Modified magnetic nanoparticles for demulsification of thick oil emulsion and preparation method of modified magnetic nanoparticles

Abstract

The invention belongs to the technical field of petroleum demulsification, and particularly discloses modified magnetic nanoparticles for demulsification of a thick oil emulsion and a preparation method of the modified magnetic nanoparticles. The modified magnetic nano particles are NiFe2O4 (at) CNTs-NH2, and the modified magnetic nano particles are prepared by loading NiFe2O4 on an aminated carbon nano tube. Different loss mechanisms of NiFe2O4 and aminated carbon nanotubes are combined, the overall wave absorbing performance of the composite material is improved, the composite material can achieve extremely high energy absorption and conversion efficiency in a microwave field, the heat effect is enhanced, meanwhile, demulsification is synergistically enhanced in combination with the non-heat effect of a microwave electromagnetic field, and the demulsification efficiency is improved. The high demulsification efficiency is achieved with an extremely low dosage and extremely short treatment time, and a breakthrough solution with high efficiency, economical efficiency and environment friendliness is provided for thick oil emulsion treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum demulsification, and particularly relates to modified magnetic nanoparticles for demulsification of heavy oil emulsions and a preparation method thereof. Background Art

[0002] Heavy oil, due to its high viscosity and poor fluidity, is difficult to efficiently extract using conventional oil recovery techniques. Instead, it relies on thermal recovery techniques such as steam flooding and fire flooding, or chemical flooding agents, which increase equipment investment and operating costs. Furthermore, heavy oil wells often contain high water content, and heavy oil and water tend to form stable emulsions, increasing the complexity of demulsification and subsequent treatment. Current demulsification technologies primarily include physical demulsification, chemical demulsification, biological demulsification, and combined demulsification. Physical demulsification utilizes external forces such as heat, electric fields, or ultrasound to disrupt the emulsion interface, offering high efficiency but high energy consumption. Chemical demulsification uses demulsifiers to reduce the strength of the interfacial film, offering significant results but also carrying environmental risks. Biological demulsification relies on microorganisms or their metabolites, offering a green and environmentally friendly approach but with lower efficiency. Combined demulsification, combining multiple techniques and adapting to complex systems, is a current research hotspot. Future demulsification technologies will develop towards green, environmentally friendly, efficient, precise, and low-energy consumption, particularly with the use of functionalized nanomaterials.

[0003] Magnetic nanoparticles offer high efficiency, precision, and controllability in emulsion breaking applications. Their superparamagnetic properties and large surface area can be enhanced through surface functionalization to interact with the emulsion interface, enabling rapid aggregation and directional separation under an applied magnetic field. Furthermore, magnetic nanoparticles are recyclable, reducing costs and environmental risks, and can maintain excellent performance under harsh conditions such as high salinity, high temperature, and high viscosity. Their synergistic effect with other demulsification technologies further enhances separation efficiency, demonstrating broad adaptability and environmentally friendly advantages. In the article "Application and Mechanism of Functionalized Magnetic Nanoparticles in Emulsion Preparation and Demulsification" published in the Journal of Physico-Chimica Sinica, Volume 34, Issue 1, 2018, pp. 49-64, Peng Kaiming et al. found that the magnetic responsiveness of MNPs influences emulsions, driving droplet deformation and migration in response to the magnetic field. When the magnetic field intensity exceeds the critical value for emulsion interface stability, droplet directional migration, extrusion, coalescence, particle desorption, and membrane structure collapse, leading to emulsion breaking. In the article "Preparation and Performance Study of CNTs / Fe3O4 Magnetic Demulsifier" published in the journal Oilfield Chemistry, Volume 39, Issue 2, 2022, pp. 360-365, Jia Xinlei et al. reported on the preparation of a magnetic demulsifier, CNTs / Fe3O4, using a solvothermal method. This magnetic demulsifier can be recycled and reused under an external magnetic field. After four cycles, the transmittance of the treated oily wastewater remained at 91.43%. In the article "Preparation of a Magnetic Nano-Demulsifier and Its Demulsification Performance for Heavy Oil Emulsions," published in the journal Chemical Industry and Engineering Progress, Volume 44, Issue 1, 2025, Wu Di from our research group reported on the preparation of a magnetic demulsifier, CuFe2O4@CNTs. The demulsifier achieved optimal efficiency when the dosage reached 2 g / L and the demulsification reaction time was approximately 30 minutes. In a nine-cycle test (demulsification-recycling-re-demulsification), the demulsification efficiency exceeded 95% in the first five cycles and exceeded 90% in the first seven cycles.

[0004] Microwave heating technology has significant advantages in demulsification applications, mainly reflected in efficient heating, low energy consumption and environmental protection. Through dielectric heating, microwave energy can directly act on the inside of the emulsion, achieving uniform and rapid temperature rise, significantly shortening the demulsification time. Microwave heating can not only improve energy utilization efficiency, but also weaken the stability of the emulsified interface through non-thermal effects, thereby enhancing the oil-water separation effect. The article "Research on the Characteristics of Microwave Radiation Crude Oil Demulsification and Dehydration" published by Yang Shiying et al. in the journal "Petroleum and Chemical Equipment", Volume 26, Issue 11, 2023, Pages 154-157, discussed the effects of microwave radiation power and radiation time on the demulsification effect, and concluded that microwave radiation demulsification is more suitable for emulsions with high water content, and the treatment efficiency can reach more than 80% for oil-water emulsions with a water content higher than 50%.

[0005] As a new type of nanomaterial, carbon nanotubes (CNTs) can achieve directional design of the material surface by precisely controlling the surface chemical properties (such as introducing functional groups such as -COOH and -NH2), or by loading functional components such as metal nanoparticles and polymer coatings with the help of covalent / non-covalent modification strategies. In addition, carbon nanotubes (CNTs) are also a high-performance absorbing material. Loading magnetic nanoparticles on the surface of CNTs or filling them inside can greatly improve the material's absorbing performance. Based on the background of magnetic and microwave demulsification technology, the present invention provides a hydrothermal method for preparing amino-modified carbon nanotube-loaded nickel ferrite magnetic nanocomposite materials, and combining them with microwaves for synergistic demulsification. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a modified magnetic nanoparticle and a synthesis method thereof, and combines the modified magnetic nanoparticle with microwave to demulsify heavy oil emulsion.

[0007] The modified magnetic nanoparticles are NiFe2O4@CNTs-NH2, which are prepared by loading NiFe2O4 on amino-modified carbon nanotubes. The specific steps are as follows:

[0008] (1) Preparation of CNTs-NH2

[0009] Prepare a mixed strong acid solution (such as 98% H2SO4 by mass and 68% HNO3 by mass in a volume ratio of 3:1), weigh MWCNTs and add them to the mixed acid solution and stir evenly, place the mixed solution in an ultrasonic cleaner and ultrasonicate for 30 minutes, heat and stir at 70°C for 6 hours after the ultrasonication, and keep the reaction under a nitrogen atmosphere throughout the process. After the reaction is completed, wash with deionized water several times until neutral, and then transfer the product to a vacuum drying oven and dry at 60°C for 12 hours to obtain carboxylated carbon nanotubes. 0.5 g of carboxylated carbon nanotubes were weighed and added to 50 ml of N,N-dimethylformamide (DMF) solution for ultrasonic dispersion for 30 minutes. 5 ml of ethylenediamine (EDA) was added under stirring. After stirring for 30 minutes, 0.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 0.3 g of N-hydroxysuccinimide (NHS) were added and stirred at 60 ° C for 12 hours. The reaction was carried out under a nitrogen atmosphere. After the reaction was completed, the residual EDA and DMF were washed away with ethanol and deionized water. The product was then transferred to a vacuum drying oven and dried at 60 ° C for 12 hours to obtain amino-treated carbon nanotubes.

[0010] (2) Preparation of NiFe2O4@CNTs-NH2

[0011] 0.06 mol Fe(NO3)3·9H2O, 0.03 mol Ni(NO3)2·6H2O, and 0.4 g CNTs-NH2 were weighed and dissolved in 50 ml ethylene glycol solution. The mixture was ultrasonicated for 30 minutes, stirred, and NaOH was added dropwise to adjust the pH of the mixture to 10. After stirring at 60°C for 2 h, the mixture was transferred to a 100 ml hydrothermal reactor and reacted at 180°C for 12 h. After cooling to room temperature, it was washed with ethanol and deionized water several times. After washing, it was placed in an oven at 60°C and dried for 10 h to obtain NiFe2O4@CNTs-NH2.

[0012] The application of the above-mentioned NiFe2O4@CNTs-NH2 in demulsification of heavy oil emulsions specifically comprises the following steps: placing the heavy oil emulsion to which NiFe2O4@CNTs-NH2 is added into a microwave device for demulsification.

[0013] Furthermore, the oil content of the heavy oil emulsion is 2235.36 mg / L-2402.82 mg / L.

[0014] Furthermore, the addition amount of the NiFe2O4@CNTs-NH2 is 0.2-1.2 g / L, preferably 1.0 g / L.

[0015] Furthermore, the radiation power of the microwave device is 70-700W, preferably 350W.

[0016] Furthermore, the irradiation time of the microwave device is 10 to 60 seconds, preferably 20 to 40 seconds.

[0017] Furthermore, after the heavy oil emulsion was demulsified using NiFe2O4@CNTs-NH2, the water phase and oil phase were separated after standing, and the oil phase was separated.

[0018] The beneficial effects of the present invention are:

[0019] The present invention provides a modified magnetic nanoparticle NiFe2O4@CNTS-NH2 and a preparation method thereof, and uses the modified magnetic nanoparticle NiFe2O4@CNTS-NH2 for demulsification of heavy oil emulsions, achieving the synergistic effect of multiple efficient demulsification mechanisms through a unique composite structure.

[0020] First, spinel NiFe2O4 generates Joule heating through hysteresis and eddy current losses in an alternating magnetic field, while amino-modified carbon nanotubes (CNTS·NH2) induce dielectric losses due to interfacial polarization and dipole polarization. The combination of these two distinct loss mechanisms significantly enhances the composite's overall microwave absorption performance, enabling it to achieve extremely high energy absorption and conversion efficiency in microwave fields. This not only significantly improves the system's thermal efficiency, effectively reducing heavy oil viscosity and softening / destroying the interfacial film, but the amino modification also further enhances the dispersion of the CNTs, expands the heat conduction interface, and strengthens the uniformity and intensity of the thermal effect.

[0021] Secondly, the application utilizes the non-thermal effect of microwave electromagnetic field to strengthen demulsification. The charge carried on the surface of magnetic nanoparticles produces a significant electric field effect in the emulsion. This effect can directly change the charge distribution on the surface of the oil droplet, adjust the electrostatic interaction force between the oil droplets, thereby effectively promoting the coalescence and sedimentation process of the oil droplets. The collaboration of this thermal effect (efficient heat generation and viscosity reduction) and non-thermal effect (electric field regulation and control coalescence) has broken through the efficiency bottleneck of traditional demulsification technology. Experimental data fully verify its excellent performance: when the optimal dosage is only 1g, after processing with optimized microwave parameters (power 350W, time 30s), the demulsification efficiency of oil-in-water type viscous oil emulsion can be as high as 98%. At the same time, based on the superparamagnetism of NiFe2O4, the material can be quickly and efficiently recovered by an external magnetic field after demulsification, which significantly reduces operating costs and environmental burden.

[0022] In summary, the present invention not only solves the problems of low microwave thermal efficiency, large demulsifier dosage, complex operation or secondary pollution in the existing technology, but also realizes synergistic demulsification by thermal / non-thermal effects through material design, achieving high demulsification efficiency with extremely low dosage and extremely short processing time, providing a breakthrough solution for the treatment of heavy oil emulsions that is both efficient, economical and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of the synthesis of magnetic nanoparticles;

[0024] Figure 2 is a diagram of a magnetic nanoparticle synthesis device of the present invention;

[0025] Figure 3 is a diagram of a microwave device of the present invention;

[0026] Figure 4 It is the demulsification effect of magnetic nanoparticles with or without microwave conditions;

[0027] Figure 5 is the effect of microwave power on the demulsification efficiency of magnetic nanoparticles;

[0028] Figure 6 is the effect of microwave time on the demulsification efficiency of magnetic nanoparticles;

[0029] Figure 7 This is a cyclic demulsification experiment of magnetic nanoparticles. DETAILED DESCRIPTION

[0030] The synthesis device of magnetic nanoparticles is as follows Figure 2As shown, the ultrasonic cleaner 1 is placed separately, the gas cylinder 2 is connected to the three-necked flask 5 through the gas tube 3 and placed in the water bath 7, the three-necked flask 5 is placed above the digital display electric stirrer 4, the stirring paddle 6 extends into the interior of the three-necked flask 5, and is finally connected to the gas collecting bottle 8 through the gas tube.

[0031] Microwave devices such as Figure 3 As shown, a loading platform 9 is placed on the base 10, a beaker 11 containing an emulsion is placed on the loading platform 9, a thermometer 13 is inserted into the beaker 11, the beaker 11 and the thermometer 13 are wrapped with a quartz tube 12, a parameter button 14 is set, and the start / stop button 15 is pressed to start working.

[0032] Preparation of a Heavy Oil Emulsion: The heavy oil produced fluid from the Karamay Oilfield in Xinjiang is a foamy oil-in-water emulsion. It easily forms semisolid clots during transportation and room temperature storage, making laboratory demulsification experiments difficult. To restore its fluidity, 40.0 g of the solidified sample and 360 mL of deionized water were placed in a 500 mL beaker, and 5 mL of a 1 g / L sodium lauryl sulfate solution was added. The mixture was placed in an 80°C water bath and sheared and dispersed at 10,000 rpm for 20 minutes using a high-speed disperser (FJ200-SH, with the probe immersed 2 cm below the liquid surface). This resulted in a uniform and stable black oil-in-water heavy oil emulsion.

[0033] Synthesis of magnetic nanoparticles: Prepare 100 ml of mixed strong acid solution (98% H2SO4 by mass and 68% HNO3 by mass in a volume ratio of 3:1) in a three-necked flask, weigh 1 g of MWCNT (purchased from Shenzhen Huiheng Graphene Technology Co., Ltd.) and add it to the mixed acid solution and stir evenly. Place the mixed solution in an ultrasonic cleaner and ultrasonicate for 30 minutes. After the ultrasonication is completed, heat and stir at 70°C for 6 hours. Keep the reaction under a nitrogen atmosphere throughout the process. After the reaction is completed, wash with deionized water several times until neutral, and then transfer the product to a vacuum drying oven and dry at 60°C for 12 hours to obtain carboxylated carbon nanotubes. 0.5 g of carboxylated carbon nanotubes were weighed and added to 50 ml of N,N-dimethylformamide (DMF) solution for ultrasonic dispersion for 30 minutes. 5 ml of ethylenediamine (EDA) was added under stirring. After stirring for 30 minutes, 0.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 0.3 g of N-hydroxysuccinimide (NHS) were added and stirred at 60 ° C for 12 hours. The reaction was carried out under a nitrogen atmosphere. After the reaction was completed, the residual EDA and DMF were washed away with ethanol and deionized water. The product was then transferred to a vacuum drying oven and dried at 60 ° C for 12 hours to obtain amino-treated carbon nanotubes. 0.06 mol Fe(NO3)3·9H2O, 0.03 mol Ni(NO3)2·6H2O, and 0.4 g CNTs-NH2 were weighed and dissolved in 50 ml ethylene glycol solution. The mixture was ultrasonicated for 30 minutes, stirred, and NaOH was added dropwise to adjust the pH of the mixture to 10. After stirring at 60°C for 2 h, the mixture was transferred to a 100 ml hydrothermal reactor and reacted at 180°C for 12 h. After cooling to room temperature, it was washed with ethanol and deionized water several times. After washing, it was placed in an oven at 60°C and dried for 10 h to obtain NiFe2O4@CNTs-NH2, named WZ-1.

[0034] The prepared heavy oil emulsion was transferred into multiple 50 mL stoppered colorimetric tubes. Different concentrations of WZ-1 were added to the colorimetric tubes according to the experimental plan. The mixture was shaken up and down for 120 seconds and then left to stand to observe the oil-water stratification. On this basis, the heavy oil emulsion with WZ-1 added was placed in a microwave device. Different microwave parameters were set according to experimental requirements, and the temperature was detected using an immersion infrared temperature sensor. After microwave treatment, the oil concentration in the emulsion before and after demulsification was measured using an infrared oil meter. The oil removal rate (i.e., demulsification performance) of WZ-1 on the heavy oil emulsion was obtained using formula (1). The demulsification efficiency was calculated as follows:

[0035]

[0036] Where: DE (%) is the demulsification efficiency, C0 and C are the oil concentrations in the aqueous phase before and after demulsification.

[0037] Example 1

[0038] Pour the black O / W thick oil emulsion into a 50ml stoppered colorimetric tube, add 0.01g, 0.02g, 0.03g, 0.04g, 0.05g, and 0.06g of magnetic nanoparticles (WZ-1) respectively, shake up and down for 120 seconds, then let it stand for 10 minutes. Use carbon tetrachloride (CCl4) to extract the residual oil in the water phase and put it into an infrared oil meter for measurement. The residual oil concentration in the water phase and the demulsifier demulsification efficiency curve are shown in Figure 2. Figure 4 As shown in (a), the initial oil content of the emulsion is 2402.82 mg / L. As the amount of WZ-1 added increases, the residual oil concentration in the aqueous phase decreases, and the demulsification efficiency improves. When the WZ-1 dosage exceeds 0.05 g, further increases in WZ-1 dosage lead to a stable residual oil concentration, and the demulsification effect does not improve significantly. The optimal dosage is determined to be 0.05 g of WZ-1 per 50 ml of heavy oil emulsion, or 1 g / L.

[0039] The black O / W thick oil emulsion was poured into a 50 ml stoppered colorimetric tube. Without adding magnetic nanoparticles (WZ-1), it was placed in a microwave device with different microwave powers for demulsification. After demulsification, it was allowed to stand for 10 minutes. The residual oil in the aqueous phase was extracted with carbon tetrachloride (CCl4) and then placed in an infrared oil analyzer for measurement. Figure 4 As shown in (b), although the penetration and heating uniformity of microwaves help promote the demulsification of emulsions, experiments show that the oil removal rate for heavy oil emulsions is relatively low. At 490W, the maximum demulsification efficiency is only about 63%.

[0040] Example 2

[0041] Pour the black O / W thick oil emulsion into a 50ml colorimetric tube, add 0.05g of magnetic nanoparticles WZ-1, set the microwave time to 30 seconds, and increase the radiation power from 70W to 700W. The setting values ​​are 10%, 30%, 50%, 70%, and 100% of the maximum rated power. The residual oil concentration in the aqueous phase and the demulsifier demulsification efficiency curve are shown in Figure 2. Figure 5 As shown, the initial oil content of the emulsion was 2235.36 mg / L. At microwave powers of 70 W and 210 W, the residual oil concentration after demulsification was around 60 mg / L, similar to the optimal demulsification effect when adding magnetic nanoparticles alone. At 350 W, the concentration dropped to 33.25 mg / L, demonstrating a higher demulsification efficiency than when adding magnetic nanoparticles alone. When microwave powers reached 490 W and 700 W, the residual oil concentrations reached 66.87 mg / L and 79.44 mg / L, respectively, indicating poor demulsification and a lower efficiency than when adding magnetic nanoparticles alone. The optimal microwave radiation power was determined to be 350 W.

[0042] Example 3

[0043] Pour the black O / W heavy oil emulsion into a 50ml colorimetric tube, add 0.05g magnetic nanoparticles, set the microwave power to 350W, increase the microwave time from 10s to 60s, and the interval is 10s. The residual oil concentration in the aqueous phase and the demulsifier demulsification efficiency curve are shown in Figure 2. Figure 6 As shown, the initial oil content of the emulsion was 2307.61 mg / L. At microwave times of 20 and 40 seconds, the residual oil concentration and demulsification efficiency were similar to those of the magnetic nanoparticles alone. At 30 seconds, the residual oil concentration reached 33.67 mg / L, indicating a higher demulsification efficiency than the magnetic nanoparticles alone. At all other time points, the demulsification efficiency was lower than that of the magnetic nanoparticles alone. The optimal microwave irradiation time was determined to be 30 seconds.

[0044] Example 4

[0045] Pour the black O / W heavy oil emulsion into a 50ml colorimetric tube, add 0.05g magnetic nanoparticles, set the microwave power to 350W, and microwave time to 30s to conduct a demulsification cycle experiment. The residual oil concentration in the aqueous phase and the demulsification efficiency curve of the demulsifier are shown in Figure 2. Figure 7 As shown in the figure, the initial oil content of the emulsion is 2378.33 mg / L. As the number of cyclic demulsification experiments increases, the demulsification efficiency gradually decreases. The demulsification efficiency can reach more than 90% in the first 5 cycles.

[0046] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A modified magnetic nanoparticle for demulsification of heavy oil emulsion, characterized in that: The modified magnetic nanoparticles are NiFe2O4@CNTs-NH2, which are prepared by loading NiFe2O4 on amino-treated carbon nanotubes.

2. An application of the modified magnetic nanoparticles according to claim 1 in demulsification of heavy oil emulsions, characterized in that: The heavy oil emulsion with NiFe2O4@CNTs-NH2 added was placed in a microwave device for demulsification.

3. The use of the modified magnetic nanoparticles according to claim 2 in demulsification of heavy oil emulsions, characterized in that: The added amount of the NiFe2O4@CNTs-NH2 is 0.2-1.2 g / L.

4. The use of the modified magnetic nanoparticles according to claim 2 in demulsification of heavy oil emulsions, characterized in that: The radiation power of the microwave device is 70-700W.

5. The use of the modified magnetic nanoparticles according to claim 2 in demulsification of heavy oil emulsions, characterized in that: The irradiation time of the microwave device is 10 to 60 seconds.

6. A method for preparing modified magnetic nanoparticles according to claim 1, characterized in that: The steps include: (1) Preparation of amino-modified carbon nanotubes; (2) Preparation of NiFe2O4@CNTs-NH2.

7. The method for preparing modified magnetic nanoparticles according to claim 6, wherein: The specific steps of step (1) are: MWCNTs are added to a mixed acid solution, ultrasonically treated, and heated and stirred for the first time under a nitrogen atmosphere. After the reaction is completed, the solution is washed to neutrality and dried to obtain carboxylated carbon nanotubes. The carboxylated carbon nanotubes and N,N-dimethylformamide are mixed, ultrasonically dispersed under a nitrogen atmosphere, ethylenediamine is added, and stirred for 30 minutes. 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide are added, and the solution is heated and stirred for a second time under a nitrogen atmosphere, washed, and dried to obtain amino-containing carbon nanotubes.

8. The method for preparing modified magnetic nanoparticles according to claim 7, wherein: The temperature of the first heating and stirring was 70° C. and the time was 6 h; the ultrasonic treatment and ultrasonic dispersion time was 30 min; the temperature of the second heating and stirring was 60° C. and the time was 12 h.

9. The method for preparing modified magnetic nanoparticles according to claim 6, wherein: The specific steps of step (2) are as follows: Fe(NO3)3·9H2O, Ni(NO3)2·6H2O, amino-treated carbon nanotubes, and ethylene glycol are mixed, ultrasonicated for 30 minutes, the pH of the mixture is adjusted to 10, stirred at 60°C for 2 hours, and then the mixture is transferred to a reactor, reacted at 180°C for 12 hours, washed, and dried to obtain NiFe2O4@CNTs-NH2.

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