Gas-sensitive macromolecular surfactants and their application in the treatment of high-salt oily sludge

Abstract

This invention relates to a gas-sensitive macromolecular surfactant and its application in the treatment of high-salt oily sludge. The gas-sensitive macromolecular surfactant is prepared by free radical polymerization using acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, long-chain alkyl methacrylate, and dialkylaminoethyl methacrylate as raw materials. The introduction of the 2-acrylamido-2-methylpropanesulfonic acid monomer endows the surfactant with excellent high-salt resistance, making it suitable for high-salt oily sludge systems with a total water-soluble salt content ≥5 wt%. The cleaning solution formulated with the gas-sensitive macromolecular surfactant exhibits highly efficient cleaning capabilities for high-salt oily sludge. After cleaning the high-salt oily sludge, alternating introduction of CO2 and N2 into the oil-containing emulsion system can regulate the hydrophilic-hydrophobic properties of the gas-sensitive macromolecular surfactant in the cleaning solution, thereby achieving separation of the cleaning solution containing the macromolecular surfactant from the oil phase. This allows the gas-sensitive macromolecular surfactant to be recycled for cleaning high-salt oily sludge.

Description

Technical Field

[0001] This invention relates to the field of harmless treatment technology for high-salt oily sludge, specifically to a gas-sensitive macromolecular surfactant and its application in the treatment of high-salt oily sludge. Background Technology

[0002] Oily sludge is mainly generated throughout the entire process of petroleum extraction, refining, and chemical production. Due to the ecotoxicity and environmental hazards of its petroleum hydrocarbon components, it has been explicitly listed as a Class HW08 hazardous waste in the National Hazardous Waste List. In recent years, my country's petroleum resource development has continued to shift towards coastal oilfields and high-salinity oilfields, with the scale of development and extraction intensity constantly increasing, resulting in a significant year-on-year increase in the production of oily sludge. Compared to conventional onshore oilfield sludge, sludge from coastal and high-salinity formations has a significantly higher salt content, with its total salt content (TSC) generally exceeding 5 wt%. This makes it highly susceptible to forming stable and difficult-to-dissolve high-salt-oil-sludge emulsion systems, leading to a significant reduction in the effectiveness of traditional treatment technologies.

[0003] Chemical thermal washing is currently the mainstream technology for treating medium-to-high concentration oily sludge. Due to its ease of operation and wide applicability, it has been widely used in the industry, but it also has several significant shortcomings. On the one hand, commonly used small-molecule surfactants (such as sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and hexadecyltrimethylammonium bromide) are not very effective at eluting heavy components such as gums and asphaltenes in total petroleum hydrocarbons, making it difficult to achieve deep purification of oily sludge. On the other hand, these small-molecule surfactants are prone to salting out in high-salt environments and are easily adsorbed by oily sludge particles, resulting in losses. Furthermore, their hydrophilic groups interact with salt ions in the system through electrostatic shielding, leading to an increase in the critical micelle concentration of the surfactant and a significant decrease in emulsification and solubilization capabilities, making them unsuitable for treating high-salt oily sludge. To overcome these limitations of small-molecule surfactants, the cleaning performance of large-molecule surfactants with strong hydrophobic structures has gradually become a research hotspot in the industry. Macromolecular surfactants, through their unique micellar solubilization and steric hindrance effects, effectively address the industry pain point of small-molecule surfactants' inability to remove heavy components such as high-carbon alkanes, gums, and asphaltenes. However, most existing macromolecular surfactants are not specifically designed for high-salt environments, and still suffer from insufficient stability and reduced cleaning efficiency in high-salt systems. Furthermore, their preparation processes are complex and costly, hindering large-scale application. Therefore, developing low-cost, high-salt-resistant macromolecular surfactants and their corresponding cleaning processes has become a key technical challenge urgently needing to be solved in the oily sludge treatment industry. Summary of the Invention

[0004] The purpose of this invention is to provide a gas-sensitive macromolecular surfactant for use in the treatment of high-salt oil sludge, wherein the gas-sensitive macromolecular surfactant can be recycled after cleaning the oil sludge.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A gas-sensitive macromolecular surfactant is prepared by free radical polymerization of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, long-chain alkyl methacrylate and dialkylaminoethyl methacrylate as raw materials in a mass ratio of (10~15):(1~5):(1~5):(10~15).

[0006] The chemical structural formula of the gas-sensitive macromolecular surfactant described in this invention is as follows:

[0007] Where w, x, y, and z represent the degree of polymerization, w = 450~1600, x = 80~350, y = 60~300, z = 450~1600; m = 12~18, n = 1~2, and the total molecular weight is 10. 3 ~10 6 g / mol.

[0008] The long-chain alkyl methacrylates described in this invention may be at least one of dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, or octadecyl methacrylate. The dialkylaminoethyl methacrylate may be at least one of dimethylaminoethyl methacrylate or diethylaminoethyl methacrylate.

[0009] The preparation process of the gas-sensitive macromolecular surfactant of this invention is as follows: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, long-chain alkyl methacrylate, and dialkylaminoethyl methacrylate are dissolved in deionized water at a mass ratio of (10~15):(1~5):(1~5):(10~15). After complete dissolution, the pH is adjusted to 6~9. A persulfate or azo initiator is added, wherein the amount of initiator accounts for 0.1~1 wt% of the total mass of all monomers. The persulfate initiator can be at least one of sodium persulfate, potassium persulfate, or ammonium persulfate, and the azo initiator can be at least one of azobisisobutyronitrile or azodicyanovalerate. The total monomers refer to the sum of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, long-chain alkyl methacrylate, and dialkylaminoethyl methacrylate. N2 is then introduced to remove oxygen for 20~40 min, followed by reaction at 50~90℃ for 6~12 h. After the reaction was completed, the product was separated and dried for 12-36 h to obtain the gas-sensitive macromolecular surfactant.

[0010] Applications of the above-mentioned gas-sensitive macromolecular surfactants in the treatment of high-salt oily sludge: The aforementioned gas-sensitive macromolecular surfactant was formulated into a cleaning solution of 0.1–1 wt%, which was then injected into a cleaning device containing high-salt oil sludge. The cleaning was carried out at 55–85°C for 0.5–2 h. The high-salt oil sludge was defined as oil sludge with a total water-soluble salt content ≥5 wt%, and the mass ratio of the cleaning solution to the high-salt oil sludge was (10–20):1. After cleaning, solid-liquid separation was performed using a centrifuge to obtain an oil-containing emulsion and de-oiled sludge. The oil-containing emulsion contained gas-sensitive macromolecular surfactants and emulsified oil droplets. The petroleum hydrocarbon content in the de-oiled sludge was determined, and the removal efficiency (RE) was calculated.

[0011] CO2 is introduced into the oil-containing emulsion at a volume ratio of (1~5):1, and the aeration time is 20~40 min to ensure that the pH value of the emulsion drops to 5.5~7.5. Under these conditions, the emulsion breaks down and separates into an oil phase and an aqueous phase. After the two phases are separated, N2 is introduced into the aqueous phase at a ratio of (2~10):1 between the volume of the aeration and the volume of the aqueous phase. The aeration time is 20~40 min. After the pH value of the aqueous phase rises to 8.5~9.5, a gas-sensitive macromolecular surfactant is added at a rate of 3~5 wt% of the initial dosage. Then, water is added to restore the volume of the cleaning solution to the initial dosage. The solution is then recycled for cleaning high-salt sludge.

[0012] Compared with the prior art, the beneficial effects of the present invention are: The gas-sensitive macromolecular surfactant provided by this invention is prepared by free radical polymerization of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, long-chain alkyl methacrylate, and dialkylaminoethyl methacrylate. By controlling the monomer ratio, 2-acrylamido-2-methylpropanesulfonic acid monomer is introduced into the framework to ensure the synergistic effect of gas-sensitive response and high-salt resistance. The 2-acrylamido-2-methylpropanesulfonic acid monomer endows it with excellent high-salt resistance, maintaining a stable micelle structure and cleaning activity in high-salt sludge systems, and efficiently eluting heavy petroleum hydrocarbon components. After cleaning high-salt sludge, alternating introduction of CO2 and N2 into the oil-containing emulsion system can regulate the hydrophilic-hydrophobic properties of the gas-sensitive macromolecular surfactant in the cleaning solution, achieving stratification and separation of the cleaning solution containing the macromolecular surfactant from the oil phase, thereby realizing surfactant regeneration and recycling.

[0013] The performance advantages of gas-sensitive macromolecular surfactants for cleaning high-salt oil sludge are shown in Table 1.

[0014] Table 1. Performance advantages of gas-sensitive macromolecular surfactants

[0015] Note: Among them, the gas-sensitive macromolecular surfactant is synthesized by free radical polymerization of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, octadecyl methacrylate and diethylaminoethyl methacrylate in a mass ratio of 10:5:2:10; the non-gas-sensitive macromolecular surfactant is obtained by free radical polymerization of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, octadecyl methacrylate and 2-(diisopropylamino)ethyl methacrylate in a mass ratio of 10:5:2:10. Detailed Implementation

[0016] The present invention will be further illustrated below with specific embodiments, which will help to understand the present invention, but does not limit the scope of the present invention.

[0017] The high-salt oily sludge samples used in the following examples and comparative examples were all taken from different batches of oily sludge actually generated in the coastal area of ​​the Dagang Oilfield in Tianjin, which are typical high-salt oily sludge from the Bohai Rim region. The total water-soluble salt content mentioned in this invention is determined as follows: first, sludge leachate is prepared according to the standard method—"Leaching Toxicity of Solid Waste: Horizontal Oscillation Method" (HJ 557—2010), and then the soluble salt content in the leachate is quantitatively determined by gravimetric method.

[0018] Example 1 Preparation of gas-sensitive macromolecular surfactant: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl methacrylate, and diethylaminoethyl methacrylate were dissolved in deionized water at a mass ratio of 10:2:2:10. After complete dissolution, the pH was adjusted to 6.5. Ammonium persulfate (0.5 wt% of the total monomer mass) was added, and the mixture was stirred for 10 min. N2 was then introduced to remove oxygen for 30 min, followed by reaction at 60 °C for 6 h. After the reaction was completed, the product was separated and dried for 24 h to obtain the gas-sensitive macromolecular surfactant.

[0019] Application of gas-sensitive macromolecular surfactants in the treatment of high-salt oily sludge: The prepared macromolecular surfactant was formulated into a cleaning solution and added to the cleaning device at a mass ratio of 20:1 with oily sludge having a total water-soluble salt content of 6.2 wt%. The cleaning was carried out at 70℃ for 1 h, with the concentration of the cleaning solution being 0.1 wt%. After cleaning, solid-liquid separation was achieved by centrifugation, yielding an oily emulsion and deoiled sludge. The oil removal rate was calculated to be 72.3% by measuring the petroleum hydrocarbon content in the deoiled sludge.

[0020] CO2 was introduced into the above oil-containing emulsion, and the gas-liquid volume ratio was controlled at 3:1. After continuous aeration for 30 min, the pH of the system dropped to 5.5, and the emulsion rapidly demulsified and separated into two phases: oil and water.

[0021] After the two phases have separated, N2 is introduced into the aqueous phase at a gas-liquid volume ratio of 5:1 for 30 minutes, causing the system pH to rise to 8.5. Subsequently, 3 wt% of the initial dosage of a gas-sensitive macromolecular surfactant is added, and water is replenished until the volume of the cleaning solution matches the initial dosage. The resulting regenerated cleaning solution can be directly used for cleaning the next batch of high-salt sludge.

[0022] This gas-sensitive macromolecular surfactant maintained an oil removal rate of 70.1% after 5 cycles and remained at 69.3% after 10 cycles, indicating that it has stable oil removal performance in high-salt systems.

[0023] Example 2 Preparation of gas-sensitive macromolecular surfactant: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, tetradecyl methacrylate and diethylaminoethyl methacrylate were dissolved in deionized water at a mass ratio of 10:2:2:10. After complete dissolution, the pH was adjusted to 6.5. Ammonium persulfate was added at a mass of 0.5 wt% of the total monomers. After stirring for 10 min, N2 was introduced to remove oxygen for 30 min. The reaction was then carried out at 60 °C for 6 h. After the reaction was completed, the product was separated and dried for 24 h to obtain the gas-sensitive macromolecular surfactant.

[0024] Application of gas-sensitive macromolecular surfactants in the treatment of high-salt oily sludge: The prepared macromolecular surfactant was formulated into a cleaning solution and added to the cleaning device at a mass ratio of 20:1 with oily sludge having a total water-soluble salt content of 6.2 wt%. The cleaning was carried out at 60℃ for 1 h, with the concentration of the cleaning solution being 0.1 wt%. After cleaning, solid-liquid separation was achieved by centrifugation, yielding an oily emulsion and deoiled sludge. The oil removal rate was calculated to be 69.5% by measuring the petroleum hydrocarbon content in the deoiled sludge.

[0025] CO2 was introduced into the above oil-containing emulsion, and the gas-liquid volume ratio was controlled at 3:1. After continuous aeration for 30 min, the pH of the system dropped to 5.5, and the emulsion rapidly demulsified and separated into two phases: oil and water.

[0026] After the two phases have separated, N2 is introduced into the aqueous phase at a gas-liquid volume ratio of 5:1 for 30 minutes, causing the system pH to rise to 8.5. Subsequently, 3 wt% of the initial dosage of a gas-sensitive macromolecular surfactant is added, and water is replenished until the volume of the cleaning solution matches the initial dosage. The resulting regenerated cleaning solution can be directly used for cleaning the next batch of high-salt sludge.

[0027] This gas-sensitive macromolecular surfactant maintained an oil removal rate of 67.5% after 5 cycles and remained at 66.1% after 10 cycles, indicating that it has stable oil removal performance in high-salt systems.

[0028] Example 3 Preparation of gas-sensitive macromolecular surfactant: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl methacrylate, and diethylaminoethyl methacrylate were dissolved in deionized water at a mass ratio of 15:2:2:15. After complete dissolution, the pH was adjusted to 6.5. Ammonium persulfate (0.5 wt% of the total monomer mass) was added, and the mixture was stirred for 10 min. N2 was then introduced to remove oxygen for 30 min, followed by reaction at 60 °C for 6 h. After the reaction was completed, the product was separated and dried for 24 h to obtain the gas-sensitive macromolecular surfactant.

[0029] Application of gas-sensitive macromolecular surfactants in the treatment of high-salt oily sludge: The prepared macromolecular surfactant was formulated into a cleaning solution and added to the cleaning device at a mass ratio of 20:1 with oily sludge having a total water-soluble salt content of 6.2 wt%. The cleaning was carried out at 60℃ for 1 h, with the concentration of the cleaning solution being 0.2 wt%. After cleaning, solid-liquid separation was achieved by centrifugation, yielding an oily emulsion and deoiled sludge. The oil removal rate was calculated to be 74.1% by measuring the petroleum hydrocarbon content in the deoiled sludge.

[0030] When CO2 is introduced into the above oil-containing emulsion and the gas-liquid volume ratio is controlled at 3:1, the system pH drops to 6.5 after continuous aeration for 30 min. The emulsion quickly breaks down and separates into two phases: oil and water.

[0031] After the two phases have separated, N2 is introduced into the aqueous phase at a gas-liquid volume ratio of 5:1 for 30 minutes, causing the system pH to rise to 9.5. Subsequently, 3 wt% of the initial dosage of a gas-sensitive macromolecular surfactant is added, and water is added until the volume of the cleaning solution matches the initial dosage. The resulting regenerated cleaning solution can be directly used for cleaning the next batch of high-salt sludge.

[0032] This gas-sensitive macromolecular surfactant maintained an oil removal rate of 72.5% after 5 cycles and 71.3% after 10 cycles, indicating that it has stable oil removal performance in high-salt systems.

[0033] Example 4 Preparation of gas-sensitive macromolecular surfactant: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl methacrylate and dimethylaminoethyl methacrylate were dissolved in deionized water at a mass ratio of 15:2:2:15. After complete dissolution, the pH was adjusted to 6.5. Ammonium persulfate was added at 0.5 wt% of the total monomer mass. After stirring for 10 min, N2 was introduced to remove oxygen for 30 min. The reaction was then carried out at 60 °C for 6 h. After the reaction was completed, the product was separated and dried for 24 h to obtain the gas-sensitive macromolecular surfactant.

[0034] Application of gas-sensitive macromolecular surfactants in the treatment of high-salt oily sludge: The prepared macromolecular surfactant was formulated into a cleaning solution and added to the cleaning device at a mass ratio of 20:1 with oily sludge having a total water-soluble salt content of 6.2 wt%. The cleaning was carried out at 60℃ for 1 h, with the concentration of the cleaning solution being 0.1 wt%. After cleaning, solid-liquid separation was achieved by centrifugation, yielding an oily emulsion and deoiled sludge. The oil removal rate was calculated to be 71.7% by measuring the petroleum hydrocarbon content in the deoiled sludge.

[0035] When CO2 is introduced into the above oil-containing emulsion and the gas-liquid volume ratio is controlled at 3:1, the system pH drops to 6.5 after continuous aeration for 30 min. The emulsion quickly breaks down and separates into two phases: oil and water.

[0036] After the two phases have separated, N2 is introduced into the aqueous phase at a gas-liquid volume ratio of 5:1 for 30 minutes, causing the system pH to rise to 9.5. Subsequently, 5 wt% of the initial dosage of a gas-sensitive macromolecular surfactant is added, and water is added until the volume of the cleaning solution is consistent with the initial dosage. The resulting regenerated cleaning solution can be directly used for cleaning the next batch of high-salt sludge.

[0037] This gas-sensitive macromolecular surfactant achieved an oil removal rate of 69.1% after 5 cycles and maintained at 66.8% after 10 cycles, indicating that it has stable oil removal performance in high-salt systems.

[0038] Example 5 Preparation of gas-sensitive macromolecular surfactant: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, octadecyl methacrylate, and diethylaminoethyl methacrylate were dissolved in deionized water at a mass ratio of 10:5:2:10. After complete dissolution, the pH was adjusted to 6.5. Ammonium persulfate was added at 0.5 wt% of the total monomer mass. The mixture was stirred for 10 min, and then N2 was introduced to remove oxygen for 30 min. The reaction was then carried out at 60 °C for 6 h. After the reaction was completed, the product was separated and dried for 24 h to obtain the gas-sensitive macromolecular surfactant.

[0039] Application of gas-sensitive macromolecular surfactants in the treatment of high-salt oily sludge: The prepared macromolecular surfactant was formulated into a cleaning solution and added to the cleaning device at a mass ratio of 20:1 with oily sludge having a total water-soluble salt content of 6.2 wt%. The cleaning was carried out at 60℃ for 1 h, with the concentration of the cleaning solution being 0.1 wt%. After cleaning, solid-liquid separation was achieved by centrifugation, yielding an oily emulsion and deoiled sludge. The oil removal rate was calculated to be 79.2% by measuring the petroleum hydrocarbon content in the deoiled sludge.

[0040] CO2 was introduced into the above oil-containing emulsion, and the gas-liquid volume ratio was controlled at 3:1. After continuous aeration for 30 min, the pH of the system dropped to 5.5, and the emulsion rapidly demulsified and separated into two phases: oil and water.

[0041] After the two phases have separated, N2 is introduced into the aqueous phase at a gas-liquid volume ratio of 5:1 for 30 minutes, causing the system pH to rise to 8.5. Subsequently, 3 wt% of the initial dosage of a gas-sensitive macromolecular surfactant is added, and water is replenished until the volume of the cleaning solution matches the initial dosage. The resulting regenerated cleaning solution can be directly used for cleaning the next batch of high-salt sludge.

[0042] This gas-sensitive macromolecular surfactant maintained an oil removal rate of 76.5% after 5 cycles and 73.8% after 10 cycles, indicating that it has stable oil removal performance in high-salt systems.

[0043] Example 6 Preparation of gas-sensitive macromolecular surfactant: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl methacrylate and diethylaminoethyl methacrylate were dissolved in deionized water at a mass ratio of 10:5:2:10. After complete dissolution, the pH was adjusted to 6.5. Ammonium persulfate was added at a mass of 0.5 wt% of the total monomers. After stirring for 10 min, N2 was introduced to remove oxygen for 30 min. The reaction was then carried out at 60 °C for 6 h. After the reaction was completed, the product was separated and dried for 24 h to obtain the gas-sensitive macromolecular surfactant.

[0044] Application of gas-sensitive macromolecular surfactants in the treatment of high-salt oily sludge: The prepared macromolecular surfactant was formulated into a cleaning solution and added to the cleaning device at a mass ratio of 20:1 with oily sludge containing 7.5 wt% water-soluble total salt. The cleaning solution was prepared at 60℃ for 1 h, with a concentration of 0.1 wt%. After cleaning, solid-liquid separation was achieved by centrifugation, yielding an oily emulsion and deoiled sludge. The oil removal rate was calculated to be 77.3% by measuring the petroleum hydrocarbon content in the deoiled sludge.

[0045] CO2 was introduced into the above oil-containing emulsion, and the gas-liquid volume ratio was controlled at 3:1. After continuous aeration for 30 min, the pH of the system dropped to 5.5, and the emulsion rapidly demulsified and separated into two phases: oil and water.

[0046] After the two phases have separated, N2 is introduced into the aqueous phase at a gas-liquid volume ratio of 5:1 for 30 minutes, causing the system pH to rise to 8.5. Subsequently, 3 wt% of the initial dosage of a gas-sensitive macromolecular surfactant is added, and water is replenished until the volume of the cleaning solution matches the initial dosage. The resulting regenerated cleaning solution can be directly used for cleaning the next batch of high-salt sludge.

[0047] This gas-sensitive macromolecular surfactant maintained an oil removal rate of 74.5% after 5 cycles and 72.7% after 10 cycles, indicating that it has stable oil removal performance in high-salt systems.

[0048] Example 7 Preparation of gas-sensitive macromolecular surfactant: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, tetradecyl methacrylate and diethylaminoethyl methacrylate were added to deionized water in a mass ratio of 10:2:5:10. After complete dissolution, the pH was adjusted to 6.5. Ammonium persulfate was added at 0.5 wt% of the total monomer mass. After stirring for 10 min, N2 was introduced to remove oxygen for 30 min. The reaction was then carried out at 60 °C for 6 h. After the reaction was completed, the product was separated and dried for 24 h to obtain the gas-sensitive macromolecular surfactant.

[0049] Application of gas-sensitive macromolecular surfactants in the treatment of high-salt oily sludge: The prepared macromolecular surfactant was formulated into a cleaning solution and added to the cleaning device at a mass ratio of 20:1 with oily sludge containing 7.5 wt% water-soluble total salt. The cleaning solution was prepared at 60℃ for 1 h, with a concentration of 0.1 wt%. After cleaning, solid-liquid separation was achieved by centrifugation, yielding an oily emulsion and deoiled sludge. The oil removal rate was calculated to be 68.4% by measuring the petroleum hydrocarbon content in the deoiled sludge.

[0050] CO2 was introduced into the above oil-containing emulsion, and the gas-liquid volume ratio was controlled at 3:1. After continuous aeration for 30 min, the pH of the system dropped to 5.5, and the emulsion rapidly demulsified and separated into two phases: oil and water.

[0051] After the two phases have separated, N2 is introduced into the aqueous phase at a gas-liquid volume ratio of 5:1 for 30 minutes, causing the system pH to rise to 8.5. Subsequently, 3 wt% of the initial dosage of a gas-sensitive macromolecular surfactant is added, and water is replenished until the volume of the cleaning solution matches the initial dosage. The resulting regenerated cleaning solution can be directly used for cleaning the next batch of high-salt sludge.

[0052] This gas-sensitive macromolecular surfactant maintained an oil removal rate of 67.7% after 5 cycles and remained at 64.3% after 10 cycles, indicating that it has stable oil removal performance in high-salt systems.

[0053] Example 8 Preparation of gas-sensitive macromolecular surfactant: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, octadecyl methacrylate, and diethylaminoethyl methacrylate were dissolved in deionized water at a mass ratio of 10:2:5:10. After complete dissolution, the pH was adjusted to 6.5. Ammonium persulfate (0.5 wt% of the total monomer mass) was added, and the mixture was stirred for 10 min. N2 was then introduced to remove oxygen for 30 min, followed by reaction at 60 °C for 6 h. After the reaction was completed, the product was separated and dried for 24 h to obtain the gas-sensitive macromolecular surfactant.

[0054] Application of gas-sensitive macromolecular surfactants in the treatment of high-salt oily sludge: The prepared macromolecular surfactant was formulated into a cleaning solution and added to the cleaning device at a mass ratio of 20:1 with oily sludge containing 7.5 wt% water-soluble total salt. The cleaning solution was prepared at 60℃ for 1 h, with a concentration of 0.3 wt%. After cleaning, solid-liquid separation was achieved by centrifugation, yielding an oily emulsion and deoiled sludge. The oil removal rate was calculated to be 76.4% by measuring the petroleum hydrocarbon content in the deoiled sludge.

[0055] When CO2 is introduced into the above oil-containing emulsion and the gas-liquid volume ratio is controlled at 3:1, the system pH drops to 6.5 after continuous aeration for 30 min. The emulsion quickly breaks down and separates into two phases: oil and water.

[0056] After the two phases have separated, N2 is introduced into the aqueous phase at a gas-liquid volume ratio of 5:1 for 30 minutes, causing the system pH to rise to 9.5. Subsequently, 3 wt% of the initial dosage of a gas-sensitive macromolecular surfactant is added, and water is added until the volume of the cleaning solution matches the initial dosage. The resulting regenerated cleaning solution can be directly used for cleaning the next batch of high-salt sludge.

[0057] This gas-sensitive macromolecular surfactant maintained an oil removal rate of 74.8% after 5 cycles and 70.7% after 10 cycles, indicating that it has stable oil removal performance in high-salt systems.

[0058] Example 9 Preparation of gas-sensitive macromolecular surfactant: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyl methacrylate, and diethylaminoethyl methacrylate were dissolved in deionized water at a mass ratio of 12:2:2:12. After complete dissolution, the pH was adjusted to 6.5. Ammonium persulfate (0.5 wt% of the total monomer mass) was added, and the mixture was stirred for 10 min. N2 was then introduced to remove oxygen for 30 min, followed by reaction at 60 °C for 6 h. After the reaction was completed, the product was separated and dried for 24 h to obtain the gas-sensitive macromolecular surfactant.

[0059] Application of gas-sensitive macromolecular surfactants in the treatment of high-salt oily sludge: The prepared macromolecular surfactant was formulated into a cleaning solution and added to the cleaning device at a mass ratio of 15:1 with oily sludge containing 7.5 wt% water-soluble total salt. The cleaning solution was prepared at 70℃ for 1 h, with a concentration of 0.1 wt%. After cleaning, solid-liquid separation was achieved by centrifugation, yielding an oily emulsion and deoiled sludge. The oil removal rate was calculated to be 74.9% by measuring the petroleum hydrocarbon content in the deoiled sludge.

[0060] CO2 was introduced into the above oil-containing emulsion, and the gas-liquid volume ratio was controlled at 3:1. After continuous aeration for 30 min, the pH of the system dropped to 5.5, and the emulsion rapidly demulsified and separated into two phases: oil and water.

[0061] After the two phases have separated, N2 is introduced into the aqueous phase at a gas-liquid volume ratio of 5:1 for 30 minutes, causing the system pH to rise to 8.5. Subsequently, 3 wt% of the initial dosage of a gas-sensitive macromolecular surfactant is added, and water is replenished until the volume of the cleaning solution matches the initial dosage. The resulting regenerated cleaning solution can be directly used for cleaning the next batch of high-salt sludge.

[0062] This gas-sensitive macromolecular surfactant maintained an oil removal rate of 73.5% after 5 cycles and 70.9% after 10 cycles, indicating that it has stable oil removal performance in high-salt systems.

[0063] Example 10 Preparation of gas-sensitive macromolecular surfactant: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, tetradecyl methacrylate and diethylaminoethyl methacrylate were added to deionized water in a mass ratio of 12:2:2:12. After complete dissolution, the pH was adjusted to 6.5. Ammonium persulfate was added at a mass of 0.5 wt% of the total monomers. After stirring for 10 min, N2 was introduced to remove oxygen for 30 min. The reaction was then carried out at 60 °C for 6 h. After the reaction was completed, the product was separated and then dried for 24 h to obtain the gas-sensitive macromolecular surfactant.

[0064] Application of gas-sensitive macromolecular surfactants in the treatment of high-salt oily sludge: The prepared macromolecular surfactant was formulated into a cleaning solution and added to the cleaning device at a mass ratio of 15:1 with oily sludge containing 7.5 wt% water-soluble total salt. The cleaning solution was prepared at 60℃ for 1 h, with a concentration of 0.1 wt%. After cleaning, solid-liquid separation was achieved by centrifugation, yielding an oily emulsion and deoiled sludge. The oil removal rate was calculated to be 70.4% by measuring the petroleum hydrocarbon content in the deoiled sludge.

[0065] CO2 was introduced into the above oil-containing emulsion, and the gas-liquid volume ratio was controlled at 3:1. After continuous aeration for 30 min, the pH of the system dropped to 5.5, and the emulsion rapidly demulsified and separated into two phases: oil and water.

[0066] After the two phases have separated, N2 is introduced into the aqueous phase at a gas-liquid volume ratio of 5:1 for 30 minutes, causing the system pH to rise to 8.5. Subsequently, 3 wt% of the initial dosage of a gas-sensitive macromolecular surfactant is added, and water is replenished until the volume of the cleaning solution matches the initial dosage. The resulting regenerated cleaning solution can be directly used for cleaning the next batch of high-salt sludge.

[0067] This gas-sensitive macromolecular surfactant maintained an oil removal rate of 67.8% after 5 cycles and remained at 65.9% after 10 cycles, indicating that it has stable oil removal performance in high-salt systems.

[0068] Comparative Example 1 Preparation of macromolecular surfactants: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, octadecyl methacrylate, and N-vinylimidazolium were dissolved in deionized water in a mass ratio of 10:5:2:10. After complete dissolution, the pH was adjusted to 7.5. Ammonium persulfate (0.1 wt% of the total monomers) was added, and the mixture was stirred for 10 min. N2 was then introduced for deoxygenation for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0069] Application of macromolecular surfactants in the treatment of high-salt oily sludge: A 0.3 wt% cleaning solution of the macromolecular surfactant was prepared and mixed with oily sludge with a total water-soluble salt content of 7.5 wt% at a mass ratio of 20:1. The mixture was then cleaned at 75 ℃ for 2 h. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge, respectively. The content of petroleum hydrocarbons in the deoiled sludge was determined, and the oil removal rate was calculated to be 65.3%.

[0070] The macromolecular surfactant has salt resistance, but lacks CO2 response reversibility and recycling characteristics. The cleaning solution prepared by it cannot be recycled for subsequent cleaning processes of high-salt sludge.

[0071] Comparative Example 2 Preparation of macromolecular surfactants: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, octadecyl methacrylate, and ethyl 2-(diisopropylamino)methacrylate were dissolved in deionized water in a mass ratio of 10:5:2:10. After complete dissolution, the pH was adjusted to 7.5. Ammonium persulfate (0.1 wt% of the total monomers) was added, and the mixture was stirred for 10 min. N2 was then introduced for deoxygenation for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0072] Application of macromolecular surfactants in the treatment of high-salt oily sludge: A 0.3 wt% cleaning solution of the macromolecular surfactant was prepared and mixed with oily sludge with a total water-soluble salt content of 7.5 wt% at a mass ratio of 20:1. The mixture was then cleaned at 75 ℃ for 2 h. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge, respectively. The content of petroleum hydrocarbons in the deoiled sludge was determined, and the oil removal rate was calculated to be 62.7%.

[0073] The macromolecular surfactant has salt resistance, but lacks CO2 response reversibility and recycling characteristics. The cleaning solution prepared by it cannot be recycled for subsequent cleaning processes of high-salt sludge.

[0074] Comparative Example 3 Preparation of macromolecular surfactants: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, octadecyl methacrylate, and 4-vinylpyridine were dissolved in deionized water in a mass ratio of 10:5:2:10. After complete dissolution, the pH was adjusted to 7.5. Ammonium persulfate (0.1 wt% of the total monomers) was added, and the mixture was stirred for 10 min. Then, nitrogen was introduced for deoxygenation for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0075] Application of macromolecular surfactants in the treatment of high-salt oily sludge: A 0.3 wt% cleaning solution of the macromolecular surfactant was prepared and mixed with oily sludge with a total water-soluble salt content of 7.5 wt% at a mass ratio of 20:1. The mixture was then cleaned at 75°C for 2 hours. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge, respectively. The content of petroleum hydrocarbons in the deoiled sludge was determined, and the oil removal rate was calculated to be 72.6%.

[0076] The macromolecular surfactant has salt resistance, but lacks CO2 response reversibility and recycling characteristics. The cleaning solution prepared by it cannot be recycled for subsequent cleaning processes of high-salt sludge.

[0077] Comparative Example 4 Preparation of macromolecular surfactants: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, octadecyl methacrylate, and dimethylaminoethyl methacrylate were dissolved in deionized water in a mass ratio of 6:2:1:1. After complete dissolution, the pH was adjusted to 7. Ammonium persulfate (0.1 wt% of the total monomers) was added, and the mixture was stirred for 10 min. N2 was then introduced to deoxygenate the system for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0078] Application of macromolecular surfactants in the treatment of high-salt oily sludge: The macromolecular surfactant was dissolved in water to prepare a 0.3 wt% cleaning solution, which was then mixed with oily sludge with a total water-soluble salt content of 7.5 wt% at a mass ratio of 20:1. The mixture was then cleaned at 75°C for 120 min. After cleaning, solid-liquid separation was performed to obtain an oily emulsion and deoiled sludge, respectively. The content of petroleum hydrocarbons in the deoiled sludge was determined, and the oil removal rate was calculated to be 75.9%.

[0079] The macromolecular surfactant has salt resistance, but lacks CO2 response reversibility and recycling characteristics. The cleaning solution prepared by it cannot be recycled for subsequent cleaning processes of high-salt sludge.

[0080] Comparative Example 5 Preparation of macromolecular surfactants: Acrylamide, octadecyl methacrylate, and diethylaminoethyl methacrylate were dissolved in deionized water at a mass ratio of 5:1:2. After complete dissolution, the pH was adjusted to 7. Ammonium persulfate (0.1 wt% of the total monomers) was added, and the mixture was stirred for 10 min. N2 was then introduced to deoxygenate the system for 30 min. Finally, the system was heated to 65 °C and stirred for 6 h. After the reaction was complete, the product was collected and dried at 40 °C for 48 h to obtain the macromolecular surfactant.

[0081] Application of macromolecular surfactants in the treatment of high-salt oily sludge: The prepared macromolecular surfactant was formulated into a cleaning solution and added to the cleaning device at a mass ratio of 20:1 with oily sludge having a total water-soluble salt content of 7.5 wt%. The cleaning was carried out at 75 ℃ for 1 h, with the concentration of the cleaning solution being 0.3 wt%. After cleaning, solid-liquid separation was achieved by centrifugation, yielding an oily emulsion and deoiled sludge. The oil removal rate was calculated to be 41.5% by measuring the petroleum hydrocarbon content in the deoiled sludge.

[0082] CO2 was introduced into the above oil-containing emulsion, and the gas-liquid volume ratio was controlled at 3:1. After continuous aeration for 30 min, the pH of the system dropped to 5.5, and the emulsion rapidly demulsified and separated into two phases: oil and water.

[0083] After the two phases have separated, N2 is introduced into the aqueous phase at a gas-liquid volume ratio of 5:1 for 30 minutes, causing the system pH to rise to 8.5. Subsequently, 3 wt% of the initial dosage of a gas-sensitive macromolecular surfactant is added, and water is replenished until the volume of the cleaning solution matches the initial dosage. The resulting regenerated cleaning solution can be directly used for cleaning the next batch of high-salt sludge.

[0084] The gas-sensitive macromolecular surfactant had an oil removal rate of 30.1% after 5 cycles and remained at 25.7% after 10 cycles, indicating that it does not have oil removal performance in high-salt systems.

[0085] Table 2 lists the key preparation parameters of the gas-sensitive macromolecular surfactant described in this invention and the comparative examples, as well as the oil removal efficiency (RE) on high-salt sludge.

[0086] Table 2. Comparison of preparation parameters and degreasing performance between the examples and comparative examples

[0087] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A gas-sensitive macromolecular surfactant, characterized in that, The gas-sensitive macromolecular surfactant is prepared by free radical polymerization of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, long-chain alkyl methacrylate and dialkylaminoethyl methacrylate in a mass ratio of (10~15):(1~5):(1~5):(10~15).

2. The gas-sensitive macromolecular surfactant as described in claim 1, characterized in that, The structural formula of the gas-sensitive macromolecular surfactant is: ， Wherein, w = 450~1600, x = 80~350, y = 60~300, z = 450~1600, m = 12~18, n = 1~2, and the total molecular weight is 10. 3 ~10 6 g / mol.

3. The gas-sensitive macromolecular surfactant as described in claim 1, characterized in that, The preparation process of the gas-sensitive macromolecular surfactant is as follows: Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, long-chain alkyl methacrylate, and dialkylaminoethyl methacrylate were dissolved in deionized water at a mass ratio of (10~15):(1~5):(1~5):(10~15). After adjusting the pH to 6~9, a persulfate or azo initiator was added; the amount of initiator accounted for 0.1~1 wt% of the total mass of all monomers. Then, N2 is introduced to remove oxygen for 20-40 minutes, followed by reaction at 50-90°C for 6-12 hours. After the reaction is completed, the product is separated and dried for 12-36 hours to obtain the gas-sensitive macromolecular surfactant.

4. The gas-sensitive macromolecular surfactant as described in claim 3, characterized in that, The persulfate initiator is at least one of sodium persulfate, potassium persulfate, or ammonium persulfate, and the azo initiator is at least one of azobisisobutyronitrile or azodicyanovalerate.

5. The gas-sensitive macromolecular surfactant as described in claim 1, characterized in that, The long-chain alkyl methacrylate is at least one of dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, or octadecyl methacrylate. The dialkylaminoethyl methacrylate is at least one of dimethylaminoethyl methacrylate or diethylaminoethyl methacrylate.

6. The application of the gas-sensitive macromolecular surfactant according to any one of claims 1-5 in the treatment of high-salt oily sludge, characterized in that, The high-salt sludge is sludge with a total water-soluble salt content ≥5 wt%. A cleaning solution of 0.1~1 wt% is prepared using the gas-sensitive macromolecular surfactant and injected into a cleaning device containing the high-salt sludge. Cleaning is performed at 55~85℃ for 0.5~2 h. The mass ratio of the cleaning solution to the high-salt sludge is (10~20):

1. After cleaning, solid-liquid separation is performed to obtain an oil-containing emulsion and de-oiled sludge, respectively. The oil-containing emulsion contains a gas-sensitive macromolecular surfactant and emulsified oil droplets. The oil removal rate is calculated by determining the petroleum hydrocarbon content in the de-oiled sludge. CO2 is introduced into the oil-containing emulsion at a ratio of (1~5):1 between the volume of the aeration and the volume of the oil-containing emulsion, and the aeration time is 20~40 min. This ensures that the pH value of the emulsion drops to 5.5~7.

5. Under these conditions, the emulsion breaks down and separates into an oil phase and an aqueous phase. After the two phases are separated, N2 is introduced into the aqueous phase at a ratio of (2~10):1 between the volume of the aeration and the volume of the oil-containing emulsion. The aeration time is 20~40 min. After the pH value of the aqueous phase rises to 8.5~9.5, a gas-sensitive macromolecular surfactant is added to the aqueous phase at a dosage of 3~5 wt% of the initial dosage. Then, water is added to restore the volume of the cleaning solution to the initial dosage. The solution is then recycled for cleaning high-salt oil sludge.

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