A method for the preparation and use of amphiphilic self-driven micromotors for active demulsifiers

Abstract

The application discloses a preparation method and application of an amphiphilic self-driven micromotor for active demulsifiers. A hydrophilic Fe3O4@FeS@MnO2 composite material is prepared through a two-step hydrothermal method and an immersion method, and then a hydrophobic material, carbon black, is asymmetrically coated on the surface of the composite material through a thermal vapor deposition method, so that the amphiphilic self-driven micromotor is constructed, and the amphiphilic self-driven micromotor is used as an active heterogeneous demulsifier. Benefited from active movement and bubble generation, the amphiphilic self-driven micromotor can push oil droplets away from the water phase, and aggregate the oil droplets to form an oil layer, so that oil-water separation is realized. After demulsification, the oily pollutants embedded in the amphiphilic self-driven micromotor can be collected through an external magnetic field and separated from the water phase, so that the effect of purifying water bodies is achieved. As an environmentally friendly heterogeneous demulsifier, the self-diffusion effect of the demulsifier in emulsified wastewater is enhanced, the demulsification treatment efficiency of emulsion pollutants is significantly improved, and recycling is facilitated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of inorganic micro-nano materials and environment, and particularly relates to a preparation method and application of amphiphilic self-driven micromotor of high-efficiency active demulsifier. BACKGROUND

[0002] The accelerated development of oil / gas exploitation and mechanical processing has generated a large amount of oily wastewater, which has caused serious damage to global public health, ecological environment and living resources. Therefore, the management of oily wastewater has become a major challenge faced by the society. The largest source of oil pollution is produced water, which is an inevitable effluent from oil refineries and oil / gas fields containing high-concentration oil. Generally, the oil in wastewater exists in the form of floating oil, dissolved oil, dispersed oil and emulsified oil, depending on the size of oil droplets under different formation conditions. Among them, emulsion wastewater has the highest stability because the structural barrier between oil droplets, spatial interaction and electrostatic repulsion are induced by shear force and interfacial active ingredients. Due to the uneven size of emulsified oil droplets and dynamic structural stability, this emulsified oily wastewater brings great difficulty to effective purification of produced water. Therefore, in order to minimize the negative impact of oily wastewater on the safety of the ecological system and maximize the use of valuable oil resources, researchers need to vigorously research and develop oil / water separation processes and oily wastewater purification technologies with energy efficiency, environmental sustainability and cost effectiveness.

[0003] With a focus on treating emulsion wastewater, researchers have developed a large number of technologies to achieve effective oil / water separation. Conventional demulsification technologies can be divided into two categories: physical demulsification and chemical demulsification. Physical demulsification methods, such as gravity separation, ultracentrifugation and physical filtration / adsorption, have problems of low efficiency, complex equipment and high energy consumption. The representative technology of chemical demulsification is chemical flocculation and adsorption, and the added flocculant destroys the interface between the oil phase and the water phase, resulting in unstable oil droplets gathering and forming larger flocculation bodies. Through sedimentation, the separation of flocculation and water can be achieved according to the density difference. Or, unlike molecular chemical agents, carbon-based materials have been reported to achieve effective demulsification, which utilizes the π-π interaction or n-π interaction between carbon-based materials and active substances in crude oil. However, homogeneous demulsifiers cannot be recycled and reused, so they may cause secondary pollution after use. At the same time, the efficiency of treating large-scale emulsion wastewater by adsorption without external mechanical assistance is very limited, which poses a challenge to in-situ treatment. Therefore, it is urgent to develop an ideal material to form a reliable demulsification technology and obtain excellent oil / water separation performance.

[0004] Artificial micro / nanomotors show great potential in environmental remediation, providing a new possible way for demulsification technology. Micro / nanomotors can exhibit autonomous motion under appropriate energy input, including electricity, light, ultrasound, and chemical energy (from external fuel or stored in the motor). Previous studies have reported that micro / nanomotors can capture oil droplets through hydrophobic interactions. For example, Au / Ni / poly(3,4-ethylenedioxythiophene) / Pt tubular micromotors modified with dodecanethiol and Mg / Ti / Ni / Au Janus micromotors have been shown to effectively adsorb oil droplets for water purification. In addition, walnut-shaped polycaprolactone-based micro-robots fabricated by a one-step electrospinning method can also capture oil droplets. However, these micromotors have the disadvantages of complex manufacturing process, insufficient lipophilic surface area, and expensive materials, which greatly hinder their large-scale and widespread application. In the manufacture of micro-motors, the use of cost-effective catalysts and hydrophobic materials can facilitate the application of micro-motors in the practical treatment of emulsion wastewater. As a transition metal oxide, MnO2 shows excellent catalytic activity. In addition, carbon black is a soot particle produced in the improper / incomplete combustion of fossil carbon-hydrogen fuels. In recent years, carbon black particles have been used as oil-absorbing materials and superhydrophobic coatings due to their micro-roughness and hydrophobic properties on the surface. Therefore, using air pollutant carbon black as an oil removal unit for demulsifiers is expected to increase the possibility of oil-water separation. SUMMARY

[0005] The first object of the present application is to provide a preparation method of active demulsifier amphiphilic self-driven micromotors, which is simple to operate, economical and reliable, environmentally friendly, and has unique self-driven characteristics. In an environment containing low concentration of hydrogen peroxide, the amphiphilic self-driven material can move autonomously with high efficiency. The method is suitable for the preparation of various types of amphiphilic self-driven micromotors with asymmetric structure and has universality.

[0006] The second object of the present application is to provide the application of the active demulsifier amphiphilic self-driven micromotors prepared by the above method in emulsion wastewater remediation to enhance the autonomous demulsification of stable emulsions by demulsifiers. It is green and environmentally friendly. In hydrogen peroxide, the micromotors move autonomously and generate micro / nano bubbles to push the oil droplets away from the water phase and aggregate to form an oil layer, enhancing oil-water separation, improving emulsion wastewater demulsification efficiency, purifying water sources, and purifying oil phase. The method is suitable for various emulsion wastewater and has universality.

[0007] To achieve the above objects, the present application mainly provides the following technical solutions:

[0008] A preparation method of active demulsifier amphiphilic self-driven micromotors, comprising the following steps:

[0009] (1) preparing magnetic Fe3O4@FeS micrometer flowers by a two-step hydrothermal method;

[0010] (2) modifying the magnetic Fe3O4@FeS microrose by MnO2 through the impregnation method to prepare a hydrophilic Fe3O4@FeS@MnO2 composite;

[0011] (3) coating the hydrophilic Fe3O4@FeS@MnO2 composite with hydrophobic carbon black through the thermal vapor deposition method to prepare an amphiphilic self-driven micromotor;

[0012] Further, a preparation method of an amphiphilic self-driven micromotor for an active demulsifier includes the following steps:

[0013] (1) dispersing ferric chloride hexahydrate, sodium citrate and sodium acetate trihydrate in ethylene glycol, transferring the formed mixed solution into an autoclave, keeping at 200℃ for 12 hours to obtain magnetic Fe3O4 nanoparticles, dispersing the obtained magnetic Fe3O4 nanoparticles, ferrous chloride tetrahydrate and thiourea in ethylene glycol, transferring the formed mixed solution into an autoclave, keeping at 200℃ for 24 hours to obtain magnetic Fe3O4@FeS microrose.

[0014] (2) dispersing the magnetic Fe3O4@FeS microrose in a high-concentration potassium permanganate solution, soaking at room temperature for 4 hours to obtain a hydrophilic Fe3O4@FeS@MnO2 composite.

[0015] (3) dispersing the hydrophilic Fe3O4@FeS@MnO2 composite in water or ethanol to form a suspension of water or ethanol containing the hydrophilic Fe3O4@FeS@MnO2 composite, coating the obtained suspension on a glass sheet to form a Fe3O4@FeS@MnO2 film, placing the Fe3O4@FeS@MnO2-coated glass sheet above a candle flame for a few seconds to asymmetrically coat the hydrophilic Fe3O4@FeS@MnO2 composite with hydrophobic carbon black to obtain an amphiphilic self-driven micromotor.

[0016] The amphiphilic self-driven micromotor prepared by the method can enhance the self-driven oil-water separation effect of the demulsifier in emulsion wastewater. The method is as follows: when repairing emulsion wastewater, by adding hydrogen peroxide and the prepared amphiphilic self-driven micromotor in the repair system, the micromotor can enhance the self-demulsification effect of the demulsifier through its self-driving and generated micro-nano bubbles, the micromotor pushes the oil droplets away from the water phase and aggregates into an oil layer, realizes oil-water separation, improves the demulsification efficiency of emulsion wastewater, purifies water sources, purifies oil phase, and does not need external energy input.

[0017] The specific steps of the amphiphilic self-driven micromotor demulsification are as follows: preparing stable oil-in-water emulsion wastewater, 6 mL of machine oil is added into 120 mL of deionized water to form a suspension, and the suspension is stirred by a homogenizer (18000 rpm) for 5 minutes to produce a stable milky white emulsion liquid. Then, 6 mL of the milky white emulsion liquid is taken, 10 mg of the prepared amphiphilic self-driven micromotor is added, and the reaction is carried out at room temperature for 10 minutes. Under the same reaction conditions, the stable emulsion without the addition of the amphiphilic self-driven micromotor, and the system containing hydrogen peroxide and the amphiphilic self-driven micromotor can realize the separation of the layered oil and water.

[0018] The amphiphilic self-driven micromotor used in the above method is not limited to the hydrophilic Fe3O4@FeS@MnO2 composite as the hydrophilic unit and carbon black as the hydrophobic unit, and any amphiphilic material with self-driven characteristics can be used as the micromotor-based demulsifier. In the oil-water separation emulsion wastewater system, the oil stain used is not limited to machine oil, and petroleum crude oil and organic solvents can also be used, and any emulsion wastewater formed by emulsification can be efficiently separated by this method.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] 1. The non-homogeneous demulsifier prepared by the present application is an amphiphilic self-driven micromotor, the hydrophilic Fe3O4@FeS@MnO2 composite is used as the hydrophilic catalytic unit and carbon black is used as the hydrophobic unit, which has the advantages of green environmental protection, rich yield, low price, uniform structure and the like, and is suitable for batch preparation of environmental functional materials. The required self-driven demulsifier is constructed in situ by a simple hydrothermal method, an immersion method and a thermal vapor deposition method, and the amphiphilic self-driven micromotor capable of autonomous movement is obtained, which avoids the use of expensive instrument materials and complex operation steps in the preparation of traditional micromotors, and has environmental benefits and economic benefits;

[0021] 2. The non-homogeneous demulsifier prepared by the present application is an amphiphilic self-driven micromotor, which can realize self-driving in emulsion, and can utilize the flower-like structure with rich catalytic sites and the asymmetric catalytic components on the micromotor to push the micromotor to move to the other side by catalyzing the decomposition of hydrogen peroxide to spray micro-nano bubbles from one side of the micromotor, so as to obtain driving force to realize autonomous movement of the micromotor, thereby pushing the oil droplets away from the water phase and gathering into an oil layer, and the micromotor can also perform tasks in narrow spaces that cannot be reached by traditional means, and can perform in-situ operation in a long distance and a large range;

[0022] 3. The self-driven non-homogeneous demulsifier prepared by the present application can destroy the stability of the emulsion by autonomous movement and the enhanced mass transfer effect of the generated micro-nano bubbles, thereby effectively improving the demulsification treatment effect of the emulsion wastewater;

[0023] 4. The prepared heterogeneous demulsifier is a heterogeneous catalyst with self-driving capability, can be separated, recycled, treated and reused after the demulsification is completed through simple magnetic control, does not cause secondary pollution, meets the green environmental protection requirement, and overcomes the shortcomings of the traditional homogeneous demulsifier. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Preparation schematic diagram of the amphiphilic self-driven micromotor prepared in embodiment 1 of the present application.

[0025] Figure 2 Scanning electron microscope (SEM) image of the amphiphilic self-driven micromotor prepared in embodiment 1 of the present application, wherein a is a magnetic Fe3O4 nanoparticle, b is a Fe3O4@FeS micrometer flower, c is a hydrophilic Fe3O4@FeS@MnO2 composite, and d is the amphiphilic self-driven micromotor.

[0026] Figure 3 X-ray energy dispersion (EDX) image and atomic percentage of the amphiphilic self-driven micromotor prepared in embodiment 1 of the present application, wherein a is an Fe element, b is an Mn element, c is an S element, d is an O element, e is a C element, and f is an atomic percentage.

[0027] Figure 4 Motion time-lapse image of the amphiphilic self-driven micromotor of embodiment 2 of the present application.

[0028] Figure 5 Relationship diagram between hydrogen peroxide concentration and speed of the amphiphilic self-driven micromotor of embodiment 3 of the present application.

[0029] Figure 6 Motion time-lapse image of the amphiphilic self-driven micromotor of embodiment 4 of the present application along the direction of a fixed magnetic field.

[0030] Figure 7 Motion time-lapse image of the amphiphilic self-driven micromotor of embodiment 4 of the present application along the direction of a changing magnetic field.

[0031] Figure 8 Motion time-lapse image of the amphiphilic self-driven micromotor of embodiment 5 of the present application pushing an oil droplet.

[0032] Figure 9 Motion time-lapse image of the amphiphilic self-driven micromotor of embodiment 5 of the present application pushing an oil droplet along the direction of a magnetic field.

[0033] Figure 10 Demulsification experiment of the amphiphilic self-driven micromotor of embodiment 6 of the present application using a bubble to drive an oil droplet to realize oil-water separation.

[0034] Figure 11Demulsification experiment of the amphiphilic self-driven micromotor of embodiment 6 of the present application for realizing oil-water separation by bubble colliding oil droplets.

[0035] Figure 12 Time-lapse images of demulsification of stable oil-in-water emulsion by the amphiphilic self-driven micromotor of embodiment 7 of the present application, wherein the left test tube contains stable oil-in-water emulsion without any demulsifier (blank control) and the right test tube contains stable oil-in-water emulsion dispersed with amphiphilic self-driven micromotor and hydrogen peroxide (demulsification performance test).

[0036] Figure 13 Time-lapse images of demulsification of stable oil-in-water emulsion by the amphiphilic self-driven micromotor of embodiment 7 of the present application, wherein A is the water phase of stable oil-in-water emulsion without any demulsifier (blank control) and B is the water phase of stable oil-in-water emulsion dispersed with self-driven micromotor and hydrogen peroxide (demulsification performance test).

[0037] Figure 14 Time-lapse images of demulsification effect of stable oil-in-water emulsion by the static amphiphilic micromotor of embodiment 8 of the present application.

[0038] Figure 15 Time-lapse images of magnetic control separation of oil stains containing amphiphilic self-driven micromotor in the direction of magnetic field from the water phase after demulsification treatment of embodiment 9 of the present application. DETAILED DESCRIPTION

[0039] The present application will be further described in detail below in combination with the drawings and specific embodiments. Embodiment 1

[0040] Preparation of amphiphilic self-driven micromotor.

[0041] As shown in Figure 1 , the amphiphilic self-driven micromotor is obtained by asymmetrically coating hydrophobic carbon black on the hydrophilic Fe3O4@FeS@MnO2 composite. The specific steps are as follows:

[0042] (1) Ferric chloride hexahydrate (1.1 g), sodium citrate (0.4 g), and sodium acetate trihydrate (3.2 g) were dispersed in ethylene glycol (34 mL), sonicated, and magnetically stirred until fully dissolved. The resulting mixture was transferred to a hydrothermal reactor and kept at 200°C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, the product was collected, washed with a large amount of ethanol, and then dried in a vacuum dryer to obtain magnetic Fe3O4 nanoparticles. The obtained magnetic Fe3O4 nanoparticles (0.04 g), ferrous chloride tetrahydrate (0.64 g), and thiourea (0.488 g) were dispersed in ethylene glycol (30 mL), sonicated, and magnetically stirred until fully dissolved. The resulting mixture was transferred to a high-pressure reactor and kept at 200°C for 24 hours. After the reaction was completed, the mixture was cooled to room temperature, the product was collected, washed with a large amount of ethanol and deionized water, and then dried in a vacuum dryer to obtain Fe3O4@FeS microflowers.

[0043] (2) Magnetic Fe3O4@FeS micro-flowers (0.01 g) were dispersed in potassium permanganate solution (70 mg / mL) and shaken and soaked for 4 hours at room temperature. After shaking, the collected product was washed with a large amount of deionized water and placed in a vacuum dryer until dry to obtain hydrophilic Fe3O4@FeS@MnO2 complex.

[0044] (3) Disperse the hydrophilic Fe3O4@FeS@MnO2 complex in water or ethanol, and after ultrasonic treatment, form a suspension of water or ethanol containing the hydrophilic Fe3O4@FeS@MnO2 complex. Coat the obtained suspension onto a glass slide, and after drying, form a Fe3O4@FeS@MnO2 film on the glass slide. Place one side of the glass slide coated with the Fe3O4@FeS@MnO2 complex layer above the flame of a candle for a few seconds. Coat the hydrophilic Fe3O4@FeS@MnO2 complex layer with a layer of hydrophobic carbon black. Scrape the hydrophilic Fe3O4@FeS@MnO2 complex layer coated with carbon black off the glass slide to obtain an amphiphilic self-driven micromotor.

[0045] The magnetic Fe3O4 nanoparticles, Fe3O4@FeS microflowers, hydrophilic Fe3O4@FeS@MnO2 composites and amphiphilic self-driven micromotors prepared in Example 1 were tested by scanning electron microscopy (SEM).

[0046] like Figure 2 The image shows SEM images of the magnetic Fe3O4 nanoparticles, Fe3O4@FeS microflowers, hydrophilic Fe3O4@FeS@MnO2 composites, and amphiphilic self-driven micromotors prepared in Example 1. Figure 2 It can be seen that the magnetic Fe3O4 nanoparticles are monodisperse spherical particles with a diameter of approximately 200 nanometers. Figure 2It can be seen from a that the Fe3O4@FeS micrometer flower is a flower-shaped microparticle with a diameter of about 5 micrometers, and magnetic Fe3O4 nanoparticles are randomly distributed on the surface of the micrometer flower. Figure 2 It can be seen from c that the hydrophilic Fe3O4@FeS@MnO2 composite is a flower-shaped microparticle with a diameter of about 6 micrometers, and MnO2 is uniformly modified on the surface of the Fe3O4@FeS micrometer flower. The modification of MnO2 does not destroy the flower structure of the Fe3O4@FeS micrometer flower. Figure 2 It can be seen from d that the amphiphilic self-driven micromotor is a flower-shaped microparticle with a diameter of about 6 micrometers, and the hydrophobic carbon black coating is asymmetrically distributed on one side of the hydrophilic Fe3O4@FeS@MnO2 composite. The asymmetric modification of the hydrophobic carbon black coating does not destroy the flower structure of the hydrophilic Fe3O4@FeS@MnO2 composite.

[0047] The amphiphilic self-driven micromotor prepared in Example 1 was subjected to X-ray energy dispersive spectroscopy (EDX) analysis.

[0048] As shown in Figure 3 , the EDX element distribution of the amphiphilic self-driven micromotor prepared in Example 1. It can be seen from Figure 3 a-e that Fe, Mn and S are uniformly distributed on the amphiphilic self-driven micromotor, and O and C elements existing in the hydrophobic carbon black are asymmetrically distributed on the amphiphilic self-driven micromotor. It can be seen from Figure 3 f that the atomic percentage shows that the amphiphilic self-driven micromotor contains 35.95% C elements, 40.01% O elements, 2.30% S elements, 12.66% Mn elements and 9.08% Fe elements. This proves the successful preparation of the amphiphilic self-driven micromotor. Example 2

[0049] In order to study the movement of the amphiphilic self-driven micromotor in a solution containing 1.0 wt% hydrogen peroxide and 0.5 wt% SDS. The mixed solution of the amphiphilic self-driven micromotor, 1.0 wt% hydrogen peroxide and 0.5 wt% SDS was dropped on a glass slide. An optical microscope equipped with an OLYMPUS cellSens Dimension system was used to take images.

[0050] As shown in Figure 4 , the motion time-lapse image of the amphiphilic self-driven micromotor in Example 2. It can be seen from Figure 4 that the MnO2 existing on one side of the micromotor continuously catalyzes the decomposition of H2O2 to generate O2 bubbles, and the abundant bubbles are ejected from one side of the micromotor, then continuously push the micromotor to move quickly. The rough flower-shaped microparticle surface provides abundant catalytic sites, which is conducive to the generation of a large number of bubbles, thereby generating a greater driving force. Example 3

[0051] To investigate the motion of amphiphilic self-driven micromotors in solutions containing 1.0 wt%, 2.0 wt%, and 3.0 wt% hydrogen peroxide and a constant 0.5 wt% SDS, a mixed solution of amphiphilic self-driven micromotors, hydrogen peroxide, and SDS was dropped onto a glass slide. The speed of the micromotors was imaged and analyzed using an optical microscope equipped with an OLYMPUS cellSens Dimension system.

[0052] like Figure 5 The graph shown illustrates the relationship between hydrogen peroxide concentration and velocity in the amphiphilic self-driven micromotor of Example 3. Figure 5 It can be seen that the speed of the micromotor is positively correlated with the fuel concentration. Therefore, the speed of the amphiphilic self-driven micromotor can be controlled by adjusting the hydrogen peroxide concentration. Due to the flower-like structure with abundant catalytic sites, this amphiphilic self-driven micromotor can achieve high-speed movement using low fuel concentrations. When the hydrogen peroxide concentration increases from 1.0 wt% to 3.0 wt%, the average speed of the amphiphilic self-driven micromotor increases from 17.59 μm / s. -1 Significantly increased to 93.64 μm s -1 . Example 4

[0053] To investigate the magnetically controlled motion behavior of an amphiphilic self-driven micromotor, a mixed solution containing an amphiphilic self-driven micromotor, 1.0 wt% hydrogen peroxide, and 0.5 wt% SDS was dropped onto a glass slide. A common magnet was used as an external magnetic field to control the motor's motion, and images were captured using an OLYMPUS cellSens Dimension system.

[0054] like Figure 6 The image shown is a magnetically controlled image of the amphiphilic self-driven micromotor in Example 4 under a fixed magnetic field direction. From... Figure 6 It can be seen that once a magnetic field is applied around the amphiphilic self-driven micromotor, the micromotor will move in the direction of the magnetic field.

[0055] like Figure 7 The image shown is a magnetically controlled image of the amphiphilic self-driven micromotor in Example 4 under varying magnetic field directions. From... Figure 7 It can be seen that the direction of motion of the amphiphilic self-driven micromotor changes with the direction of the surrounding magnetic field. This indicates that the amphiphilic self-driven micromotor possesses excellent magnetic properties, enabling it to be guided by an external magnetic field to narrow target areas inaccessible by traditional tools, and to be recovered by an external magnetic field after demulsification, thereby improving the recovery and reuse efficiency of the demulsifier. Example 5

[0056] To investigate the motion behavior of an amphiphilic self-driven micromotor in an oil-in-water emulsion, a mixed oil-in-water emulsion containing an amphiphilic self-driven micromotor, 1.0 wt% hydrogen peroxide, and 0.5 wt% SDS was dropped onto a glass slide. Images were captured using an OLYMPUS cellSens Dimension system.

[0057] like Figure 8 As shown, this is a time-lapse image of the motion of the amphiphilic self-driven micromotor pushing oil droplets in an oil-in-water emulsion in Example 5. From... Figure 8 It can be seen that the amphiphilic self-driven micromotor with bubble tails moves randomly in the emulsion, and can also pass through a cluster of crowded oil droplets, "cleaning" a relatively clean path. This indicates that the autonomous movement of the prepared amphiphilic self-driven micromotor can disrupt the stability of the oil-in-water emulsion, achieving a demulsification effect.

[0058] like Figure 9 As shown, this is a time-lapse image of the motion of an amphiphilic self-driven micromotor in an oil-in-water emulsion, propelling oil droplets along a magnetic field direction. From... Figure 9 It can be seen that under the input of an external magnetic field, the magnetically responsive amphiphilic micromotor exhibits a "customized" magnetically guided demulsification trajectory, including linear motion, arc motion, and sharp turning motion. This indicates that the amphiphilic self-driven micromotor can move along a customizable path in oil-in-water emulsions, and that the amphiphilic self-driven micromotor possesses programmable potential in demulsification processes. Example 6

[0059] To investigate the demulsification experiment of an amphiphilic self-driven micromotor in an oil-in-water emulsion, a test tube containing an amphiphilic self-driven micromotor and 1.0 wt% hydrogen peroxide dispersed in the oil-in-water emulsion was placed. Images were taken using a mobile phone.

[0060] like Figure 10 As shown, this is a time-lapse image illustrating the demulsification process in Example 6, where the amphiphilic self-driven micromotor utilizes air bubbles to drive oil droplets in an oil-in-water emulsion, achieving oil-water separation. From... Figure 10 It can be seen that: First, the amphiphilic self-driven micromotor captures oil droplets, forming oily contaminants (oil droplet 1 and oil droplet 2) encapsulated within the micromotor. Bubbles generated by the amphiphilic self-driven micromotor continue to expand within the oil droplets, promoting their upward movement. Then, the bubbles and oil droplets meet and merge, leading to the formation of larger oil droplets (oil droplet 1+2). With the help of the bubbles, the larger oil droplets continue to rise within the emulsion. Finally, oil droplets 1+2 float to the gas-liquid interface.

[0061] like Figure 11 The image shows a time-lapse demulsification delay of the amphiphilic self-driven micromotor in Example 6, which utilizes bubble collisions with oil droplets to achieve oil-water separation in an oil-in-water emulsion. From... Figure 11It can be seen that the bubbles (bubbles 1-4) generated by the amphiphilic self-driven micromotor continuously collide with the oil droplets, causing the oil droplets to move upwards and flow into the upper separated oil phase. Example 7

[0062] To study the demulsification performance of amphiphilic self-driven micromotor in oil-in-water emulsion, two test tubes were filled with stable oil-in-water emulsion (blank control) and oil-in-water emulsion dispersed with amphiphilic self-driven micromotor and 1.0 wt% hydrogen peroxide (demulsification performance test), respectively. Every interval, the test tube image was taken using a mobile phone. At the same time, the lower solution was dropped on a glass slide, and the image was taken using the OLYMPUS cellSens Dimension system.

[0063] As shown in Figure 12 , the demulsification effect comparison time-lapse images of Example 7 in the stable oil-in-water emulsion without adding amphiphilic self-driven micromotor (blank control) and adding amphiphilic self-driven micromotor (demulsification performance test), respectively. From Figure 12 It can be seen that compared with the stable oil-in-water emulsion without micromotor (blank control), the amphiphilic self-driven micromotor can disturb the emulsion system and induce demulsification in a short time after 10 minutes, thereby achieving efficient oil-water separation.

[0064] From Figure 13 A, for the oil-in-water emulsion without micromotor (blank control), the oil droplets were still dispersed in the water phase after 30 minutes, which proved the stability of the oil-in-water emulsion without external disturbance. From Figure 13 B, after applying the amphiphilic self-driven micromotor in the oil-in-water emulsion, the number of oil droplets in the water phase was significantly reduced after 15 minutes. After 30 minutes, the oil droplets were almost completely removed from the water phase. This indicates that once the amphiphilic self-driven micromotor is added to the oil-in-water emulsion, it can quickly reach the oil / water interface through autonomous movement. At the same time, the continuous movement of the micromotor destroys the stability of the emulsion, leading to the coalescence of small oil droplets into larger sizes. When the oil droplets have enough volume to overcome the resistance from water, a buoyancy channel is formed, and then the oil and water are completely separated. Example 8

[0065] To study the demulsification performance of static amphiphilic micromotor in oil-in-water emulsion, an oil-in-water emulsion dispersed with static amphiphilic micromotor was filled in a test tube. Every interval, the test tube image was taken using a mobile phone. At the same time, the lower solution was dropped on a glass slide, and the image was taken using the OLYMPUS cellSens Dimension system.

[0066] As shown in Figure 14 , the demulsification effect time-lapse images of Example 8 in the stable oil-in-water emulsion with static amphiphilic micromotor. FromFigure 14 It can be seen that after standing for 30 minutes, the oil droplets are still dispersed in the water phase, and there is no oil-water layering effect, which proves that the static micromotor does not have demulsification effect. Example 9

[0067] In order to study the magnetic control separation experiment of oil droplets after demulsification treatment of the amphiphilic self-driven micromotor. The oil droplets wrapped with amphiphilic self-driven micromotor on the glass slide, using ordinary magnet as external magnetic field to separate oil stains in water phase, at the same time using OLYMPUS cellSens Dimension system to take pictures.

[0068] As Figure 15 shown, the oil stains wrapped with amphiphilic self-driven micromotor in example 9 are quickly separated from the water phase. From Figure 15 It can be seen that due to the amphiphilicity and magnetism of the micromotor, after demulsification, the oil stains wrapped with amphiphilic self-driven micromotor can be separated and removed by external magnetic field, leaving the purified water phase. The process is fast and easy to operate.

Claims

1. A method for preparing an amphiphilic self-driven micromotor for use as an active demulsifier, characterized in that, Includes the following steps: (1) Preparation of Fe3O4@FeS micro-flowers by a two-step hydrothermal method; (2) Prepare hydrophilic Fe3O4@FeS@MnO2 complex by modifying MnO2 on magnetic Fe3O4@FeS microflowers by impregnation method: Disperse magnetic Fe3O4@FeS microflowers in a high concentration of potassium permanganate solution and soak at room temperature to obtain hydrophilic Fe3O4@FeS@MnO2 complex; (3) Prepare an amphiphilic self-driven micromotor by asymmetric coating of hydrophobic carbon black on a hydrophilic Fe3O4@FeS@MnO2 composite by thermal vapor deposition: disperse the hydrophilic Fe3O4@FeS@MnO2 composite in a liquid to form a suspension containing the hydrophilic Fe3O4@FeS@MnO2 composite, coat the obtained suspension on a planar carrier to form a Fe3O4@FeS@MnO2 film, place the planar carrier coated with Fe3O4@FeS@MnO2 above the flame of a candle for a few seconds, and asymmetricly coat the hydrophilic Fe3O4@FeS@MnO2 composite with hydrophobic carbon black to obtain an amphiphilic self-driven micromotor.

2. The method for preparing an amphiphilic self-driven micromotor for an active demulsifier according to claim 1, characterized in that, Specifically, (1) involves dispersing ferric chloride hexahydrate, sodium citrate, and sodium acetate trihydrate in ethylene glycol, transferring the resulting mixed solution to a high-pressure reactor for reaction, and obtaining magnetic Fe3O4 nanoparticles; then dispersing the obtained magnetic Fe3O4 nanoparticles, ferrous chloride tetrahydrate, and thiourea in ethylene glycol, transferring the resulting mixed solution to a high-pressure reactor, and obtaining Fe3O4@FeS micro-flowers.

3. The method for preparing an amphiphilic self-driven micromotor for an active demulsifier according to claim 2, characterized in that, The reaction temperature of the autoclaves is 200℃.

4. An application of an amphiphilic self-driven micromotor for use with active demulsifiers, characterized in that, The amphiphilic self-driven micromotor prepared by any one of claims 1 to 3 is used as a demulsifier, and the prepared amphiphilic self-driven micromotor and hydrogen peroxide are added to the emulsion wastewater.

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