Modified cobalt tetroxide magnetic nanoparticles, and synthesis device, method and application thereof

Abstract

The application provides modified tricobalt tetraoxide magnetic nanoparticles and a synthesis device, method and application thereof, adopts a water solution method to synthesize anion polyacrylamide grafted tricobalt tetraoxide magnetic nanoparticles Co3O4@HPAM; finally, dispersion changes of the magnetic nanoparticles before and after modification, influences on emulsion stability and influences of the magnetic nanoparticle concentration after modification on the emulsion stability are compared and analyzed in sequence. The synthesis device is simple in manufacture and convenient in operation; the anion polyacrylamide modified magnetic nanoparticles Co3O4@HPAM is an anion flocculation type magnetic nanoparticle which is strong in dispersion, free from pollution, non-flammable, easy to recycle and capable of being repeatedly used, can not only greatly improve the stability of the emulsion, but also reduce the use of chemical agents, makes the water quality of the emulsion broken when transported to a station more clear, and avoids secondary environmental pollution.

Description

Technical Field

[0001] This invention provides modified cobalt tetroxide magnetic nanoparticles, their synthesis apparatus, method, and applications, belonging to the technical field of improving emulsion stability. Background Technology

[0002] Heavy oil contains more macromolecular substances such as gums and asphaltenes than conventional petroleum, resulting in higher density, higher viscosity, and poorer flowability. This makes heavy oil extraction and transportation difficult, necessitating viscosity reduction treatments. Common methods include: heating for viscosity reduction, dilution for viscosity reduction, ultrasonic viscosity reduction, modification for viscosity reduction, and microbial viscosity reduction. However, all these methods have certain limitations.

[0003] Emulsification viscosity reduction has been widely used in recent years. It involves mixing a surfactant solution of a certain concentration with heavy oil at a specific temperature to form a low-viscosity O / W (oil-in-water) emulsion. This emulsion can fundamentally improve the rheological properties of heavy oil and significantly reduce its flow resistance. However, some challenges remain. Emulsifying viscosity reducers are prone to deactivation under high salinity and high temperature environments, and the stability of the emulsion is generally poor when the amount of emulsifier added is too small. Conversely, excessive emulsifier addition can lead to difficulties in demulsification and dehydration. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides anionic polyacrylamide-modified cobalt tetroxide magnetic nanoparticles, their synthesis apparatus, method, and applications, and applies them to the study of improving emulsion stability.

[0005] This invention utilizes the surface and small size effects of magnetic nanoparticles, as well as their significant magnetic responsiveness. These properties enable the magnetic nanoparticles to rapidly disperse and adsorb at the oil-water interface, thereby affecting the stability of the emulsion. Furthermore, after completing their transportation task, the magnetic nanoparticles remain in the aqueous phase during demulsification. They can be recovered by applying an external magnetic field, enabling recycling and avoiding secondary pollution to the environment.

[0006] Previous experiments on the emulsification of heavy oil by magnetic nanoparticles and surfactants showed that unmodified Co3O4 had a low promoting effect on emulsion stability, the separated water was relatively turbid, and the unmodified magnetic nanoparticles exhibited poor dispersibility, settling completely within 30 minutes. Therefore, this invention aims to modify the magnetic nanoparticles to improve their dispersibility, thereby increasing emulsion stability while reducing the amount of magnetic nanoparticles used. This also results in clearer separated water, further simplifying demulsification and dehydration processes and preventing environmental pollution.

[0007] The specific technical solution is as follows:

[0008] First, a device for synthesizing modified cobalt tetroxide magnetic nanoparticles is provided, including a double-layered three-necked flask capable of realizing a circulating water bath. The first opening at the top of the double-layered three-necked flask is provided with a first glass stopper, which is connected to a nitrogen cylinder through a first rubber tube. The second opening at the top of the double-layered three-necked flask is provided with a second glass stopper, which is connected to a stirrer. The third opening at the top of the double-layered three-necked flask is provided with a third glass stopper, which is connected to a water tank (12) through a second rubber tube. The bottom and top of the outer layer of the double-layered three-necked flask are respectively provided with an inlet (9) and an outlet (10) for a circulating water bath, and both the inlet (9) and the outlet (10) are connected to a water bath control device (11).

[0009] The first and third glass stoppers are both glass stoppers with rubber stoppers, and the second glass stopper is a glass stopper with double rubber stoppers.

[0010] The present invention also provides a method for synthesizing modified cobalt tetroxide magnetic nanoparticles, using the above-mentioned apparatus, comprising the following steps:

[0011] S1. Calculate the specific mass of each raw material, dissolve the weighed raw materials in distilled water, and stir thoroughly with a glass rod to form a homogeneous solution; the raw materials include amide monomer AM monomer, acrylic acid AA monomer, magnetic nanoparticles Co3O4, gelatin, and citric acid.

[0012] The mass proportions of each raw material in the solution are as follows: 15% amide monomer (AM monomer), 15% acrylic acid monomer (AA monomer), 9% magnetic nanoparticles (Co3O4), 3% gelatin, and 2% citric acid.

[0013] S2. Add NaOH solution dropwise to the fully dissolved solution in S1, adjust the pH of the system to 8 to prevent the magnetic nanoparticles from settling, stir the system evenly and quickly add it to a double-walled three-necked flask, turn on the circulating water bath set to 45℃, and turn on nitrogen gas at the same time. After purging nitrogen gas for 30 minutes, add ammonium persulfate solution through the first or third port, add sodium bisulfite solution after 5 minutes, and continue to purge nitrogen gas for 10 minutes to remove air from the container. Initiate the reaction for 3 hours to obtain a black gel.

[0014] The NaOH solution has a mass concentration of 300%; the ammonium persulfate monomer in the ammonium sulfate solution accounts for 0.3% of the total mass; and the sodium bisulfite monomer in the sodium bisulfite solution accounts for 0.2% of the total mass.

[0015] S3. Take out the black gel and place it in a petri dish. Place the petri dish in a drying oven set at 70°C and dry the black gel until the surface is dry. Cut it into small pieces with scissors, place it in a beaker, add acetone solution and soak it. Seal it with plastic wrap and after 24 hours, pour out the acetone solution and soak it in anhydrous ethanol to remove residual homopolymer and monomer. After 24 hours, place the obtained product in a petri dish and dry it in a drying oven set at 70°C until constant weight. After removing it and cooling it to room temperature, crush it with a crusher to obtain anionic polyacrylamide modified cobalt tetroxide magnetic nanoparticles.

[0016] The anionic polyacrylamide-modified cobalt tetroxide magnetic nanoparticles obtained in this invention are used to improve the dispersibility of magnetic nanoparticles, prolong sedimentation time, and enhance the stability of emulsions. The specific method is as follows:

[0017] First, solutions of cobalt tetroxide magnetic nanoparticles with and without modification, each with a concentration of 1000 mg / L, were prepared and placed in sampling bottles for observation of the difference in dispersibility before and after modification. Then, a certain mass of the anionic polyacrylamide-modified cobalt tetroxide magnetic nanoparticles was weighed and placed in an Erlenmeyer flask, and distilled water was added to prepare a concentration of 30000 mg / L. Using an HX-IID ultrasonic cell disruptor, the ultrasonic frequency was set to 28 kHz and the ultrasonic time to 20 min, thus preparing the magnetic nanoparticle stock solution.

[0018] Then weigh the heavy oil, calculate the required magnetic nanoparticle concentration based on the mass of the heavy oil, and drop the required magnetic nanoparticle mother liquor into the heavy oil containing the surfactant. Stir at 1000 r / min for 3 min to ensure thorough mixing.

[0019] Anionic polyacrylamide-modified cobalt tetroxide magnetic nanoparticles exhibit surface effects and small size effects. More importantly, they possess inherent magnetism, facilitating recycling and reuse. These modified magnetic nanoparticles not only improve their dispersibility and extend sedimentation time but also significantly enhance the stability of emulsions, reducing costs and preventing secondary environmental pollution.

[0020] The beneficial effects of this invention are as follows:

[0021] The preparation of anionic polyacrylamide (HPAM) grafted and modified magnetic nanoparticles Co3O4 by water dissolution not only improves its dispersibility and prolongs the sedimentation time, but also greatly promotes the stability of the emulsion, and the precipitated water is also clearer. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the device structure of the present invention;

[0023] Figure 2a This is a schematic diagram of the glass stopper structure with rubber stopper of the present invention;

[0024] Figure 2b This is a schematic diagram of the glass stopper structure with double rubber stoppers of the present invention;

[0025] Figure 2c The present invention is a stirring rod with double rows of blades;

[0026] Figure 3a This is a comparison chart of the dispersibility of magnetic nanoparticles before and after modification after standing for 0 minutes;

[0027] Figure 3b This is a comparison chart of the dispersibility of magnetic nanoparticles before and after modification after standing for 120 minutes;

[0028] Figure 4 The effect of magnetic nanoparticles on the stability of emulsions before and after modification is illustrated in the example.

[0029] Figure 5 The effect of modified magnetic nanoparticle concentration on emulsion stability is illustrated in the example. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments are implemented based on the technical solution of the present invention, and detailed implementation processes are given. However, the scope of protection of the present invention is not limited to the following magnetic nanoparticles and embodiments:

[0031] First, a device for synthesizing modified cobalt tetroxide magnetic nanoparticles is provided, such as... Figure 1 As shown, the device includes a double-walled three-necked flask 8 capable of generating a circulating water bath. The first opening at the top of the double-walled three-necked flask 8 is equipped with a first glass stopper 3, which is connected to a nitrogen cylinder 1 via a first rubber tube 2. The second opening at the top of the double-walled three-necked flask 8 is equipped with a second glass stopper 5, which is connected to a stirrer 4. The third opening at the top of the double-walled three-necked flask 8 is equipped with a third glass stopper 6, which is connected to a water tank 12 via a second rubber tube 7. The bottom and top of the outer layer of the double-walled three-necked flask 8 are respectively equipped with an inlet 9 and an outlet 10 for the circulating water bath, and both the inlet 9 and the outlet 10 are connected to a water bath control device 11.

[0032] To ensure an oxygen-free environment within the double-walled three-necked flask 8 during the synthesis process, the stoppers of the double-walled three-necked flask 8 were modified. Both the first glass stopper 3 and the third glass stopper 6 are now glass stoppers with rubber seals. (See...) Figure 2a The second glass stopper 5 is a glass stopper with double rubber stoppers; see the enlarged partial view below. Figure 2bThe rubber stopper has a channel in the middle for the stirring rod, which facilitates stirring with the plastic stirring rod and prevents air from entering. Before the experiment, the airtightness of the apparatus needs to be checked. Open the valve of nitrogen cylinder 1. If bubbles appear in water bucket 12, it proves that the apparatus is properly connected and has good airtightness.

[0033] The mixer 4 is equipped with a stirring rod with double rows of stirring blades, such as... Figure 2c .

[0034] To verify the effectiveness of anionic polymer-modified magnetic nanoparticles in promoting the stability of heavy oil emulsions, a comparative experiment was conducted in this invention:

[0035] S1. Preparation of heavy oil emulsion

[0036] First, prepare a solution of 0.5% (w / w) CAB-35 activated water. Then, mix the heavy oil and binary activated water at a mass ratio of 7:3 and let the sample stand in a constant temperature water bath at 25°C for 30 minutes. Remove the sample and stir it using a mechanical electric stirrer at a speed of 1000 rpm for 3 minutes to ensure thorough mixing, resulting in a heavy oil emulsion with a water content of 30%.

[0037] Preparation of S2 and CAB-35-modified magnetic nanoparticle-stabilized heavy oil emulsions

[0038] (1) Synthesis of modified magnetic nanoparticles: First, the synthesis apparatus was constructed and its airtightness was checked. Then, the weighed acrylamide monomer (AM), acrylic acid (AA), Co3O4, citric acid, and gelatin were dissolved in distilled water. The mass fraction of Co3O4 in the solution was 9%, the mass fraction of both monomers was 15%, the mass fraction of gelatin was 3%, and the mass fraction of citric acid was 2%. After complete dissolution, the mixture was stirred evenly and added to a three-necked flask. The three-necked flask was placed in a constant temperature water bath. The polymerization system was brought to the initiation temperature of 45°C at pH=8. Nitrogen gas was introduced for 30 min, and 0.3% of the total mass fraction of ammonium persulfate of monomers was added dropwise. After 5 min, 0.2% of the total mass fraction of sodium bisulfite solution of monomers was added to initiate the reaction for 3 h, resulting in a black gel. The colloid was removed, and the anionic polyacrylamide-modified Co3O4 was dried and then cut into small pieces with scissors. It was first soaked in acetone for 24 hours, and then soaked in anhydrous ethanol for 24 hours to remove homopolymer and residual monomer. The resulting black solid was placed in a petri dish, and then the product was placed in a 70°C forced-air drying oven to dry to constant weight. After cooling, it was crushed with a crusher to obtain a powder sample, which is the anionic polyacrylamide-modified magnetic nanoparticle Co3O4@CPAM.

[0039] (2) Preparation of the mother liquor of the modified magnetic nanoparticles: Weigh a certain mass of the modified magnetic nanoparticles Co3O4 and Co3O4@HPAM respectively, place them in an Erlenmeyer flask and add distilled water to make the mass concentration of the magnetic nanoparticles 30000mg / L. Then use an HX-ⅡD ultrasonic cell disruptor, set the ultrasonic frequency to 28kHz, and ultrasonically disperse for 20min to prepare the mother liquor of the magnetic nanoparticles.

[0040] (3) CAB-35-Co3O4 stabilized heavy oil emulsion: First, a certain mass of dehydrated heavy oil was weighed and mixed with monovalent active water in a 7:3 ratio in a 250mL beaker. The mixed sample was placed in a 25℃ constant temperature water bath for 30min. After 30min, a certain amount of magnetic nanoparticle mother liquor was added to the 250mL beaker, and the mixture was stirred at 1000r / min for 3min to obtain an emulsion stabilized by the amphoteric surfactant CAB-35 and magnetic nanoparticles Co3O4. The prepared emulsion was poured into a 50mL colorimetric tube, which was then placed in a 25℃ constant temperature water bath. The height of the precipitated water was measured every 30min for 4h, and the total height of the emulsion was measured at the end. The water separation rate of the emulsion was determined by the bottle test method, where the height of the precipitated water reflected the water separation rate. The lower the height of the separated water, the lower the water separation rate, the higher the emulsification efficiency, and the better the emulsion stability. The formula for calculating the water separation rate is (1).

[0041]

[0042] Where: f—water separation rate, %;

[0043] V1 — The volume of water separated, in mL;

[0044] V2—total water volume, mL;

[0045] H1—Height of separated water, mm;

[0046] H2—Total water height, mm.

[0047] Example 1

[0048] (1) Dissolve the amphoteric surfactant CAB-35 in distilled water, wherein the mass concentration of CAB-35 is 0.5% and the mass ratio of oil to water is 7:3. After mixing the oil and water, let it stand in a constant temperature water bath at 25℃ for 30 minutes.

[0049] (2) Prepare a mother liquor of pre-modified magnetic nanoparticles Co3O4@HPAM and post-modified magnetic nanoparticles grafted with anionic polyacrylamide. The concentration of the mother liquor is 30000 mg / L. The water used in the mother liquor is distilled water. An ultrasonic cell disruptor is used in the preparation of the mother liquor. The ultrasonic frequency is set to 28 kHz and the ultrasonic time is 20 min.

[0050] (3) After 30 min, magnetic nanoparticle solution was added dropwise to the emulsion sample to make the mass concentration of magnetic nanoparticles in the emulsion 400 mg / L. Then, it was continuously stirred with a mechanical stirrer at a speed of 1000 r / min for 3 min. Then, it was placed in a constant temperature water bath at 25℃ and the water separation height was measured every 30 min for a total measurement time of 4 h. After the test was completed, it was placed in an oven for 24 h. When the bubbles in the colorimetric tube were eliminated, the total height of the emulsion was measured and the water separation rate was calculated according to formula (1).

[0051] (4) The effect of magnetic nanoparticles on stabilizing emulsions before and after modification was analyzed by comparative method, such as... Figure 3a and Figure 3b As shown. Figure 3a and Figure 3b The components, in order, are: simple CAB-35, Co3O4, and Co3O4@HPAM.

[0052] Example 2

[0053] (1) Dissolve the amphoteric surfactant CAB-35 in distilled water, wherein the mass concentration of CAB-35 is 0.5% and the mass ratio of oil to water is 7:3. After mixing the oil and water, let it stand in a constant temperature water bath at 25℃ for 30 minutes.

[0054] (2) Prepare a mother liquor of modified magnetic nanoparticles grafted with anionic polyacrylamide and cobalt tetroxide Co3O4@HPAM. The concentration of the mother liquor is 30000 mg / L. The water used in the mother liquor is distilled water. An ultrasonic cell disruptor is used in the preparation of the mother liquor. The ultrasonic frequency is set to 28 kHz and the ultrasonic time is 20 min.

[0055] (3) After 30 min, Co3O4@HPAM solution was added dropwise to the emulsion sample to make the mass concentration of the modified magnetic nanoparticles 200, 400, 600, 800, 1000 and 1200 ppm respectively. Then, the sample was continuously stirred with a mechanical stirrer at a speed of 1000 r / min for 3 min. Then, the sample was placed in a constant temperature water bath at 25℃ and the water separation height was measured every 30 min for a total measurement time of 4 h. After the test was completed, the sample was placed in an oven for 24 h. When the bubbles in the colorimetric tube were eliminated, the total height of the emulsion was measured and the water separation rate was calculated according to formula (1).

[0056] (4) The effect of the concentration of modified magnetic nanoparticles on the water separation rate of the emulsion is shown in [reference needed]. Figure 4 .

[0057] Depend on Figure 3a and Figure 3b The results show that, without the addition of any magnetic nanoparticles, the water separation rates of the emulsion after 4 hours were 45.61%, 38.67%, and 6.45% after the addition of modified magnetic nanoparticles (Co3O4). These results indicate that the modified magnetic nanoparticles significantly improved the stability of the emulsion compared to the unmodified ones.

[0058] Depend on Figure 4 It can be seen that as the concentration of modified magnetic nanoparticles Co3O4@HPAM increases, the water separation rate of the emulsion gradually decreases. When the concentration of Co3O4@HPAM is 400ppm, the water separation rate is only 6.45%, which can significantly improve the stability of the emulsion.

Claims

1. A method for synthesizing modified cobalt tetroxide magnetic nanoparticles, using a synthesis apparatus for modified cobalt tetroxide magnetic nanoparticles, including a double-walled three-necked flask (8) capable of realizing a circulating water bath, wherein the first opening of the top of the double-walled three-necked flask (8) is provided with a first glass stopper (3), and the first glass stopper (3) is connected to a nitrogen cylinder (1) through a first rubber tube (2); the second opening of the top of the double-walled three-necked flask (8) is provided with a second glass stopper (5), and a stirrer (4) is connected to the second glass stopper (5); the third opening of the top of the double-walled three-necked flask (8) is provided with a third glass stopper (6), and the third glass stopper (6) is connected to a water tank (12) through a second rubber tube (7); the bottom and top of the outer layer of the double-walled three-necked flask (8) are respectively provided with an inlet (9) and an outlet (10) of a circulating water bath, and both the inlet (9) and the outlet (10) are connected to a water bath control device (11); The first glass stopper (3) and the third glass stopper (6) are both glass stoppers with rubber stoppers, and the second glass stopper (5) is a glass stopper with double rubber stoppers; Its features are, Includes the following steps: S1. Calculate the specific mass of each raw material, dissolve the weighed raw materials in distilled water, and stir thoroughly with a glass rod to form a homogeneous solution; the raw materials include amide monomer AM monomer, acrylic acid AA monomer, magnetic nanoparticles Co3O4, gelatin, and citric acid. S2. Add NaOH solution dropwise to the fully dissolved solution in S1, adjust the pH of the system to 8 to prevent the magnetic nanoparticles from settling, stir the system evenly and then quickly add it to a double-walled three-necked flask (8), turn on the circulating water bath set at 45°C, turn on the nitrogen gas at the same time, and after 30 min of nitrogen gas, add ammonium persulfate solution through the first or third port, add sodium bisulfite solution after 5 min, and continue to purge nitrogen gas for 10 min to remove the air inside the container, initiate the reaction for 3 h, and obtain a black gel. S3. Take out the black gel and place it in a petri dish. Place the petri dish in a drying oven set at 70°C and dry the black gel until the surface is dry. Cut it into small pieces with scissors, place it in a beaker, add acetone solution and soak it. Seal it with plastic wrap and after 24 hours, pour out the acetone solution and soak it in anhydrous ethanol to remove residual homopolymer and monomer. After 24 hours, place the obtained product in a petri dish and dry it in a drying oven set at 70°C until constant weight. After removing it and cooling it to room temperature, crush it with a crusher to obtain anionic polyacrylamide modified cobalt tetroxide magnetic nanoparticles.

2. The method for synthesizing modified cobalt tetroxide magnetic nanoparticles according to claim 1, characterized in that, In S1, the mass ratio of each raw material in the solution is as follows: 15% amide monomer AM monomer, 15% acrylic acid AA monomer, 9% magnetic nanoparticles Co3O4, 3% gelatin, and 2% citric acid.

3. The method for synthesizing modified cobalt tetroxide magnetic nanoparticles according to claim 1, characterized in that, In S2, the NaOH solution has a mass concentration of 300%; the ammonium persulfate monomer in the ammonium sulfate solution accounts for 0.3% of the total mass; and the sodium bisulfite monomer in the sodium bisulfite solution accounts for 0.2% of the total mass.

4. Modified cobalt tetroxide magnetic nanoparticles, characterized in that, Obtained by the preparation method according to any one of claims 1 to 3.

5. The application of the modified cobalt tetroxide magnetic nanoparticles according to claim 4, characterized in that, As a material to improve the stability of emulsions.

6. The method for improving emulsion stability using modified cobalt tetroxide magnetic nanoparticles as described in claim 4, characterized in that, Includes the following steps: First, weigh the modified cobalt tetroxide magnetic nanoparticles and place them in an Erlenmeyer flask. Add distilled water to prepare a mass concentration of 30000 mg / L. Set the ultrasonic frequency of the HX-ⅡD ultrasonic cell disruptor to 28 kHz and place the Erlenmeyer flask in the ultrasonic cell disruptor for 20 minutes to prepare a uniform magnetic nanoparticle mother liquor. Then weigh the heavy oil, calculate the required magnetic nanoparticle concentration based on the mass of the heavy oil, and drop the required magnetic nanoparticle mother liquor into the heavy oil containing the surfactant. Stir for 3 minutes at a stirring speed of 1000 r / min to ensure thorough mixing.

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