the number of branches of the fatty acid group is 1, 2 or 3, preferably at most 1. In one embodiment, Y in R1 to R5 is selected from -(CH2)9-, -(CH2)6CH=CH(CH2)7- or -(CH2)3CH=CHCH2CH=CH(CH2)7-.

[0054] In one embodiment of the present disclosure, Z1 to Z4 are each independently selected from the following groups:

[0055] in Indicates the chemical bond connecting Z1~Z4 and R1~R4; —* indicates that Z1~Z4 and or In the above embodiment, " The meaning of "chemical bond connecting Z1 to Z4 and R1 to R4" includes Represents the chemical bond connecting Z1 and R1, Represents the chemical bond connecting Z2 and R2, represents the chemical bond connecting Z35 and R3, Represents the chemical bond connecting Z4 and R4.

[0056] “—* indicates Z1~Z4 and or The meaning of "chemical bond connected by" includes - * indicates that Z1 and The chemical bond connecting Z2 and The chemical bond connecting Z3 and The chemical bond connecting Z4 and Chemical bonds connecting.

[0057] In one embodiment of the present disclosure, Z5 is selected from in Indicates the chemical bond connecting Z5 and R5; —* indicates that Z5 and Chemical bonds connecting.

[0058] In one embodiment of the present disclosure, the compound represented by Formula 1 or Formula 2 has the structure represented by the following formulas (I) to (VI):

[0059] In the above embodiment, the compound has a branched spatial structure and intramolecular sugar ring steric hindrance, which can reduce the generation of bubbles and promote the fusion between bubbles.

[0060] In a preferred embodiment of the present disclosure, X1 to X2 are selected from -(CH2) n -, n is selected from any integer from 0 to 10, for example, n can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. When n is 0, X1 or X2 is an empty structure (direct bond), and the two carbon atoms on -CHOH- are directly connected; preferably, n is selected from any integer from 0 to 3, for example, n can be 0, 1, 2 or 3.

[0061] In another embodiment of the present disclosure, X1 to X2 are selected from substituted or unsubstituted -(CH2) having 4 to 10 carbon atoms. m1 -U-(CH2) m2 -, substituted or unsubstituted -(CH2) m1 -U-(CH2) m2 - is selected from a substituted or unsubstituted group W, wherein the unsubstituted group W is selected from the group consisting of: in Represents a chemical bond; the substituted group W has one or more substituents, each of which is independently selected from deuterium, fluorine, cyano, methyl, ethyl, n-propyl, isopropyl or tert-butyl; preferably, X1 to X2 are selected from It is easy to understand that in the case of substituted -(CH2) m1 -U-(CH2) m2 In the case of 2,3-dithienyl, the substituents may be located at the 4-position and / or the 5-position.

[0062] In the context of the present invention, compounds of formula 1 and / or formula 2 are also referred to as bio-based surfactants or oligomeric bio-based surfactants.

[0063] In the context of the present invention, foam height refers to the maximum foam height reached by the foam in a foaming test.

[0064] In the context of the present invention, the foam stability time refers to the time that the foam remains stable. Specifically, it refers to the time it takes for the foam to decrease from the maximum foam height (also called the initial foam height) to a foam height less than half of the initial height. The foam stability time is also called the foam half-life.

[0065] In one embodiment of the present disclosure, the foaming height of the compound is lower than 10mL, for example, the foaming height can be 10mL, 9mL, 8mL, 7mL, 6mL, 5mL, 4mL, 3mL, 2mL, 1mL, or a value between any two thereof; the foaming time is lower than 60s, for example, the foaming time can be 60s, 50s, 40s, 30s, 20s, 10s, or a value between any two thereof; the contact angle is lower than 20°, for example, the contact angle can be 20°, 18°, 15°, 12°, 10°, 8°, 6°, 4°, 2°, or a value between any two thereof. In the above embodiment, the foaming height of the above compound is low, the foaming ability is poor, and the contact angle is small, the wetting reversal ability is strong, and the oily interface can be flipped into a strong water-wet interface, which can be used as a green and efficient low-foaming oil detergent.

[0066] The compounds of the first aspect of the present invention are suitable as surfactants, preferably high-efficiency surfactants. Compared with conventional fossil-derived surfactants, the raw material sophorolipids of the compounds of the present invention are of biological origin and have obvious advantages in terms of renewability and carbon emissions. In addition, compared with chemically synthesized surfactants, surfactants of biological origin have advantages in terms of biodegradability.

[0067] A second aspect of the present disclosure provides a method for preparing a bio-based surfactant composition, the method comprising:

[0068] S1. Prepare a solution of sophorolipid in water, and adjust the pH of the sophorolipid aqueous solution to 1.0-5.0 with acid to obtain a first solution;

[0069] S2, adding an aldehyde cross-linking agent to the first solution and reacting to obtain a second solution;

[0070] S3, adjusting the pH of the second solution to 6 to 8.5 with a base to obtain a bio-based surfactant composition;

[0071] The sophorolipids include acid-type sophorolipids and / or lactone-type sophorolipids, and the acid-type sophorolipids have a structure as shown in Formula 3 below:

[0072] The lactone-type sophorolipid has a structure as shown in Formula 4 below:

[0073] wherein RZ- is selected from R1-Z1-, R2-Z2-, R3-Z3-, R4-Z4- or R5-Z5-, Z' and Z1 to Z5 are each independently selected from a disaccharide group; R1 to R5 are each independently selected from a linear or branched, saturated or unsaturated fatty acid group having 12 to 22 carbon atoms, preferably -CH(CH3)-Y-COOH, wherein Y is selected from a saturated or unsaturated linear hydrocarbon group having 9 to 19 carbon atoms, preferably a linear alkyl group or a mono- or polyunsaturated alkenyl group;

[0074] The aldehyde crosslinking agent is selected from CHO-X1-CHO or CHO-X2-CHO, wherein X1 to X2 are selected from -(CH2) n - or -(CH2) with 4 to 10 carbon atoms m1 -U-(CH2) m2 -, wherein U represents a substituted or unsubstituted thienylene group, m1 and m2 represent the number of CH2 and are each independently 0 or 1; n represents the number of CH2 and n is selected from any integer between 0 and 12.

[0075] Preferably, at least 80%, preferably at least 90%, more preferably at least 95% of the primary hydroxyl groups on the glucose groups of the sophorolipid are free. In other words, the primary hydroxyl groups on the glucose groups are esterified with acetic acid only to a low degree.

[0076] The preparation method disclosed herein has mild conditions, is simple and easy to implement, does not generate three wastes, and can produce oligomeric bio-based surfactants with lower critical micelle concentration and better surface activity.

[0077] In one embodiment of the present disclosure, in step S1, the acid-type sophorolipid is selected from one or more of the structures shown in the following formulas 5-7:

[0078] The lactone-type sophorolipid is selected from one or more of the structures shown in the following formulas 8-10:

[0079] Without being bound by a particular theory, it is believed that the method of the present invention achieves ring opening of the intramolecular ring of the sophorolipid, forming a chain structure with a linear distribution of hydrophilic and lipophilic groups. In addition, the aldehyde crosslinking agent connects two or three molecules together, shortening the molecular distance and promoting a close molecular arrangement. Both aspects enhance the surface activity of the bio-based surfactant of the present invention.

[0080] In one embodiment, the content of sophorolipid in the sophorolipid aqueous solution is 5 to 30 weight % based on the total weight of the sophorolipid aqueous solution.

[0081] In one embodiment, the water used to prepare the aqueous solution of sophorolipids is selected from one or more of deionized water, distilled water and ultrapure water. In one embodiment, the acid is selected from one or more of hydrochloric acid, sulfuric acid and phosphoric acid. Step S1 is carried out under stirring at a temperature of 10 to 40°C and a time of 20 to 120 minutes. In the above embodiment, the preferred sophorolipids are selected to produce oligomeric bio-based surfactants with better wetting, emulsifying and solubilizing properties. The sophorolipids can be commercially available chemical reagents or prepared according to methods known in the art. Preferably, the sophorolipids are sophorolipids prepared by biological fermentation, preferably industrial sophorolipids. According to a preferred aspect, the sophorolipids prepared by biological fermentation are used in the method of the second aspect of the present invention as purchased, without the need for prior purification. Due to the cost advantage of industrial sophorolipids, this further reduces the production cost of the bio-based surfactant of the present invention.

[0082] In one embodiment of the present disclosure, in step (2), the molar ratio of the aldehyde cross-linking agent to the sophorolipid in the first solution is 1: (2 to 4), preferably 1: (2 to 3). The aldehyde cross-linking agent is selected from glyoxal, malondialdehyde, succinyldialdehyde, glutaraldehyde, adipaldehyde or heptanedialdehyde, preferably glyoxal, succinyldialdehyde or glutaraldehyde. Thiophene-2,3-dicarboxaldehyde (CAS No. 932-41-2), thiophene-2,3-diacetaldehyde, thiophene-2,4-dicarboxaldehyde (CAS No. 932-93-4), thiophene-2,4-diacetaldehyde, thiophene-2,5-dicarboxaldehyde (CAS No. 932-95-6) or thiophene-2,5-dicarboxaldehyde, preferably thiophene-2,3-dicarboxaldehyde. The base can be selected from one or more of sodium hydroxide, potassium hydroxide, ammonia water, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate. In step S2, preferably, the temperature is 10-40°C and the time is 3-6 hours.

[0083] In step S3, preferably, the base is selected from one or more of sodium hydroxide, potassium hydroxide, aqueous ammonia, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate.

[0084] Preferably, step S3 is carried out with stirring at a temperature of 10 to 40° C. for a time of 5 to 120 minutes.

[0085] In the above embodiment, the aldehyde-based cross-linking agent may be a pure product or an aqueous solution with any mass fraction, for example, an aqueous solution with a mass fraction of 25% to 50%.

[0086] A third aspect of the present disclosure provides a bio-based surfactant composition prepared by the method described in the second aspect of the present disclosure.

[0087] Alternatively, the third aspect of the present disclosure provides a bio-based surfactant composition comprising an effective amount of the compound of Formula 1 and / or Formula 2 provided by the first aspect of the present disclosure for exerting a surface active function.

[0088] The bio-based surfactant composition prepared using the disclosed method exhibits low foaming height, poor foam stabilization, and a small contact angle, making it suitable as a green and efficient low-foaming oil cleaning agent. Specifically, the bio-based surfactant composition exhibits a foaming height of less than 10 mL, a foam stabilization time of less than 60 seconds, and a contact angle of less than 20°.

[0089] In the context of the present invention, the contact angle refers to the angle between the surface of the liquid and the contour of the contact surface when a liquid and a solid are in contact with an interface therebetween.

[0090] A fourth aspect of the present disclosure provides the use of the compound of the first aspect of the present disclosure and the bio-based surfactant composition of the third aspect for cleaning oilfield oil-containing solids, cleaning oily contaminants, and for the production of pesticides, pharmaceuticals, and daily chemicals. Specifically, the use of the bio-based surfactant composition for cleaning oilfield oil-containing solids includes using the oligomeric bio-based surfactant as a cleaning agent, oil washing agent, or rinsing agent for oilfield oil-containing solids to clean soil contaminated with heavy oil.

[0091] In one embodiment, the use of the oligomeric bio-based surfactant in the cleaning of oil-containing solids in oil fields includes: mixing an aqueous solution obtained by diluting the bio-based surfactant composition with water with the oil-containing solids, the mixing temperature being 50 to 80°C and the time being 2 to 8 hours; wherein the concentration of the bio-based surfactant composition in the aqueous solution is 10 to 30,000 mg / L, and the weight ratio of the oil-containing solids to the aqueous solution is 1:(3 to 10), preferably 1:(5 to 10). The concentration of the bio-based surfactant composition in the aqueous solution is, for example, 10 mg / L, 50 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, 250 mg / L, 300 mg / L, 400 mg / L, 500 mg / L, 600 mg / L, 700 mg / L, 800 mg / L, 900 mg / L, 1000 mg / L, 5000 mg / L, 10000 mg / L, 15000 mg / L, 20000 mg / L, 25000 mg / L, 30000 mg / L, or a range consisting of any two thereof. Alternatively, the sum of the concentrations of the compounds represented by Formula 1 and Formula 2 in the aqueous solution is 1 to 3000 mg / L, and the weight ratio of the oil-containing solid to the aqueous solution is 1:(3 to 10), preferably 1:(5 to 10). The sum of the concentrations of the compounds represented by Formula 1 and Formula 2 in the aqueous solution is, for example, 1 mg / L, 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, 90 mg / L, 100 mg / L, 500 mg / L, 1000 mg / L, 1500 mg / L, 2000 mg / L, 2500 mg / L, 3000 mg / L, or a range consisting of any two thereof. The oil-containing solid includes oil-containing soil, oil-containing sludge, oil-stained stainless steel, or oil-stained ceramic.

[0092] Example

[0093] The present disclosure is further illustrated by the following examples, but the present disclosure is not limited thereto. Unless otherwise specified, the raw materials used in the examples and comparative examples of the present disclosure were purchased from commercial channels and were pure reagents.

[0094] The mass spectrometer used in the Examples and Comparative Examples was a Bruker ultrafleXtreme. The mass spectrometry detection conditions were as follows: the ionization source was MALDI-TOF positive ion mode; the sheath gas flow rate was 45 arb, the auxiliary gas flow rate was 10 arb, the capillary voltage was 3300 V, and the capillary temperature was 350°C.

[0095] Example 1

[0096] Step S1: Weigh 10 mmols lactone-type sophorolipid (purchased from Shandong Qilu Biotechnology Co., Ltd., with a mass content of 50%) into a round-bottom flask, add 50 g of distilled water, and stir magnetically at room temperature (25 ± 2 ° C) to obtain a sophorolipid aqueous solution, wherein the sophorolipid content is 20% by weight; then slowly add hydrochloric acid while adding and performing a first stirring, adjust the pH value of the system to 3.0, and continue magnetic stirring at room temperature (25 ± 2 ° C) for 30 minutes to obtain a first solution;

[0097] Step S2: Slowly add 0.8 g of a 50 wt% aqueous solution of glutaraldehyde (aldehyde crosslinker, 4 mmols, purchased from Inokai) to the first solution, wherein the molar ratio of glutaraldehyde to the sophorolipid in the first solution is 1:2.5; continue stirring the reaction at room temperature (25 ± 2 ° C) for 4 h, stop the reaction, and obtain a second solution.

[0098] Step S3: Slowly add 10 wt% sodium hydroxide aqueous solution to the second solution while performing a second stirring, and adjust the pH of the system to 7.0 to obtain an oligomeric bio-based surfactant composition, denoted as OSL-C1. OSL-C1 comprises a mixture having the structures shown in Formulas (I) to (VI):

[0099] X1-X2 are -(CH2)3-, R1-R5 are -CH(CH3)-Y-COOM, and Y is -(CH2)6CH=CH(CH2)7-, with a mass fraction of 10.4% and a reaction conversion rate of ≥99.5%, based on glutaraldehyde.

[0100] The oligomeric bio-based surfactant product was separated and purified by silica gel column, and the purified product was acidified by ion exchange resin and then analyzed by mass spectrometry: Theoretically, a single acid-type sophorolipid molecule (molecular formula C 30 H 54 O 13 , structural formula ) is 622.36. The reaction of sophorolipids with glutaraldehyde to form dimerization products does not leave any group or atom. Therefore, the relative molecular mass of dimerized sophorolipids = 2*Mr (acid-type sophorolipids) + Mr (glutaraldehyde) = 2*622.36+100.11 = 1344.83. In positive ion mode, since acid-type molecules are uncharged, they must be mixed with Na + Only after binding can the molecular ion peak information be obtained, so the theoretical molecular ion peak mass-to-charge ratio of the dimerized sophorolipid product is 1344.83+23=1367.83. As shown in Figure 1, the MALDI-TOF mass spectrum shows a mass peak with a mass-to-charge ratio of 1367.745, which is the same as the molecular ion peak after dimerized sophorolipid is added with one sodium ion ([M+Na] +) corresponds exactly. The trimeric sophorolipid product removes two equivalents of water during the reaction, and its theoretical relative molecular mass is 1931.13. The theoretical mass-to-charge ratio of the molecular ion peak after sodium addition is 1954.13, which corresponds to the peak with a mass-to-charge ratio of 1954.272 in Figure 1. Mass spectrometry results show that when the molar ratio of aldehyde to sophorolipid is 1:2.5, the active substance obtained is mainly dimeric sophorolipid, and the content of trimeric sophorolipid is relatively small.

[0101] Example 2

[0102] The method of Example 1 was adopted, except that in step S1, 10 mmols of sophorolipid was added to 20 g of distilled water, and the sophorolipid content in the obtained sophorolipid aqueous solution was 38% by weight; in step S2, 0.72 g of a 40 wt% aqueous solution of succinaldehyde (3.33 mmols) was slowly added to the first solution, wherein the molar ratio of succinaldehyde to the sophorolipid in the first solution was 1:3, and the reaction was stirred at room temperature for 5 hours. Finally, an oligomeric bio-based surfactant was obtained, which was designated as OSL-C2. OSL-C2 includes a mixture having a structure shown in formula (I) to (VI), wherein X1 to X2 are -(CH2)2-, R1 to R5 are -CH(CH3)-Y-COOM, and Y is -(CH2)6CH=CH(CH2)7-, with a mass fraction of 19.6% and a reaction conversion rate of ≥99%. The conversion rate is based on glutaraldehyde.

[0103] Example 3

[0104] The method of Example 1 was adopted, except that, in step (1), 10 mmols of sophorolipid was added to 10 g of distilled water, and the sophorolipid content in the obtained sophorolipid aqueous solution was 55 wt %; in step (2), 0.29 g of a 40 wt % aqueous solution of glyoxal (5 mmols) was slowly added to the first solution, wherein the molar ratio of glyoxal to the sophorolipid in the first solution was 1:2. Finally, an oligomeric bio-based surfactant was obtained, designated as OSL-C3. OSL-C3 includes a mixture having structures shown in formulas (I) to (VI), wherein X1 to X2 are -(CH2)0-, R1 to R5 are -CH(CH3)-Y-COOH, and Y is -(CH2)6CH=CH(CH2)7-, with a mass fraction of 27.8% and a reaction conversion rate of ≥98.5%. The conversion rate is based on glutaraldehyde.

[0105] Example 4

[0106] The method of Example 1 was adopted, except that, in step (2), 0.56 g of thiophene-2,3-dicarboxaldehyde (4 mmols) was slowly added to the first solution, wherein the molar ratio of thiophene-2,3-dicarboxaldehyde to the sophorolipid in the first solution was 1:2.5. Finally, an oligomeric bio-based surfactant was obtained, which was designated as OSL-C4. OSL-C4 includes a mixture having structures shown in formulas (I) to (VI), wherein X1 to X2 are R1 to R5 are -CH(CH3)-Y-COOH, Y is -(CH2)6CH=CH(CH2)7-, and the mass fraction thereof is 10.8%, and the reaction conversion rate is ≥98%. The conversion rate is based on glutaraldehyde.

[0107] Example 5:

[0108] The method of Example 1 was used, except that in step S1, 10 mmol of succinic acid-type sophorolipid was added as a reaction raw material to 20 g of distilled water for reaction, and the other reaction conditions and steps remained unchanged, and finally an oligomeric bio-based surfactant was obtained, which was recorded as OSL-C5. The molecular structure of OSL-C5 is the same as that of OSL-C1, and the reaction conversion rate is ≥99%. The conversion rate is based on glutaraldehyde.

[0109] Comparative Example 1

[0110] 100 mmols of lactone-type sophorolipid (purchased from Shandong Qilu Biotechnology Group Co., Ltd.) was dissolved in 500 mL of N, N-dimethylformamide and stirred continuously at 50 ° C until completely dissolved. Then, 0.2 mol of sulfur trioxide pyridine complex was added and reacted at 80 ° C for 4 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain sulfonated modified sophorolipid with the structural formula The yield was 99%.

[0111] Comparative Example 2:

[0112] The method of Example 1 is adopted, except that, in step S2, 0.4 g of a 50 wt% aqueous solution of glutaraldehyde (aldehyde crosslinker, 2 mmols, purchased from Inokai) is slowly added to the first solution so that the molar ratio of glutaraldehyde to the sophorolipid in the first solution is 1: 5, and the remaining reaction steps and reaction conditions remain unchanged, and an oligomeric bio-based surfactant is finally obtained, which is recorded as OSL-C6. The molecular structure of OSL-C6 is the same as that of OSL-C1, and the reaction conversion rate is ≥99.5%, based on glutaraldehyde. However, the lactone-type sophorolipid in the product is excessive, and the content of the acid-type sophorolipid obtained by hydrolysis of the unreacted lactone-type sophorolipid is high (mass fraction 20-25%).

[0113] Test Example 1

[0114] The foaming ability and foam stability of the oligomeric bio-based surfactants prepared in Examples 1 to 4, the sulfonated modified sophorolipids prepared in Comparative Example 1, and the unmodified sophorolipids were evaluated:

[0115] The foaming ability and foam stability were evaluated using a Roche foam tester in accordance with the method of GB / T7462-94. The test temperature was controlled at 25±1°C, the water used in the test was deionized water, and the concentration of the aqueous solution of the test sample was 1000 mg / L. The change in foam height over time was recorded every 10 seconds until the foam height was less than half of the initial height. The initial foam height was recorded as h, and the time it took for the foam height to drop to half of the initial height was recorded as t. 1 / 2 The higher the h value, the stronger the foaming ability. 1 / 2 The larger the value, the higher the foam stability. The measurement results are shown in Table 1:

[0116] Table 1

[0117] As can be seen from the data in Table 1, compared with the unmodified sophorolipids and sulfonated modified sophorolipids, the oligomeric bio-based surfactant modified by the method disclosed herein has a reduced foaming ability, the initial foam height is no more than 3 mL, and the foam completely collapses within 10 s. This is because the branched structure of the modified molecule is not conducive to the generation of foam and can promote the fusion between foams, so that the oligomeric bio-based surfactant exhibits almost no foaming characteristics.

[0118] As can be seen from the data in Table 1, compared to unmodified sophorolipids and sulfonated modified sophorolipids, the foaming ability of the oligomeric bio-based surfactant modified by the method disclosed herein is reduced, the initial foam height is not higher than 3 mL, and the foam completely bursts within 10 s. This is because the branched structure of the modified molecule is not conducive to the generation of foam, and can promote the fusion and polymerization between the generated foams, promote the thinning and rupture of the interfacial film structure of the foam, and ultimately cause the oligomeric bio-based surfactant to exhibit almost no foaming properties. In addition, the comparison of the results of OSL-1 and OSL-6 shows that if the product contains more unreacted sophorolipid raw materials, it will be detrimental to the low-foaming advantage of the product.

[0119] Test Example 2

[0120] The wetting ability of the oligomeric bio-based surfactants prepared in Examples 1 to 4, the sulfonated modified sophorolipids prepared in Comparative Example 1, and the unmodified sophorolipids were evaluated:

[0121] First, Shengli Y8X heavy oil was evenly coated on a clean glass slide at high temperature and allowed to cool naturally. The contact angle of a droplet of an aqueous solution of the test sample on the glass slide was measured using the sessile drop method using a KRUSSDSA100 contact angle meter. The concentrations of the aqueous solution of the test sample were 10 mg / L, 100 mg / L, and 1000 mg / L, respectively. The contact angle experiment was controlled at 25°C. The timing began when the droplet reached the oily interface. After equilibrating for 1 minute, the contact angle was photographed and fitted. The measurement results are shown in Table 2:

[0122] Table 2

[0123] The data results in Table 2 show that when the concentration is 1000 mg / L, the contact angle of the unmodified sophorolipid aqueous solution droplet on the heavy oil coated surface is higher than 50°. When the concentration is reduced to 100 mg / L, the contact angle increases to 58.8°, and when the concentration is reduced to 10 mg / L, the contact angle increases to 102.3°, and no longer has a wetting reversal effect. The contact angles of the sulfonated modified sophorolipids at the same concentration are 2 to 11° lower than those of the unmodified sophorolipids. In contrast, the contact angles of the oligomeric bio-based surfactants disclosed in the present invention are all lower than 18° within the above concentration range, which is more than 20° lower than that before modification or sulfonated modified sophorolipids, thereby being able to turn the heavy oil covered surface into a strong water-wet surface. Its wetting reversal effect is greatly improved compared to unmodified sophorolipids and sulfonated modified sophorolipids, and the dosage is lower. At the same time, the comparison of the results of OSL-1 and OSL-6 shows that the ratio of reactants has a greater influence on the wetting reversal performance of the product. When the amount of sophorolipid raw material is too excessive, the unreacted raw material will cause the wettability reversal performance of the product to decrease.

[0124] Test Example 3

[0125] The oil washing ability of the oligomeric bio-based surfactants prepared in Examples 1 to 4, the sulfonated modified sophorolipids prepared in Comparative Example 1, and the unmodified sophorolipids was evaluated:

[0126] Uncontaminated soil (from the Y8X block of Shengli Oilfield) was crushed and dried in a 150°C constant temperature oven for 6 hours. The dried soil was sieved with a 100-mesh sieve. The sieved soil and crude oil were placed in a constant temperature oven at 80°C for 8 hours. 85g of dried soil was added to 15g of heavy oil from the Y8X block of Shengli Oilfield (density of 0.903g / mL) and mixed evenly at 80°C. The soil mixed with crude oil was placed in a constant temperature oven at 50°C for aging for one week to prepare an oil-containing soil sample with an oil content of 15%. The oligomeric bio-based surfactants and unmodified sophora fermentation biosurfactants prepared in Examples 1 to 4 were prepared into a 1000mg / L oil washing system with tap water.

[0127] Weigh 10g of an oily soil sample with a 15% oil content, add 60mL of the oil-washing system to a conical flask, seal it, and place it in a Jinyi SHZ-88 water bath constant-temperature oscillator, heat it to 50°C, and shake it at a constant rate of 30 rpm for 3 hours. After cooling to room temperature, let it settle and separate. The solution and the washed crude oil are separated from the solid phase. The separated solid is dried at 100°C to a constant weight and its weight is measured (m). Finally, the cleaning efficiency of the oil-washing system is calculated using the following formula:

[0128] Cleaning efficiency = (10g – m) / (1.5g) × 100%. The calculation results are shown in Table 3:

[0129] Table 3

[0130] The results in Table 3 show that the oligomeric bio-based surfactant disclosed herein can have a good cleaning effect on the crude oil-contaminated soil in the Shengli Y8X block, and its cleaning efficiency can reach more than 85%, which is more than 15% higher than the cleaning efficiency of the unmodified sophorolipid and more than 12% higher than the sulfonated modified sophorolipid.

[0131] At the same time, the comparison of the results of OSL-1 and OSL-6 showed that the ratio of reactants should be reasonably controlled within the optimal range, otherwise it would have an adverse effect on the oil washing efficiency of the product.

[0132] Test Example 4

[0133] The biodegradability of a product is determined by the ratio of biological oxygen demand (BOD) to chemical oxygen demand (COD) (B / C ratio). The larger the B / C ratio, the more biodegradable the product. It is generally considered that a compound is readily biodegradable when the B / C ratio is ≥ 0.3. COD is determined using the standard method specified in HJ828-2017, and BOD testing is performed using the standard method specified in HJ505-2009.

[0134] The B / C ratio of the products is shown in Table 4.

[0135] Table 4

[0136] As can be seen from Table 4, the B / C ratios of the products of the examples and comparative examples are higher than that of the unmodified sophorolipids, and most of them are ≥0.30. This shows that the biodegradation of the products is not affected after structural modification by this method.

[0137] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.

[0138] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0139] In addition, the various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A compound represented by Formula 1 or Formula 2: X1 to X2 are each independently selected from -(CH2) n - or -(CH2) with 4 to 10 carbon atoms m1 -U-(CH2) m2 -, wherein U represents a substituted or unsubstituted thienylene group, m1 and m2 represent the number of CH2, and are each independently 0 or 1; Wherein n represents the number of CH2, and n is selected from any integer between 0 and 12; Z1-Z5 are each independently selected from disaccharide groups, R1-R5 are each independently selected from linear or branched, saturated or unsaturated fatty acid groups with 12 to 22 carbon atoms or their salt forms, preferably -CH(CH3)-Y-COOM, wherein Y is selected from saturated or unsaturated linear hydrocarbon groups with 9 to 19 carbon atoms, preferably linear alkyl groups or mono- or poly-unsaturated alkenyl groups, and M represents H, a monovalent metal cation or a monovalent non-metal cation, preferably Na + , K + , Li + NH4 + .

2. The compound according to claim 1, characterized in that Z1 to Z4 are each independently selected from the following groups: in Represents the chemical bond connecting Z1~Z4 and R1~R4; Indicates Z1~Z4 and or Chemical bonds connected.

3. The compound and salt thereof according to claim 1 or 2, characterized in that: Z5 is selected from in represents the chemical bond connecting Z5 and R5; Indicates Z5 and Chemical bonds connected.

4. The compound according to any one of claims 1 to 3, characterized in that The compound has the structure shown in the following formula (I) to (VI): wherein X1 and X2 each independently have the meaning defined in claim 1.

5. The compound according to any one of claims 1 to 4, characterized in that X1~X2 is selected from -(CH2) n -, n is selected from any integer in the range of 0 to 10, preferably, n is selected from any integer in the range of 0 to 3; X1 to X2 are selected from -(CH2) having 4 to 10 carbon atoms m1 -U-(CH2) m2 -, -(CH2) m1 -U-(CH2) m2 - is selected from substituted or unsubstituted groups W, wherein the unsubstituted group W is selected from the following Groups composed of: in represents a chemical bond; the substituted group W has one or more substituents, each of which is independently selected from deuterium, fluorine, cyano, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl; preferably, X1 to X2 are selected from The Y is selected from -(CH2)9-, -(CH2)6CH=CH(CH2)7- or -(CH2)3CH=CHCH2CH=CH(CH2)7-.

6. A bio-based surfactant composition comprising an effective amount of the compound of Formula 1 and / or Formula 2 according to any one of claims 1 to 5 for exerting a surface active function.

7. The bio-based surfactant composition according to claim 6, characterized in that The bio-based surfactant composition has a foaming height of less than 10 mL, a foam stabilization time of less than 60 s, and a contact angle of less than 20°.

8. The bio-based surfactant composition according to claim 6 or 7, characterized in that The bio-based surfactant composition has a ratio of biological oxygen demand to chemical oxygen demand greater than 0.

25.

9. A method for preparing a bio-based surfactant composition, characterized in that: The method comprises: S1, preparing a solution of sophorolipid in water, adjusting the pH of the sophorolipid aqueous solution to 1.0-5.0 with acid to obtain a first solution; S2, adding an aldehyde cross-linking agent to the first solution and reacting to obtain a second solution; S3, adjusting the pH of the second solution to 6-8.5 with a base to obtain a bio-based surfactant composition; The sophorolipids include acid-type sophorolipids and / or lactone-type sophorolipids, and the acid-type sophorolipids have a structure as shown in Formula 3 below: The lactone-type sophorolipid has a structure as shown in Formula 4: wherein RZ- is selected from R1-Z1-, R2-Z2-, R3-Z3-, R4-Z4- or R5-Z5-, Z' and Z1 to Z5 are each independently selected from disaccharide groups; R1 to R5 are each independently selected from linear or branched, saturated or unsaturated fatty acid groups having 12 to 22 carbon atoms, preferably -CH(CH3)-Y-COOH, wherein Y is selected from saturated or unsaturated linear hydrocarbon groups having 9 to 19 carbon atoms, preferably linear alkyl groups or mono- or poly-unsaturated alkenyl groups; The aldehyde crosslinking agent is selected from CHO-X1-CHO or CHO-X2-CHO, wherein X1 to X2 are selected from -(CH2) n - or -(CH2) with 4 to 10 carbon atoms m1 -U-(CH2) m2 -, wherein U represents a substituted or unsubstituted thienylene group, m1 and m2 represent the number of CH2 and are each independently 0 or 1; n represents the number of CH2 and n is selected from any integer between 0 and 12.

10. The method according to claim 9, characterized in that In step S1, the method has one or more of the following features: The acid-type sophorolipid is selected from one or more of the structures shown in the following formulas 5-7: The lactone-type sophorolipid is selected from one or more of the structures shown in the following formulas 8-10: The content of sophorolipid in the sophorolipid aqueous solution is 5 to 30 weight % based on the total weight of the sophorolipid aqueous solution; The water used to prepare the sophorolipid aqueous solution is selected from one or more of deionized water, distilled water and ultrapure water; The acid is selected from one or more of hydrochloric acid, sulfuric acid and phosphoric acid; and Step S1 is carried out under stirring at a temperature of 10 to 40° C. for a time of 20 to 120 minutes.

11. The method according to claim 9 or 10, characterized in that: In step S2, the method has one or more of the following features: The molar ratio of the aldehyde cross-linking agent to the sophorolipid in the first solution is 1:(2-4), preferably 1:(2-3); the aldehyde cross-linking agent is selected from glyoxal, malondialdehyde, succindialdehyde, glutaraldehyde, adipaldehyde or heptanedialdehyde, preferably glyoxal, succindialdehyde or glutaraldehyde; thiophene-2,3-dicarboxaldehyde, thiophene-2,3-diacetaldehyde, thiophene-2,4-dicarboxaldehyde, thiophene-2,4-diacetaldehyde, thiophene-2,5-dicarboxaldehyde or thiophene-2,5-diacetaldehyde, preferably thiophene-2,3-dicarboxaldehyde; The temperature of step S2 is 10-40° C. and the time is 3-6 hours.

12. The method according to claims 9-11, characterized in that: In step S3, the method has one or more of the following features: The alkali is selected from one or more of sodium hydroxide, potassium hydroxide, ammonia water, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate; Step S3 is carried out under stirring at a temperature of 10 to 40° C. for a time of 5 to 120 minutes.

13. The method according to claims 9-11, characterized in that: The method comprises step S4: The compounds represented by Formula 1 and / or Formula 2 are separated and purified from the biosurfactant composition.

14. A bio-based surfactant composition prepared by the method according to any one of claims 9 to 12.

15. The bio-based surfactant composition according to claim 14, characterized in that The bio-based surfactant composition has a foaming height of less than 10 mL, a foam stabilization time of less than 60 s, and a contact angle of less than 20°.

16. Use of the compound according to any one of claims 1 to 5 as a surfactant.

17. Use of the bio-based surfactant composition according to any one of claims 6 to 8, 14 and 15 in cleaning of oil-containing solids in oil fields, cleaning of oil pollution, pesticides, medicines or daily chemicals.

18. The use according to claim 17, characterized in that The use of the bio-based surfactant composition in cleaning oil-containing solids in oil fields comprises: mixing an aqueous solution obtained by diluting the bio-based surfactant composition with water with the oil-containing solids, wherein the mixing temperature is 50 to 80° C. and the mixing time is 2 to 8 hours; Wherein, the concentration of the bio-based surfactant composition in the aqueous solution is 10 to 30,000 mg / L, and the weight ratio of the oil-containing solid to the aqueous solution is 1:(3 to 10), preferably 1:(5 to 10); Alternatively, the sum of the concentrations of the compounds represented by Formula 1 and Formula 2 in the aqueous solution is 1 to 3000 mg / L, and the weight ratio of the oil-containing solid to the aqueous solution is 1:(3 to 10), preferably 1:(5 to 10).

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