Preparation method of amphiphilic ZIF composite material demulsifier

Abstract

The invention relates to an amphiphilic ZIF composite material demulsifier and a preparation method thereof, and belongs to the technical field of oil and gas field produced liquid treatment. The demulsifying agent takes a cobalt-based zeolite imidazate framework material (ZIF-67) as a carrier, is endowed with a super-hydrophobic surface through normal hexane modification, and is loaded with hydrophilic ferroferric oxide nanoparticles to form a composite material with hydrophilic and hydrophobic characteristics. The preparation method comprises the following steps: synthesis of Fe3O4 nanoparticles, compounding of ZIF-67 and Fe3O4, and surface modification. The material can be efficiently adsorbed on an oil-water interface, destroys the stability of an emulsion, realizes rapid oil-water separation, has a magnetic recovery function, can be repeatedly used, and has the advantages of high efficiency, environmental friendliness and low cost.

Description

Technical Field

[0001] This invention relates to a novel demulsifier for metal-frame composite materials, specifically to a method for synthesizing amphiphilic metal-frame composite materials. Background Technology

[0002] In the mid-to-late stages of oil and gas extraction, produced fluids often contain a large number of stubborn emulsion systems, requiring demulsification to achieve efficient oil-water separation. Currently, widely used chemical demulsifiers mostly rely on traditional surfactants, which have limited efficiency under complex mineralization and high-temperature environments, require large quantities, and are prone to secondary pollution. In recent years, demulsification technology based on solid nanomaterials has attracted widespread attention due to its high efficiency, recyclability, and environmental friendliness. Among them, metal-organic frameworks (MOFs) have shown potential in emulsion separation due to their high specific surface area, tunable pore structure, and surface chemical properties. Zeolite imidazole ester frameworks (ZIFs), as a typical class of MOFs, have advantages such as simple synthesis, structural stability, and ease of functionalization; however, their intrinsic hydrophilic and hydrophobic properties make them difficult to directly adapt to diverse oil-water interfaces. Existing research has explored the use of solid particles such as silica and carbon-based materials as demulsifiers; however, they still have shortcomings in terms of interfacial adsorption strength, cycle stability, and environmental compatibility. Therefore, this study developed a novel nanocomposite demulsifier by designing the surface of ZIF materials to be amphiphilic and regulating their interfacial behavior, aiming to improve its demulsification efficiency and applicability to oilfield emulsions. Summary of the Invention

[0003] The purpose of this invention is to synthesize a novel amphiphilic ZIF composite demulsifier. By surface modification, a superhydrophobic cobalt-based zeolite imidazole ester framework material (ZIF-67) is prepared and grafted with iron oxide to make it amphiphilic, thereby improving the demulsification ability of the composite material.

[0004] The technical solution of the present invention is as follows:

[0005] 1. A method for preparing an amphiphilic ZIF composite demulsifier, comprising the following steps:

[0006] (I) The preparation process of Fe3O4 nanoparticles is as follows:

[0007] (1) Weigh 1.39 g of ferrous sulfate heptahydrate (FeSO4·7H2O) and 1.352 g of ferric chloride hexahydrate (FeCl3·7H2O).

[0008] (2) Add the weighed medicines to 15.0 mL of deionized water and mix them for later use.

[0009] (3) Under ultrasonic conditions at 40°C, the above mixed solution was added dropwise to 20 mL of a solution with a concentration of 3.5 mol·L⁻¹. -1The reaction continues for 30 minutes in ammonia water.

[0010] (4) After the reaction was completed, the Fe3O4 nanoparticles were collected by centrifugation, washed repeatedly with anhydrous ethanol, and then vacuum dried at 45°C for 10 hours.

[0011] (II) Preparation of demulsifier for amphiphilic ZIF composite materials, the specific process is as follows:

[0012] (1) Weigh out 0.58 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O), 0.05 g of Fe3O4 nanoparticles and 1.5 g of di-methylimidazole.

[0013] (2) Weigh out the cobalt nitrate hexahydrate and Fe3O4 nanoparticles and add them to 40 mL of deionized water and add 17 mL of n-hexane. Use sonication to disperse them evenly.

[0014] (3) Add dimethylimidazole to 40 mL of deionized water and sonicate it to disperse it evenly.

[0015] (4) Add the two solutions together into the flask and stir mechanically at 50 °C for 24 h.

[0016] (5) After the reaction is complete, the product is collected by centrifugation and washed five times with anhydrous ethanol. It is then dried in a vacuum drying oven to obtain the amphiphilic ZIF composite demulsifier.

[0017] (III) Demulsification experiment of amphiphilic ZIF composite material with demulsifier, the specific procedure is as follows:

[0018] (1) Mix 7 mL of liquid paraffin and 7 mL of solution containing 100 mg·L⁻¹ -1 SDS deionized water is added to a test tube and emulsified by vortexing at a certain frequency to form a stable emulsion.

[0019] (2) Add different masses of amphiphilic ZIF composite demulsifier to the above emulsion.

[0020] (3) Every 10 minutes, the vortex oscillator was used to oscillate at 4000 rpm, and the demulsification status was recorded.

[0021] Furthermore, in steps (i) and (3), the ultrasonic power is 750 W.

[0022] Furthermore, in steps (i) and (4), the centrifugation speed is 8000 r / min, centrifugation is performed 3 times, and each time is 5 min. After each centrifugation, the supernatant is removed and anhydrous ethanol is added back.

[0023] Furthermore, in steps (ii), (2), and (3), the ultrasonic power is 750 W.

[0024] Furthermore, in step (ii) (4), the mechanical stirring speed is 250 r / min.

[0025] Furthermore, in step (iii) (1), the vortex oscillator is subjected to high-speed shearing at a speed of 4000 rpm for 6 minutes and then allowed to stand still.

[0026] The working principle of the demulsifier of the amphiphilic ZIF composite material prepared in this invention is as follows:

[0027] Amphiphilic ZIF-67 composites, as nanomaterials, possess ideal properties as highly efficient demulsifiers. The ZIF-67 metal-organic framework shell, after being modified with hexane, exhibits superhydrophobicity and strong oleophilicity. The supported Fe3O4 nanoparticles not only provide magnetic responsiveness but also contribute hydrophilic interaction sites due to their inherent hydrophilic surface. This integration of hydrophilic and hydrophobic components through composite and surface modification enables the material to exhibit precise wettability balance and directional alignment at the oil-water interface. When applied to stable emulsion systems, the composite material, with its high specific surface area and surface energy at the nanoscale, rapidly migrates and accumulates at the oil-water interface. Its amphiphilic characteristics allow it to readily occupy interfacial sites, displacing or interfering with existing emulsion stabilizers (such as surfactants or solid particles). This interfacial adsorption significantly alters the mechanical properties of the interfacial film; its rigid structure and asymmetric interfacial occupancy reduce the film's elasticity and strength, making the interfacial film between dispersed phase droplets (such as oil droplets) easier to thin and rupture, thereby promoting droplet aggregation and coarsening, ultimately achieving rapid separation of the oil and water phases. After demulsification, the dispersed Fe3O4@ZIF-67 particles can be efficiently recovered and recycled under an external magnetic field due to the magnetic properties of their cores, demonstrating good economic efficiency and environmental friendliness. The advantages of this invention are:

[0028] (1) The preparation method adopted in this invention has a clear process route, mild experimental conditions, simple equipment, controllable reaction process, easy preparation of the overall product, wide availability of raw materials, and relatively low preparation cost.

[0029] (2) The present invention performs surface functionalization modification on ZIF-67 to make it both hydrophilic and hydrophobic, thereby significantly enhancing its adsorption capacity at the oil-water interface.

[0030] (3) The present invention has stable and efficient demulsification, and also has magnetic recovery properties, which reduces the pollution to the environment. Attached Figure Description

[0031] Figure 1 This is a SEM image of the amphiphilic ZIF composite material of the present invention;

[0032] Figure 2The FT-IR spectrum of the amphiphilic ZIF composite material of this invention;

[0033] Figure 3 This is a contact angle diagram of the amphiphilic ZIF composite material of the present invention;

[0034] Figure 4 This is the elemental analysis diagram of the amphiphilic ZIF composite material of the present invention;

[0035] Figure 5 This is a graph showing the demulsification efficiency of the amphiphilic ZIF composite material of this invention over 60 minutes.

[0036] Figure 6 These are macroscopic and microscopic photographs of the amphiphilic ZIF composite emulsion of the present invention.

[0037] Figure 7 This is a recycling test diagram of the amphiphilic ZIF composite material of the present invention. Specific implementation methods

[0038] This invention proposes a method for preparing a novel amphiphilic ZIF composite demulsifier. To make the advantages and technical solutions of this invention clearer and more explicit, the invention will be described in detail below with reference to specific implementation examples.

[0039] All the raw materials required for this invention can be purchased through commercial channels.

[0040] Example 1:

[0041] First, weigh 1.39 g of ferrous sulfate heptahydrate (FeSO4·7H2O) and 1.352 g of ferric chloride hexahydrate (FeCl3·7H2O), and add them separately to 15.0 mL of deionized water, then mix them. Under ultrasonic conditions at 60°C, add the above mixed solution dropwise to 20 mL of a 3.5 mol·L⁻¹ solution. -1 The reaction was carried out in ammonia water for 30 min. After the reaction, the Fe3O4 nanoparticles were collected by centrifugation, washed repeatedly with anhydrous ethanol, and then vacuum dried at 45°C for 10 hours.

[0042] Example 2:

[0043] First, weigh 0.58 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O), 0.05 g of Fe3O4 nanoparticles, and 1.5 g of di-methylimidazole. Add the weighed cobalt nitrate hexahydrate and Fe3O4 nanoparticles to 40 mL of deionized water, and then add 17 mL of n-hexane. Sonicate the mixture to disperse it evenly. Next, add di-methylimidazole to 40 mL of deionized water and sonicate to disperse it evenly. Add both solutions to a flask and stir mechanically at 50 °C for 24 h. After the reaction is complete, centrifuge to collect the product, wash five times with anhydrous ethanol, and dry in a vacuum drying oven to obtain the amphiphilic ZIF composite demulsifier.

[0044] Example 3:

[0045] Weigh out 7 mL of liquid paraffin and 7 mL of solution containing 200 mg·L⁻¹ using a graduated cylinder. -1 SDS-deionized water was added to a test tube, and the mixture was vortexed at a certain frequency to emulsify it, forming a stable emulsion. Different masses of amphiphilic ZIF composite demulsifier were added to the emulsion. The mixture was vortexed at 4000 rpm every 10 minutes, and the demulsification process was recorded.

[0046] Parts not described in detail in this embodiment and English abbreviations are common knowledge in this industry and can be found online, so they will not be described here. All the chemical reagents involved are available on the market.

[0047] For any parts not mentioned in this invention, existing technologies can be used as a reference.

[0048] It should be noted that any equivalent substitutions made by those skilled in the art based on the teachings of this invention should be within the scope of protection of this invention.

Claims

1. A method for preparing an amphiphilic ZIF composite demulsifier, characterized in that... Including the following step; (I) The preparation process of Fe3O4 nanoparticles is as follows: (1) Weigh 1.39 g of ferrous sulfate heptahydrate (FeSO4·7H2O) and 1.352 g of ferric chloride hexahydrate (FeCl3·7H2O); (2) Add the weighed medicines to 15.0 mL of deionized water and mix them for later use; (3) Under ultrasonic conditions at 40°C, the above mixed solution was added dropwise to 20 mL of a solution with a concentration of 3.5 mol·L⁻¹. -1 The reaction continues for 30 minutes in ammonia water; (4) After the reaction was completed, the Fe3O4 nanoparticles were collected by centrifugation, washed repeatedly with anhydrous ethanol, and then vacuum dried at 45°C for 10 hours. (II) Preparation of demulsifier for amphiphilic ZIF composite materials, the specific process is as follows: (1) Weigh out 0.58 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O), 0.05 g of Fe3O4 nanoparticles and 1.5 g of di-methylimidazole; (2) Weigh out the cobalt nitrate hexahydrate and Fe3O4 nanoparticles and add them to 40 mL of deionized water and add 17 mL of n-hexane. Sonicate the mixture to disperse it evenly. (3) Add dimethylimidazole to 40 mL of deionized water and sonicate it to disperse it evenly; (4) Add the two solutions together into the flask and stir mechanically at 50 °C for 24 h; (5) After the reaction is complete, the product is collected by centrifugation and washed five times with anhydrous ethanol. It is then dried in a vacuum drying oven to obtain the amphiphilic ZIF composite demulsifier. (III) Demulsification experiment of amphiphilic ZIF composite material with demulsifier, the specific procedure is as follows: (1) Mix 7 mL of liquid paraffin and 7 mL of solution containing 200 mg·L⁻¹ -1 SDS deionized water is added to a test tube and emulsified by vortexing at a certain frequency to form a stable emulsion. (2) Add different masses of amphiphilic ZIF composite demulsifier to the above emulsion; (3) The emulsion was shaken at 4000 rpm every 10 min and the demulsification was recorded. The emulsion was obtained by shearing and allowing it to stand.

2. The method for preparing the amphiphilic ZIF composite material according to claim 1, characterized in that: In steps (i) and (3), the temperature of the ultrasonic reaction should be 40 ℃ and the reaction time should be 30 min.

3. The method for preparing the amphiphilic ZIF composite material according to claim 1, characterized in that: In steps (i) and (3), the molar mass ratio of ferric chloride hexahydrate to ferrous sulfate heptahydrate is 1:

1.

4. The method for preparing the amphiphilic ZIF composite material according to claim 1, characterized in that: In step (ii) (2), the cobalt nitrate hexahydrate and Fe3O4 nanoparticles need to be added to deionized water and n-hexane and sonicated for 2 h.

5. The method for preparing the amphiphilic ZIF composite material according to claim 1, characterized in that: In step (ii) (2), 17 mL of n-hexane solvent is added to deionized water to make the mass ratio of n-hexane 15%, which is the mass ratio of n-hexane to the total solution.

6. The method for preparing the amphiphilic ZIF composite material according to claim 1, characterized in that: In step (ii) (2), 0.05 g of Fe3O4 nanoparticles are added to make the modification amount 1:12, that is, the mass ratio of Fe3O4 nanoparticles to cobalt nitrate hexahydrate.

7. The method for preparing the amphiphilic ZIF composite material according to claim 1, characterized in that: In step (ii) (5), the solution is placed in a centrifuge and the rotation speed is 8000 r / min for 5 min. This process is repeated five times.

8. The method for preparing the amphiphilic ZIF composite material according to claim 1, characterized in that: In step (iii) (1), an equal volume of paraffin oil is added to water to achieve an oil-to-water ratio of 1:1, and the water contains 100 mg·L⁻¹. -1 SDS.

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