A water-soluble demulsifier and preparation method thereof

Abstract

The present invention provides a water-soluble demulsifier and a preparation method thereof, which belongs to the field of oilfield chemical technology, comprising the following steps: step S1, under ice bath conditions, dissolving PEO-PPO in a dilute sulfuric acid solution, adding a potassium permanganate solution, heating and stirring to obtain carboxylated PEO-PPO; step S2, dissolving the carboxylated PEO-PPO in N,N-dimethylformamide, adding EDC and NHS, stirring the reaction, and obtaining an activated NHS ester solution; step S3, dissolving isoleucine in PBS buffer, slowly adding the activated NHS ester solution, stirring at room temperature, controlling the pH, and purifying to obtain isoleucine-grafted PEO-PPO, i.e., a water-soluble demulsifier. The present invention can achieve the purpose of efficient demulsification of the demulsifier.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemical industry, in particular to a water-soluble demulsifier and a preparation method thereof. Background Art

[0002] During the extraction, transportation, and processing of crude oil, it mixes with formation water or injection water and is subjected to external mechanical forces, easily forming stable water-in-oil (W / O) or oil-in-water (O / W) emulsions. These emulsions are typically composed of crude oil, water, emulsifiers, and mechanical impurities. Their stability primarily stems from the presence of an interfacial membrane. This membrane structure, formed by the adsorption of natural emulsifiers (such as asphaltenes and colloids) at the oil-water interface, possesses high mechanical strength and elasticity. This impacts oilfield production and efficiency, significantly increasing costs. Demulsifiers are widely used in fields such as oil extraction, wastewater treatment, the food industry, and the papermaking industry. While some progress has been made in the development of demulsifiers, technical challenges remain, such as insufficient adaptability and the need for improved stability.

[0003] Patent application publication number CN110921773A discloses a demulsifier for oilfield wastewater. The demulsifier is composed of the following components by mass: 30% to 40% polyether, 25% to 30% polyaluminium oxide, 13% to 18% citric acid, 8% to 10% surfactant, 5% to 10% carboxymethyl cellulose, and the remainder water, with the sum of the mass percentages of the above components being 100%. This invention is capable of separating oil and water from wastewater and causing oil droplets to aggregate and flocculate. It also discloses a method for preparing the demulsifier for oilfield wastewater, comprising weighing, ball milling, and stirring to obtain the demulsifier. The demulsifier prepared by this method is capable of demulsifying oilfield wastewater to a certain extent, achieving oil-water separation, but its demulsification efficiency is still insufficient.

[0004] Therefore, it is necessary to provide a method for preparing a water-soluble demulsifier to solve the problems existing in the above-mentioned prior art. Summary of the Invention

[0005] In view of this, the present invention provides a water-soluble demulsifier and a preparation method thereof, which can achieve the purpose of efficient demulsification of the demulsifier.

[0006] The specific scheme of the present invention is as follows: a method for preparing a water-soluble demulsifier comprises the following steps:

[0007] Step S1: dissolving PEO-PPO in a dilute sulfuric acid solution under ice bath conditions, then adding potassium permanganate solution, heating and stirring to obtain carboxylated PEO-PPO;

[0008] Step S2: dissolving the carboxylated PEO-PPO in N,N-dimethylformamide, adding EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide) and NHS (N-hydroxysuccinimide), and stirring to react to obtain an activated NHS ester solution;

[0009] Step S3: dissolving isoleucine in PBS buffer, slowly adding activated NHS ester solution, stirring at room temperature, controlling pH, and purifying to obtain isoleucine-grafted PEO-PPO, i.e., a water-soluble demulsifier.

[0010] PEO-PPO (polyethylene oxide-polypropylene oxide) block copolymers can adjust their HLB values ​​through varying block ratios, making them suitable for different types of emulsions. The hydrophobicity of the PPO segments changes with the environment, automatically adjusting their adsorption behavior, enhancing demulsification efficiency and increasing the stability of the demulsifier. The PPO segments anchor the oil phase, while the PEO segments extend into the water phase, significantly reducing the oil-water interfacial tension and weakening the emulsion's stability. They also displace the natural emulsifier from the oil-water interfacial membrane through competitive adsorption, disrupting the membrane and enabling rapid demulsification.

[0011] The present invention uses isoleucine grafted onto PEO-PPO as a demulsifier. The isoleucine's branched hydrophobic groups synergistically interact with the hydrophobic PPO segments in PEO-PPO, enhancing the demulsifier's adsorption capacity at the oil-water interface. This allows the demulsifier to more effectively penetrate the interfacial film formed by the emulsifier, destabilizing it and achieving demulsification. Furthermore, the grafted copolymer is more tightly arranged in the interfacial film, reducing interfacial tension, accelerating oil droplet coalescence, and improving demulsification efficiency.

[0012] The amino group of isoleucine is protonated under acidic conditions, imparting cationic properties to the copolymer. This neutralization effect disrupts negatively charged emulsion droplets, promoting droplet coalescence and enhancing the demulsifier's effectiveness. Furthermore, as a natural amino acid, isoleucine can make the demulsifier more environmentally friendly.

[0013] Preferably, in step S1, the concentration of dilute sulfuric acid is 0.5 mol / L.

[0014] Preferably, in step S1, the heating and stirring temperature is 60-65° C. and the time is 5-7 h.

[0015] Preferably, in step S2, N,N-dimethylformamide is in an anhydrous state.

[0016] Avoid side reactions that may lead to a decrease in the grafting rate of isoleucine carboxylated PEO-PPO.

[0017] Preferably, in step S2, the stirring reaction is carried out in an ice bath; the stirring reaction time is 2-3 h.

[0018] The carboxylic acid group of carboxylated PEO-PPO was activated into NHS ester to increase the reactivity with amino groups.

[0019] Preferably, in step S3, the stirring time at room temperature is 12-14 hours, and the pH is 7-7.5.

[0020] The amino group of isoleucine was covalently linked to an activated NHS ester to achieve grafting.

[0021] Preferably, in step S3, magnolol is added after purification for compounding.

[0022] Magnolol has an amphiphilic molecular structure that effectively adsorbs to the oil-water interface, reducing interfacial tension and thus disrupting the stable interfacial film formed by the emulsifier. The hydrophobic aromatic ring of magnolol is compatible with the oil phase, while the phenolic hydroxyl groups interact with water through hydrogen bonds, replacing the adsorption sites of the original emulsifier and accelerating the coalescence of emulsion droplets. After compounding, magnolol helps form a denser interfacial film, further improving demulsification efficiency.

[0023] In addition, magnolol also has antibacterial properties. When treating oil fields or industrial wastewater, the antibacterial properties of magnolol can reduce the phenomenon of microbial metabolites promoting emulsion stability.

[0024] Preferably, the compounding comprises the following steps: dissolving magnolol in ethanol, adding the solution to the purified solution after ultrasonic dispersion, stirring at a speed of 400-600 rpm for 1.5-3 hours, and controlling the pH to 7-8.

[0025] To achieve the above object, the present invention further provides a water-soluble demulsifier prepared by the above method for preparing a water-soluble demulsifier, characterized in that it comprises the following components in parts by weight:

[0026] 3-5 parts of isoleucine, 8-10 parts of activated NHS ester solution.

[0027] The above weight proportions of the components of the present invention can achieve better demulsification performance of the demulsifier.

[0028] Preferably, the following components in parts by weight are also included:

[0029] 0.5-1 part of magnolol;

[0030] The activated NHS ester solution comprises the following raw materials in parts by weight: 10-15 parts of carboxylated PEO-PPO, 2-3 parts of EDC and 1.5-2.5 parts of NHS.

[0031] The above technical solution of the present invention includes at least the following beneficial effects:

[0032] (1) PEO-PPO can adapt to different types of emulsions, increase the stability of the demulsifier, and significantly reduce the oil-water interfacial tension, weaken the stability of the emulsion. It can also replace the natural emulsifier on the oil-water interfacial film through competitive adsorption, destroy the oil-water interfacial film, and achieve rapid demulsification.

[0033] (2) The side-chain hydrophobic groups of isoleucine can produce a synergistic effect with the hydrophobic PPO segments in PEO-PPO, enabling the demulsifier to more effectively destroy the interfacial film formed by the emulsifier and achieve demulsification. In addition, the copolymer after grafting isoleucine can be arranged more tightly in the interfacial film, thereby reducing interfacial tension, accelerating the coalescence of oil droplets, and improving demulsification efficiency.

[0034] (3) The amino group of isoleucine is protonated under acidic conditions, giving the demulsifier cationic properties, which in turn destroys the negatively charged emulsion droplets through charge neutralization, promotes the coalescence of emulsion droplets, and enhances the demulsification effect of the demulsifier. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0036] Example 1

[0037] 500 mL of 0.5 mol / L dilute sulfuric acid solution was placed in a three-necked flask and placed in an ice-water bath. 50 g of PEO-PPO block copolymer was then weighed and slowly added to the dilute sulfuric acid solution with stirring to obtain a clear solution. 5 g of potassium permanganate was dissolved in 100 mL of deionized water, transferred to a dropping funnel, and slowly added dropwise to the clear solution. The mixture was heated to 62°C and stirred at 500 rpm for 6 h. The mixture was then washed, extracted, and rotary evaporated. The mixture was then vacuum dried at 45°C for 12 h to obtain carboxylated PEO-PPO.

[0038] 200 mL of anhydrous N,N-dimethylformamide was placed in a three-necked flask, and 10 g of carboxylated PEO-PPO was added. Under ice bath conditions, nitrogen was continuously introduced into the three-necked flask, and 2 g of EDC and 1.5 g of NHS were added in sequence. Stirring was started at 400 rpm. After reacting for 2.5 h, the solution was purified and centrifuged to obtain an activated NHS ester solution.

[0039] 4 g of isoleucine was dissolved in 100 mL of PBS buffer, and then 8 g of activated NHS ester solution was slowly added dropwise, the pH was controlled at 7.0-7.5, and the mixture was stirred for 13 h for purification to obtain isoleucine-grafted PEO-PPO.

[0040] Take 0.5g of magnolol and add it to 100mL of anhydrous ethanol, ultrasonically disperse it for 30min, add it to the isoleucine grafted PEO-PPO solution, start stirring at a speed of 500rpm for 2h, adjust the pH to 7-8, and centrifuge to obtain a water-soluble demulsifier.

[0041] Example 2

[0042] 500 mL of 0.5 mol / L dilute sulfuric acid solution was placed in a three-necked flask and placed in an ice-water bath. 50 g of PEO-PPO block copolymer was then weighed and slowly added to the dilute sulfuric acid solution with stirring to obtain a clear solution. 5 g of potassium permanganate was dissolved in 100 mL of deionized water, transferred to a dropping funnel, and slowly added dropwise to the clear solution. The mixture was heated to 60°C and stirred at 500 rpm for 7 h. The mixture was then washed, extracted, rotary evaporated, and dried under vacuum at 45°C for 12 h to obtain carboxylated PEO-PPO.

[0043] 200 mL of anhydrous N,N-dimethylformamide was placed in a three-necked flask, and 12 g of carboxylated PEO-PPO was added. Under ice bath conditions, nitrogen was continuously introduced into the three-necked flask, and 2.4 g of EDC and 1.8 g of NHS were added in sequence. Stirring was started at 400 rpm. After reacting for 3 h, the solution was purified and centrifuged to obtain an activated NHS ester solution.

[0044] 3 g of isoleucine was dissolved in 100 mL of PBS buffer, and then 8 g of activated NHS ester solution was slowly added dropwise, the pH was controlled at 7.0-7.5, and the mixture was stirred for 12 h for purification to obtain isoleucine-grafted PEO-PPO.

[0045] Take 1g of magnolol and add it to 100mL of anhydrous ethanol, ultrasonically disperse it for 30min, add it to the isoleucine grafted PEO-PPO solution, start stirring at a speed of 600rpm, stirring for 1.5h, adjust the pH to 7-8, and centrifuge to obtain a water-soluble demulsifier.

[0046] Example 3

[0047] 500 mL of 0.5 mol / L dilute sulfuric acid solution was placed in a three-necked flask and placed in an ice-water bath. 50 g of PEO-PPO block copolymer was then weighed and slowly added to the dilute sulfuric acid solution with stirring to obtain a clear solution. 5 g of potassium permanganate was dissolved in 100 mL of deionized water, transferred to a dropping funnel, and slowly added dropwise to the clear solution. The mixture was heated to 65°C and stirred at 500 rpm for 5 h. The mixture was then washed, extracted, rotary evaporated, and dried under vacuum at 45°C for 12 h to obtain carboxylated PEO-PPO.

[0048] 200 mL of anhydrous N,N-dimethylformamide was placed in a three-necked flask, and 10 g of carboxylated PEO-PPO was added. Under ice bath conditions, nitrogen was continuously introduced into the three-necked flask, and 2 g of EDC and 1.5 g of NHS were added in sequence. Stirring was started at 300 rpm. After reacting for 3 h, the solution was purified and centrifuged to obtain an activated NHS ester solution.

[0049] 4 g of isoleucine was dissolved in 100 mL of PBS buffer, and then 9 g of activated NHS ester solution was slowly added dropwise, the pH was controlled at 7.0-7.5, and the mixture was stirred for 13 h for purification to obtain isoleucine-grafted PEO-PPO.

[0050] Take 1g of magnolol and add it to 100mL of anhydrous ethanol, ultrasonically disperse it for 30min, add it to the isoleucine grafted PEO-PPO solution, start stirring at 600rpm, stirring for 2h, adjust the pH to 7-8, and centrifuge to obtain a water-soluble demulsifier.

[0051] Example 4

[0052] 500 mL of 0.5 mol / L dilute sulfuric acid solution was placed in a three-necked flask and placed in an ice-water bath. 50 g of PEO-PPO block copolymer was then weighed and slowly added to the dilute sulfuric acid solution with stirring to obtain a clear solution. 5 g of potassium permanganate was dissolved in 100 mL of deionized water, transferred to a dropping funnel, and slowly added dropwise to the clear solution. The mixture was heated to 62°C and stirred at 500 rpm for 5.5 hours. The mixture was then washed, extracted, rotary evaporated, and dried under vacuum at 45°C for 12 hours to obtain carboxylated PEO-PPO.

[0053] 200 mL of anhydrous N,N-dimethylformamide was placed in a three-necked flask, and 15 g of carboxylated PEO-PPO was added. Under ice bath conditions, nitrogen was continuously introduced into the three-necked flask, and 3 g of EDC and 2.5 g of NHS were added in sequence. Stirring was started at 350 rpm. After reacting for 3 h, the mixture was purified and centrifuged to obtain an activated NHS ester solution.

[0054] 3 g of isoleucine was dissolved in 100 mL of PBS buffer, and then 8 g of activated NHS ester solution was slowly added dropwise, the pH was controlled at 7.0-7.5, and the mixture was stirred for 12 h for purification to obtain isoleucine-grafted PEO-PPO.

[0055] Take 0.5g of magnolol and add it to 100mL of anhydrous ethanol, ultrasonically disperse it for 30min, add it to the isoleucine grafted PEO-PPO solution, start stirring at a speed of 400rpm for 3h, adjust the pH to 7-8, and centrifuge to obtain a water-soluble demulsifier.

[0056] Example 5

[0057] 500 mL of 0.5 mol / L dilute sulfuric acid solution was placed in a three-necked flask and placed in an ice-water bath. 50 g of PEO-PPO block copolymer was then weighed and slowly added to the dilute sulfuric acid solution with stirring to obtain a clear solution. 5 g of potassium permanganate was dissolved in 100 mL of deionized water, transferred to a dropping funnel, and slowly added dropwise to the clear solution. The mixture was heated to 65°C and stirred at 500 rpm for 5.5 hours. The mixture was then washed, extracted, rotary evaporated, and dried under vacuum at 45°C for 12 hours to obtain carboxylated PEO-PPO.

[0058] 200 mL of anhydrous N,N-dimethylformamide was placed in a three-necked flask, and 15 g of carboxylated PEO-PPO was added. Under ice bath conditions, nitrogen was continuously introduced into the three-necked flask, and 3 g of EDC and 2.5 g of NHS were added in sequence. Stirring was started at 400 rpm. After reacting for 2 h, the solution was purified and centrifuged to obtain an activated NHS ester solution.

[0059] 5 g of isoleucine was dissolved in 100 mL of PBS buffer, and then 10 g of activated NHS ester solution was slowly added dropwise, the pH was controlled at 7.0-7.5, and the mixture was stirred for 12 h for purification to obtain isoleucine-grafted PEO-PPO.

[0060] Take 1g of magnolol and add it to 100mL of anhydrous ethanol, ultrasonically disperse it for 30min, add it to the isoleucine grafted PEO-PPO solution, start stirring at a speed of 450rpm, stirring for 2.5h, adjust the pH to 7-8, and centrifuge to obtain a water-soluble demulsifier.

[0061] Example 6

[0062] 500 mL of 0.5 mol / L dilute sulfuric acid solution was placed in a three-necked flask and placed in an ice-water bath. 50 g of PEO-PPO block copolymer was then weighed and slowly added to the dilute sulfuric acid solution with stirring to obtain a clear solution. 5 g of potassium permanganate was dissolved in 100 mL of deionized water, transferred to a dropping funnel, and slowly added dropwise to the clear solution. The mixture was heated to 60°C and stirred at 500 rpm for 6.5 h. The mixture was then washed, extracted, rotary evaporated, and dried under vacuum at 45°C for 12 h to obtain carboxylated PEO-PPO.

[0063] 200 mL of anhydrous N,N-dimethylformamide was placed in a three-necked flask, and 10 g of carboxylated PEO-PPO was added. Under ice bath conditions, nitrogen was continuously introduced into the three-necked flask, and 2 g of EDC and 1.5 g of NHS were added in sequence. Stirring was started at 300 rpm. After reacting for 3 h, the solution was purified and centrifuged to obtain an activated NHS ester solution.

[0064] 5 g of isoleucine was dissolved in 100 mL of PBS buffer, and then 9 g of activated NHS ester solution was slowly added dropwise, the pH was controlled at 7.0-7.5, and the mixture was stirred for 14 h for purification to obtain isoleucine-grafted PEO-PPO.

[0065] Take 1g of magnolol and add it to 100mL of anhydrous ethanol, ultrasonically disperse it for 30min, add it to the isoleucine grafted PEO-PPO solution, start stirring at a speed of 550rpm for 2h, adjust the pH to 7-8, and centrifuge to obtain a water-soluble demulsifier.

[0066] Example 7

[0067] 500 mL of 0.5 mol / L dilute sulfuric acid solution was placed in a three-necked flask and placed in an ice-water bath. 50 g of PEO-PPO block copolymer was then weighed and slowly added to the dilute sulfuric acid solution with stirring to obtain a clear solution. 5 g of potassium permanganate was dissolved in 100 mL of deionized water, transferred to a dropping funnel, and slowly added dropwise to the clear solution. The mixture was heated to 60°C and stirred at 500 rpm for 6 h. The mixture was then washed, extracted, and rotary evaporated. The mixture was then vacuum dried at 45°C for 12 h to obtain carboxylated PEO-PPO.

[0068] 200 mL of anhydrous N,N-dimethylformamide was placed in a three-necked flask, and 12 g of carboxylated PEO-PPO was added. Under ice bath conditions, nitrogen was continuously introduced into the three-necked flask, and 2.5 g of EDC and 2 g of NHS were added in sequence. Stirring was started at 350 rpm. After reacting for 2.5 h, the mixture was purified and centrifuged to obtain an activated NHS ester solution.

[0069] 4.5 g of isoleucine was dissolved in 100 mL of PBS buffer, and then 10 g of activated NHS ester solution was slowly added dropwise, the pH was controlled at 7.0-7.5, and the mixture was stirred for 13 h. Purification was performed to obtain isoleucine-grafted PEO-PPO, which was a water-soluble demulsifier.

[0070] Example 8

[0071] 500 mL of 0.5 mol / L dilute sulfuric acid solution was placed in a three-necked flask and placed in an ice-water bath. 50 g of PEO-PPO block copolymer was then weighed and slowly added to the dilute sulfuric acid solution with stirring to obtain a clear solution. 5 g of potassium permanganate was dissolved in 100 mL of deionized water, transferred to a dropping funnel, and slowly added dropwise to the clear solution. The mixture was heated to 60°C and stirred at 500 rpm for 6 h. The mixture was then washed, extracted, and rotary evaporated. The mixture was then vacuum dried at 45°C for 12 h to obtain carboxylated PEO-PPO.

[0072] 200 mL of anhydrous N,N-dimethylformamide was placed in a three-necked flask, and 12 g of carboxylated PEO-PPO was added. Under ice bath conditions, nitrogen was continuously introduced into the three-necked flask, and 2.5 g of EDC and 2 g of NHS were added in sequence. Stirring was started at 350 rpm. After reacting for 2.5 h, the mixture was purified and centrifuged to obtain an activated NHS ester solution.

[0073] 4.5 g of isoleucine was dissolved in 100 mL of PBS buffer, and then 10 g of activated NHS ester solution was slowly added dropwise, the pH was controlled at 7.0-7.5, and the mixture was stirred for 13 h for purification to obtain isoleucine-grafted PEO-PPO.

[0074] Take 1g of magnolol and add it to 100mL of anhydrous ethanol, ultrasonically disperse it for 30min, add it to the isoleucine grafted PEO-PPO solution, start stirring at a speed of 550rpm for 2h, adjust the pH to 7-8, and centrifuge to obtain a water-soluble demulsifier.

[0075] The present invention also carried out comparative examples and related tests.

[0076] Comparative Example 1

[0077] The only difference between Comparative Example 1 and Example 1 is that isoleucine is not used to graft PEO-PPO in Comparative Example 1. Other compositions and preparation methods are the same as those in Example 1, and a water-soluble demulsifier is prepared.

[0078] Comparative Example 2

[0079] The only difference between Comparative Example 2 and Example 1 is that Comparative Example 2 directly compounded PEO-PPO and isoleucine. Other compositions and preparation methods were the same as those in Example 1 to prepare a water-soluble demulsifier.

[0080] Comparative Example 3

[0081] Comparative Example 3 uses an oilfield wastewater demulsifier disclosed in the patent application document with publication number CN110921773A.

[0082] Performance testing

[0083] Based on the petroleum and natural gas industry standard SY5281-2000 Crude Oil Demulsifier Performance Test Method (Bottle Test Method), demulsification experiments were conducted on the water-soluble demulsifiers prepared in Examples 1-8 and Comparative Examples 1-3. Crude oil emulsion (O / W type, oil content 10%) and the water-soluble demulsifiers prepared in Examples 1-8 and Comparative Examples 1-3 were added to a stoppered graduated cylinder, shaken 100 times, and thoroughly mixed. The cylinders were then placed in water baths at 25°C and 55°C for 20 and 40 minutes, respectively. The mass-to-volume ratio of demulsifier to crude oil emulsion was 750 mg / L. The test results are shown in Table 1 below.

[0084] Table 1

[0085]

[0086] As can be seen from the results in Table 1 above, the demulsification effect of the demulsifier prepared in Comparative Example 1 is greatly reduced compared with the demulsifier prepared in Examples 1-8, indicating that isoleucine grafted PEO-PPO can increase the density of the demulsifier at the oil-water interface film arrangement, thereby accelerating the coalescence of oil droplets and improving the demulsification efficiency of the demulsifier; the demulsifier prepared in Comparative Example 2 is slightly lower than the demulsification efficiency at room temperature than the demulsifier prepared in Examples 1-8, but both are significantly different from the demulsification efficiency of the demulsifier prepared in Examples 1-8, indicating that isoleucine and PEO-PPO are directly compounded, and it is difficult to achieve a synergistic effect between the two; the demulsifier used in Comparative Example 3 has a significant difference in demulsification effect compared with the demulsifier prepared in the embodiment of the present invention, indicating that the technical solution of the present invention is better.

[0087] The difference between Example 7 and Example 8 is that Example 7 does not contain magnolol. As can be seen from the results in Table 1, the demulsification effect of the demulsifier prepared in Example 7 is somewhat different from that in Example 8, indicating that magnolol can promote the destruction of the oil-water interface film by the demulsifier, thereby improving the demulsification effect of the demulsifier.

[0088] The above is a preferred embodiment of the present invention. Those skilled in the art may make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a water-soluble demulsifier, characterized in that: The following steps are involved: Step S1: dissolving PEO-PPO in a dilute sulfuric acid solution under ice bath conditions, then adding potassium permanganate solution, heating and stirring to obtain carboxylated PEO-PPO; Step S2, dissolving the carboxylated PEO-PPO in N,N-dimethylformamide, adding EDC and NHS, and stirring to react to obtain an activated NHS ester solution; Step S3: dissolving isoleucine in PBS buffer, slowly adding activated NHS ester solution, stirring at room temperature, controlling pH, and purifying to obtain isoleucine-grafted PEO-PPO, i.e., a water-soluble demulsifier.

2. The method for preparing a water-soluble demulsifier according to claim 1, wherein: In step S1, the concentration of dilute sulfuric acid is 0.5 mol / L.

3. The method for preparing a water-soluble demulsifier according to claim 1, wherein: In step S1, the heating and stirring temperature is 60-65° C. and the time is 5-7 hours.

4. The method for preparing a water-soluble demulsifier according to claim 1, wherein: In the step S2, N,N-dimethylformamide is in an anhydrous state.

5. The method for preparing a water-soluble demulsifier according to claim 1, wherein: In step S2, the stirring reaction is carried out in an ice bath; the stirring reaction time is 2-3 hours.

6. The method for preparing a water-soluble demulsifier according to claim 1, wherein: In step S3, the stirring time at room temperature is 12-14 hours, and the pH is 7-7.

5.

7. The method for preparing a water-soluble demulsifier according to claim 1, wherein: In step S3, the purified product is compounded with magnolol.

8. The method for preparing a water-soluble demulsifier according to claim 7, wherein: The compounding comprises the following steps: dissolving magnolol in ethanol, adding the magnolol into the purified solution after ultrasonic dispersion, stirring at a speed of 400-600 rpm for 1.5-3 hours, and controlling the pH value to be 7-8.

9. A water-soluble demulsifier, characterized in that: The water-soluble demulsifier is prepared by the preparation method of any one of claims 1 to 8, comprising the following components in parts by weight: 3-5 parts of isoleucine, 8-10 parts of activated NHS ester solution.

10. A water-soluble demulsifier according to claim 9, characterized in that: Also includes the following components in parts by weight: 0.5-1 part of magnolol; The activated NHS ester solution comprises the following raw materials in parts by weight: 10-15 parts of carboxylated PEO-PPO, 2-3 parts of EDC and 1.5-2.5 parts of NHS.

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