A demulsifier, its preparation method and application

Abstract

The present application relates to a kind of demulsifiers and its preparation method and application.The preparation method includes the following steps: (1) glycerol and p-hydroxy isophthalic acid are mixed, esterification is carried out, and branched prepolymer is obtained;(2) branched prepolymer is mixed with L-arginine, and amide reaction is carried out, and branched body is obtained;(3) branched body is mixed with carboxyl-terminated agent, and amide reaction is carried out, and the demulsifier is obtained.The demulsifier prepared by the specific preparation method can realize the efficient demulsification of high-salt crude oil emulsion, has the advantages of low toxicity, high demulsification efficiency, wide pH range, biodegradable.

Description

Technical Field

[0001] This invention relates to the field of oilfield oily wastewater treatment technology, and in particular to a demulsifier, its preparation method, and its application. Background Technology

[0002] Complex emulsions and oily wastewater generated by industrial processes such as coal mining, materials processing, and oil extraction impact equipment and aquatic resources. To comply with industrial and environmental regulations, emulsions or oily wastewater must be dehydrated or deoiled before further treatment or discharge. For example, exported crude oil must undergo dehydration treatment, with the water content in the oil sample not exceeding 0.5 wt%, and the maximum oil concentration in the discharged water within 5-100 mg / L. Therefore, efficient and rapid demulsification and dehydration of various complex emulsions can significantly reduce production costs and environmental pollution in the petroleum industry. However, as liquids extracted from crude oil become more complex and have higher water content, conventional polymer demulsifiers are increasingly unable to meet production requirements. Therefore, various demulsification methods, including physical, biological, chemical, and combined methods, have been developed for the separation of oil and water in emulsions and oily wastewater.

[0003] Chemical demulsification is considered a more efficient and economical method for treating various complex emulsions and oily wastewater. In the early stages of oilfield development, propylene oxide-polymerized ethylene oxide (PO-EO) block copolymers, nonylphenol-formaldehyde (NPF) resin polyethers, hyperbranched polyethers (HBPE), and other modified polyether demulsifiers are mainly used to separate water-in-oil (W / O) emulsions. For example, CN110975338A discloses a composite demulsifier, the components of which include demulsifier A, demulsifier B, and demulsifier C, wherein demulsifier A, demulsifier B, and demulsifier C are block polymers formed by reacting propylene oxide, ethylene oxide, maleic anhydride, and different initiators. CN118325063A discloses a method for preparing a high-temperature resistant polyether demulsifier. Using m-dinitrobenzoic acid, triethanolamine, allyl chloride, and mercaptopropyltriethoxysilane containing nano-silica as raw materials, an esterification reaction, quaternization reaction, click reaction, and reduction reaction are performed to prepare a silica-containing hexaamino quaternary ammonium salt. This salt is then reacted with bisphenol A and formaldehyde through a condensation reaction to prepare a modified initiator. Under sodium hydroxide as a catalyst, it undergoes a free radical addition reaction with propylene oxide and ethylene oxide to finally prepare the high-temperature resistant polyether demulsifier. The high-temperature resistant polyether demulsifier exhibits good high-temperature resistance and demulsification / dehydration properties. CN115558096A discloses a comb-type cashew phenol polyether demulsifier. This demulsifier has strong surface activity, requires a small amount for demulsification, has a fast demulsification speed, a clear interface, high demulsification efficiency, excellent stability and temperature resistance, and its preparation method is low-cost, simple, safe, and has a high yield. In addition to traditional W / O polymer demulsifiers, ethyl cellulose (EC), amphiphilic ionic liquids (AmILs) and their polymers have been developed for demulsifying W / O emulsions.

[0004] However, with the increasing use of enhanced oil recovery (EOR), produced fluids are shifting from w / o emulsions to o / w emulsions or more complex w / o / w emulsions. More importantly, compared to w / o emulsions, o / w emulsions are more complex and stable due to increased water content, the widespread use of displacement agents, and the inferior quality of unconventional oilfields. Therefore, efficient separation of stable and complex o / w and / or w / o / w emulsions is of great significance.

[0005] Existing polymeric demulsifiers mostly rely on petroleum-based raw materials (such as propylene oxide / ethylene oxide), which have problems such as poor biodegradability and high environmental toxicity; some bio-based demulsifiers (such as single starch / cellulose derivatives) have defects such as simple structure (mainly linear), insufficient functional groups (containing only hydroxyl / carboxyl groups) and low demulsification efficiency.

[0006] Therefore, developing demulsifiers that combine hyperbranched structures (enhancing interfacial adsorption), amphoteric groups (adapting to different emulsion types), fully bio-based raw materials, and green preparation processes has become an urgent technical problem to be solved. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a demulsifier, its preparation method, and its application. Through a specific preparation method, the prepared demulsifier can achieve highly efficient demulsification of high-salt crude oil emulsions, and possesses advantages such as low toxicity, high demulsification efficiency, a wide applicable pH range, and biodegradability.

[0008] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a demulsifier, the method comprising the following steps: (1) Glycerol and p-hydroxyisophthalic acid are mixed and esterified to obtain a branched prepolymer; (2) The branched prepolymer is mixed with L-arginine and subjected to an amidation reaction to obtain the branched product; (3) The branched body is mixed with a carboxyl-containing end-capping agent and subjected to an amidation reaction to obtain the demulsifier.

[0009] In this invention, a three-step reaction is used to synergistically assemble multiple bio-based raw materials such as glycerol, p-hydroxyisophthalic acid, and arginine, simultaneously achieving the integration of aromatic rings, amphoteric groups, and hyperbranched structures, thus avoiding the functional limitations of single bio-based raw materials (such as lignin / starch alone). The demulsifier molecule of this invention simultaneously contains amino, carboxyl, and guanidine groups (triple amphoteric sites), making it suitable for both O / W and W / O emulsions. The emulsifier of this invention also possesses a hyperbranched star structure, which can reduce the toxicity of the demulsifier.

[0010] Preferably, an acidic catalyst is added during the mixing process described in step (1).

[0011] Preferably, the acidic catalyst comprises p-toluenesulfonic acid.

[0012] Preferably, the mass ratio of glycerol to acidic catalyst is 1:(0.05-0.4), for example, it can be 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3 or 1:0.35, etc.

[0013] Preferably, the mixing step in step (1) is to mix glycerol and p-hydroxyisophthalic acid in a solvent.

[0014] Preferably, the solvent includes a mixture of ethanol and water.

[0015] Preferably, the mass ratio of the mixed solvent of ethanol and water to glycerol is (5-10):1, for example, it can be 6:1, 7:1, 7.5:1, 8:1 or 9:1, etc.

[0016] Preferably, in the mixed solvent of ethanol and water, the mass ratio of ethanol to water is (0.8-2.4):1, for example, it can be 1.0:1, 1.2:1, 1.5:1, 1.8:1 or 2.0:1, etc.

[0017] Preferably, the mass ratio of glycerol to p-hydroxyisophthalic acid is 1:(2-5), for example, it can be 1:2.5, 1:3, 1:3.5, 1:4 or 1:4.5, etc.

[0018] In this invention, in step (1), the mass ratio of glycerol, p-hydroxyisophthalic acid, and acidic catalyst must be strictly controlled within the range of 1:(2-5):(0.05-0.4) to ensure the formation of an ideal hyperbranched structure and reduce product toxicity. If the proportion of p-hydroxyisophthalic acid is too low (<2), the degree of branching is insufficient, and linear structures or even cross-linking may occur, affecting the demulsification efficiency; if the proportion is too high (>5), the degree of polymerization will be limited, and the residual free acid will increase the difficulty of purification and potential toxicity. If the proportion of p-toluenesulfonic acid catalyst is too low (<0.05), the reaction rate is slow and the polymerization is uneven; if the proportion is too high (>0.4), side reactions such as etherification may occur, causing the product to darken in color, and the catalyst residue will significantly increase the toxicity and irritation of the final product, deviating from the original intention of low toxicity design. Therefore, limiting the mass ratio within this range can ensure that the esterification reaction is stable and controllable, forming a regular hyperbranched framework, and can also avoid structural defects and safety risks caused by excessive raw materials or catalysts.

[0019] Preferably, the esterification reaction in step (1) is carried out under nitrogen protection.

[0020] Preferably, the reaction temperature of the esterification reaction in step (1) is 70-90℃, for example, it can be 75℃, 78℃, 80℃, 83℃ or 85℃.

[0021] Preferably, the reaction time of the esterification reaction in step (1) is 4-8 h, for example, it can be 5 h, 5.5 h, 6 h, 6.5 h or 7 h.

[0022] Preferably, the esterification reaction in step (1) is followed by a post-treatment step, wherein the post-treatment method includes vacuum distillation.

[0023] Preferably, the temperature of vacuum distillation in step (1) is 30-65°C, for example, it can be 35°C, 40°C, 45°C, 50°C or 60°C.

[0024] Preferably, the pressure of the vacuum distillation in step (1) is 0.01-0.1 MPa, for example, it can be 0.02 MPa, 0.04 MPa, 0.05 MPa, 0.06 MPa or 0.08 MPa, etc.

[0025] Preferably, the mass ratio of L-arginine to branched prepolymer is (0.5-4):1, for example, it can be 0.8:1, 1:1, 2:1, 2.5:1 or 3:1, and more preferably (0.5-2):1.

[0026] In this invention, limiting the mass ratio of L-arginine to the branched prepolymer within a specific range introduces amphiphilic groups, broadening the pH range of the demulsifier. The mass ratio of L-arginine to the branched prepolymer must be controlled within this range. Insufficient L-arginine leads to inadequate hydrophilic modification, poor water solubility of the product, fewer oleic acid grafting sites, disruption of amphiphilic balance, and reduced demulsification efficiency. Excessive L-arginine results in raw material waste and a burden on purification; excess arginine may remain, affecting product purity and stability, and even hindering effective oleic acid incorporation. A suitable ratio is crucial for ensuring adequate grafting, structural stability, excellent demulsification performance, and controlled toxicity.

[0027] Preferably, after the amidation reaction in step (2), a post-treatment step is further included. The post-treatment method includes cooling the mixture to 20-50°C (e.g., 25°C, 30°C, 35°C, 40°C, or 45°C), adding deionized water, and filtering to remove insoluble matter.

[0028] Preferably, the mass ratio of deionized water to branched prepolymer is (3-10):1, for example, it can be 4:1, 5:1, 6:1, 7:1, 8:1 or 9:1, etc.

[0029] Preferably, the reaction temperature of the amidation reaction in step (2) is 70-95℃, for example, it can be 75℃, 80℃, 85℃, 90℃ or 93℃.

[0030] Preferably, the reaction time of the amidation reaction in step (2) is 3-6 h, for example, it can be 3.5 h, 4 h, 4.5 h, 5 h or 5.5 h.

[0031] Preferably, the amidation reaction in step (2) is carried out under nitrogen protection.

[0032] In this invention, a long-chain organic compound containing a carboxyl group is used as a capping agent, which can adjust the lipophilicity of the demulsifier and accelerate the diffusion of the demulsifier to the oil-water interface.

[0033] Preferably, the carboxyl-containing end-capping agent in step (3) includes oleic acid.

[0034] Preferably, the mass ratio of oleic acid to branched body is (1-4):1, for example, it can be 1.5:1, 2:1, 2.5:1, 3:1 or 3.5:1, etc.

[0035] Preferably, the reaction temperature of the amidation reaction in step (3) is 70-90°C, for example, it can be 75°C, 78°C, 80°C, 83°C or 85°C.

[0036] Preferably, the reaction time of the amidation reaction in step (3) is 2-5 h, for example, it can be 2.5 h, 3 h, 3 h, 3.5 h or 4 h.

[0037] Preferably, the mixing step in step (3) involves dispersing the branched body in a solvent and then adding a carboxyl-containing end-capping agent.

[0038] Preferably, the solvent includes water or a mixture of ethanol and water.

[0039] Preferably, step (3) after the amidation reaction further includes a post-treatment step, wherein the post-treatment method includes vacuum distillation.

[0040] Preferably, the temperature of vacuum distillation in step (3) is 30-60°C, for example, it can be 35°C, 40°C, 45°C, 50°C or 55°C.

[0041] Preferably, the pressure of the vacuum distillation in step (3) is 0.01-0.1 MPa, for example, it can be 0.02 MPa, 0.04 MPa, 0.05 MPa, 0.06 MPa or 0.08 MPa, etc.

[0042] In a second aspect, the present invention provides a demulsifier prepared by the preparation method described in the first aspect.

[0043] Thirdly, the present invention provides an application of the demulsifier as described in the second aspect in oil-water separation.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The "glycerol-p-hydroxyisophthalic acid-arginine-oleic acid" multi-bio-based raw materials are synergistically assembled to simultaneously achieve the integration of aromatic rings, amphoteric groups and hyperbranched structures, avoiding the functional limitations of single bio-based raw materials (such as only lignin / starch); (2) Most existing bio-based demulsifiers contain only a single acid / basic group. The demulsifier molecule in this invention contains amine, carboxyl and guanidine groups (triple amphipathic sites), which are suitable for both O / W and W / O type emulsions. (3) Existing technologies mostly use toxic solvents such as dimethylformamide (DMF). This invention uses an ethanol-water green solvent system, with a reaction temperature ≤95℃, a solvent recovery rate >85%, and no organic solvent emissions. (4) The demulsifier in this invention has high demulsification efficiency (>92% within 30 min), is easily biodegradable, and has low environmental toxicity. Attached Figure Description

[0045] Figure 1 This is a flowchart of the preparation method of the demulsifier in this invention.

[0046] Figure 2 This is a photograph of the demulsifier prepared in Example 1 of the present invention.

[0047] Figure 3 This is the Fourier transform infrared spectrum of the demulsifier prepared in Example 2 of the present invention.

[0048] Figure 4 This is a diagram showing the demulsification effect of the demulsifier prepared in Example 3 of the present invention. Detailed Implementation

[0049] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0050] Example 1 A demulsifier and its preparation method, the preparation method comprising the following steps: (1) Glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid were added to a four-necked flask equipped with a water separator, and an ethanol-water mixture was added. The mixture was stirred until completely dissolved. Under nitrogen protection, the temperature was raised to 80°C and refluxed for 6 h. During the reaction, the generated water was continuously removed through the water separator. After the reaction was completed, the ethanol-water mixture was removed by vacuum distillation to obtain a brown, viscous branched prepolymer. The mass ratio of glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid is 1:4:0.2, the mass ratio of ethanol-water mixed solvent to glycerol is 8:1, and the pressure and temperature of vacuum distillation are 0.01 MPa and 50℃, respectively.

[0051] (2) Add L-arginine to the branched prepolymer, heat to 80°C, and stir under nitrogen protection for 4 h to carry out melt amidation reaction. After the reaction is completed, cool to 30°C, add deionized water, stir thoroughly to dissolve the unreacted L-arginine, then filter, collect the insoluble matter, and wash with deionized water 3 times to remove residual L-arginine to obtain a pale yellow branched body; The mass ratio of L-arginine to branched prepolymer is 2:1, and the mass ratio of deionized water to branched prepolymer is 8:1.

[0052] (3) The branched body was dispersed in an ethanol-water mixed solvent, oleic acid was added, the temperature was raised to 85°C, and the reaction was stirred for 3 h. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was cooled to room temperature to obtain the demulsifier. The mass ratio of oleic acid to branched body is 3:1, and the pressure and temperature of vacuum distillation are 0.01 MPa and 50℃, respectively.

[0053] Figure 2 The image shows a physical sample of the demulsifier obtained in Example 1. From... Figure 2 As can be seen from the above, the demulsifier (solvent is water) prepared in Example 1 is a clear, pale yellow, viscous liquid.

[0054] Example 2 A demulsifier and its preparation method, the preparation method comprising the following steps: (1) Glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid were added to a four-necked flask equipped with a water separator, and an ethanol-water mixture was added. The mixture was stirred until completely dissolved. Under nitrogen protection, the temperature was raised to 90°C and refluxed for 4 h. During the reaction, the generated water was continuously removed through the water separator. After the reaction was completed, the ethanol-water mixture was removed by vacuum distillation to obtain a brown, viscous branched prepolymer. The mass ratio of glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid was 1:5:0.4, the mass ratio of ethanol-water mixed solvent to glycerol was 10:1, and the pressure and temperature of vacuum distillation were 0.05 MPa and 65℃, respectively.

[0055] (2) Add L-arginine to the branched prepolymer, heat to 95°C, and stir under nitrogen protection for 3 h to carry out melt amidation reaction. After the reaction is completed, cool to 50°C, add deionized water, stir thoroughly to dissolve the unreacted L-arginine, then filter, collect the insoluble matter, and wash with deionized water 3 times to remove residual L-arginine to obtain a pale yellow branched body; The mass ratio of L-arginine to branched prepolymer is 4:1, and the mass ratio of deionized water to branched prepolymer is 10:1.

[0056] (3) The branched body was dispersed in an ethanol-water mixed solvent, oleic acid was added, the temperature was raised to 90°C, and the reaction was stirred for 2 h. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was cooled to room temperature to obtain the demulsifier. The mass ratio of oleic acid to branched body is 4:1, and the pressure and temperature of vacuum distillation are 0.04 MPa and 60℃, respectively.

[0057] Figure 3 The image shows the FTIR spectrum of the demulsifier obtained in Example 2. Figure 3 As can be seen from the data, the demulsifier prepared in Example 2 exhibits good performance at a wavenumber of 3330 cm⁻¹. -1 2490 cm -1 2090 cm -1 1990 cm -1 1625 cm-1 1473 cm -1 1106 cm -1 892 cm -1 579 cm -1 There is a distinct absorption peak at this point.

[0058] Example 3 A demulsifier and its preparation method, the preparation method comprising the following steps: (1) Glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid were added to a four-necked flask equipped with a water separator, and an ethanol-water mixture was added. The mixture was stirred until completely dissolved. Under nitrogen protection, the temperature was raised to 70°C and refluxed for 8 h. During the reaction, the generated water was continuously removed through the water separator. After the reaction was completed, the ethanol-water mixture was removed by vacuum distillation to obtain a brown, viscous branched prepolymer. The mass ratio of glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid was 1:2:0.05, the mass ratio of ethanol-water mixed solvent to glycerol was 5:1, and the pressure and temperature of vacuum distillation were 0.1 MPa and 30℃, respectively.

[0059] (2) Add L-arginine to the branched prepolymer, heat to 70°C, and stir under nitrogen protection for 6 h to carry out melt amidation reaction. After the reaction is completed, cool to 20°C, add deionized water, stir thoroughly to dissolve the unreacted L-arginine, then filter, collect the insoluble matter, and wash with deionized water 3 times to remove residual L-arginine to obtain a pale yellow branched body; The mass ratio of L-arginine to branched prepolymer is 0.5:1, and the mass ratio of deionized water to branched prepolymer is 3:1.

[0060] (3) The branched body was dispersed in an ethanol-water mixed solvent, oleic acid was added, the temperature was raised to 70°C, and the reaction was stirred for 5 h. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was cooled to room temperature to obtain the demulsifier. The mass ratio of oleic acid to branched body is 1:1, and the pressure and temperature of vacuum distillation are 0.1 MPa and 30℃, respectively.

[0061] Figure 4 This is a diagram showing the demulsification effect of the demulsifier obtained in Example 3. From... Figure 4 As can be seen from the data, the emulsion treated with the demulsifier prepared in Example 3 showed obvious stratification, with the lower aqueous phase being clear and transparent.

[0062] Example 4 A demulsifier and its preparation method, the preparation method comprising the following steps: (1) Glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid were added to a four-necked flask equipped with a water separator, and an ethanol-water mixture was added. The mixture was stirred until completely dissolved. Under nitrogen protection, the temperature was raised to 75°C and refluxed for 5 h. During the reaction, the generated water was continuously removed through the water separator. After the reaction was completed, the ethanol-water mixture was removed by vacuum distillation to obtain a brown, viscous branched prepolymer. The mass ratio of glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid was 1:3:0.2, the mass ratio of ethanol-water mixed solvent to glycerol was 9:1, and the pressure and temperature of vacuum distillation were 0.01 MPa and 60℃, respectively.

[0063] (2) Add L-arginine to the branched prepolymer, heat to 80°C, and stir under nitrogen protection for 5 h to carry out melt amidation reaction. After the reaction is completed, cool to 30°C, add deionized water, stir thoroughly to dissolve the unreacted L-arginine, then filter, collect the insoluble matter, and wash with deionized water 3 times to remove residual L-arginine to obtain a pale yellow branched body; The mass ratio of L-arginine to branched prepolymer is 2:1, and the mass ratio of deionized water to branched prepolymer is 8:1.

[0064] (3) The branched body was dispersed in an ethanol-water mixed solvent, oleic acid was added, the temperature was raised to 80°C, and the reaction was stirred for 3 h. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was cooled to room temperature to obtain the demulsifier. The mass ratio of oleic acid to branched body is 2:1, and the pressure and temperature of vacuum distillation are 0.01 MPa and 40℃, respectively.

[0065] Comparative Example 1 A demulsifier and its preparation method are different from those in Example 1, except that L-arginine is not added during preparation.

[0066] Specifically, the preparation method includes the following steps: (1) Glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid were added to a four-necked flask equipped with a water separator, and an ethanol-water mixture was added. The mixture was stirred until completely dissolved. Under nitrogen protection, the temperature was raised to 80°C and refluxed for 6 h. During the reaction, the generated water was continuously removed through the water separator. After the reaction was completed, the ethanol-water mixture was removed by vacuum distillation to obtain a brown, viscous branched product. The mass ratio of glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid is 1:4:0.2, the mass ratio of ethanol-water mixed solvent to glycerol is 8:1, and the pressure and temperature of vacuum distillation are 0.01 MPa and 50℃, respectively.

[0067] (2) The branched body was dispersed in an ethanol-water mixed solvent, oleic acid was added, the temperature was raised to 85°C, and the reaction was stirred for 3 h. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was cooled to room temperature to obtain the demulsifier. The mass ratio of oleic acid to branched body is 3:1, and the pressure and temperature of vacuum distillation are 0.01 MPa and 50℃, respectively.

[0068] Comparative Example 2 A demulsifier and its preparation method are disclosed, which differ from Example 1 only in that oleic acid is not added during preparation.

[0069] Specifically, the preparation method includes the following steps: (1) Glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid were added to a four-necked flask equipped with a water separator, and an ethanol-water mixture was added. The mixture was stirred until completely dissolved. Under nitrogen protection, the temperature was raised to 80°C and refluxed for 6 h. During the reaction, the generated water was continuously removed through the water separator. After the reaction was completed, the ethanol-water mixture was removed by vacuum distillation to obtain a brown, viscous branched prepolymer. The mass ratio of glycerol, p-hydroxyisophthalic acid, and p-toluenesulfonic acid is 1:4:0.2, the mass ratio of ethanol-water mixed solvent to glycerol is 8:1, and the pressure and temperature of vacuum distillation are 0.01 MPa and 50℃, respectively.

[0070] (2) L-arginine was added to the branched prepolymer, the temperature was raised to 80°C, and the mixture was stirred for 4 h under nitrogen protection to carry out the melt amidation reaction. After the reaction was completed, the mixture was cooled to 30°C, deionized water was added, and the mixture was stirred thoroughly to dissolve the unreacted L-arginine. The mixture was then filtered, the insoluble matter was collected, and the mixture was washed three times with deionized water to remove the residual L-arginine, thus obtaining the pale yellow branched body, which is the demulsifier. The mass ratio of L-arginine to branched prepolymer is 2:1, and the mass ratio of deionized water to branched prepolymer is 8:1.

[0071] Test methods Demulsification rate test: High-salt crude oil emulsion (salt concentration of 10%, COD concentration of 20 g / L) was used as the test object, and the prepared demulsifier was added at a concentration of 300 mg / L. The sample was placed in a constant temperature water bath at 60℃ and allowed to settle for 30 min. The amount of water removed at different time points was recorded, and the dehydration rate (i.e., demulsification rate) was calculated.

[0072] The demulsification rate test refers to SY / T 5280 "General Technical Conditions for Crude Oil Demulsifiers" and SY / T 5281 "Performance Test Method for Crude Oil Demulsifiers (Bottle Test Method)".

[0073] The test results are shown in Table 1.

[0074] Table 1 The test results show that: (1) As can be seen from Examples 1-4, the demulsifier prepared by the present invention through a specific preparation method can achieve efficient demulsification of high-salt crude oil emulsions and has the advantages of low toxicity, high demulsification efficiency, wide pH range and biodegradability.

[0075] (3) It can be seen from the comparison between Example 1 and Comparative Examples 1-2 that the demulsifier prepared by the specific method of the present invention is not used, and the demulsification effect is worse.

[0076] In summary, this invention utilizes a three-step reaction to synergistically assemble multiple bio-based raw materials such as glycerol, p-hydroxyisophthalic acid, and arginine, simultaneously achieving the integration of aromatic rings, amphoteric groups, and hyperbranched structures, thus avoiding the functional limitations of single bio-based raw materials. The demulsifier molecule of this invention simultaneously contains amine, carboxyl, and guanidine groups (triple amphoteric sites), making it suitable for both O / W and W / O emulsions. The emulsifier of this invention also possesses a hyperbranched structure, which can reduce the toxicity of the demulsifier.

[0077] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a demulsifier, characterized in that, The preparation method includes the following steps: (1) Glycerol and p-hydroxyisophthalic acid are mixed and esterified to obtain a branched prepolymer; (2) The branched prepolymer is mixed with L-arginine and subjected to an amidation reaction to obtain the branched product; (3) The branched body is mixed with a carboxyl-containing end-capping agent and subjected to an amidation reaction to obtain the demulsifier.

2. The preparation method according to claim 1, characterized in that, An acidic catalyst is added during the mixing process described in step (1); Preferably, the acidic catalyst comprises p-toluenesulfonic acid; Preferably, the mass ratio of glycerol to acidic catalyst is 1:(0.05-0.4).

3. The preparation method according to claim 1 or 2, characterized in that, The mixing step in step (1) is to mix glycerol and p-hydroxyisophthalic acid in a solvent; Preferably, the solvent comprises a mixture of ethanol and water; Preferably, the mass ratio of the mixed solvent of ethanol and water to glycerol is (5-10):1; Preferably, in the mixed solvent of ethanol and water, the mass ratio of ethanol to water is (0.8-2.4):1; Preferably, the mass ratio of glycerol to p-hydroxyisophthalic acid is 1:(2-5).

4. The preparation method according to any one of claims 1-3, characterized in that, The esterification reaction in step (1) is carried out under nitrogen protection; Preferably, the reaction temperature of the esterification reaction in step (1) is 70-90℃; Preferably, the reaction time of the esterification reaction in step (1) is 4-8 h; Preferably, the esterification reaction in step (1) further includes a post-treatment step, wherein the post-treatment method includes vacuum distillation; Preferably, the temperature of vacuum distillation in step (1) is 30-65°C; Preferably, the pressure of the vacuum distillation in step (1) is 0.01-0.1 MPa.

5. The preparation method according to any one of claims 1-4, characterized in that, The mass ratio of L-arginine to branched prepolymer is (0.5-4):1; Preferably, after the amidation reaction in step (2), a post-treatment step is further included. The post-treatment method includes cooling the mixture to 20-50°C, adding deionized water, and filtering to remove the insoluble matter. Preferably, the mass ratio of the deionized water to the branched prepolymer is (3-10):

1.

6. The preparation method according to any one of claims 1-5, characterized in that, The reaction temperature for the amidation reaction in step (2) is 70-95℃; Preferably, the reaction time for the amidation reaction in step (2) is 3-6 h; Preferably, the amidation reaction in step (2) is carried out under nitrogen protection.

7. The preparation method according to any one of claims 1-6, characterized in that, The carboxyl-containing end-capping agent in step (3) includes oleic acid; Preferably, the mass ratio of oleic acid to branched body is (1-4):

1.

8. The preparation method according to any one of claims 1-7, characterized in that, The reaction temperature for the amidation reaction in step (3) is 70-90℃; Preferably, the reaction time for the amidation reaction in step (3) is 2-5 h; Preferably, the mixing step in step (3) involves dispersing the branched body in a solvent and then adding a carboxyl-containing end-capping agent; Preferably, the solvent comprises water or a mixture of ethanol and water; Preferably, after the amidation reaction in step (3), a post-treatment step is further included, wherein the post-treatment method includes vacuum distillation; Preferably, the temperature of the vacuum distillation in step (3) is 30-60℃; Preferably, the pressure of the vacuum distillation in step (3) is 0.01-0.1 MPa.

9. A demulsifier, characterized in that, The demulsifier is prepared by the preparation method according to any one of claims 1-8.

10. The application of the demulsifier as described in claim 9 in oil-water separation.

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