A method for synthesizing and preparing a praseodymium-doped magnetic carbon nanomaterial demulsifier

Abstract

The application relates to a synthesis and preparation method of a praseodymium-doped magnetic carbon nanomaterial demulsifier. The synthesis and preparation method of the magnetic carbon nanomaterial demulsifier comprises the following steps: ultrasonic dispersion of carbon nanotubes, preparation of oxidized carbon nanotubes, preparation of praseodymium-doped oxidized carbon nanotubes, preparation of praseodymium-doped magnetic carbon nanomaterial demulsifiers and the like. The praseodymium-doped magnetic carbon nanomaterial demulsifier prepared by the application has the characteristics of high oil-water demulsification efficiency, no secondary pollution caused by the oil-water demulsification process, reusability, stable performance, low preparation cost and the like, and is very suitable for application in the oil-water separation process in the oilfield production process.

Description

TECHNICAL FIELD

[0001] The application relates to a synthesis preparation method of a praseodymium-doped magnetic carbon nanomaterial demulsifier and belongs to the field of petroleum chemical industry. BACKGROUND

[0002] For the exploited crude oil, the most important step is to remove the water in the crude oil. For the method for demulsifying and dewatering the crude oil, the most common and economic method is to demulsify through a chemical method, namely, adding a certain amount of a demulsifier into the emulsion to force the crude oil and water to be separated, and the method is quite mature and has a quite wide application in oil fields. Traditional demulsifiers are mainly composed of phenolic amine resin, phenolic resin and other polyether demulsifiers, and superhigh molecular weight demulsifiers such as hyperbranched polyamide-amine, the demulsifiers have the advantages of small dosage, short demulsification time and thus are favored by the market. Therefore, the magnetic demulsifier emerges as the times require.

[0003] The magnetic demulsifier is a new composite material obtained by compounding magnetic nanoparticles and demulsifiers or other particles with excellent demulsification capacity through the charge effect between the particles, van der waals force attraction or other means, and has the characteristics of the magnetic particles, namely, the ability of being adsorbed by a magnet, and can also demulsify and quickly separate the oil and water phases. The magnetic demulsifier has the advantages of meeting the requirements of oil field demulsification and realizing multiple uses. Due to the diversification of chemical demulsifiers, the types of the magnetic demulsifiers are gradually increasing, and with the diversified development of inorganic nanomaterials, introducing the inorganic nanomaterials into the research of the magnetic demulsifier has become a research hotspot.

[0004] The carbon nanomaterial is a kind of material with high heat in recent years and has been widely researched in the fields of batteries, medical treatment and photocatalysis. For the carbon nanomaterial, the successfully prepared carbon nanomaterials include graphene, carbon nanotubes and carbon nanospheres, which are all composed of the same hexagonal sp2 carbon atom array. Meanwhile, the graphene gradually attracts the interest of researchers due to the special electronic behavior of the graphene in a magnetic field and at low temperature. Due to the properties of the sp2 carbon atom of the carbon nanomaterial and the properties such as large specific surface area and low surface energy of the nanomaterial, the carbon nanomaterial is considered to be an excellent demulsifier material. However, there are few comparative studies on various carbon nanomaterials at present, and therefore, it is of great significance to study the preparation process of the carbon nanomaterial demulsifier and the magnetic demulsifier material. SUMMARY

[0005] In order to overcome the above technical problems existing in the prior art field, the purpose of the present application is to provide a synthesis preparation process of a praseodymium-doped magnetic carbon nanomaterial demulsifier.

[0006] The application provides a synthesis and preparation method of a praseodymium-doped magnetic carbon nanomaterial demulsifier.

[0007] Step (1) ultrasonic dispersion of carbon nanotubes

[0008] The weighed carbon nanotubes are mixed with deionized water, and the carbon nanotubes are completely dispersed in the deionized water through ultrasonic waves;

[0009] Step (2) preparation of oxidized carbon nanotubes

[0010] A certain amount of ultrasonically dispersed carbon nanotubes is taken in a beaker, then a certain amount of potassium persulfate is added to the dispersion, and the pH value of the mixed system is adjusted with potassium hydroxide, then the mixed solution is poured into a three-necked flask under water bath conditions, and mechanical stirring is continuously performed for a certain period of time, and a condensation reflux device is installed at the same time. After the reaction is completed, the pH value of the mixed solution is adjusted with deionized water, and the oxidized carbon nanotubes are centrifuged at a certain speed, and the precipitate is collected and repeatedly washed with deionized water. Finally, the product is dried at a certain temperature;

[0011] Step (3) preparation of praseodymium-doped oxidized carbon nanotubes

[0012] (1) a certain amount of praseodymium nitrate is taken in a beaker, and an appropriate amount of dimethylbenzene is added as a solvent to form a rare earth ion solution;

[0013] (2) a certain amount of oxidized carbon nanotubes is added to the rare earth ion solution, and stirring is continuously performed to form a mixed solution of oxidized carbon nanotubes and rare earth ions;

[0014] (3) the mixed solution is heated to a certain temperature, and the reaction is performed for a period of time to form a precipitate of rare earth elements and oxidized carbon nanomaterials;

[0015] (4) the obtained praseodymium-doped oxidized carbon nanotube precipitate is repeatedly washed with ethanol and dried at a certain temperature for a certain period of time to obtain praseodymium-doped oxidized carbon nanotubes;

[0016] Step (4) preparation of a praseodymium-doped magnetic carbon nanomaterial demulsifier

[0017] (1) first, acetylacetone iron, oleylamine, oleic acid and octadecene are weighed according to a certain molar ratio and uniformly mixed, then a certain amount of prepared praseodymium-doped oxidized carbon nanotubes is added to the mixture in a solvent of dibenzyl ether, and all the materials are uniformly mixed through ultrasonic dispersion;

[0018] (2) then the mixture is poured into a PPL-lined inner liner, and the air is removed through nitrogen, and then the mixture is placed in a hydrothermal reaction kettle and reacted at a certain temperature for a certain period of time. After the temperature of the reaction kettle decreases to room temperature, the product in the kettle is taken out;

[0019] (3) using a magnet to adsorb the product, using a mixture of anhydrous ethanol and n-hexane with a certain volume ratio to repeatedly clean the finished product, and then placing the product in an oven at a certain temperature for a certain time to obtain the praseodymium-doped magnetic carbon nanomaterial demulsifier product.

[0020] Preferably, the ultrasonic dispersion of the carbon nanotubes in step (1) comprises weighing 50-150 mg of carbon nanotubes and mixing with 80-140 mL of deionized water, and ultrasonically dispersing for 40-75 min to completely disperse the carbon nanotubes in the deionized water.

[0021] In the method, the carbon nanotubes are dispersed in deionized water by ultrasonic waves, which is simple, efficient and easy to realize industrialization. The carbon nanotubes are dispersed in deionized water because the dispersion increases the specific surface area of the carbon nanotubes in deionized water, which reduces the surface energy. On the one hand, a large specific surface area is conducive to contact with subsequent reactants to improve the reaction rate. On the other hand, the reduction of surface energy also reduces the difficulty of subsequent reactions. The higher the dispersion degree of the carbon nanotubes, the better the effect of the subsequent reaction.

[0022] Preferably, the preparation of the oxidized carbon nanotubes in step (2) comprises taking 20-60 mL of the ultrasonically dispersed carbon nanotubes into a beaker, then adding 0.8-1.5 g of potassium persulfate to the dispersion, and adjusting the pH of the mixture to 12-14 with a 0.1-0.3 mol / L potassium hydroxide solution. Then, under water bath conditions, pour the mixture into a three-necked flask and continuously mechanically stir for 5-10 h while installing a condensation reflux device. After the reaction is completed, adjust the pH of the mixture to 7-8 with deionized water, centrifuge the oxidized carbon nanotubes at a speed of 4000-5500 rpm / min, collect the precipitate, repeatedly wash the oxidized carbon nanotubes (Ox-CNTs) with deionized water, and finally dry the product at 50-70°C for 18-36 h.

[0023] The synthetic environment created by the method in preparing the oxidized carbon nanotubes is an alkaline environment. In general, the synthetic environment created by conventional preparation methods is a strong acidic environment with concentrated nitric acid and concentrated sulfuric acid. However, in an acidic environment, the length of the carbon nanotubes is cut off, greatly changing the surface morphology of the carbon nanotubes, and the cut-off carbon nanotubes are not easy to collect. However, the use of potassium hydroxide to create an alkaline environment does not have this defect, and the synthesized oxidized carbon nanotubes have good effects and high purity. Potassium persulfate is used to provide oxygen sources during the reaction. Under water bath conditions, potassium persulfate can decompose and release oxygen, which can fully contact and react with the carbon nanotubes in the solution system to generate oxidized carbon nanotubes.

[0024] As preferred, the preparation of the praseodymium-doped carbon nanotube in step (3) comprises (1) taking 5-10 g of praseodymium nitrate in a beaker, adding 50-100 mL of dimethylbenzene as a solvent, and continuously stirring to form a rare earth ion solution. (2) Taking 2-6 g of carbon nanotube oxide and adding it to the rare earth ion solution, and continuously stirring to form a mixed solution of carbon nanotube oxide and rare earth ions. (3) Heating the mixed solution to 20-60°C, and reacting for 1-4 h to form a precipitate of rare earth elements and carbon nanomaterials. (4) Washing the obtained praseodymium-doped carbon nanotube precipitate with ethanol repeatedly, and drying it at a temperature of 20-60°C for 6-12 h to obtain praseodymium-doped carbon nanotubes.

[0025] In the method, the rare earth element praseodymium is creatively doped in the carbon nanotube oxide, and the strong magnetism of the rare earth element praseodymium can significantly enhance the magnetism of the magnetic carbon nanomaterial. The strong magnetism helps to better disperse and suspend particles, and improves the demulsification effect. The rare earth element has strong surface activity, which can improve the dispersibility and stability of the material, help to prevent particle aggregation and precipitation, and enhance the demulsification effect. Moreover, the rare earth element can interact with the surface of the carbon nanomaterial, form chemical bonds or surface modification, and make the interaction between particles stronger, thereby enhancing the dispersibility and stability of the material. Moreover, the introduction of the rare earth element can adjust the surface charge distribution of the carbon nanomaterial, improve the electrostatic interaction between particles, and reduce the attraction between particles, which is beneficial to maintaining the dispersed state.

[0026] As preferred, the preparation of the magnetic carbon nanomaterial demulsifier in step (3) comprises (1) first, weighing and mixing the materials according to the molar ratio of iron acetylacetone to oleylamine, oleic acid, and octadecene as 1:(1-3):(1-3):(1-2), and then adding 1-3 g of the prepared praseodymium-doped carbon nanotube to the mixture in 20-40 mL of dibenzyl ether solvent, and mixing all the materials uniformly by ultrasonic dispersion. (2) Then pour the mixture into a PPL-lined inner liner, remove the air with nitrogen, and put it into a hydrothermal reaction kettle at 200-250°C for 3-6 h. After the temperature of the reaction kettle decreases to room temperature, take out the product in the kettle. (3) Use a magnet to adsorb the product, and repeatedly wash the finished product with a mixture of absolute ethanol and n-hexane in a volume ratio of 1:(1-2), and then dry the product at 60-80°C for 8-16 h to obtain the finished product of the magnetic carbon nanomaterial demulsifier.

[0027] In the method, the sp 2The prepared oxidized carbon nanotubes of the structure of carbon nanotubes jointly react in the process of synthesizing ferroferric oxide to generate magnetic carbon nanometer demulsifiers, which have magnetism, large specific surface area, low surface energy and other properties, can have very excellent oil-water separation demulsification effect, and in the preparation process, acetylacetone iron is used as the main raw material for synthesizing nano ferroferric oxide together with oleic acid and octadecene as reducing agents, oleylamine as a surfactant and dibenzyl ether as a solvent, the prepared ferroferric oxide has the characteristics of high purity, small particle size and very uniform particle distribution, so that the reaction process of the prepared magnetic carbon nanometer demulsifier is more simple and rapid, and the product quality is higher.

[0028] The praseodymium-doped magnetic carbon nanometer material demulsifier prepared by the application has the advantages of high oil-water demulsification efficiency, no secondary pollution in the oil-water demulsification process, reusability, stable performance and low preparation cost, and is very suitable for application in the oil-water separation process in oilfield production. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a synthesis and preparation process flow chart of a praseodymium-doped magnetic carbon nanometer material demulsifier. DETAILED DESCRIPTION

[0030] Example 1

[0031] The application provides a synthesis and preparation of a praseodymium-doped magnetic carbon nanometer material demulsifier, which comprises the following steps:

[0032] Step (1) ultrasonic dispersion of carbon nanotubes

[0033] 50 mg of carbon nanotubes is weighed and mixed with 80 mL of deionized water, and ultrasonic dispersion is performed for 40 min to completely disperse the carbon nanotubes in the deionized water;

[0034] Step (2) preparation of oxidized carbon nanotubes

[0035] 20 mL of the ultrasonically dispersed carbon nanotubes are taken in a beaker, then 0.8 g of potassium persulfate is added to the dispersion, and the pH value of the mixed system is adjusted to 12 by using a 0.1 mol / L potassium hydroxide solution, then the mixed solution is poured into a three-necked flask under water bath conditions, and mechanical stirring is continuously performed for 5 h while a condensation reflux device is installed. After the reaction is completed, the pH of the mixed solution is adjusted to 8 with deionized water, and the oxidized carbon nanotubes are centrifuged at a speed of 4000 rpm / min, and the precipitate is collected and repeatedly washed with deionized water, and finally, the product is dried at 50℃ for 18 h;

[0036] Step (3) preparation of praseodymium-doped oxidized carbon nanotubes

[0037] (1) Take 5g praseodymium nitrate in a beaker, add 50mL dimethylbenzene as a solvent, and continuously stir to form a rare earth ion solution;

[0038] (2) Take 2g of carbon nanotube oxide and add it to the rare earth ion solution, and continuously stir to form a mixed solution of carbon nanotube oxide and rare earth ions;

[0039] (3) The mixed solution is reacted at 20°C for 1h to form a precipitate of rare earth elements and carbon nanomaterials;

[0040] (4) The obtained praseodymium-doped carbon nanotube oxide precipitate is repeatedly washed with ethanol and dried at 20°C for 6h to obtain praseodymium-doped carbon nanotube oxide;

[0041] Step (4) Preparation of praseodymium-doped magnetic carbon nanomaterial demulsifier

[0042] (1) First, the materials are weighed according to the molar ratio of iron acetylacetone to oleylamine, oleic acid, and octadecene as 1:1:1:1 and mixed uniformly, then 1g of the prepared carbon nanotube oxide is added to the mixture in 20mL of dibenzyl ether solvent, and all the materials are mixed uniformly by ultrasonic dispersion;

[0043] (2) Then pour the mixture into a PPL-lined inner liner, remove the air with nitrogen, and put it into a hydrothermal reaction kettle at 200°C for 3h, then take out the product in the kettle after the temperature of the kettle drops to room temperature;

[0044] (3) The product is adsorbed with a magnet, and the finished product is repeatedly washed with a mixture of absolute ethanol and n-hexane in a volume ratio of 1:1, then the product is placed in an oven at 60°C for 8h to obtain the finished product of the magnetic carbon nanomaterial demulsifier.

[0045] Example 2

[0046] Step (1) Ultrasonic dispersion of carbon nanotubes

[0047] Weigh 90mg of carbon nanotubes and mix with 100mL of deionized water, and ultrasonically disperse for 50min to completely disperse the carbon nanotubes in the deionized water;

[0048] Step (2) Preparation of carbon nanotube oxide

[0049] Take 30 mL ultrasonic dispersion of carbon nanotubes in a beaker, then add 1.0 g of potassium persulfate to the dispersion, and adjust the pH of the mixture to 13 with 0.2 mol / L potassium hydroxide solution, then pour the mixture into a three-necked flask under water bath conditions, and continue mechanical stirring for 6 h while installing a condensation reflux device. After the reaction is completed, adjust the pH of the mixture to 7.8 with deionized water, centrifuge the oxidized carbon nanotubes at a speed of 4500 rpm / min, collect the precipitate, and repeatedly wash the oxidized carbon nanotubes (Ox-CNTs) with deionized water. Finally, dry the product at 60°C for 20 h;

[0050] Step (3) Preparation of Praseodymium-doped Oxidized Carbon Nanotubes

[0051] (1) Take 6 g of praseodymium nitrate in a beaker, add 60 mL of dimethylbenzene as a solvent, and continuously stir to form a rare earth ion solution;

[0052] (2) Take 3 g of oxidized carbon nanotubes and add them to the rare earth ion solution, and continuously stir to form a mixed solution of oxidized carbon nanotubes and rare earth ions;

[0053] (3) The mixed solution is reacted at 30°C for 2 h to form a precipitate of rare earth elements and oxidized carbon nanomaterials;

[0054] (4) The obtained praseodymium-doped oxidized carbon nanotube precipitate is repeatedly washed with ethanol and dried at 30°C for 8 h to obtain praseodymium-doped oxidized carbon nanotubes;

[0055] Step (4) Preparation of Praseodymium-doped Magnetic Carbon Nanomaterial Demulsifier

[0056] (1) First, weigh and mix the materials according to the molar ratio of iron acetylacetone, oleylamine, oleic acid, and octadecene as 1:2:1:1, then add 2 g of the prepared praseodymium-doped oxidized carbon nanotubes to the mixture in 25 mL of dibenzyl ether solvent, and mix all the materials uniformly by ultrasonic dispersion;

[0057] (2) Then pour the mixture into a PPL-lined inner liner, remove the air with nitrogen, and place it in a hydrothermal reaction kettle at 220°C for 4 h. After the temperature of the reaction kettle decreases to room temperature, take out the product in the kettle;

[0058] (3) Use a magnet to adsorb the product, repeatedly wash the finished product with a mixture of absolute ethanol and n-hexane in a volume ratio of 1:1.3, then dry the product at 65°C for 10 h to obtain the finished product of the magnetic carbon nanomaterial demulsifier.

[0059] Example 3

[0060] Step (1) Ultrasonic dispersion of carbon nanotubes

[0061] Weigh 120 mg of carbon nanotubes and mix with 120 mL of deionized water, and ultrasonically disperse for 60 min and completely disperse the carbon nanotubes in the deionized water;

[0062] Step (2) Preparation of oxidized carbon nanotubes

[0063] Take 40 mL of ultrasonically dispersed carbon nanotubes in a beaker, then add 1.3 g of potassium persulfate to the dispersion, and adjust the pH of the mixture to 13.5 with a 0.2 mol / L potassium hydroxide solution, then pour the mixture into a three-necked flask under water bath conditions, and continuously mechanically stir for 8 h while installing a condensation reflux device. After the reaction is completed, adjust the pH of the mixture to 7.6 with deionized water, and centrifuge the oxidized carbon nanotubes at a speed of 5000 rpm / min, collect the precipitate, and repeatedly wash the oxidized carbon nanotubes (Ox-CNTs) with deionized water. Finally, the product is dried at 65°C for 24 h;

[0064] Step (3) Preparation of praseodymium-doped oxidized carbon nanotubes

[0065] (1) Take 8 g of praseodymium nitrate in a beaker, add 80 mL of dimethylbenzene as a solvent, and continuously stir to form a rare earth ion solution;

[0066] (2) Take 3 g of oxidized carbon nanotubes and add to the rare earth ion solution, and continuously stir to form a mixed solution of oxidized carbon nanotubes and rare earth ions;

[0067] (3) The mixed solution is reacted at 40°C for 3 h to form a precipitate of rare earth elements and oxidized carbon nanomaterials;

[0068] (4) The obtained praseodymium-doped oxidized carbon nanotube precipitate is repeatedly washed with ethanol and dried at 40°C for 10 h to obtain praseodymium-doped oxidized carbon nanotubes;

[0069] Step (4) Preparation of praseodymium-doped magnetic carbon nanomaterial demulsifier

[0070] (1) First, weigh and mix the materials according to the molar ratio of acetylacetone iron, oleylamine, oleic acid, and octadecene as 1:2:2:1, then add 2.5 g of the prepared praseodymium-doped oxidized carbon nanotubes to the mixture in 30 mL of dibenzyl ether solvent, and mix all the materials uniformly by ultrasonic dispersion;

[0071] (2) Then pour the mixture into a PPL-lined inner liner, remove the air with nitrogen, and put it into a hydrothermal reaction kettle, react at 240°C for 5 h, and then take out the product in the kettle after the temperature of the kettle decreases to room temperature;

[0072] (3) The product is adsorbed by a magnet, and the product is repeatedly cleaned by a mixed liquid of anhydrous ethanol and n-hexane in a volume ratio of 1:1.5, and then the product is placed in an oven at 70°C for 12h to obtain the finished product of the magnetic carbon nanomaterial demulsifier.

[0073] Example 4

[0074] Step (1) Ultrasonic dispersion of carbon nanotubes

[0075] 150mg of carbon nanotubes is weighed and mixed with 140mL of deionized water, and ultrasonic dispersion is performed for 75min to completely disperse the carbon nanotubes in the deionized water;

[0076] Step (2) Preparation of oxidized carbon nanotubes

[0077] 40mL of the ultrasonic dispersion of carbon nanotubes is taken in a beaker, then 1.5g of potassium persulfate is added to the dispersion, and the pH value of the mixture is adjusted to 14 with a 0.3mol / L potassium hydroxide solution, then the mixture is poured into a three-necked flask under water bath conditions, and mechanical stirring is continued for 10h while a condensation reflux device is installed. After the reaction is completed, the pH of the mixture is adjusted to 7 with deionized water, and the oxidized carbon nanotubes are centrifuged at a speed of 5500rpm / min, and the precipitate is collected and repeatedly washed with deionized water. Finally, the product is placed in an oven at 70°C for 36h;

[0078] Step (3) Preparation of praseodymium-doped oxidized carbon nanotubes

[0079] (1) 10g of praseodymium nitrate is taken in a beaker, 100mL of dimethylbenzene is added as a solvent, and a rare earth ion solution is formed by continuous stirring;

[0080] (2) 5g of oxidized carbon nanotubes is added to the rare earth ion solution, and continuous stirring is performed to form a mixed solution of oxidized carbon nanotubes and rare earth ions;

[0081] (3) The mixed solution is reacted at 50°C for 4h to form a precipitate of rare earth elements and oxidized carbon nanomaterials;

[0082] (4) The obtained praseodymium-doped oxidized carbon nanotube precipitate is repeatedly washed with ethanol and dried at 50°C for 12h to obtain praseodymium-doped oxidized carbon nanotubes;

[0083] Step (4) Preparation of praseodymium-doped magnetic carbon nanomaterial demulsifier

[0084] (1) First, the materials are weighed according to the molar ratio of acetylacetone iron to oleylamine, oleic acid, and octadecene as 1:3:3:1 and mixed uniformly, then 3.0 g of prepared praseodymium-doped carbon nanotube oxide is added to the mixture in 40 mL of dibenzyl ether solvent, and all the materials are mixed uniformly by ultrasonic dispersion;

[0085] (2) Then the mixture is poured into a PPL-lined liner, and the air is removed with nitrogen, and placed in a hydrothermal reactor, and reacted at 250°C for 6h, and after the temperature of the reactor is reduced to room temperature, the product in the reactor is taken out;

[0086] (3) The product is adsorbed by a magnet, and the finished product is repeatedly washed with a mixture of absolute ethanol and n-hexane in a volume ratio of 1:2, and then the product is dried at 80°C for 16h to obtain the finished product of the magnetic carbon nanomaterial demulsifier.

[0087] Comparative Example 1

[0088] Step (1) Ultrasonic dispersion of carbon nanotubes

[0089] 50 mg of carbon nanotubes is weighed and mixed with 80 mL of deionized water, and ultrasonic dispersion is performed for 40 min to completely disperse the carbon nanotubes in the deionized water;

[0090] Step (2) Preparation of carbon nanotube oxide

[0091] 20 mL of ultrasonically dispersed carbon nanotubes is taken in a beaker, then 0.8 g of potassium permanganate is added to the dispersion, and the pH of the mixture is adjusted to 4 with 0.1 mol / L hydrochloric acid solution, then the mixture is poured into a three-necked flask under water bath conditions, and mechanical stirring is continued for 5h, while a reflux condenser is installed. After the reaction is completed, the pH of the mixture is adjusted to 8 with deionized water, and the carbon nanotube oxide is centrifuged at a speed of 4000 rpm / min, and the precipitate is collected and repeatedly washed with deionized water. Finally, the product is dried at 50°C for 18h;

[0092] Step (3) Preparation of magnetic carbon nanomaterial demulsifier

[0093] (1) First, the materials are weighed according to the molar ratio of acetylacetone iron to oleylamine, oleic acid, and octadecene as 1:3:3:1 and mixed uniformly, then 3.0 g of prepared praseodymium-doped carbon nanotube oxide is added to the mixture in 40 mL of dibenzyl ether solvent, and all the materials are mixed uniformly by ultrasonic dispersion;

[0094] (2) Then the mixture is poured into a PPL-lined liner, and the air is removed with nitrogen, and placed in a hydrothermal reactor, and reacted at 250°C for 6h, and after the temperature of the reactor is reduced to room temperature, the product in the reactor is taken out;

[0095] (3) The product is adsorbed by a magnet, and the finished product is repeatedly cleaned with a mixture of anhydrous ethanol and n-hexane in a volume ratio of 1:1, and then the product is dried at 60°C for 8h to obtain the finished product of the magnetic carbon nanomaterial demulsifier.

[0096] Comparative Example 2

[0097] Step (1) Ultrasonic dispersion of carbon nanotubes

[0098] 150mg of carbon nanotubes was weighed and mixed with 140mL of deionized water, and ultrasonic dispersion was performed for 40min to completely disperse the carbon nanotubes in the deionized water;

[0099] Step (2) Preparation of oxidized carbon nanotubes

[0100] 60mL of the ultrasonically dispersed carbon nanotubes was taken in a beaker, then 1.5g of potassium permanganate was added to the dispersion, and the pH value of the mixture was adjusted to 2 with a 0.3mol / L hydrochloric acid solution, then the mixture was poured into a three-necked flask under water bath conditions, and mechanical stirring was continued for 10h while a condensation reflux device was installed. After the reaction was completed, the pH of the mixture was adjusted to 7 with deionized water, and the oxidized carbon nanotubes were centrifuged at a speed of 5500rpm / min, and the precipitate was collected and repeatedly washed with deionized water. Finally, the product was dried at 70°C for 36h;

[0101] Step (3) Preparation of magnetic carbon nanomaterial demulsifier

[0102] (1) First, the materials were weighed and mixed according to the molar ratio of ferrous sulfate to oleylamine, sodium hydroxide, and ammonia water as 1:3:3:1, and then 3g of the prepared oxidized carbon nanotubes were added to the mixture in 40mL of dibenzyl ether solvent, and all the materials were mixed uniformly by ultrasonic dispersion;

[0103] (2) Then the mixture was poured into a PPL-lined inner liner, and the air was removed with nitrogen, and placed in a hydrothermal reaction kettle at 250°C for 6h. After the temperature of the reaction kettle decreased to room temperature, the product in the kettle was taken out;

[0104] (3) The product was adsorbed by a magnet, and the finished product was repeatedly cleaned with a mixture of anhydrous ethanol and n-hexane in a volume ratio of 1:2, and then the product was dried at 80°C for 16h to obtain the finished product of the magnetic carbon nanomaterial demulsifier.

[0105] The praseodymium-doped magnetic carbon nanomaterial demulsifiers prepared in Examples 1-4 and Comparative Examples 1 and 2 were detected respectively, and the specific detection method was as follows:

[0106] Particle size test

[0107] The particle size of the demulsifier was tested using a FRITSCH A22 NeXT Nan type nano laser particle size tester, and the average value was obtained by multiple tests.

[0108] Demulsification test of magnetic demulsifier

[0109] According to the method for testing the performance of oil demulsifiers (bottle test method) in SY / T 5281-2000, the demulsification performance of the praseodymium-doped magnetic carbon nanomaterial demulsifier was evaluated. First, the emulsion was added to the prepared glass bottle. Then, the praseodymium-doped magnetic demulsifier was added to the glass bottle, and the test tube without the demulsifier was used as a blank control. The glass bottle was shaken 100 times within 30 seconds to ensure that the demulsifier was completely dispersed in the emulsion. Finally, the demulsification effect was observed after 5 minutes of standing. After the demulsification experiment, the water content in the upper oil phase was calculated using a WKT-A9 Karl Fischer moisture meter, and the experimental data was recorded.

[0110] Recycling test of magnetic demulsifier

[0111] At the end of the demulsification test, the demulsifier was separated from the oil and water phases using a magnet, and then washed with a mixture of ethanol and n-hexane (1:1 by volume). The demulsifier was then cleaned using an ultrasonic cleaner for 15 minutes to ensure complete dispersion. The demulsifier was then recovered using an external magnetic field, and the washing process was repeated three to four times until the solution was colorless and transparent. The demulsifier was then dried in a vacuum environment at 65°C for 12 hours before being used in the next demulsification experiment. The experimental data was recorded.

[0112] Table 1: Particle size test results

[0113] Examples Particle size (nm) 1 530 2 518 3 496 4 485 Comparative Example 1 685 Comparative Example 2 597

[0114] As shown in Table 1, the particle size of the praseodymium-doped magnetic carbon nanomaterial demulsifier in Examples 1-4 was smaller than that of the magnetic carbon nanomaterial demulsifier prepared in Comparative Examples 1 and 2. This is because the ferrous sulfide used in the comparative examples was used as the iron source, and ammonia was used as the reducing agent to prepare the nano-magnetic carbon nanomaterial demulsifier. The particle size of the prepared magnetic carbon nanomaterial demulsifier was higher than that of the magnetic carbon nanomaterial demulsifier prepared using iron acetylacetate and oleylamine, oleic acid, and octadecene. The higher the particle size, the greater the impact on the demulsification effect of the demulsifier. Moreover, the rare earth element praseodymium was creatively introduced in the examples. The introduction of rare earth elements can adjust the surface charge distribution of carbon nanomaterials, improve the electrostatic interaction between particles, reduce the attraction between particles, and help maintain the dispersed state, reducing the possibility of material aggregation and reducing the particle size.

[0115] Table 2: Demulsification test results of magnetic demulsifier

[0116] Examples Residual moisture content (%) 1 0.25 2 0.21 3 0.19 4 0.15 Comparative Example 1 0.45 Comparative Example 2 0.37

[0117] From Table 2, it can be seen that the residual moisture content of the praseodymium-doped magnetic carbon nanomaterial demulsifiers of Examples 1-4 after demulsification is less than that of the magnetic carbon nanomaterial demulsifiers prepared in Comparative Examples 1 and 2. Since the acid environment used in the preparation of the oxidized carbon nanotubes in the comparative examples greatly cuts the carbon nanotubes and changes the structure of the carbon nanotubes, the demulsifiers prepared thereby are not as good as the demulsifiers prepared in the examples in the demulsification effect under alkaline conditions, and thus the structure of the oxidized carbon nanotubes greatly affects the demulsification capacity of the magnetic demulsifier.

[0118] Table 3. Recovery test results of the magnetic demulsifiers

[0119] Examples Residual moisture content after 5 times (%) Residual moisture content after 10 times (%) 1 0.27 0.35 2 0.23 0.26 3 0.20 0.23 4 0.16 0.19 Comparative Example 1 0.47 0.59 Comparative Example 2 0.42 0.51

[0120] From Table 3, it can be seen that the residual moisture content in the oil phase does not change much when the demulsifiers prepared in Examples 1-4 and Comparative Examples are repeatedly tested for the demulsification performance, which fully embodies the advantage of the magnetic demulsifier, i.e., the magnetic demulsifier can be recycled by using an external magnetic field, so as to reduce the use cost of the demulsifier. When the demulsification experiment is performed for the 10th time in the test, the demulsification performance of the demulsifiers of the examples and the comparative examples all decreases to different extents, which shows that a certain amount of oil phase is adsorbed on the surface of the magnetic demulsifier, and cannot be completely removed by washing, which leads to a decrease in the adsorption sites of the magnetic demulsifier, thereby affecting the demulsification performance. From Table 3, it can be seen that the demulsification performance of the demulsifiers prepared in the examples decreases by a smaller amplitude than that of the demulsifiers prepared in the comparative examples. Therefore, it can be considered that the demulsifiers prepared by the method have good demulsification capacity and perform well in the recovery test, and have good recyclability.

[0121] The specific embodiments are merely illustrative of the present application, and are not a limitation on the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, and as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for the synthesis of a Pr-doped magnetic carbon nanomaterial demulsifier, characterized by Comprise: Step (1) ultrasonic dispersion of carbon nanotubes Mix the weighed carbon nanotubes with deionized water, and use ultrasonic waves to completely disperse the carbon nanotubes in the deionized water. Step (2) preparation of oxidized carbon nanotubes Take a certain amount of ultrasonic dispersion of carbon nanotubes into a beaker, then add a certain amount of potassium persulfate into the dispersion, and adjust the pH value of the mixed system to alkaline with potassium hydroxide, then pour the mixed solution into a three-necked flask under water bath condition, and continuously mechanically stir for a certain period of time, while installing a condensation reflux device; after the reaction is completed, adjust the pH value of the mixed solution with deionized water, centrifuge at a certain speed, collect the precipitate, and repeatedly wash the oxidized carbon nanotubes Ox-CNTs with deionized water, and finally dry the oxidized carbon nanotube product at a certain temperature. Step (3) preparation of praseodymium-doped oxidized carbon nanotubes 1) Take a certain amount of praseodymium nitrate into a beaker, add an appropriate amount of dimethylbenzene as a solvent, and continuously stir to form a rare earth ion solution; 2) Take a certain amount of the oxidized carbon nanotubes into the rare earth ion solution, and continuously stir to form a mixed solution of oxidized carbon nanotubes and rare earth ions; 3) Heat the mixed solution to a certain temperature, react for a period of time, and form praseodymium-doped oxidized carbon nanotube precipitate; 4) The obtained praseodymium-doped oxidized carbon nanotube precipitate is repeatedly washed with ethanol and dried at a certain temperature for a certain period of time to obtain praseodymium-doped oxidized carbon nanotubes. Step (4) preparation of praseodymium-doped magnetic carbon nanomaterial demulsifier 1) First, weigh the materials according to the certain molar ratio of acetylacetone iron, oleylamine, oleic acid, and octadecene, and mix them evenly, then add a certain amount of the prepared praseodymium-doped oxidized carbon nanotubes to the mixture in the solvent dibenzyl ether, and mix all the materials evenly by ultrasonic dispersion; 2) Then pour the mixture into a PPL-lined inner liner, remove the air with nitrogen, and put it into a hydrothermal reaction kettle, react at a certain temperature for a certain period of time, and then take out the kettle product after the temperature of the kettle decreases to room temperature; 3) Use a magnet to adsorb the product, repeatedly wash the finished product with a mixture of a certain volume ratio of anhydrous ethanol and n-hexane, and then dry the product at a certain temperature for a certain period of time to obtain the praseodymium-doped magnetic carbon nanomaterial demulsifier product.

2. The method according to claim 1, wherein the method is characterized by: Step (1) ultrasonic dispersion of carbon nanotubes includes weighing 50-150 mg of carbon nanotubes and mixing with 80-140 mL of deionized water, and then ultrasonic dispersion for 40-75 min to completely disperse the carbon nanotubes in the deionized water.

3. The method according to claim 1, wherein the method is characterized by: Step (3) preparation of praseodymium-doped oxidized carbon nanotubes includes taking 5-10 g of praseodymium nitrate into a beaker, adding 50-100 mL of dimethylbenzene as a solvent, and continuously stirring to form a rare earth ion solution.

4. The method according to claim 1, wherein the method is characterized by: Step (3) preparation of praseodymium-doped oxidized carbon nanotubes includes taking 2-6 g of the oxidized carbon nanotubes into the rare earth ion solution, and continuously stirring to form a mixed solution of oxidized carbon nanotubes and rare earth ions.

5. The method according to claim 1, wherein the method is characterized by: Step (3) preparation of praseodymium-doped oxidized carbon nanotubes includes heating the mixed solution to 20-60℃, reacting for 1-4 h, and forming praseodymium-doped oxidized carbon nanotube precipitate.

6. The method according to claim 1, wherein the method is characterized by: Step (3) preparation of praseodymium-doped carbon nanotube oxide includes precipitating the obtained praseodymium-doped carbon nanotube oxide, repeatedly washing with ethanol, and drying at a temperature of 20-60°C for 6-12 hours to obtain praseodymium-doped carbon nanotube oxide.

7. The method according to claim 1, wherein the method is characterized by: Step (4) preparation of praseodymium-doped magnetic carbon nanomaterial demulsifier includes first, weighing and mixing materials according to a molar ratio of acetylacetone iron, oleylamine, oleic acid, and octadecene of 1:(1-3):(1-3):(1-2), then adding 1-3 g of the prepared praseodymium-doped carbon nanotube oxide to the mixture in 20-40 mL of dibenzyl ether solvent, and mixing all the materials uniformly by ultrasonic dispersion.

8. The method according to claim 1, wherein the method is characterized by: Step (4) preparation of praseodymium-doped magnetic carbon nanomaterial demulsifier includes pouring the mixture into a PPL-lined inner liner, removing air with nitrogen, placing into a hydrothermal reaction kettle, and reacting at 200-250°C for 3-6 hours, after the temperature of the reaction kettle drops to room temperature, taking out the product in the kettle.

9. The method according to claim 1, wherein the method is characterized by: Step (4) preparation of praseodymium-doped magnetic carbon nanomaterial demulsifier includes adsorbing the product with a magnet, repeatedly washing the finished product with a mixture of anhydrous ethanol and n-hexane in a volume ratio of 1:(1-2), then placing the product in an oven to dry at 60-80°C for 8-16 hours to obtain the finished product of praseodymium-doped magnetic carbon nanomaterial demulsifier.

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