Water-soluble demulsifier and preparation method thereof

Abstract

The invention provides a water-soluble demulsifier and a preparation method thereof, and belongs to the technical field of oilfield chemical engineering, and the preparation method comprises the following steps: step S1, under an ice bath condition, dissolving PEO-PPO in a dilute sulfuric acid solution, then adding a potassium permanganate solution, heating and stirring to obtain carboxylated PEO-PPO; s2, dissolving the carboxylated PEO-PPO in N, N-dimethylformamide, adding EDC and NHS, and carrying out a stirring reaction so as to obtain an activated NHS ester solution; and S3, dissolving isoleucine in a PBS buffer solution, slowly adding the activated NHS ester solution, stirring at normal temperature, controlling the pH value, and purifying to obtain isoleucine grafted PEO-PPO, namely the water-soluble demulsifier. The purpose of efficient demulsification of the demulsifier can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield chemicals, and specifically relates to a water-soluble demulsifier and a preparation method thereof. Background Technique

[0002] During the processes of crude oil extraction, transportation, and processing, it is prone to form stable water-in-oil (W / O) or oil-in-water (O / W) emulsions when mixed with formation water or injected water and subjected to external mechanical forces. Such emulsions are usually composed of crude oil, water, emulsifiers, and mechanical impurities. Their stability mainly stems from the existence of an interfacial film, which is formed by natural emulsifiers (such as asphaltenes and resins) adsorbed on the oil-water interface, having relatively high mechanical strength and elasticity, resulting in the impact on oilfield production and production efficiency and increasing a large amount of costs. Demulsifiers are widely used in fields such as oil extraction, sewage treatment, food industry, and paper industry. At present, certain achievements have been made in the development of demulsifiers, but there are still technical challenges, such as insufficient adaptability and the need to improve stability, etc.

[0003] The patent application document with the publication number CN110921773A discloses a demulsifier for oilfield sewage, which is composed of the following components in mass percentage: polyether 30% - 40%, polymeric aluminum oxide 25% - 30%, citric acid 13% - 18%, surfactant 8% - 10%, carboxymethyl cellulose 5% - 10%, and the balance is water, and the sum of the mass percentages of the above components is 100%. This invention can separate oil and water in sewage and cause a large amount of oil droplets to aggregate and flocculate. It also discloses a preparation method of a demulsifier for oilfield sewage, including weighing, ball milling, and stirring in sequence to obtain the demulsifier for oilfield sewage. The demulsifier prepared by this scheme can, to a certain extent, demulsify oilfield wastewater and achieve the effect of oil-water separation, but its demulsification efficiency is still insufficient.

[0004] Therefore, a preparation method of a water-soluble demulsifier is needed 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 preparation method of a water-soluble demulsifier includes the following steps: Step S1: Under ice bath conditions, dissolve PEO-PPO in dilute sulfuric acid solution, then add potassium permanganate solution, and heat and stir to obtain carboxylated PEO-PPO; Step S2: Dissolve carboxylated PEO-PPO in N,N-dimethylformamide, add EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide) and NHS (N-hydroxysuccinimide), and stir for reaction to obtain an activated NHS ester solution; Step S3: Dissolve isoleucine in PBS buffer solution, slowly add the activated NHS ester solution, stir at room temperature, control the pH, and purify to obtain isoleucine-grafted PEO-PPO, that is, a water-soluble demulsifier.

[0007] The PEO-PPO (polyethylene oxide-polypropylene oxide) block copolymer can regulate the HLB value through different block ratios, so as to be compatible with different types of emulsions. Moreover, the hydrophobicity of the PPO block can change with the environment, automatically adjust the adsorption behavior, enhance the demulsification efficiency, and increase the stability of the demulsifier. The PPO block can anchor the oil phase, and the PEO block extends into the water phase, which can significantly reduce the oil-water interfacial tension, weaken the stability of the emulsion, and can also displace the natural emulsifier on the oil-water interfacial film through competitive adsorption, destroying the oil-water interfacial film, so that the demulsifier can achieve rapid demulsification.

[0008] The present invention uses isoleucine-grafted PEO-PPO as a demulsifier. The branched-chain hydrophobic group of isoleucine and the hydrophobic PPO block in PEO-PPO can produce a synergistic effect, enhancing the adsorption ability of the demulsifier at the oil-water interface, enabling the demulsifier to more effectively insert into the interfacial film formed by the emulsifier, destroying the stability of the interfacial film, and thus achieving demulsification. Moreover, the arrangement of the grafted copolymer in the interfacial film can be more compact, thereby reducing the interfacial tension, accelerating the coalescence of oil droplets, and improving the demulsification efficiency.

[0009] The amino group of isoleucine is protonated under acidic conditions, which can endow the copolymer with cationic properties, thereby destroying the negatively charged emulsion droplets through charge neutralization, promoting the coalescence of emulsion droplets, and enhancing the demulsification effect of the demulsifier. In addition, isoleucine, as a natural amino acid, can make the demulsifier more environmentally friendly.

[0010] Preferably, in the step S1, the concentration of the dilute sulfuric acid is 0.5 mol / L.

[0011] Preferably, in the step S1, the temperature of heating and stirring is 60-65 °C, and the time is 5-7 h.

[0012] Preferably, in the step S2, the N,N-dimethylformamide is in an anhydrous state.

[0013] Avoid side reactions, resulting in a decrease in the grafting rate of isoleucine carboxylated PEO-PPO.

[0014] Preferably, in the step S2, the stirring reaction is carried out under ice bath conditions; the time of the stirring reaction is 2-3 h.

[0015] The carboxyl groups of carboxylated PEO-PPO are activated into NHS esters to improve the reactivity with amino groups.

[0016] Preferably, in the step S3, the time of stirring at room temperature is 12-14 h, and the pH is 7-7.5.

[0017] The amino group of isoleucine is covalently linked to the activated NHS ester to achieve grafting.

[0018] Preferably, in the step S3, magnolol is added for compounding after purification.

[0019] Magnolol has an amphiphilic molecular structure, can effectively adsorb at the oil-water interface, reduce the interfacial tension, and thus destroy the stable interfacial film formed by the emulsifier. The hydrophobic aromatic ring of magnolol is affinity with the oil phase, and the phenolic hydroxyl group interacts with water through hydrogen bonds, replacing the adsorption sites of the original emulsifier, accelerating the coalescence of emulsion droplets. After compounding, magnolol helps to form a denser interfacial film, further improving the demulsification efficiency.

[0020] In addition, magnolol also has antibacterial properties. When treating oilfield or industrial wastewater, the antibacterial properties of magnolol can reduce the phenomenon that microbial metabolites promote the stability of the emulsion.

[0021] Preferably, the compounding includes the following steps: dissolving magnolol in ethanol, adding it to the purified solution after ultrasonic dispersion, stirring at a speed of 400-600 rpm for 1.5-3 h, and controlling the pH to be 7-8.

[0022] To achieve the above object, the present invention also provides a water-soluble demulsifier prepared by the preparation method of the above water-soluble demulsifier, which is characterized by comprising the following components in parts by weight: Isoleucine 3-5 parts, activated NHS ester solution 8-10 parts.

[0023] The components of the present invention in the above parts by weight can make the demulsification performance of the demulsifier reach a better effect.

[0024] Preferably, it further comprises the following components in parts by weight: Magnolol 0.5-1 part; The activated NHS ester solution comprises the following raw materials in parts by weight: carboxylated PEO-PPO 10-15 parts, EDC 2-3 parts, and NHS 1.5-2.5 parts.

[0025] The above technical solutions of the present invention at least include the following beneficial effects: (1) PEO-PPO can adapt to different types of emulsions, increase the stability of the demulsifier, and can also significantly reduce the oil-water interfacial tension, weaken the stability of the emulsion, and displace the natural emulsifier on the oil-water interfacial film through competitive adsorption to destroy the oil-water interfacial film and achieve rapid demulsification.

[0026] (2) The branched-chain hydrophobic group of isoleucine and the hydrophobic PPO chain segment in PEO-PPO can produce a synergistic effect, enabling the demulsifier to more effectively destroy the interfacial film formed by the emulsifier and achieve demulsification. Moreover, the copolymer grafted with isoleucine can be arranged more closely in the interfacial film, thereby reducing the interfacial tension, accelerating the coalescence of oil droplets, and improving the demulsification efficiency.

[0027] (3) The amino group of isoleucine is protonated under acidic conditions, endowing the demulsifier with cationic properties, and then destroying the negatively charged emulsion droplets through charge neutralization to promote the coalescence of emulsion droplets and enhance the demulsification effect of the demulsifier. Specific Embodiments

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 part of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0029] Example 1 Take 500 mL of a dilute sulfuric acid solution with a concentration of 0.5 mol / L and place it in a three-necked flask. Place it in an ice-water bath, then weigh 50 g of the PEO-PPO block copolymer, slowly add it to the dilute sulfuric acid solution, and stir evenly to obtain a transparent solution. Dissolve 5 g of potassium permanganate in 100 mL of deionized water, transfer it to a dropping funnel, and slowly drip it into the transparent solution. Heat it to 62 °C, start stirring, with a stirring speed of 500 rpm, react for 6 h, wash, extract, rotary evaporate, and vacuum dry at 45 °C for 12 h to obtain carboxylated PEO-PPO.

[0030] Take 200 mL of anhydrous N,N-dimethylformamide and place it in a three-necked flask. Add 10 g of carboxylated PEO-PPO. Under ice bath conditions, continuously introduce nitrogen into the three-necked flask, sequentially add 2 g of EDC and 1.5 g of NHS, start stirring, with a stirring speed of 400 rpm. After reacting for 2.5 h, carry out purification and centrifugation to obtain an activated NHS ester solution.

[0031] Dissolve 4 g of isoleucine in 100 mL of PBS buffer solution, and then slowly drip 8 g of the activated NHS ester solution, control the pH to 7.0 - 7.5, stir for 13 h, carry out purification to obtain isoleucine-grafted PEO-PPO.

[0032] Take 0.5 g of magnolol and add it to 100 mL of absolute ethanol. Ultrasonically disperse for 30 min, then add it to the isoleucine-grafted PEO-PPO solution. Start stirring at a stirring speed of 500 rpm for 2 h. Adjust the pH to 7 - 8 and centrifuge to obtain a water-soluble demulsifier.

[0033] Example 2 Take 500 mL of a 0.5 mol / L dilute sulfuric acid solution and place it in a three-necked flask. Place it in an ice-water bath. Then weigh 50 g of PEO-PPO block copolymer and slowly add it to the dilute sulfuric acid solution and stir evenly to obtain a transparent solution. Dissolve 5 g of potassium permanganate in 100 mL of deionized water, transfer it to a dropping funnel, and slowly drop it into the transparent solution. Heat to 60 °C, start stirring at a stirring speed of 500 rpm, react for 7 h, wash, extract, rotary evaporate, and vacuum dry at 45 °C for 12 h to obtain carboxylated PEO-PPO.

[0034] Take 200 mL of anhydrous N,N-dimethylformamide and place it in a three-necked flask. Add 12 g of carboxylated PEO-PPO. Under ice-bath conditions, continuously pass nitrogen into the three-necked flask. Add 2.4 g of EDC and 1.8 g of NHS in sequence. Start stirring at a stirring speed of 400 rpm. After reacting for 3 h, carry out purification and centrifugation to obtain an activated NHS ester solution.

[0035] Dissolve 3 g of isoleucine in 100 mL of PBS buffer solution, and then slowly drop 8 g of the activated NHS ester solution. Control the pH to 7.0 - 7.5 and stir for 12 h. Carry out purification to obtain isoleucine-grafted PEO-PPO.

[0036] Take 1 g of magnolol and add it to 100 mL of absolute ethanol. Ultrasonically disperse for 30 min, then add it to the isoleucine-grafted PEO-PPO solution. Start stirring at a stirring speed of 600 rpm for 1.5 h. Adjust the pH to 7 - 8 and centrifuge to obtain a water-soluble demulsifier.

[0037] Example 3 Take 500 mL of a 0.5 mol / L dilute sulfuric acid solution and place it in a three-necked flask. Place it in an ice-water bath. Then weigh 50 g of PEO-PPO block copolymer and slowly add it to the dilute sulfuric acid solution and stir evenly to obtain a transparent solution. Dissolve 5 g of potassium permanganate in 100 mL of deionized water, transfer it to a dropping funnel, and slowly drop it into the transparent solution. Heat to 65 °C, start stirring at a stirring speed of 500 rpm, react for 5 h, wash, extract, rotary evaporate, and vacuum dry at 45 °C for 12 h to obtain carboxylated PEO-PPO.

[0038] Place 200 mL of anhydrous N,N-dimethylformamide in a three-necked flask, add 10 g of carboxylated PEO-PPO, and continuously introduce nitrogen into the three-necked flask under an ice bath. Then, add 2 g of EDC and 1.5 g of NHS in sequence. Start stirring at a speed of 300 rpm. After reacting for 3 h, perform purification and centrifugation to obtain an activated NHS ester solution.

[0039] Dissolve 4 g of isoleucine in 100 mL of PBS buffer solution, and then slowly drop 9 g of the activated NHS ester solution into it. Control the pH to be 7.0 - 7.5, stir for 13 h, perform purification to obtain isoleucine-grafted PEO-PPO.

[0040] Take 1 g of magnolol and add it to 100 mL of anhydrous ethanol. Ultrasonically disperse for 30 min, then add it to the isoleucine-grafted PEO-PPO solution. Start stirring at a speed of 600 rpm for 2 h, adjust the pH to 7 - 8, and centrifuge to obtain a water-soluble demulsifier.

[0041] Example 4 Place 500 mL of a 0.5 mol / L dilute sulfuric acid solution in a three-necked flask, place it in an ice-water bath, and then weigh 50 g of PEO-PPO block copolymer and slowly add it to the dilute sulfuric acid solution and stir evenly to obtain a transparent solution. Dissolve 5 g of potassium permanganate in 100 mL of deionized water, transfer it to a dropping funnel, and slowly drop it into the transparent solution. Heat to 62 °C, start stirring at a speed of 500 rpm, react for 5.5 h, wash, extract, rotary evaporate, and vacuum dry at 45 °C for 12 h to obtain carboxylated PEO-PPO.

[0042] Place 200 mL of anhydrous N,N-dimethylformamide in a three-necked flask, add 15 g of carboxylated PEO-PPO, and continuously introduce nitrogen into the three-necked flask under an ice bath. Then, add 3 g of EDC and 2.5 g of NHS in sequence. Start stirring at a speed of 350 rpm. After reacting for 3 h, perform purification and centrifugation to obtain an activated NHS ester solution.

[0043] Dissolve 3 g of isoleucine in 100 mL of PBS buffer solution, and then slowly drop 8 g of the activated NHS ester solution into it. Control the pH to be 7.0 - 7.5, stir for 12 h, perform purification to obtain isoleucine-grafted PEO-PPO.

[0044] Take 0.5 g of magnolol and add it to 100 mL of anhydrous ethanol. Ultrasonically disperse for 30 min, then add it to the isoleucine-grafted PEO-PPO solution. Start stirring at a speed of 400 rpm for 3 h, adjust the pH to 7 - 8, and centrifuge to obtain a water-soluble demulsifier.

[0045] Example 5 Place 500 mL of a dilute sulfuric acid solution with a concentration of 0.5 mol / L in a three-necked flask, place it in an ice-water bath, then weigh 50 g of the PEO-PPO block copolymer, slowly add it to the dilute sulfuric acid solution, and stir evenly to obtain a transparent solution. Dissolve 5 g of potassium permanganate in 100 mL of deionized water, transfer it to a dropping funnel, and slowly drop it into the transparent solution. Heat to 65 °C, start stirring at a stirring speed of 500 rpm, react for 5.5 h, wash, extract, rotary evaporate, and vacuum dry at 45 °C for 12 h to obtain carboxylated PEO-PPO.

[0046] Place 200 mL of anhydrous N,N-dimethylformamide in a three-necked flask, add 15 g of carboxylated PEO-PPO, and continuously pass nitrogen into the three-necked flask under ice-bath conditions. Add 3 g of EDC and 2.5 g of NHS in sequence, start stirring at a stirring speed of 400 rpm, and after reacting for 2 h, carry out purification and centrifugation to obtain an activated NHS ester solution.

[0047] Dissolve 5 g of isoleucine in 100 mL of PBS buffer solution, and then slowly drop 10 g of the activated NHS ester solution, control the pH to 7.0 - 7.5, stir for 12 h, and carry out purification to obtain isoleucine-grafted PEO-PPO.

[0048] Take 1 g of magnolol and add it to 100 mL of anhydrous ethanol, ultrasonically disperse for 30 min, add it to the isoleucine-grafted PEO-PPO solution, start stirring at a stirring speed of 450 rpm, stir for 2.5 h, adjust the pH to 7 - 8, and centrifuge to obtain a water-soluble demulsifier.

[0049] Example 6 Place 500 mL of a dilute sulfuric acid solution with a concentration of 0.5 mol / L in a three-necked flask, place it in an ice-water bath, then weigh 50 g of the PEO-PPO block copolymer, slowly add it to the dilute sulfuric acid solution, and stir evenly to obtain a transparent solution. Dissolve 5 g of potassium permanganate in 100 mL of deionized water, transfer it to a dropping funnel, and slowly drop it into the transparent solution. Heat to 60 °C, start stirring at a stirring speed of 500 rpm, react for 6.5 h, wash, extract, rotary evaporate, and vacuum dry at 45 °C for 12 h to obtain carboxylated PEO-PPO.

[0050] Place 200 mL of anhydrous N,N-dimethylformamide in a three-necked flask, add 10 g of carboxylated PEO-PPO, and continuously pass nitrogen into the three-necked flask under ice-bath conditions. Add 2 g of EDC and 1.5 g of NHS in sequence, start stirring at a stirring speed of 300 rpm, and after reacting for 3 h, carry out purification and centrifugation to obtain an activated NHS ester solution.

[0051] Dissolve 5 g of isoleucine in 100 mL of PBS buffer, and then slowly drop 9 g of activated NHS ester solution, control the pH to 7.0 - 7.5, stir for 14 h, and perform purification to obtain isoleucine-grafted PEO-PPO.

[0052] Take 1 g of magnolol and add it to 100 mL of absolute ethanol, ultrasonically disperse for 30 min, add it to the isoleucine-grafted PEO-PPO solution, start stirring, the stirring speed is 550 rpm, the stirring time is 2 h, adjust the pH to 7 - 8, and centrifuge to obtain a water-soluble demulsifier.

[0053] Example 7 Place 500 mL of a 0.5 mol / L dilute sulfuric acid solution in a three-necked flask, place it in an ice-water bath, then weigh 50 g of PEO-PPO block copolymer, slowly add it to the dilute sulfuric acid solution, and stir evenly to obtain a transparent solution. Dissolve 5 g of potassium permanganate in 100 mL of deionized water, transfer it to a dropping funnel, and slowly drop it into the transparent solution, heat to 60 °C, start stirring, the stirring speed is 500 rpm, react for 6 h, wash, extract, rotary evaporate, and vacuum dry at 45 °C for 12 h to obtain carboxylated PEO-PPO.

[0054] Take 200 mL of anhydrous N,N-dimethylformamide and place it in a three-necked flask, add 12 g of carboxylated PEO-PPO, under ice bath conditions, continuously introduce nitrogen into the three-necked flask, add 2.5 g of EDC and 2 g of NHS in sequence, start stirring, the stirring speed is 350 rpm, after reacting for 2.5 h, perform purification and centrifugation to obtain an activated NHS ester solution.

[0055] Dissolve 4.5 g of isoleucine in 100 mL of PBS buffer, and then slowly drop 10 g of activated NHS ester solution, control the pH to 7.0 - 7.5, stir for 13 h, and perform purification to obtain isoleucine-grafted PEO-PPO, which is the water-soluble demulsifier.

[0056] Example 8 Place 500 mL of a 0.5 mol / L dilute sulfuric acid solution in a three-necked flask, place it in an ice-water bath, then weigh 50 g of PEO-PPO block copolymer, slowly add it to the dilute sulfuric acid solution, and stir evenly to obtain a transparent solution. Dissolve 5 g of potassium permanganate in 100 mL of deionized water, transfer it to a dropping funnel, and slowly drop it into the transparent solution, heat to 60 °C, start stirring, the stirring speed is 500 rpm, react for 6 h, wash, extract, rotary evaporate, and vacuum dry at 45 °C for 12 h to obtain carboxylated PEO-PPO.

[0057] Place 200 mL of anhydrous N,N-dimethylformamide in a three-necked flask, add 12 g of carboxylated PEO-PPO, and continuously introduce nitrogen into the three-necked flask under an ice bath. Then, sequentially add 2.5 g of EDC and 2 g of NHS. Start stirring at a speed of 350 rpm. After reacting for 2.5 h, perform purification by centrifugation to obtain an activated NHS ester solution.

[0058] Dissolve 4.5 g of isoleucine in 100 mL of PBS buffer solution, and then slowly drop 10 g of the activated NHS ester solution into it. Control the pH to be 7.0 - 7.5, stir for 13 h, and perform purification to obtain isoleucine-grafted PEO-PPO.

[0059] Take 1 g of magnolol and add it to 100 mL of anhydrous ethanol. Ultrasonically disperse it for 30 min, then add it to the isoleucine-grafted PEO-PPO solution. Start stirring at a speed of 550 rpm for 2 h, adjust the pH to 7 - 8, and centrifuge to obtain a water-soluble demulsifier.

[0060] The present invention also conducted comparative examples and related tests.

[0061] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is only that in Comparative Example 1, isoleucine was not used to graft PEO-PPO, and the other components and preparation methods are the same as those in Example 1, and a water-soluble demulsifier was prepared.

[0062] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is only that in Comparative Example 2, PEO-PPO and isoleucine were directly compounded, and the other components and preparation methods are the same as those in Example 1, and a water-soluble demulsifier was prepared.

[0063] Comparative Example 3 Comparative Example 3 used a demulsifier for oilfield sewage disclosed in the patent application document with the publication number CN110921773A.

[0064] Performance detection test Taking the petroleum and natural gas industry standard SY5281-2000 Crude Oil Demulsifier Performance Test Method (bottle test method) as the standard, a demulsification experiment was carried out on the water-soluble demulsifiers prepared in Examples 1 - 8 and Comparative Examples 1 - 3. The 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 after fully mixing, placed in a water bath at 25 °C and 55 °C for 20 and 40 min. The mass-volume ratio of the demulsifier to the crude oil emulsion was 750 mg / L, and the test results are shown in Table 1 below.

[0065] Table 1

[0066] As can be seen from the results in Table 1 above, the demulsification effect of the demulsifier prepared in Comparative Example 1 has a significant decrease compared with that of the demulsifiers prepared in Examples 1-8. This shows that isoleucine grafted PEO-PPO can improve the compactness of the arrangement of the demulsifier at the oil-water interface film, thereby accelerating the coalescence of oil droplets and enhancing the demulsification efficiency of the demulsifier. Compared with the demulsifiers prepared in Examples 1-8, the decrease in the demulsification efficiency at room temperature of the demulsifier prepared in Comparative Example 2 is slightly greater than that at 55 °C, but there is still a large gap in the demulsification efficiency with the demulsifiers prepared in Examples 1-8. This indicates that it is difficult to achieve the synergistic effect of isoleucine and PEO-PPO by direct compounding. There is an obvious gap in the demulsification effect between the demulsifier used in Comparative Example 3 and the demulsifier prepared in the examples of the present invention, indicating that the technical solution of the present invention is more excellent.

[0067] The difference between Example 7 and Example 8 is that honokiol was not compounded in Example 7. As can be seen from the results in Table 1, there is a certain gap in the demulsification effect of the demulsifier prepared in Example 7 compared with that in Example 8, indicating that honokiol can promote the destruction of the oil-water interface film by the demulsifier, thereby enhancing the demulsification effect of the demulsifier.

[0068] The above are the preferred embodiments of the present invention. Without departing from the principle of the present invention, those of ordinary skill in the art can also make several improvements and refinements, which should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a water-soluble demulsifier, characterized in that, It includes the following steps: Step S1: Under ice bath conditions, dissolve PEO-PPO in dilute sulfuric acid solution, then add potassium permanganate solution, heat and stir to obtain carboxylated PEO-PPO; Step S2: Dissolve carboxylated PEO-PPO in N,N-dimethylformamide, add EDC and NHS, stir and react to obtain an activated NHS ester solution; Step S3: Dissolve isoleucine in PBS buffer solution, slowly add the activated NHS ester solution, stir at room temperature, control the pH, and purify to obtain isoleucine-grafted PEO-PPO, that is, a water-soluble demulsifier.

2. The preparation method of a water-soluble demulsifier according to claim 1, characterized in that, In step S1, the concentration of the dilute sulfuric acid is 0.5 mol / L.

3. The preparation method of a water-soluble demulsifier according to claim 1, characterized in that, In step S1, the temperature of heating and stirring is 60-65 °C, and the time is 5-7 h.

4. The preparation method of a water-soluble demulsifier according to claim 1, characterized in that, In step S2, N,N-dimethylformamide is in an anhydrous state.

5. The preparation method of a water-soluble demulsifier according to claim 1, characterized in that, In step S2, the stirring reaction is carried out under ice bath conditions; the time of the stirring reaction is 2-3 h.

6. The preparation method of a water-soluble demulsifier according to claim 1, characterized in that, In step S3, the time of stirring at room temperature is 12-14 h, and the pH is 7-7.

5.

7. The preparation method of a water-soluble demulsifier according to claim 1, characterized in that, After purification in step S3, it is also compounded with magnolol.

8. The preparation method of a water-soluble demulsifier according to claim 7, characterized in that, The compounding includes the following steps: dissolve magnolol in ethanol, add it to the purified solution after ultrasonic dispersion, stir at a speed of 400-600 rpm for 1.5-3 h, and control the pH to be 7-8.

9. A water-soluble demulsifier, characterized in that, Prepared by using the preparation method of a water-soluble demulsifier according to any one of claims 1-8, and includes the following components in parts by weight: Isoleucine 3-5 parts, activated NHS ester solution 8-10 parts.

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

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