Magnetic material for oil-water separation, preparation thereof and oil-water separation method and device

Abstract

The application discloses a kind of magnetic material for oil-water separation and its preparation and oil-water separation method and device. First, magnetite or magnetite is made into magnetic particles, which is dispersed in carboxymethyl cellulose aqueous solution and ultrasonic treatment, then solid-liquid separation and use magnet to collect particles, obtain CMC filled magnetic particles;The CMC filled magnetic particles are dispersed in the organic solvent of ethyl cellulose, ultrasonic treatment, then solid-liquid separation and use magnet to collect particles, obtain the magnetic material for oil-water separation. Oil-water separation device includes separation column, coil, upper grid and lower grid arranged in separation column, and magnetic material filled between upper grid and lower grid. By adding alternating magnetic field to oil-water separation device, realize small amplitude vibration of magnetic iron ball in oil-water mixture, improve the efficiency of small oil droplet coalescence, effectively separate emulsified oil-water. The application can efficiently separate emulsified oil-water, with low energy consumption, low cost and environmental protection.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wastewater treatment, and particularly relates to a magnetic material for oil-water separation, a preparation method of the magnetic material, and an oil-water separation method and device. BACKGROUND

[0002] In the industrial production process, such as petroleum chemical industry, daily chemical industry, textile, leather, steel manufacturing and metal processing industry, a large amount of oil-containing wastewater is generated every day. Since the 1990s, most of the oil fields in China have entered the middle and late stages of production, and the water content in the produced liquid has increased year by year, and the water content of some well fluids has exceeded 95%. The oil in the oil-containing wastewater causes serious damage to the natural environment and ecological environment, pollutes the water body, and affects the safety of residents' drinking water. The oil on the surface of the water body can hinder the penetration of oxygen, causing the water body to be anoxic and smelly, and causing the death of organisms. Some hydrocarbons in oil can cause biological deformity or carcinogenesis. These oil-water mixtures are extremely harmful to the environment and human health, and therefore need to be effectively treated, and there is an urgent need for efficient oil-water separation technology.

[0003] The oil-water separation process can be divided into a crude oil dehydration process for extracting crude oil from an oil-water mixture, and an oil-containing wastewater treatment process for removing oil and other impurities from oil-containing wastewater (the oil content is usually less than 1%). So far, the main methods for separating oil and water in industry include air flotation, gravity separation, adsorption separation, coagulation and flocculation. However, these methods are not easy to remove ultrafine emulsified oil droplets, especially when the particle size of the emulsified oil droplets is less than 20 μm, an electric field needs to be applied or a chemical substance needs to be added to break the emulsion, resulting in energy consumption and secondary pollution, and the cost is high. Membrane separation technology can be used to separate various emulsified oil-water, especially surfactant-containing emulsions, due to its high separation efficiency and simple operation process, but its application in industrial treatment of oil-containing wastewater is still limited by problems such as membrane pollution and easy clogging.

[0004] Therefore, the separation of oil-containing wastewater, especially the separation of emulsified oil-water, is a global challenge. It is necessary to develop a new oil-water separation treatment method. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the deficiencies and defects mentioned in the above background, and to provide a magnetic material for oil-water separation, a preparation method of the magnetic material, and an oil-water separation method and device, which can efficiently separate emulsified oil-water, has low energy consumption, low cost and is environmentally friendly.

[0006] To solve the above technical problems, the technical solution provided by the present application is as follows:

[0007] A preparation method of a magnetic material for oil-water separation, comprising the following steps:

[0008] (1) crushing magnetite or maghemite into magnetic particles;

[0009] (2) dispersing the magnetic particles in a carboxymethyl cellulose aqueous solution and ultrasonic treatment, then solid-liquid separation and collecting the particles with a magnet to obtain CMC-filled magnetic particles;

[0010] (3) dispersing the CMC-filled magnetic particles in an organic solvent of ethyl cellulose, ultrasonic treatment, then solid-liquid separation and collecting the particles with a magnet to obtain a magnetic material for oil-water separation.

[0011] As a further improvement, the particle size of the magnetic particles in step (1) is 1-4 mm.

[0012] As a further improvement, the concentration of the carboxymethyl cellulose aqueous solution in step (2) is 0.8-1.5 wt%, and the ultrasonic treatment is 20-40 minutes.

[0013] As a further improvement, the organic solvent in step (3) is toluene, the concentration of ethyl cellulose is 0.8-1.5 wt%, and the ultrasonic treatment is 20-40 minutes.

[0014] The present application provides a magnetic material for oil-water separation, which is prepared by the method.

[0015] The present application provides an oil-water separation device, which comprises a separation column, a coil surrounding the outer wall of the separation column, an upper grid and a lower grid arranged in the separation column, and the magnetic material for oil-water separation of claim 5 arranged between the upper grid and the lower grid.

[0016] As a further improvement, it further comprises a feed inlet arranged at the bottom of the separation column and a jet device connected with the feed inlet, and an oil outlet arranged at the top of the separation column.

[0017] As a further improvement, it further comprises a monitoring system, which comprises an oil-water interface detector arranged at the upper part of the separation column, for stopping feeding when the oil layer thickness reaches the position of the oil-water interface detector, and the oil layer is discharged through the oil outlet.

[0018] As a further improvement, the packing rate of the magnetic material for oil-water separation in the separation column is 45-80%.

[0019] The present application provides an oil-water separation method, which uses the oil-water separation device to separate oil and water, comprising the following steps:

[0020] (1) passing the oil-water mixture into the separation column;

[0021] (2) the coil is passed through alternating current, the magnetic field size is set to 4-6Gs, the frequency is set to 30-45hz, oil-water separation is carried out, the oil-water mixture is stopped to pass through after being kept for 0.5-2h;

[0022] (3) clean water is passed through in the separation column and weak alkali is added, the magnetic field size is adjusted to 8-12Gs, the frequency is adjusted to 50-70hz, the magnetic material is cleaned and recovered after being kept for 10-30min.

[0023] Compared with the prior art, the beneficial effects of the present application are:

[0024] The present application adopts natural mineral as a basic material, i.e. magnetite or magnetite hematite as an initial material, breaks and grinds the original mineral, obtains stable small magnetic balls with magnetism through balling technology, and then uses CMC and EC to make the surface of the small magnetic balls form a hydrophobic layer, so that the magnetic material for oil-water separation is prepared. Compared with other synthetic materials, the mineralization of the natural mineral has strong stability, longer service life, and more complex applicable environment. The natural mineral can be recycled in the oil-water mixture for multiple times, and the oil-water separation effect is good.

[0025] In the preparation of magnetic material, since the magnetic hematite and magnetite minerals have good hydrophilicity, and have active hydroxyl groups on their structure surface, through the primary reaction of sodium carboxymethyl cellulose (CMC) and iron oxide (Fe3O4) particles, the structure surface of sodium carboxymethyl cellulose has abundant hydroxyl and carboxyl groups, which can associate with the active hydroxyl groups on the surface of magnetite to form a stable hydrophilic surface, and expand the distribution sites of the hydroxyl groups on the surface of magnetite, providing more hydroxyl sites for subsequent EC adsorption, and preparing magnetic response and interfacial activity composite magnetic particles composed of inner magnetic core and outer interfacial activity material. Secondly, the ethyl cellulose (EC) solution is adsorbed on the CMC, and the EC is the most widely used water-insoluble cellulose. One end of the EC associates with the hydroxyl groups in the CMC in the organic solvent, and the other end contacts with the outside world as a hydrophobic end, forming a stable hydrophobic interface, so as to form a stable hydrophobic layer on the surface of the magnetic particles. Compared with the previous preparation method, the method for synthesizing the composite magnetic particles with magnetic response and interfacial activity by continuously adsorbing different cellulose materials without unnecessary derivatization reaction is much simpler, and has higher energy efficiency and less waste. The synthesized composite magnetic particles have high interfacial activity, so they can effectively divide at the oil-water interface. The ultrafine dispersed oil droplets in the multiphase emulsion can be captured by the hydrophobic surface of the magnetic material, and then the oil-water separation controlled by the external magnetic field can be effectively realized. The adsorption of CMC on the surface of bare iron oxide not only enhances the subsequent adsorption of EC on the surface of the CMC substrate iron oxide, but also greatly improves the colloidal stability of the iron oxide dispersion. Compared with one-time chemicals, the amount of chemicals is reduced, and the material has the characteristics of recyclability. Compared with the traditional demulsification method, CMC and EC are green materials, non-toxic and biocompatible, the interfacial activity nanoparticles prepared have environmental friendliness, and can more effectively demulsify and separate the emulsified oil-water mixture.

[0026] The application adopts a magnetic field control technology, and by adding an alternating magnetic field to an oil-water separation device, the force condition of the magnetic iron balls is changed under the action of the external magnetic field, so that the magnetic iron balls can vibrate at a certain frequency in the oil-water mixture. Compared with the conventional static contact, under the action of the magnetic control, the hydrophobic magnetic iron balls and the oil droplet interface contact effect is better, the coalescence is strengthened, the efficiency of small oil droplet coalescence is improved, and the emulsified oil and water is effectively separated. At the same time, based on the double action of flow field turbulence and magnetic field regulation, no clogging coalescence can be realized. At the same time, the suspended solids and solid impurities attached to the magnetic iron balls can be separated by inertial force, and high-efficiency clean recycling of materials can be realized.

[0027] Under the premise of magnetic field control, all processes of separation of the application are carried out in the separation column, the technology is systematized, the magnetic field regulation is centralized, the process is more stable, the inside of the separation column adopts the form of countercurrent, the oil-water mixture is fully contacted with the magnetic particles, and the oil-water mixture after separation and stratification is avoided from mixing again, the separation efficiency is ensured, the disturbance of the particles under the action of the magnetic field is strengthened, and the residual material is conveniently cleaned. The separation device can be connected in series and circulated, the oil-water separation effect is improved, the separation device can be automatically modified, has strong extensibility, and has large development space. The whole separation process has low energy consumption, low cost and environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0029] Figure 1 is a relationship diagram of the number of cycles and the oil removal rate;

[0030] Figure 2 is a relationship diagram of the particle size and the oil removal rate;

[0031] Figure 3 is a relationship diagram of the interstitial porosity and the oil removal rate;

[0032] Figure 4 is a schematic diagram of an oil-water separation device of one specific embodiment of the present application.

[0033] Wherein: 1, separation column; 2, upper grid; 3, lower grid; 4, oil-water interface detector; 5, magnetic particles; 6, feed inlet; 7, oil outlet; 8, coil; a, magnetic field line. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the present application, the following will combine the drawings and the preferred embodiments to make a more comprehensive and detailed description of the present application, but the protection scope of the present application is not limited to the following specific embodiments.

[0035] Unless otherwise defined, all professional terms used in the following have the same meaning as generally understood by those skilled in the art. The professional terms used in this paper are only for the purpose of describing the specific embodiments and are not intended to limit the protection scope of the present application.

[0036] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0037] Preparation of magnetic material for oil-water separation

[0038] Reagents: sodium carboxymethylcellulose (molecular weight 250 000 g / mol; degree of substitution 0.7), ethyl cellulose (ethoxyl content 42%), magnetite, toluene (ACS grade), acetone (ACS grade), methanol (ACS grade), ethanol (commercial alcohol; 99%), 2-propanol (ACS grade).

[0039] Preparation process of magnetic material for oil-water separation:

[0040] The magnetite was washed and then ground to fully dissociate. The raw ore was initially crushed using a jaw crusher, and then ground using a jar mill to dissociate it to the micron level, avoiding excessive fineness of the particle surface properties, with a particle size distribution centered around 400 mesh (38 μιη).

[0041] The crushed ore particles were agglomerated into 1, 2, 3, 4 mm Fe304 particles using a balling process, with the magnetic balls being highly mineralized and having highly stable structural properties. 20 g of magnetic Fe304 particles were washed with acetone and dried under a nitrogen stream.

[0042] The washed magnetic Fe304 particles were dispersed in a 1.0 wt% CMC (carboxymethylcellulose) aqueous solution using an ultrasonic disintegrator. The mixture was placed in an ultrasonic bath for 30 minutes, and the magnetic particles were fixed with CMC carboxymethylcellulose. The mixture was filtered, washed three times with deionized water, and then washed three times with ethanol. After each washing, the particles were collected using a powerful permanent magnet, and CMC-filled magnetic particles were obtained.

[0043] The CMC-filled magnetic particles were dispersed in a 1.0 wt% EC (ethyl cellulose) toluene solution, and then placed in an ultrasonic bath for 30 min. The mixture was filtered, washed three times with toluene, and then washed three times with ethanol. After each washing, the resulting particles were collected using a permanent magnet. The recovered particles were dried in a vacuum drying oven at 105°C for 12 h, and a magnetic material for oil-water separation was prepared.

[0044] Example 2 Oil-water separation device

[0045] As Figure 4, the oil-water separation device comprises a separation system, an oil-water feeding system, a water and oil discharging system, a coil magnetic field regulating system and a monitoring system. The separation system comprises a separation column 1, an upper grid 2 and a lower grid 3 arranged in the separation column 1, and magnetic particles 5 (magnetic material for oil-water separation prepared in Example 1) filled between the upper grid 2 and the lower grid 3; the oil-water feeding system comprises a feeding port 6 and a jet device arranged at the bottom of the separation column 1; the water and oil discharging system comprises an oil outlet 7 and a water outlet (not shown) arranged at the top of the separation column 1; the coil magnetic field regulating device comprises a coil 8 arranged outside the separation column 1; and the monitoring system comprises an oil-water interface detection meter 4.

[0046] The ratio of the height H of the separation column 1 to the bottom diameter D is preferably 25, and the separation efficiency is the highest.

[0047] The feeding port 6 is in the form of a funnel structure, which is provided with a jet device, and the oil-water mixture is injected into the separation column 1 at a speed of about 15 m / h, so that the oil-water mixture has a certain momentum and fully contacts with the magnetic particles, so that the oil-water mixture is fully separated.

[0048] The coil 8 is installed around the separation column 1, and alternating current is applied to the coil 8 to generate an alternating magnetic field in the separation column 1 (the magnetic field distribution is shown in Figure 4 ), so that the magnetic particles make irregular vibration in the system, the coalescence effect is strengthened, the magnetic control oil droplet coalescence is realized without blockage, and the oil-water separation is strengthened.

[0049] By applying an alternating magnetic field, the motion state of the magnetic particles in the system is regulated by changing the type, size and frequency of the magnetic field: during the coalescence process, the system is magnetized to make the particles produce disturbance, the oil-water-high-activity interface collides and contacts with each other, the interface effect is enhanced, the high-interface-activity magnetic hydrophobic particles and oil droplets contact with each other more effectively, the coalescence is strengthened, the oil droplet coalescence effect is better, and the oil-water separation degree is higher. At the same time, based on the double effects of flow field turbulence and magnetic field regulation, the suspended matter and solid impurities attached to the magnetic particles are separated by inertial force, the coalescence without blockage is realized, and the material can be efficiently cleaned and recycled.

[0050] During the process of magnetic field regulation oil droplet coalescence and oil-water separation, the frequency of the magnetic field should not be too fast, and the size should not be too large, so as to avoid the decrease of the coalescence effect caused by the reduction of the contact time. In the preferred embodiment, after the magnetic control coalescence disturbance at a frequency of 40 hz and a magnetic field size of 5Gs for about 1 h, the oil-water mixture is stopped, clean water is added, and a weak base such as sodium carbonate is added to clean and recycle the system. At this time, the magnetic field is increased to a frequency of 60 hz and a magnetic field size of 10Gs and maintained for 20 min, the iron ball amplitude is increased, the magnetic particles are fully cleaned, and the material is efficiently cleaned and recycled. After the cleaning is completed, the magnetic field and the feeding port are closed, and the magnetic particles are recycled using a permanent magnet.

[0051] The upper and lower grids function to fix the magnetic particles, and the lower grid 3 also functions as a primary sieve to exclude larger impurities in the oil-water mixture to prevent the system from being blocked.

[0052] After the oil-water mixture passes through the separation system, the oil and water are separated, the separation effect is good, the stratification effect is obvious, the oil layer is on the top and the water layer is on the bottom, and the monitoring system plays an important role in the process. When the thickness of the oil layer after stratification reaches the position of the oil-water interface detector 4, the system stops feeding, the oil layer leaves the system through the oil outlet 7, and the next step can be processed. It can also be separated for multiple times and finally separated from the system.

[0053] In the system, the materials of the rest of the system are non-magnetic materials except the magnetic particles.

[0054] The system has the advantages of simple design, flexible operation, strong practicability, low cost, high oil removal efficiency, recycling of high interfacial activity magnetic particles, and solving the blocking and pollution problems caused by traditional methods. It not only has strong practicability and low cost, but also is beneficial to environmental protection and resource recycling.

[0055] Example 3: Oil-water separation effect of different magnetic particles

[0056] In order to explore the influence of the size of the magnetic particles and the separation time on the separation effect, the following test is designed:

[0057] Experiment 1:

[0058] 20ml edible oil was dispersed in 100ml deionized water, heated to 40℃, and stirred for 20min to obtain an oil-water mixed reaction system; 1mm diameter magnetic particles treated by high interfacial activity modification (magnetic material for oil-water separation prepared in Example 1) were placed between the upper and lower grids in the separation column 1 at a 65% interstitial rate, and were repeatedly oscillated in the oil-water for 20min (using the device of Example 2, magnetic field size 5Gs, frequency 40hz); a dropper was used to take part of the sample in the water layer for oil removal rate detection.

[0059] Experiment 2:

[0060] 20ml edible oil was dispersed in 100ml deionized water, heated to 40℃, and stirred for 20min to obtain an oil-water mixed reaction system; 2mm diameter magnetic particles treated by high interfacial activity modification (magnetic material for oil-water separation prepared in Example 1) were placed between the upper and lower grids in the separation column 1 at a 65% interstitial rate, and were repeatedly oscillated in the oil-water for 20min (using the device of Example 2, magnetic field size 5Gs, frequency 40hz); a dropper was used to take part of the sample in the water layer for oil removal rate detection.

[0061] Experiment three:

[0062] 20ml edible oil was dispersed in 100ml deionized water, heated to 40℃, stirred for 20min, to obtain oil-water mixed reaction system; 3mm diameter of magnetic particles (magnetic material for oil-water separation prepared in example 1) treated by high interfacial activity modification was placed between the upper and lower grid in separation column 1 with 65% interstitial filling rate, and was repeatedly oscillated in oil-water for 20min (using the device of example 2, magnetic field size 5Gs, frequency 40hz); part of the sample in water layer was taken by dropper for oil removal rate detection.

[0063] Experiment four:

[0064] 20ml edible oil was dispersed in 100ml deionized water, heated to 40℃, stirred for 20min, to obtain oil-water mixed reaction system; 4mm diameter of magnetic particles (magnetic material for oil-water separation prepared in example 1) treated by high interfacial activity modification was placed between the upper and lower grid in separation column 1 with 65% interstitial filling rate, and was repeatedly oscillated in oil-water for 20min (using the device of example 2, magnetic field size 5Gs, frequency 40hz); part of the sample in water layer was taken by dropper for oil removal rate detection.

[0065] The oil content in water was determined by ultraviolet spectrophotometry. The oil removal rate (%) calculation formula is In the formula, Co is the initial oil content of crude oil emulsion, C t is the oil content after oil-water separation of crude oil emulsion.

[0066] The cycle number and oil removal rate measurement results of experiment one are shown in table one.

[0067] Table one oil removal rate measurement table

[0068]

[0069] After three times of water removal treatment, the oil removal rate is basically stable and unchanged, and the cumulative treatment time is 1h. And in the 10 times of cycle test, the oil removal rate basically remains unchanged. Compared with the oil-water separation effect of commonly used fiber particles Figure 1 .

[0070] The measurement results of different experiments are shown in Figure 2 and table two.

[0071] Table two oil removal rate measurement table of different particle sizes

[0072]

[0073] The smaller the particle size, the higher the interfacial activity, the larger the specific surface area, and the stronger the oil-water interface effect, so the oil removal rate is higher.

[0074] Effect of oil-water separation of different particle interstitial rate of example 4

[0075] In order to explore the influence of different interstitial rate of magnetic particles in the system on the separation effect, the following test is designed:

[0076] Experiment five:

[0077] 20ml edible oil was dispersed in 100ml deionized water, heated to 40℃, stirred for 20min, and an oil-water mixed reaction system was obtained; 1mm diameter magnetic particles (magnetic material for oil-water separation prepared in example 1) treated by high interfacial activity modification were placed between the upper and lower grids in the separation column 1 with 50% interstitial rate, and were repeatedly oscillated in oil-water for 20min (using the device of example 2, magnetic field size 5Gs, frequency 40hz); part of the sample in the water layer was taken with a dropper for oil removal rate detection.

[0078] Experiment six:

[0079] 20ml edible oil was dispersed in 100ml deionized water, heated to 40℃, stirred for 20min, and an oil-water mixed reaction system was obtained; 1mm diameter magnetic particles (magnetic material for oil-water separation prepared in example 1) treated by high interfacial activity modification were placed between the upper and lower grids in the separation column 1 with 65% interstitial rate, and were repeatedly oscillated in oil-water for 20min (using the device of example 2, magnetic field size 5Gs, frequency 40hz); part of the sample in the water layer was taken with a dropper for oil removal rate detection.

[0080] Experiment seven:

[0081] 20ml edible oil was dispersed in 100ml deionized water, heated to 40℃, stirred for 20min, and an oil-water mixed reaction system was obtained; 1mm diameter magnetic particles (magnetic material for oil-water separation prepared in example 1) treated by high interfacial activity modification were placed between the upper and lower grids in the separation column 1 with 80% interstitial rate, and were repeatedly oscillated in oil-water for 20min (using the device of example 2, magnetic field size 5Gs, frequency 40hz); part of the sample in the water layer was taken with a dropper for oil removal rate detection.

[0082] Experiment eight:

[0083] 20ml edible oil was dispersed in 100ml deionized water, heated to 40℃, stirred for 20min, to obtain an oil-water mixed reaction system; 1mm diameter magnetic particles (magnetic material for oil-water separation prepared in Example 1) treated by high interfacial activity modification were placed in the separation column 1 at 90% interstitial filling rate between the upper and lower grids, and were repeatedly oscillated in the oil-water for 20min (using the device of Example 2, magnetic field size 5Gs, frequency 40hz); a dropper was used to take part of the sample in the water layer for oil removal rate detection.

[0084] The interstitial filling rate (%) is the ratio of the total volume of the particles to the volume of the separation column, and the calculation formula is In the formula, N is the number of magnetic particles, V0 is the volume of a single magnetic particle, and V is the effective volume of the entire separation column.

[0085] The measurement results of different experiments are shown as Figure 3 and Table 3.

[0086] Table 3 Oil removal rate measurement table of different magnetic particle interstitial filling rates

[0087]

[0088] It can be seen that the optimal interstitial filling rate is 50%, the disturbance of the reinforced iron ball under the action of the magnetic field has the highest oil removal rate, and it is convenient to clean the residues.

[0089] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Therefore, any simple modification, equivalent change and modification of the above embodiment according to the technical essence of the present application, which does not deviate from the technical scheme of the present application, shall fall within the protection scope of the technical scheme of the present application.

Claims

1. A method of oil-water separation, characterized by, The oil-water separation device is used for oil-water separation; The oil-water separation device comprises a separation column, a coil surrounding the outer wall of the separation column, an upper grid and a lower grid arranged in the separation column, and a magnetic material for oil-water separation arranged between the upper grid and the lower grid; the interstitial filling rate of the magnetic material for oil-water separation in the separation column is 45-80%; The magnetic material for oil-water separation is prepared by the following method: (1) crushing magnetite or magnetite hematite to form magnetic particles by balling, wherein the particle size of the magnetic particles is 1-4 mm; (2) dispersing the magnetic particles in a carboxymethyl cellulose aqueous solution and ultrasonic treatment, then solid-liquid separation and collecting the particles with a magnet to obtain CMC-filled magnetic particles; (3) dispersing the CMC-filled magnetic particles in an organic solvent of ethyl cellulose, ultrasonic treatment, then solid-liquid separation and collecting the particles with a magnet to obtain the magnetic material for oil-water separation; The oil-water separation method comprises the following steps: (1) passing the oil-water mixture into the separation column; (2) passing alternating current into the coil, setting the magnetic field size at 4-6 Gs and the frequency at 30-45 hz, carrying out oil-water separation, maintaining for 0.5-2 h, and stopping passing the oil-water mixture; (3) passing clean water and adding a weak base into the separation column, adjusting the magnetic field size to 8-12 Gs and the frequency to 50-70 hz, maintaining for 10-30 min, and carrying out cleaning and recovery of the magnetic material.

2. The oil-water separation method according to claim 1, characterized by, The oil-water separation device further comprises a feed inlet arranged at the bottom of the separation column and a jet device connected with the feed inlet, and an oil outlet arranged at the top of the separation column.

3. The oil-water separation method of claim 1, wherein, The oil-water separation device further comprises a monitoring system, wherein the monitoring system comprises an oil-water interface detection meter arranged at the upper part of the separation column, and is used for stopping feeding when the oil layer thickness reaches the position of the oil-water interface detection meter, and the oil layer is discharged through the oil outlet.

4. The oil-water separation method of claim 1, wherein, The concentration of the carboxymethyl cellulose aqueous solution is 0.8-1.5 wt%, and the ultrasonic treatment time is 20-40 min.

5. The oil-water separation method of claim 1, wherein The organic solvent is toluene, the concentration of ethyl cellulose is 0.8-1.5 wt%, and the ultrasonic treatment time is 20-40 min.

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