An oligomeric bio-based surfactant, and methods of making and using the same

Abstract

The present disclosure relates to an oligomeric bio-based surfactant, a preparation method and application thereof, the oligomeric bio-based surfactant has the structure shown in formula 1 or formula 2: X1-X2 is selected from -(CH2) n Or a substituted or unsubstituted thiophene group with 4-10 carbon atoms, n represents the number of CH2, and n is selected from any integer from 0 to 12; Z1-Z5 are each independently selected from a disaccharide group, R1-R5 are each independently selected from -CH(CH3)-Y-COOH, wherein Y is selected from a saturated or unsaturated linear alkyl group with 9-19 carbon atoms. Compared with unmodified sophorolipids, the oligomeric bio-based surfactant of the present disclosure has a lower contact angle and higher wettability; at the same time, the molecule has a branched space structure and intramolecular sugar ring steric hindrance, which can promote the fusion between bubbles, exhibit low foam characteristics, and has good industrial application prospects as a green and efficient low-foaming bio-based cleaning agent.

Description

Technical Field

[0001] This disclosure relates to surfactants, and more specifically, to an oligomeric bio-based surfactant, its preparation method, and its application. Background Technology

[0002] Surfactants are amphiphilic compounds containing both hydrophilic head groups and hydrophobic tail chains, possessing unique functions such as foaming, wetting, solubilizing, and emulsifying. Traditional surfactant preparation processes rely on petroleum-derived products, resulting in poor biodegradability and making them difficult-to-treat environmental pollutants. In recent years, bio-based surfactants such as sophorolipids and rhamnolipides obtained through bio-fermentation have been considered alternatives to traditional petroleum-based synthetic surfactants due to their green, non-toxic, easily degradable, and highly efficient characteristics. They are gradually being applied in industrial cleaning, daily chemicals, oil extraction, environmental protection (especially soil leaching), and pharmaceuticals. Currently, while the cost of bio-fermentation products is within a controllable range, their price remains relatively high, ranging from 2 to 5 times that of petroleum-based synthetic surfactants. Improving the application efficiency of bio-based surfactants and reducing the dosage of chemicals used are crucial for their industrial promotion and application.

[0003] Stevens' research group reported a series of novel disophorolipids (ACS Sustainable Chemistry & Engineering, 2018, 6, 7, 8992-9005) and evaluated their antibacterial and transfection properties. The reported synthesis of disophorolipids requires at least 4-6 steps, including transesterification ring-opening of the sophorolipid, esterification protection of the sugar ring hydroxyl group, conversion of the tail chain ester group to an aldehyde group, condensation of the aldehyde group with an alkylamine to form a Schiff base, subsequent reduction, deprotection of the sugar ring hydroxyl group of the reduction product, and quaternization of the tertiary amine linker. Clearly, this method involves numerous reaction steps, resulting in low overall yield and making industrial scale-up difficult. Furthermore, the foaming and cleaning properties of the disophorolipid products in water were not evaluated, and the advantages of low consumption and high efficiency of the dimer product were not demonstrated; therefore, its potential applications remain to be further explored.

[0004] Furthermore, in industrial cleaning or soil rinsing, the large amount of foam generated by surfactants is difficult to manage, significantly increasing the difficulty of post-cleaning or rinsing processes. Therefore, low-foaming surfactants are preferred as cleaning or rinsing 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 select the best product. Summary of the Invention

[0005] The purpose of this disclosure is to provide an oligomeric bio-based surfactant, its preparation method, and its application. The oligomeric bio-based surfactant provided in this disclosure has a branched spatial structure, which enhances its ability to strip oil phases. When used to clean oily soil, it achieves excellent cleaning results with a cleaning efficiency of over 85%, and it produces almost no foaming, reducing the difficulty of subsequent rinsing.

[0006] To achieve the above objectives, the first aspect of this disclosure provides an oligomeric bio-based surfactant having a structure as shown in Formula 1 or Formula 2:

[0007]

[0008] X1 to X2 are selected from -(CH2) n - or a substituted or unsubstituted thiophene group having 4 to 10 carbon atoms, where n represents the number of CH2 atoms and is selected from any integer from 0 to 12; Z1 to Z5 are each independently selected from disaccharide groups, and R1 to R5 are each independently selected from -CH(CH3)-Y-COOH, where Y is selected from a saturated or unsaturated straight-chain alkyl group having 9 to 19 carbon atoms.

[0009] Optionally, Z1 to Z4 are each independently selected from the following groups: in This indicates the chemical bonds connecting Z1 to Z4 with R1 to R4; —* indicates the bonds connecting Z1 to Z4 with… or Connecting chemical bonds.

[0010] Optionally, Z5 is selected from in This indicates the chemical bond connecting Z5 and R5; —* indicates the bond between Z5 and R5. Connecting chemical bonds.

[0011] Optionally, the oligomeric bio-based surfactant has the structure shown in formulas (I) to (VI):

[0012] .

[0013] Optionally, X1 to X2 are selected from -(CH2). n When n is selected from any integer from 0 to 10, preferably, n is selected from any integer from 0 to 3; when X1 to X2 are selected from substituted or unsubstituted thiophene groups having 4 to 10 carbon atoms, the thiophene group is selected from substituted or unsubstituted group W, wherein the unsubstituted group W is selected from the group consisting of the following groups: in The group W 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... The Y is selected from -(CH2)9-, -(CH2)6CH=CH(CH2)7- or -(CH2)3CH=CHCH2CH=CH(CH2)7-.

[0014] Optionally, the oligomeric bio-based surfactant 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°.

[0015] A second aspect of this disclosure provides a method for preparing oligomeric bio-based surfactants, the method comprising:

[0016] (1) Prepare a sophorolipid aqueous solution by adjusting the pH of the sophorolipid aqueous solution to 1.0-5.0 with acid and stirring for the first time to obtain the first solution;

[0017] (2) Contact the first solution with the aldehyde crosslinking agent to obtain the second solution; adjust the pH of the second solution to 7.0-8.5 with alkali and perform a second stirring.

[0018] The sophorolipids include acidic sophorolipids and / or lactone-type sophorolipids, wherein the acidic sophorolipids have the structure shown in Formula 3: The lactone-type sophorolipid has the structure shown in Formula 4: Wherein RZ- is selected from R1-Z1-, R2-Z2-, R3-Z3-, R4-Z4-, or R5-Z5-, and Z' and Z1 to Z5 are each independently selected from disaccharides; R1 to R5 are each independently selected from -CH(CH3)-Y-COOH, where Y is selected from saturated or unsaturated straight-chain alkyl groups with 9 to 19 carbon atoms; the aldehyde crosslinking agent is selected from CHO-X1-CHO or CHO-X2-CHO, where X1 to X2 are selected from -(CH2) n - or a substituted or unsubstituted thiophene group with 4 to 10 carbon atoms, where n represents the number of CH2 atoms and is selected from any integer from 0 to 12.

[0019] Optionally, in step (1), the acidic sophorolipid is selected from one or more of the following structures:

[0020]

[0021]

[0022] The lactone-type sophorolipid is selected from one or more of the following structures:

[0023]

[0024] Based on the total weight of the sophorolipid aqueous solution, the content of sophorolipid in the sophorolipid aqueous solution is 5-30% by weight; the water used to prepare the sophorolipid aqueous solution is selected from one or more of deionized water, distilled water and ultrapure water;

[0025] The acid is selected from one or more of hydrochloric acid, sulfuric acid and phosphoric acid; the temperature of the first stirring is 10-40℃ and the time is 20-120 min.

[0026] Optionally, in step (2), the molar ratio of the aldehyde crosslinking agent to the sophorolipid in the first solution is 1:(2-4), preferably 1:(2-3); the aldehyde crosslinking agent is selected from alkyl dialdehyde or thiophene dialdehyde; the alkyl dialdehyde is selected from glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, adipaldehyde or heptaaldehyde, preferably glyoxal, succinaldehyde or glutaraldehyde; the thiophene dialdehyde is selected from thiophene-2,3-dicarboxaldehyde, thiophene-2,4-dicarboxaldehyde or thiophene-2,5-dicarboxaldehyde, preferably thiophene-2,3-dicarboxaldehyde; the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate; the second stirring temperature is 10-40℃, and the time is 3-6h.

[0027] The third aspect of this disclosure provides an oligomeric bio-based surfactant prepared using the method described in the second aspect of this disclosure.

[0028] Optionally, the oligomeric bio-based surfactant 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°.

[0029] This fourth aspect of the disclosure provides the application of the oligomeric bio-based surfactants described in the first and third aspects of the disclosure in oilfield oil solids cleaning, oil stain cleaning, pesticide formulation, and daily chemical products.

[0030] Optionally, the application of the oligomeric bio-based surfactant in the cleaning of oily solids in oilfields includes: mixing an aqueous solution containing the oligomeric bio-based surfactant with oily solids, wherein the mixing temperature is 50-80°C and the mixing time is 2-8 hours; wherein the concentration of the oligomeric bio-based surfactant in the aqueous solution is 3000-30000 mg / L, and the weight ratio of the oily solids to the aqueous solution is 1:(3-10), preferably 1:(5-10).

[0031] Through the above technical solution, this disclosure provides an oligomeric bio-based surfactant, its preparation method, and its application. This oligomeric bio-based surfactant is formed by chemically linking the hydroxyl groups of sophorolipids with the aldehyde groups of an aldehyde crosslinking agent to form modified sophorolipid dimers or trimers. Compared to unmodified sophorolipids, the oligomeric bio-based surfactant of this disclosure has a lower contact angle and higher wettability. Furthermore, it possesses a branched spatial structure and intramolecular sugar ring steric hindrance, which can reduce foam generation and promote foam fusion. The preparation method of this disclosure is mild, simple, and generates no waste, and can produce oligomeric bio-based surfactants with lower critical micelle concentrations and better surface activity. When used to clean oil-contaminated soil, this oligomeric bio-based surfactant has a contact angle of less than 18°, can turn the oil-covered surface into a strongly water-wetted surface, has excellent oil-phase stripping ability, and produces almost no foam, reducing the difficulty of subsequent rinsing. Compared to unmodified sophorolipids, the oligomeric bio-based surfactant disclosed herein has a cleaning efficiency of over 85% for heavy oil contaminated soil, and the critical micelle concentration is reduced by 1 to 2 orders of magnitude, making it more resistant to dilution and requiring a lower dosage.

[0032] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0033] 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:

[0034] Figure 1 This is the mass spectrum of the oligomeric bio-based surfactant prepared in Example 1 of this disclosure. Detailed Implementation

[0035] 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.

[0036] The first aspect of this disclosure provides an oligomeric bio-based surfactant having a structure as shown in Formula 1 or Formula 2:

[0037]

[0038] X1 to X2 are selected from -(CH2) n- or a substituted or unsubstituted thiophene group having 4 to 10 carbon atoms, where n represents the number of CH2 atoms and is selected from any integer from 0 to 12; Z1 to Z5 are each independently selected from disaccharide groups, and R1 to R5 are each independently selected from -CH(CH3)-Y-COOH, where Y is selected from a saturated or unsaturated straight-chain alkyl group having 9 to 19 carbon atoms.

[0039] The oligomeric bio-based surfactant disclosed herein is formed by chemically linking the hydroxyl groups of sophorolipids with the aldehyde groups of an aldehyde crosslinking agent to form modified sophorolipid dimers or trimers. Compared to unmodified sophorolipids, the oligomeric bio-based surfactant disclosed herein has a lower contact angle and higher wettability, and possesses a branched spatial structure and intramolecular sugar ring steric hindrance, which can reduce foam generation and promote foam fusion. Sophorolipids are typically composed of two parts: hydrophilic sophorose (two glucose molecules linked by a β-1,2 glycosidic bond) and hydrophobic saturated or unsaturated long-chain ω- (or ω-1) hydroxy fatty acids.

[0040] The types of R1 to R5 are not limited depending on the fatty acid chain to which the sophorolipid is attached. 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-.

[0041] In one embodiment of this disclosure, Z1 to Z4 are each independently selected from the following groups: in This indicates the chemical bonds connecting Z1 to Z4 with R1 to R4; —* indicates the bonds connecting Z1 to Z4 with… or Connecting chemical bonds. In the above embodiments, " The meaning of "representing the chemical bonds connecting Z1~Z4 and R1~R4" includes: This indicates the chemical bond connecting Z1 and R1. The chemical bond connecting Z2 and R2 This indicates the chemical bond connecting Z3 and R3. This represents the chemical bond connecting Z4 and R4.

[0042] "—* indicates Z1~Z4 and" or The meaning of "connected chemical bonds" includes—* indicates Z1 and The chemical bonds connecting them, —* indicates Z2 and The chemical bonds connecting them, —* indicates Z3 and The chemical bonds are linked; -* indicates Z4 and Connecting chemical bonds.

[0043] In one embodiment of this disclosure, Z5 is selected from... in This indicates the chemical bond connecting Z5 and R5; -* indicates the bond between Z5 and R5. Connecting chemical bonds.

[0044] In one embodiment of this disclosure, the oligomeric bio-based surfactant has the structure shown in formulas (I) to (VI):

[0045] In the above embodiments, the oligomeric bio-based surfactant has a branched spatial structure and intramolecular sugar ring steric hindrance, which can reduce foam generation and promote the fusion of foams.

[0046] In one embodiment of this disclosure, X1 to X2 are selected from -(CH2). n When n is 0, 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, and the carbon atoms on the two -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.

[0047] In another embodiment of this disclosure, when X1 to X2 are selected from substituted or unsubstituted thiophene groups having 4 to 10 carbon atoms, the thiophene group is selected from substituted or unsubstituted group W, wherein the unsubstituted group W is selected from the group consisting of: in The group W 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...

[0048] In one embodiment of this disclosure, the foaming height of the oligomeric bio-based surfactant is less than 10 mL, for example, the foaming height can be 10 mL, 9 mL, 8 mL, 7 mL, 6 mL, 5 mL, 4 mL, 3 mL, 2 mL, 1 mL, or any value between two of these; the foam stabilization time is less than 60 s, for example, the foam stabilization time can be 60 s, 50 s, 40 s, 30 s, 20 s, 10 s, or any value between two of these; and the contact angle is less than 20°, for example, the contact angle can be 20°, 18°, 15°, 12°, 10°, 8°, 6°, 4°, 2°, or any value between two of these. In the above embodiment, the oligomeric bio-based surfactant has a low foaming height, poor foam stabilization ability, and a small contact angle, resulting in a strong wetting reversal ability. It can reverse an oily interface into a strongly watery interface, and can be used as a green and efficient low-foaming degreasing agent.

[0049] A second aspect of this disclosure provides a method for preparing oligomeric bio-based surfactants, the method comprising:

[0050] (1) Prepare a sophorolipid aqueous solution by adjusting the pH of the sophorolipid aqueous solution to 1.0-5.0, preferably 2.0-4.0, with acid, and perform a first stirring to obtain a first solution;

[0051] (2) The first solution is brought into contact with the aldehyde crosslinking agent to obtain the second solution; the pH of the second solution is adjusted to 7.0-8.5, preferably 7.0-7.5, using an alkali, and then stirred for the second time;

[0052] The sophorolipids include acidic sophorolipids and / or lactone-type sophorolipids, wherein the acidic sophorolipids have the structure shown in Formula 3 below: The lactone-type sophorolipid has the structure shown in Formula 4: Wherein RZ- is selected from R1-Z1-, R2-Z2-, R3-Z3-, R4-Z4-, or R5-Z5-, and Z' and Z1 to Z5 are each independently selected from disaccharides; R1 to R5 are each independently selected from -CH(CH3)-Y-COOH, where Y is selected from saturated or unsaturated straight-chain alkyl groups with 9 to 19 carbon atoms; the aldehyde crosslinking agent is selected from CHO-X1-CHO or CHO-X2-CHO, where X1 to X2 are selected from -(CH2) n - or a substituted or unsubstituted thiophene group with 4 to 10 carbon atoms, where n represents the number of CH2 atoms and is selected from any integer from 0 to 12.

[0053] The preparation method disclosed herein is mild, simple and easy to implement, generates no waste, and can produce oligomeric bio-based surfactants with lower critical micelle concentrations and better surface activity.

[0054] In one embodiment of this disclosure, in step (1), the acidic sophorolipid is selected from one or more of the following structures:

[0055]

[0056] In another embodiment, the lactone-type sophorolipid described in step (1) is selected from one or more of the following structures:

[0057]

[0058] In one embodiment, based on the total weight of the sophorolipid aqueous solution, the content of sophorolipid in the sophorolipid aqueous solution is 5-30% by weight; 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; the temperature of the first stirring is 10-40°C, and the time is 20-120 min. In the above embodiment, the preferred sophorolipid can be used to prepare oligomeric bio-based surfactants with better wetting, emulsifying, and solubilizing properties. The sophorolipid can be a commercially available chemical reagent or prepared according to methods known in the art.

[0059] In one embodiment of this disclosure, in step (2), the molar ratio of the aldehyde crosslinking agent to the sophorolipid in the first solution is 1:(2-4), preferably 1:(2-3); the aldehyde crosslinking agent is selected from alkyl dialdehyde or thiophene dialdehyde; the alkyl dialdehyde is selected from glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, adipaldehyde or heptaaldehyde, preferably glyoxal, succinaldehyde or glutaraldehyde; the thiophene dialdehyde is selected from thiophene-2,3-dicarboxaldehyde (CAS No. 932-41-2), thiophene-2,4-dicarboxaldehyde (CAS No. 932-93-4) or thiophene-2,5-dicarboxaldehyde (CAS No. 932-95-6), preferably thiophene-2,3-dicarboxaldehyde; the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate; the temperature of the second stirring is 10-40℃, and the time is 3-6h. In the above embodiments, the aldehyde crosslinking agent can be a pure product or an aqueous solution of any mass fraction, such as an aqueous solution of 25% or 50% by mass.

[0060] The third aspect of this disclosure provides an oligomeric bio-based surfactant prepared using the method described in the second aspect of this disclosure.

[0061] The oligomeric bio-based surfactant prepared using the method disclosed herein has the characteristics of low foaming height, poor foam stabilization ability, and small contact angle, and can be used as a green and efficient low-foaming detergent. Specifically, the oligomeric bio-based surfactant 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°.

[0062] This fourth aspect of the disclosure provides the application of the oligomeric bio-based surfactant described in the first and third aspects of the disclosure in the cleaning of oily solids in oilfields, oil stain removal, pesticide formulation, and daily chemical products. Specifically, the application of the oligomeric bio-based surfactant in the cleaning of oily solids in oilfields includes using the oligomeric bio-based surfactant as a cleaning agent, oil washing agent, or rinsing agent for oily solids in oilfields to clean soil contaminated with heavy oil.

[0063] In one embodiment, the application of the oligomeric bio-based surfactant in cleaning oily solids in oilfields includes: mixing an aqueous solution containing the oligomeric bio-based surfactant with oily solids, wherein the mixing temperature is 50–80°C and the mixing time is 2–8 hours; wherein the concentration of the oligomeric bio-based surfactant in the aqueous solution is 3000–30000 mg / L, and the weight ratio of the oily solids to the aqueous solution is 1:(3–10), preferably 1:(5–10). The oily solids include oily soil, oily sludge, oily stainless steel, or oily ceramics.

[0064] 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.

[0065] The mass spectrometer used in the examples and comparative examples was a Bruker UltrafleXtreme. The detection conditions for mass spectrometry were as follows: ionization source in MALDI-TOF positive ion mode; sheath gas flow rate of 45 arb, auxiliary gas flow rate of 10 arb, capillary voltage of 3300 V, and capillary temperature of 350 °C.

[0066] Example 1

[0067] (1) Weigh 12.4 g (10 mmol / s) of lactone-type sophorolipid (purchased from Shandong Qilu Biotechnology Co., Ltd., with a mass content of 50% and a structural formula of...). Add 50g of distilled water to a round-bottom flask and stir magnetically at room temperature (25±2℃) until homogeneous to obtain a sophorolipid aqueous solution containing 20% ​​by weight. Then slowly add hydrochloric acid while stirring for the first time to adjust the pH of the system to 3.0. Continue stirring magnetically at room temperature (25±2℃) for 30 minutes to obtain the first solution.

[0068] (2) Slowly add 0.8 g of 50 wt% glutaraldehyde aqueous solution (aldehyde crosslinking agent, 4 mmol / L, purchased from Inokai) to the first solution, wherein the molar ratio of glutaraldehyde to sophorolipid in the first solution is 1:2.5; continue stirring at room temperature (25±2℃) for 4 h, then stop the reaction to obtain the second solution. Slowly add 10 wt% sodium hydroxide aqueous solution to the second solution while stirring for the second time, and adjust the pH of the system to 7.0 to obtain the oligomeric bio-based surfactant, denoted as OSL-C1. OSL-C1 comprises a mixture having the structures shown in formulas (I) to (VI):

[0069] X1~X2 are -(CH2)3-, R1~R5 are -CH(CH3)-Y-COOH, Y is -(CH2)6CH=CH(CH2)7-, and its mass fraction is 10.4%.

[0070] Mass spectrometry analysis of this oligomeric bio-based surfactant was performed, and the MALDI-TOF mass spectrum is shown below. Figure 1 As shown, the mass spectrum peak with a mass-to-charge ratio of 1367.745 corresponds to the molecular ion peak ([M+Na)) after the addition of one sodium ion to the disosophorolipid. + Mass spectrometry results showed that, under the condition that the molar ratio of aldehyde to sophorolipid was 1:2.5, the active substance obtained was mainly disophorolipid, while the content of trisophorolipid was relatively small and the large molecular weight made it difficult to form a peak. Therefore, the peak intensity of trisophorolipid in the mass spectrometry was very low.

[0071] Example 2

[0072] The method of Example 1 was adopted, with the only difference being that in step (1), 12.4 g (10 mmol) of sophorolipid was added to 20 g of distilled water, and the content of sophorolipid in the obtained sophorolipid aqueous solution was 38% by weight; in step (2), 0.72 g of 40 wt% succinaldehyde aqueous solution (3.33 mmol) was slowly added to the first solution, wherein the molar ratio of succinaldehyde to sophorolipid in the first solution was 1:3, and the reaction was stirred at room temperature for 5 h. Finally, an oligomeric bio-based surfactant, denoted as OSL-C2, was obtained. OSL-C2 comprises a mixture having the structures shown in formulas (I) to (VI), wherein X1 to X2 are -(CH2)2-, R1 to R5 are -CH(CH3)-Y-COOH, Y is -(CH2)6CH=CH(CH2)7-, and its mass fraction is 19.6%.

[0073] Example 3

[0074] The method of Example 1 was adopted, with the only difference being that in step (1), 12.4 g (10 mmol) of sophorolipid was added to 10 g of distilled water, and the content of sophorolipid in the resulting sophorolipid aqueous solution was 55% by weight; in step (2), 0.29 g of 40 wt% glyoxal aqueous solution (5 mmol) was slowly added to the first solution, wherein the molar ratio of glyoxal to sophorolipid in the first solution was 1:2. The resulting oligomeric bio-based surfactant was denoted as OSL-C3. OSL-C3 comprises a mixture having the 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%.

[0075] Example 4

[0076] The method of Example 1 was used, except that in step (2), 0.56 g of thiophene-2,3-dicarboxaldehyde (4 mmol / s) was slowly added to the first solution, wherein the molar ratio of thiophene-2,3-dicarboxaldehyde to sophorolipid in the first solution was 1:2.5. The resulting oligomeric bio-based surfactant was designated OSL-C4. OSL-C4 comprises a mixture having the 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 their mass fraction is 10.8%.

[0077] Comparative Example 1

[0078] 68.88 g (100 mmol) 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 the reaction was carried out 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 [structural formula would be inserted here]. The yield was 99%.

[0079] Test Example 1

[0080] The foaming ability and foam stability of the oligomeric bio-based surfactants prepared in Examples 1-4, the sulfonated modified sophorolipids prepared in Comparative Example 1, and the unmodified sophorolipids were evaluated:

[0081] The foaming capacity and foam stability were evaluated using a Roche foam analyzer according to the method in GB / T 7462-94. The test temperature was controlled at 25±1℃, and the water used in the test was deionized water. The concentration of the aqueous solution of the test samples 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 taken 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:

[0082] Table 1

[0083] surfactants h / mL <![CDATA[t 1 / 2 / s]]> OSL-C1 2 - OSL-C2 3 - OSL-C3 2 - OSL-C4 2 - Sulfonated modified sophorolipids 8 40 Unmodified sophorolipids 10 60

[0084] As can be seen from the data in Table 1, compared with unmodified sophorolipids and sulfonated sophorolipids, the oligomeric bio-based surfactants modified by the method of this disclosure have reduced foaming ability, with an initial foam height of no more than 3 mL, and the foam completely collapses within 10 seconds. This is because the branched structure after the molecular reaction is not conducive to foam generation and can promote the fusion between foams, thus making the oligomeric bio-based surfactant exhibit almost no foaming properties.

[0085] Test Example 2

[0086] The wetting ability of the oligomeric bio-based surfactants prepared in Examples 1-4, the sulfonated modified sophorolipid prepared in Comparative Example 1, and the unmodified sophorolipid was evaluated:

[0087] First, Victory Y8X heavy oil was evenly coated onto a clean glass slide at high temperature and allowed to cool naturally. Then, the contact angle was measured using a KRUSSDSA100 contact angle meter with the concentrations of the aqueous solutions of the test samples (10 mg / L, 100 mg / L, and 1000 mg / L) on the slide surface via the seated drop method. The temperature was controlled at 25℃. Timing began when the droplet reached the oil interface, and after 1 minute of equilibration, the contact angle was obtained by photographing and fitting the image. The measurement results are shown in Table 2.

[0088] Table 2

[0089]

[0090] Table 2 shows that at a concentration of 1000 mg / L, the contact angle of unmodified sophorolipid aqueous solution droplets 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°, no longer exhibiting a wetting and turning effect. Meanwhile, the contact angles of sulfonated sophorolipids at the same concentration are 2–11° lower than those of unmodified sophorolipids. In contrast, the oligomeric bio-based surfactant of this disclosure exhibits contact angles below 18° within the above concentration range, a reduction of more than 20° compared to unmodified or sulfonated sophorolipids, thereby enabling the heavy oil-coated surface to turn into a strongly water-wetted surface. Its wetting and turning effect is significantly improved compared to unmodified and sulfonated sophorolipids, and the dosage is lower.

[0091] Test Example 3

[0092] The oil-washing ability of the oligomeric bio-based surfactants prepared in Examples 1-4, the sulfonated modified sophorolipid prepared in Comparative Example 1, and the unmodified sophorolipid was evaluated:

[0093] Uncontaminated soil (from the Shengli Oilfield Y8X block) 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 were placed in an 80℃ constant temperature oven for 8 hours. 85g of the dried soil was mixed with 15g of heavy oil (density 0.903g / mL) from the Shengli Oilfield Y8X block and thoroughly mixed at 80℃. The soil mixed with crude oil was aged in a 50℃ constant temperature oven for one week to prepare an oil-containing soil sample with an oil content of 15%. A 1000mg / L wash oil system was prepared by mixing the oligomeric bio-based surfactants obtained in Examples 1-4 and unmodified sophorolipids with tap water.

[0094] Weigh 10g of oil-containing soil sample with an oil content of 15%, add 60mL of the oil washing system to an Erlenmeyer flask, seal, and place in a Jinyi SHZ-88 water bath constant temperature shaker to heat to 50℃, maintaining a constant speed of 30rpm for 3 hours. After cooling to room temperature, allow to settle and separate the solution and the washed crude oil from the solid phase. Dry the separated solid at 100℃ to constant weight and weigh it (m). Finally, calculate the cleaning efficiency of the oil washing system using the following formula:

[0095] Cleaning efficiency = (10g – m) / (1.5g) × 100%; the calculation results are shown in Table 3:

[0096] Table 3

[0097] surfactants Cleaning efficiency (%) OSL-C1 86.8 OSL-C2 85.2 OSL-C3 85.5 OSL-C4 86.7 Sulfonated modified sophorolipids 73.2 Unmodified sophorolipids 70.1

[0098] The results in Table 3 show that the oligomeric bio-based surfactant disclosed herein can effectively clean the crude oil contaminated soil in the Shengli Y8X block, with a cleaning efficiency of over 85%, which is more than 15% higher than that of unmodified sophorolipids and more than 12% higher than that of sulfonated sophorolipids.

[0099] 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.

[0100] 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.

[0101] 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. An oligomeric bio-based surfactant, characterized in that, The oligomeric bio-based surfactant has a structure shown in the following Formula 1 or Formula 2: X1~X2are selected from -(CH2) n - or a substituted or unsubstituted thiophene group having 4 to 10 carbon atoms, n represents the number of CH2, and n is selected from any one of integers from 0 to 12; Z1~Z5 are each independently selected from a disaccharide group, and R1~R5 are each independently selected from -CH(CH3)-Y-COOH, wherein Y is selected from a saturated or unsaturated linear alkyl group having 9~19 carbon atoms.

2. The oligobiobased surfactant according to claim 1, characterized in that, Z1to Z4are each independently selected from the following groups: ; wherein represents the chemical bond by which Z1to Z4are attached to R1to R4; represents the chemical bond by which Z1to Z4are attached to or R1to R4.

3. The oligobiobased surfactant according to claim 1, characterized in that, Z5is selected from wherein represents a chemical bond by which Z5is attached to R5; represents a chemical bond by which Z5is attached to R5.

4. The oligobiobased surfactant according to claim 1, characterized in that, The oligomeric bio-based surfactant has a structure shown in the following Formula (I)~(VI): 。 5. The oligobiobased surfactant according to claim 1, characterized in that, X1~X2are selected from -(CH2) n - when n is selected from any integer between 0 and 10; X1~X2are selected from substituted or unsubstituted thiophene groups having a carbon number of 4 to 10, wherein the thiophene groups are selected from substituted or unsubstituted groups W, wherein the unsubstituted groups W are selected from the group consisting of: ; wherein represents a chemical bond; the substituted groups W have one or more substituents, each independently selected from deuterium, fluorine, cyano, methyl, ethyl, n-propyl, i-propyl or t-butyl; Y is selected from -(CH2)9-, -(CH2)6CH=CH(CH2)7- or -(CH2)3CH=CHCH2CH=CH(CH2)7-.

6. The oligobiobased surfactant according to claim 5, characterized in that, X1~X2are selected from -(CH2) n - wherein n is selected from any integer between 0 and 3.

7. The oligobiobased surfactant according to claim 5, characterized in that, X1~X2are selected from .

8. The oligobiobased surfactant according to claim 1, characterized in that, The oligomeric bio-based surfactant has a foaming height of less than 10 mL, a foam stability time of less than 60 s, and a contact angle of less than 20°.

9. A method of making an oligomeric bio-based surfactant, characterized in that, The method comprises: (1) preparing a sophorolipid aqueous solution, adjusting the pH of the sophorolipid aqueous solution to 1.0~5.0 using an acid, and performing first stirring to obtain a first solution; (2) contacting the first solution with an aldehyde-based crosslinking agent to obtain a second solution; adjusting the pH of the second solution to 7.0~8.5 using a base, and performing second stirring; The sophorolipids include acid-type sophorolipids having a structure shown in Formula 3 below: and / or lactone-type sophorolipids having a structure shown in Formula 4 below: ; wherein R-Z- is selected from R1-Z1-, R2-Z2-, R3-Z3-, R4-Z4- or R5-Z5-, Z' and Z1~Z5 are each independently selected from a disaccharide-ylidene group; R1~R5 are each independently selected from -CH(CH3)-Y-COOH, Y is selected from a saturated or unsaturated linear alkyl group having 9~19 carbon atoms; The aldehyde-based crosslinking agent is selected from the group consisting of CHO-X1-CHO or CHO-X2-CHO, wherein X1~X2is selected from the group consisting of -(CH2) n - or a substituted or unsubstituted thiophene group having 4 to 10 carbon atoms, n represents the number of CH2, and n is selected from any one of the integers from 0 to 12.

10. The method of claim 9, wherein, In step (1), the acid sophorolipids are selected from one or several of the structures shown below: , , ; The lactone-type sophorolipids are selected from one or several of the structures shown below: , , ; The content of sophorolipid in the sophorolipid aqueous solution is 5~30% by weight based on the total weight of the sophorolipid aqueous solution; and the water used for preparing 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 the first stirring is performed at a temperature of 10~40℃ for 20~120 min.

11. The method of claim 9, wherein, In step (2), the molar ratio of the aldehyde-based crosslinking agent to sophorolipid in the first solution is 1:(2~4); and the aldehyde-based crosslinking agent is selected from an alkyl dialdehyde or a thiophene dialdehyde; The alkyl dialdehyde is selected from glyoxal, malondialdehyde, butanedial, pentanedial, hexanedial or heptanedial, and the thiophene dialdehyde is selected from thiophene-2, 3-dialdehyde, thiophene-2, 4-dialdehyde or thiophene-2, 5-dialdehyde; The base is selected from one or more of sodium hydroxide, potassium hydroxide, aqueous ammonia, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate; and the second stirring is performed at a temperature of 10~40℃ for 3~6 h.

12. The method of claim 11, wherein, In step (2), the molar ratio of the aldehyde-based crosslinking agent to sophorolipid in the first solution is 1:(2~3).

13. The method of claim 11, wherein, The alkyl dialdehyde is glyoxal, butanedial or pentanedial; and / or, the thiophene dialdehyde is thiophene-2, 3-dialdehyde.

14. An oligomeric bio-based surfactant prepared by the method of any one of claims 9~13.

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

16. Use of the oligomeric bio-based surfactant of any one of claims 1~8 and claims 14~15 in oilfield oily solid cleaning, oil stain cleaning, pesticide formulation and daily chemicals.

17. Use according to claim 16, characterized in that, The use of the oligomeric bio-based surfactant in oilfield oily solid cleaning comprises mixing an aqueous solution containing the oligomeric bio-based surfactant with the oily solid, and the mixing is performed at a temperature of 50~80℃ for 2~8 h. The concentration of the oligomeric bio-based surfactant in the aqueous solution is 3000-30000 mg / L, and the weight ratio of the oil-containing solid to the aqueous solution is 1:(3-10).

18. The use according to claim 17, characterized in that, The weight ratio of the oil-containing solid to the aqueous solution is 1:(5-10).

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