Oligomer microsphere particle as well as preparation method and application thereof

Abstract

The invention relates to the field of nano materials, and discloses an oligomer microsphere particle as well as a preparation method and application thereof. The oligomer microsphere particle comprises a core part, a middle layer part and a shell part, the core part comprises nanoparticles, the middle layer part comprises silicon dioxide, and the shell part comprises an oligomer as shown in a formula I and an oligomer as shown in a formula II; r and R'are respectively and independently selected from-OCH2CH3 or-OCH3, x is 1 to 3, k is an integer from 1 to 5, m is an integer from 4 to 12, R1 is H or C6-C15 alkyl, y is 1 to 3, and q is an integer from 4 to 12. The oligomer microsphere particles comprise nanoparticles, silicon dioxide, a hydrophilic oligomer and an oleophylic oligomer, the hydrophilic oligomer has excellent tackifying property and emulsifying property, the oleophylic oligomer can enrich oil drops, and water and oil drops in oily sewage can be effectively separated when the oligomer microsphere particles are placed in an oil-water environment.

Description

Technical Field

[0001] The present invention relates to the field of nanomaterials, and in particular to oligomer microsphere particles, a preparation method and application thereof. Background Art

[0002] In the fields of petroleum and natural gas industry, fuel chemical industry, environmental science and resource utilization, there are large amounts of oily wastewater. If it is not effectively treated, it will have a very adverse impact on people's lives, resource recovery and the ecological environment. Oil in oily wastewater mostly exists in the form of floating oil, dispersed oil, emulsified oil and micron-sized oil droplets. Different forms require different treatment methods. Treatment methods can generally be divided into chemical, biological, physical and other methods. With economic growth and the development of the oil industry, the composition of oily wastewater has become more complex, and the difficulty of separation has continued to increase. In recent years, many researchers at home and abroad have carried out a large number of related studies. New materials such as new water treatment membranes and adsorption sponges have been widely used to separate floating oil, dispersed oil and even emulsified oil, achieving good separation effects and economic benefits.

[0003] In the petroleum industry, most mature oilfields have entered the mid-to-late-stage development phase, and the water content of produced fluids is increasing annually, increasing the pressure and costs on produced fluid treatment plants. Currently, the combined water content of produced fluids from most oil wells exceeds 98%, resulting in tens of thousands of cubic meters of oily wastewater requiring treatment and separation daily at water treatment plants. Furthermore, the widespread use of production-enhancing measures such as chemical flooding and steam flooding during oilfield development has led to more complex composition and properties of produced fluids, characterized by high viscosity and strong emulsion stability of oil droplets and suspended solids in water. This further complicates oil-water separation, with the treatment of fine oil-in-water (O / W) droplets being particularly challenging. Currently, conventional demulsifiers and demulsification technologies are primarily targeted at specific oily wastewater types, severely limiting their scope of application. Furthermore, they require high demulsification temperatures and consume significant energy. While it's impossible to predict that a single demulsification technology or demulsifier is perfectly effective for all oily wastewater, expanding the scope of their applicability will be a key area of continued research. Therefore, it is crucial to develop a new type of high-efficiency and universal low-temperature water treatment material, especially for the separation of oil droplets in water, to provide technical support for environmental protection, energy conservation and consumption reduction, and increase in crude oil reserves and production. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems of the existing technology that oil droplets in water are difficult to separate and the core-shell particles have single performance. The present invention provides oligomer microsphere particles and their preparation method and application. The oligomer microsphere particles contain nanoparticles, silica, hydrophilic oligomers and lipophilic oligomers. The hydrophilic oligomers have excellent viscosity increasing and emulsifying properties, and the lipophilic oligomers can enrich oil droplets. Placing them in an oil-water environment can effectively separate water and oil droplets in oily wastewater.

[0005] To achieve the above objectives, the first aspect of the present invention provides an oligomer microsphere particle, wherein the oligomer microsphere particle comprises a core portion, an intermediate layer portion, and a shell portion, wherein the core portion comprises nanoparticles, the intermediate layer portion comprises silicon dioxide, and the shell portion comprises an oligomer represented by Formula I and an oligomer represented by Formula II;

[0006]

[0007] wherein R and R' are each independently selected from -OCH2CH3 or -OCH3, x is 1-3, k is an integer of 1-5, and m is an integer of 4-12.

[0008] R1 is H or a C6-C15 alkyl group, y is 1-3, and q is an integer of 4-12.

[0009] A second aspect of the present invention provides a method for preparing oligomer microsphere particles, wherein the method comprises:

[0010] (1) synthesizing silica in situ on the surface of the nanoparticles under a first stirring condition at a first temperature to obtain particles I;

[0011] (2) heating to a second temperature, adding particles I to a mixed solution of paraffin and water, and forming an oil-in-water emulsion under a second stirring condition;

[0012] (3) adding a first silane coupling agent to the emulsion of step (2) to carry out a first grafting reaction on the particle I; and then adding 2-acrylamido-2-methylpropanesulfonic acid in the presence of a water-soluble initiator and a water-soluble promoter to carry out a first polymerization reaction to obtain particles II;

[0013] (4) removing the paraffin on the surface of particle II, adding a second silane coupling agent, and performing a second grafting reaction; in the presence of an oil-soluble initiator and an oil-soluble promoter, adding an oil-soluble monomer, performing a second polymerization reaction, and separating to obtain the oligomer microsphere particles;

[0014] Wherein, the first silane coupling agent is selected from acrylamide silane coupling agents;

[0015] The second silane coupling agent is selected from vinyl silane coupling agents.

[0016] The third aspect of the present invention provides oligomer microsphere particles prepared by the above preparation method.

[0017] A fourth aspect of the present invention provides a use of the aforementioned oligomer microsphere particles in oil-water separation of oily wastewater.

[0018] Through the above technical solution, the present invention has the following beneficial effects:

[0019] (1) The present invention performs amphiphilic modification on the magnetic particles, so that the prepared oligomer microsphere particles contain hydrophilic oligomers and lipophilic oligomers, have excellent emulsification properties, can achieve the separation of fine oil droplets, and enrich the performance of core-shell particles;

[0020] The shell part contains hydrophilic oligomers, which have excellent viscosity-increasing and emulsifying properties. In an oil-water environment, it can further reduce the surface tension of water and destroy the interfacial balance of emulsified fine oil droplets. The shell part contains lipophilic oligomers, which have excellent oil droplet enrichment ability. In an oil-water environment, it can enrich oil droplets and help separate water and oil droplets.

[0021] The middle layer contains silicon dioxide, which can effectively prevent the corrosion of nanoparticles in complex oil-water environments, thereby achieving effective protection for the nanoparticles.

[0022] (2) The preparation method of the present invention coats silica on the nanoparticles, thereby improving the stability of the nanoparticles after the silica coating, so that the obtained oligomer microsphere particles can be applied to complex oil-water environments; and through the regulation of the emulsion interface, paraffin is partially coated on the surface of the particle I, the uncoated part is hydrophilically modified and subjected to a first polymerization reaction, and then the coated paraffin is removed, and the exposed surface is subjected to a lipophilic modification and a second polymerization reaction, thereby obtaining oligomer microsphere particles with rich properties.

[0023] Furthermore, by synthesizing the shell portion of the oligomer represented by formula I and the oligomer represented by formula II having specific structures, the size of the oligomer microsphere particles can be accurately controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the formation of an oil-in-water emulsion after the particles I of the present invention are partially coated. DETAILED DESCRIPTION

[0025] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0026] The first aspect of the present invention provides an oligomer microsphere particle, wherein the oligomer microsphere particle comprises a core portion, an intermediate layer portion, and a shell portion, wherein the core portion comprises nanoparticles, the intermediate layer portion comprises silicon dioxide, and the shell portion comprises an oligomer represented by Formula I and an oligomer represented by Formula II;

[0027]

[0028] wherein R and R' are each independently selected from -OCH2CH3 or -OCH3, x is 1-3, k is an integer of 1-5, and m is an integer of 4-12.

[0029] R1 is H or a C6-C15 alkyl group, y is 1-3, and q is an integer of 4-12.

[0030] In the present invention, * is a linking site on the intermediate layer that connects to the oligomer on the shell portion.

[0031] In the present invention, m and q are the degrees of polymerization of the oligomer represented by Formula I and the oligomer represented by Formula II, respectively. The degree of polymerization is measured by calculating the degree of polymerization m by the ratio of the peak area of methyl hydrogen atoms in 2-acrylamido-2-methylpropanesulfonic acid to the peak area of methylene groups in the coupling agent in the H NMR spectrum, and calculating the degree of polymerization q by the ratio of the peak area of hydrogen atoms on the benzene ring to the peak area of methylene groups in the coupling agent in the H NMR spectrum.

[0032] In the present invention, the nanoparticles are coated with silicon dioxide, which can improve the stability of the nanoparticles and enable the coated nanoparticles to adapt to complex oil-water environments.

[0033] Furthermore, the shell portion comprises an oligomer represented by formula I, which has excellent viscosity-increasing and emulsifying properties. When placed in an oil-water environment, it can further reduce the surface tension of water and destroy the interfacial balance of emulsified fine oil droplets. The shell portion comprises an oligomer represented by formula II, which is lipophilic and can quickly capture and enrich oil droplets, and has excellent oil-water separation performance.

[0034] Furthermore, R and R' are each independently -OCH2CH3, k is an integer of 1-3, and m is an integer of 4-8.

[0035] Furthermore, R1 is H, a C8 alkyl group or a C12 alkyl group, and q is an integer of 4-8.

[0036] In the present invention, based on the total mass of the oligomer microsphere particles, the content of the nanoparticles is 32-57wt%, the content of the intermediate layer is 22-34wt%, the content of the oligomer represented by formula I is 2.5-15wt%, and the content of the oligomer represented by formula II is 14-27wt%.

[0037] In the present invention, the solution after the in-situ synthesis reaction, the solution after the first grafting reaction, the solution after the first polymerization reaction, the solution after the second grafting reaction, and the solution after the second polymerization reaction are washed and purified respectively to obtain the mass of the remaining unreacted substance. The mass of the remaining unreacted substance is subtracted from the total mass of the input materials. According to the change in mass before and after, the masses of the intermediate layer, the oligomer represented by formula I, and the oligomer represented by formula II are respectively obtained. The masses are then divided by the total mass of the oligomer microsphere particles to obtain the corresponding contents of each. The nanoparticle content is obtained by dividing the mass of the nanoparticles by the total mass of the oligomer microsphere particles.

[0038] In the present invention, the contents of the oligomer represented by formula I and the oligomer represented by formula II satisfying the above ranges enable the oligomer microsphere particles to have better hydrophilic and lipophilic properties, thereby improving the oil-water separation effect.

[0039] Furthermore, based on the total mass of the oligomer microsphere particles, the content of the nanoparticles is 40-53wt%, the content of the intermediate layer is 25-34wt%, the content of the oligomer represented by formula I is 5-11wt%, and the content of the oligomer represented by formula II is 14-22wt%.

[0040] According to the present invention, the particle size of the oligomer microsphere particles is 300-800 nm.

[0041] In the present invention, the size of the oligomer microsphere particles meeting the above range is beneficial to destroying the oil-water interface balance and promoting oil-water separation.

[0042] Furthermore, the particle size of the oligomer microsphere particles is 400-600 nm.

[0043] According to the present invention, the particle size of the nanoparticles is 100-400 nm.

[0044] In the present invention, the particle sizes of the oligomer microsphere particles and the nanoparticles are measured by a BeNano 180Pro nanoparticle size analyzer.

[0045] In the present invention, the nanoparticles meeting the above size range can make the oligomer microsphere particles have a suitable size and can stably exist at the oil-water interface.

[0046] Furthermore, the particle size of the nanoparticles is 200-300 nm.

[0047] According to the present invention, the nanoparticles are at least one selected from a metal element, a metal alloy and a metal oxide.

[0048] In the present invention, the nanoparticles are magnetic particles, which can be separated by an external magnetic field during preparation and application in oil-water separation, thereby improving preparation efficiency and application efficiency.

[0049] Furthermore, the nanoparticles are ferrosoferric oxide.

[0050] A second aspect of the present invention provides a method for preparing oligomer microsphere particles, wherein the method comprises:

[0051] (1) synthesizing silica in situ on the surface of the nanoparticles under a first stirring condition at a first temperature to obtain particles I;

[0052] (2) heating to a second temperature, adding particles I to a mixed solution of paraffin and water, and forming an oil-in-water emulsion under a second stirring condition;

[0053] (3) adding a first silane coupling agent to the product of step (2) to carry out a first grafting reaction on the particle I; and then adding 2-acrylamido-2-methylpropanesulfonic acid in the presence of a water-soluble initiator and a water-soluble promoter to carry out a first polymerization reaction to obtain particles II;

[0054] (4) removing the paraffin on the surface of particle II, adding a second silane coupling agent, and performing a second grafting reaction; in the presence of an oil-soluble initiator and an oil-soluble promoter, adding an oil-soluble monomer, performing a second polymerization reaction, and separating to obtain the oligomer microsphere particles;

[0055] Wherein, the first silane coupling agent is selected from acrylamide silane coupling agents;

[0056] The second silane coupling agent is selected from vinyl silane coupling agents.

[0057] In the present invention, coating the nanoparticles with silicon dioxide improves the stability of the nanoparticles, making them suitable for use in complex oil-water environments.

[0058] Furthermore, by first heating to a second temperature, the particles I are contacted with a mixed solution of paraffin and water to form an oil-in-water emulsion, and the surface of the particles I is partially coated with paraffin by controlling the emulsion interface. Specifically, Figure 1 As shown, particles I in the oil-in-water emulsion are partially embedded in the oil phase paraffin, forming a structure in which the surface of the particles I is partially coated with paraffin, and a first grafting reaction and a first polymerization reaction are performed on the uncoated portion; then the coated paraffin is removed, and a second grafting reaction and a second polymerization reaction are performed on the exposed surface of the intermediate layer, ultimately obtaining amphiphilic modified oligomer microsphere particles.

[0059] In the present invention, the in-situ synthesis of silica is a conventional method for in-situ synthesis of silica in the art. The following is a particularly preferred method for in-situ synthesis of silica: a silicon source is added to an alcohol solvent.

[0060] According to the present invention, the alcohol solvent is selected from at least one of methanol, ethanol, n-butanol, isobutanol and propylene glycol, preferably ethanol.

[0061] According to the present invention, the nanoparticles are selected from at least one of a metal element, a metal alloy and a metal oxide, and are preferably ferrosoferric oxide.

[0062] In the present invention, the nanoparticles are magnetic particles. When prepared and applied to oil-water separation, the particles I, particles II and oligomer microsphere particles containing the nanoparticles can be separated from the oil and water by an external magnetic field, thereby improving the preparation efficiency and application efficiency.

[0063] In the present invention, the magnetic field is a common magnetic field. A preferred embodiment uses a magnetic field brought by a NiFeB magnet with a brand of N35, and the magnetic induction intensity is 1170-1210 mT.

[0064] According to the present invention, the weight ratio of the nanoparticles to the silicon source is 1:0.4-0.9.

[0065] In the present invention, the weight ratio of nanoparticles to silicon source meeting the above range can ensure that the surface of the nanoparticles is evenly coated with silicon dioxide, effectively protecting the nanoparticles and preventing the weakening of the nanoparticles' magnetism, and can also provide sufficient reaction sites for the subsequent grafting reaction.

[0066] Furthermore, the weight ratio of the nanoparticles to the silicon source is 1:0.5-0.8.

[0067] The amount of the alcohol solvent used in the present invention is conventionally selected so as to allow the nanoparticles to be evenly dispersed therein.

[0068] According to the present invention, in step (2), the amount of the particles I is 8-20 parts by weight relative to 100 parts by weight of the mixed solution of paraffin and water.

[0069] In the present invention, the specific amount of the mixed solution of paraffin wax and water and the particles I is such that the particles I can be stably present at the interface between water and paraffin wax, so that the surface of the particles I is evenly coated with paraffin wax, thereby protecting the surface and preventing the coated portion from participating in the first grafting reaction and the first polymerization reaction.

[0070] The mixed solution of paraffin wax and water is an oil-in-water mixed solution. In a particularly preferred embodiment, in the mixed solution of paraffin wax and water, the weight ratio of paraffin wax to water is 1:3-10, preferably 1:5-8.

[0071] Furthermore, relative to 100 parts by weight of the mixed solution of paraffin and water, the amount of the particles I is 10-18 parts by weight.

[0072] According to the present invention, the first silane coupling agent is selected from (3-acrylamidopropyl)triethoxysilane and / or (3-acrylamidopropyl)trimethoxysilane, preferably (3-acrylamidopropyl)triethoxysilane.

[0073] In the present invention, when the first silane coupling agent is (3-acrylamidopropyl)triethoxysilane, the -OCH3CH2 therein undergoes a dehydration reaction with the -OH in the SiO2 on the intermediate layer to form a -Si-O- connection, or it may not be hydrolyzed and exist in the form of -OCH3CH2, and the double bond provides a reaction site for the next step of graft polymerization.

[0074] According to the present invention, the water-soluble initiator is selected from potassium persulfate and / or ammonium persulfate, preferably potassium persulfate.

[0075] According to the present invention, the water-soluble promoter is selected from tetramethylethylenediamine and / or ethylenediamine, preferably tetramethylethylenediamine.

[0076] According to the present invention, the weight ratio of the particles I to the first silane coupling agent is 1:0.01-0.05.

[0077] In the present invention, the amount of the specific particles I and the first silane coupling agent can control the uniform distribution of the coupling agent on the particle surface, thereby achieving effective control of the number of hydrophilic groups.

[0078] Furthermore, the weight ratio of the particles I to the first silane coupling agent is 1:0.02-0.035.

[0079] According to the present invention, the weight ratio of the first silane coupling agent to the 2-acrylamido-2-methylpropanesulfonic acid is 1:20-40.

[0080] In the present invention, when the weight ratio meets the above range, the prepared hydrophilic oligomer has excellent viscosity-increasing and emulsifying properties, destroys the interfacial balance of emulsified fine oil droplets, and greatly improves the oil-water separation effect.

[0081] Furthermore, the weight ratio of the first silane coupling agent to the 2-acrylamido-2-methylpropanesulfonic acid is 1:25-35.

[0082] According to the present invention, the weight ratio of the first silane coupling agent, the water-soluble initiator and the water-soluble promoter is 1:0.4-0.8:0.2-0.5.

[0083] In the present invention, when the above weight ratio range is met, the first polymerization reaction proceeds more fully, and its application in the field of oil-water separation is beneficial to promoting the progress of oil-water separation.

[0084] Furthermore, the weight ratio of the first silane coupling agent, the water-soluble initiator and the water-soluble promoter is 1:0.6-0.8:0.3-0.5.

[0085] According to the present invention, in step (4), the specific step of removing the paraffin on the surface of particles II includes: dispersing the particles II in an oil-soluble solvent to remove the paraffin coated on the particles II.

[0086] In the present invention, the inventors achieve partial coating of the surface of the particle I with paraffin through emulsion interface regulation, ensuring that only a portion of the surface of the particle I undergoes the first grafting reaction and the first polymerization reaction. The particle I is then placed in an oil-soluble solution, the surface-coated paraffin is removed, and the unreacted portion of the intermediate layer surface undergoes a second grafting reaction and a second polymerization reaction, thereby achieving amphiphilic modification of the oligomer microsphere particles, destroying the interfacial balance of the emulsified fine oil droplets, and greatly improving the oil-water separation effect.

[0087] According to the present invention, the oil-soluble solvent is selected from at least one of xylene and / or toluene, preferably xylene.

[0088] According to the present invention, the second silane coupling agent is selected from vinyltriethoxysilane and / or vinyltrimethoxysilane, preferably vinyltriethoxysilane.

[0089] According to the present invention, the oil-soluble initiator is selected from azobisisobutyronitrile and / or benzoyl peroxide, preferably azobisisobutyronitrile.

[0090] According to the present invention, the oil-soluble promoter is selected from dodecyl mercaptan and / or tert-dodecyl mercaptan, preferably dodecyl mercaptan.

[0091] According to the present invention, the oil-soluble monomer is selected from at least one of styrene, octylstyrene, p-dodecylstyrene and p-aminostyrene, preferably at least one of styrene, octylstyrene and p-dodecylstyrene.

[0092] According to the present invention, the amount of the particles II is 5-20 parts by weight relative to 100 parts by weight of the oil-soluble solvent.

[0093] In the present invention, the amount within the above range can ensure that particles II are fully dispersed in the oil-soluble solvent, which is conducive to removing the paraffin coating on the surface of particles II, exposing the unreacted intermediate layer surface, and performing the second grafting reaction.

[0094] Furthermore, relative to 100 parts by weight of the oil-soluble solvent, the amount of the particles II is 5-15 parts by weight.

[0095] According to the present invention, the weight ratio of the particles II to the second silane coupling agent is 1:0.02-0.05.

[0096] In the present invention, when the weight ratio satisfies the above range, the coupling agent can be evenly distributed on the surface of the particles, so that the particles have excellent lipophilicity.

[0097] Furthermore, the weight ratio of the particles II to the second silane coupling agent is 1:0.025-0.045.

[0098] According to the present invention, the weight ratio of the second silane coupling agent to the oil-soluble monomer is 1:40-80.

[0099] In the present invention, when the above weight ratio range is met, the obtained oligomer represented by formula II has better lipophilicity and can enrich oil droplets in water.

[0100] Furthermore, the weight ratio of the second silane coupling agent to the oil-soluble monomer is 1:40-70.

[0101] According to the present invention, the weight ratio of the second silane coupling agent, the oil-soluble initiator and the oil-soluble promoter is 1:0.4-0.9:0.2-0.5.

[0102] In the present invention, when the above weight ratio range is met, the second polymerization reaction proceeds more fully, and the obtained oligomer microsphere particles are applied in the field of oil-water separation, which is beneficial to promote the oil-water separation.

[0103] Furthermore, the weight ratio of the second silane coupling agent, the oil-soluble initiator and the oil-soluble promoter is 1:0.45-0.8:0.3-0.45.

[0104] In the present invention, when the type or amount of the first silane coupling agent, the second silane coupling agent, or the oil-soluble monomer, and the amount of 2-acrylamido-2-methylpropanesulfonic acid are changed, due to the different reactivity between different types of first silane coupling agents, different types of second silane coupling agents, or different types of oil-soluble monomers, the components cooperate with each other, which will cause the content of the oligomer represented by formula I or the oligomer represented by formula II in the finally prepared polyacrylamide composite core-shell particles to change.

[0105] According to the present invention, the first temperature is 35-65° C., preferably 45-60° C., and the first stirring time is 1-3 hours, preferably 1.5-2.5 hours.

[0106] According to the present invention, the second temperature is 80-95° C., and the second stirring time is 35-60 min.

[0107] In the present invention, the second temperature is higher than the melting point of paraffin wax, so that the nanoparticles are fully dispersed in the mixed solution of paraffin wax and water. The temperature after cooling is lower than the melting point of paraffin wax, so that the paraffin wax can be coated on the surface of particles II in solid form. Furthermore, when the second temperature is controlled to meet the above range, it is possible to ensure that the subsequent first grafting reaction and the second grafting reaction proceed smoothly, so that the oligomer core-shell particles obtained contain the required content of the oligomer represented by formula I and the content of the oligomer represented by formula II.

[0108] The melting point of paraffin wax is not unique. In a particularly preferred embodiment of the present invention, the melting point of paraffin wax is 47°C-64°C, preferably 49-52°C.

[0109] Furthermore, the second temperature is 80-90° C., and the second stirring time is 40-50 min.

[0110] According to the present invention, the first grafting reaction is carried out at a third temperature of 80-95° C., preferably 80-90° C., and the time of the first grafting reaction is 1-5 hours, preferably 1.5-3.5 hours.

[0111] According to the present invention, the conditions of the first polymerization reaction include: the first polymerization reaction temperature is 80-95° C., and the first polymerization reaction time is 1-3 hours.

[0112] In the present invention, when the temperature and time of the first polymerization reaction meet the above ranges, the oligomer represented by Formula I obtained has excellent viscosity-increasing and emulsifying properties, can further reduce the surface tension of water, and destroy the interfacial balance of emulsified fine oil droplets.

[0113] Furthermore, the conditions of the first polymerization reaction include: the first polymerization reaction temperature is 80-90° C., and the first polymerization reaction time is 1-2 hours.

[0114] According to the present invention, the removal of the paraffin coated on the surface of the particle III is carried out at a fourth temperature, which is 70-90°C, preferably 75-85°C.

[0115] According to the present invention, the conditions of the second grafting reaction include: the temperature of the second grafting reaction is 70-90° C., preferably 75-85° C., and the time of the second grafting reaction is 1-4 hours, preferably 1.5-2.5 hours.

[0116] According to the present invention, the conditions of the second polymerization reaction include: the temperature of the second polymerization reaction is 70-90° C., and the time of the second polymerization reaction is 1-3 hours.

[0117] In the present invention, when the temperature and time of the second polymerization reaction meet the above ranges, the obtained oligomer represented by Formula II has excellent lipophilicity and can enrich oil droplets in oil-water.

[0118] Furthermore, the conditions of the second polymerization reaction include: a temperature of the second polymerization reaction of 75-85° C., and a time of the second polymerization reaction of 1.5-2.5 hours.

[0119] The third aspect of the present invention provides oligomer microsphere particles prepared by the above preparation method.

[0120] A fourth aspect of the present invention provides a use of the aforementioned oligomer microsphere particles in oil-water separation of oily wastewater.

[0121] In the present invention, the oily wastewater mainly includes water and emulsified suspended oil droplets, and the content of suspended oil droplets in the oily wastewater (i.e., the oil content) changes dynamically within a certain range. For example, the oil content in the oily wastewater is 130-150 mg / L.

[0122] The present invention will be described in detail below through examples.

[0123] The particle size of oligomer microspheres and nanoparticles was determined using a BeNano 180Pro nanoparticle size analyzer.

[0124] Oil content in wastewater: tested in accordance with the petroleum industry standard "SY / T0530-2011 Determination of Oil Content in Oilfield Produced Water - Spectrophotometry";

[0125] Oil removal rate: According to the petroleum industry standard "SY / T0530-2011 Determination of Oil Content in Oilfield Produced Water - Spectrophotometry", the oil contents before and after separation treatment are C1 and C2 respectively, and the oil removal rate (%) is calculated using the formula: (1-C2 / C1)×100%.

[0126] Nanoparticles: Fe3O4 particles, with the particle sizes shown in Table 1, were purchased from Ningbo Luofei Nanotechnology Co., Ltd.

[0127] Ethyl orthosilicate, (3-acrylamidopropyl)triethoxysilane, potassium persulfate, tetramethylethylenediamine, 2-acrylamido-2-methylpropanesulfonic acid, vinyltriethoxysilane, azobisisobutyronitrile, dodecylmercaptan, styrene, octylstyrene, p-dodecylstyrene; ethanol, paraffin (brand 52#, melting point 49-52°C), and xylene are all commercially available products.

[0128] Example 1

[0129] S1. Add 16 g of Fe3O4 particles to 100 g of ethanol solution, heat to 65°C, add 6.4 g of ethyl orthosilicate, and stir for 1 h. After separation and drying, obtain particles I-1, wherein the weight ratio of Fe3O4 particles to silicon source is 1:0.4;

[0130] S2. Weigh 15 g of the above-mentioned particles I-1 and add it to 150 g of a paraffin / water mixed solution at 95°C, where the ratio of paraffin to water is 1:5, and perform a second stirring for 35 minutes to form a stable paraffin-in-water emulsion; wherein the content of particles I-1 is 10 parts by weight relative to 100 parts by weight of the mixed solution.

[0131] S3. Add 0.15 g of (3-acrylamidopropyl)triethoxysilane to the emulsion of step S2 for a first grafting reaction. The first grafting reaction time is 2 h and the first grafting reaction temperature is 95° C. Add 0.06 g of potassium persulfate and 0.0525 g of ethylene thiourea, and then dropwise add 6 g of an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid (wherein the mass of 2-acrylamido-2-methylpropanesulfonic acid is 3 g) for a first polymerization reaction. The temperature is 95° C., the polymerization reaction time is 3 hours, and an external magnetic field is used to separate the magnetic particles. The particles are dried in a natural state, washed with a large amount of water, and then vacuum-dried to obtain particles II-1; wherein, the weight ratio of particles I-1 to the first silane coupling agent is 1:0.01, the weight ratio of the first silane coupling agent to 2-acrylamido-2-methylpropanesulfonic acid is 1:20, and the weight ratio of the first silane coupling agent, the water-soluble initiator, and the water-soluble promoter is 1:0.4:0.35.

[0132] S4. Weigh 10 g of the above-mentioned particles II-1 and add them to 100 g of xylene and disperse them evenly. At 90 ° C, add 0.2 g of vinyltriethoxysilane for a second grafting reaction, the second grafting reaction time is 1 hour, add 0.1 g of azobisisobutyronitrile and 0.06 g of dodecyl mercaptan, and then add dropwise 32 g of a xylene solution of p-dodecylstyrene (wherein the mass of p-dodecylstyrene is 16 g) to carry out a second polymerization reaction. The polymerization reaction temperature is 90 ° C and the polymerization reaction time is 1 hour. The particles are separated by an external magnetic field, washed with a large amount of xylene, and dried in vacuo at 50 ° C to obtain oligomer microsphere particles A1; wherein the weight ratio of particles II-1 to the second silane coupling agent is 1:0.02, the weight ratio of the second silane coupling agent to the oil-soluble monomer is 1:80, and the weight ratio of the second silane coupling agent, the oil-soluble initiator and the oil-soluble promoter is 1:0.5:0.3.

[0133] Based on the total mass of the oligomer microsphere particles A1, the content of the nanoparticles is 56.19wt%, the content of the intermediate layer is 22.50wt%, the content of the oligomer represented by formula I (m is 8) is 2.76wt%, and the content of the oligomer represented by formula II (q is 4) is 18.55wt%.

[0134] Example 2

[0135] S1. Add 22 g of Fe3O4 particles to 200 g of ethanol solution, heat to 50°C, add 11 g of ethyl orthosilicate and perform a first stirring for 2.5 h. After separation and drying, obtain particles I-2; wherein the weight ratio of Fe3O4 particles to silicon source is 1:0.5.

[0136] S2. Weigh 30 g of the above-mentioned particles I-2 and add them to 200 g of a paraffin wax / water mixed solution at 83° C., where the ratio of paraffin wax to water is 1:5, and perform a second stirring for 40 minutes to form a stable paraffin wax-in-water emulsion, wherein the amount of particles I-2 used is 15 parts by weight relative to 100 parts by weight of the mixed solution;

[0137] S3, to the product of step S2, 0.66g of (3-acrylamidopropyl) triethoxysilane was added to carry out a first grafting reaction, the first grafting reaction time was 3.5h, the first grafting reaction temperature was 83°C, 0.429g of potassium persulfate and 0.33g of ethylene thiourea were added, and then 33g of an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid (wherein the mass of 2-acrylamido-2-methylpropanesulfonic acid was 16.5g) was added dropwise to carry out a first polymerization reaction, and the polymerization reaction was carried out. The reaction temperature is 83° C., the polymerization reaction time is 1 hour, and the magnetic particles are separated by using an external magnetic field. The particles are dried in a natural state, washed with a large amount of water, and then vacuum-dried to obtain particles II-2; wherein, the weight ratio of particles I-2 to the first silane coupling agent is 1:0.022, the weight ratio of the first silane coupling agent to 2-acrylamido-2-methylpropanesulfonic acid is 1:25, and the weight ratio of the first silane coupling agent, the water-soluble initiator, and the water-soluble promoter is 1:0.65:0.5.

[0138] S4, weighing 20g of the above-mentioned particles II-2 was added to 400g of xylene and uniformly dispersed. At 80°C, 0.5g of vinyltriethoxysilane was added for a second grafting reaction. The second grafting reaction time was 1.5h. 0.2g of azobisisobutyronitrile and 0.1g of dodecyl mercaptan were added dropwise. 62g of a xylene solution of octylstyrene (wherein the mass of octylstyrene was 32.5g) was added to carry out a second polymerization reaction. The polymerization reaction temperature was 80°C and the polymerization reaction time was 1.5h. The particles were separated by an external magnetic field and washed with a large amount of xylene. The particles were vacuum dried at 50°C to obtain oligomer microsphere particles A2, wherein the weight ratio of particles II-2 to the second silane coupling agent was 1:0.025, the weight ratio of the second silane coupling agent to the oil-soluble monomer was 1:65, and the weight ratio of the second silane coupling agent, the oil-soluble initiator and the oil-soluble promoter was 1:0.4:0.2.

[0139] Based on the total mass of the oligomer microsphere particles A2, the content of the nanoparticles is 52.74wt%, the content of the intermediate layer is 26.36wt%, the content of the oligomer represented by formula I (m is 8) is 5.45wt%, and the content of the oligomer represented by formula II (q is 4) is 15.45wt%.

[0140] Example 3

[0141] S1. Add 30 g of Fe3O4 particles to 200 g of ethanol solution, heat to 45°C, add 21 g of ethyl orthosilicate and perform a first stirring for 2 h. After separation and drying, obtain particles I-3; wherein the weight ratio of Fe3O4 particles to silicon source is 1:0.7.

[0142] S2. Weigh 45 g of the above-mentioned particles I-3 and add them to 200 g of a paraffin / water mixed solution at 87° C., where the ratio of paraffin to water is 1:5, and perform a second stirring, the second stirring time being 50 min; to form a stable paraffin-in-water emulsion, wherein the amount of particles I-3 is 22.5 parts by weight relative to 100 parts by weight of the mixed solution.

[0143] S3. Add 1.26 g of (3-acrylamidopropyl)triethoxysilane to the product of step S2 for a first grafting reaction. The first grafting reaction time is 2 h, the first grafting reaction temperature is 87 ° C. 0.756 g of potassium persulfate and 0.378 g of ethylene thiourea are added, and then 88.2 g of an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid (wherein the mass of 2-acrylamido-2-methylpropanesulfonic acid is 44.1 g) is added dropwise to carry out a first polymerization reaction. The reaction temperature is 87° C., the polymerization reaction time is 1.5 h, and the magnetic particles are separated by using an external magnetic field. The particles are dried in a natural state, washed with a large amount of water, and then vacuum-dried to obtain particles II-3; wherein, the weight ratio of particles I-3 to the first silane coupling agent is 1:0.028, the weight ratio of the first silane coupling agent to 2-acrylamido-2-methylpropanesulfonic acid is 1:35, and the weight ratio of the first silane coupling agent, the water-soluble initiator, and the water-soluble promoter is 1:0.6:0.3.

[0144] S4, weighing 24g of the above particles II-3, adding them to 200g of xylene, uniformly dispersing them, adding 0.84g of vinyltriethoxysilane at 85°C for a second grafting reaction, the second grafting reaction time being 2.5h, adding 0.588g of azobisisobutyronitrile and 0.336g of dodecyl mercaptan, and then adding dropwise 117.6g of a xylene solution of p-dodecylstyrene (wherein the mass of p-dodecylstyrene is 58.8g), and carrying out a second polymerization reaction The polymerization reaction temperature was 85°C, the polymerization reaction time was 2h, the particles were separated by an external magnetic field, washed with a large amount of xylene, and vacuum dried at 50°C to obtain oligomer microsphere particles A3; wherein, the weight ratio of particles II-3 to the second silane coupling agent was 1:0.035, the weight ratio of the second silane coupling agent to the oil-soluble monomer was 1:70, and the weight ratio of the second silane coupling agent, the oil-soluble initiator and the oil-soluble promoter was 1:0.7:0.4.

[0145] Based on the total mass of the oligomer microsphere particles A3, the content of the nanoparticles is 42.35wt%, the content of the intermediate layer is 29.64wt%, the content of the oligomer represented by formula I (m is 7) is 6.95wt%, and the content of the oligomer represented by formula II (q is 4) is 21.06wt%.

[0146] Example 4

[0147] S1. Add 34 g of Fe3O4 particles to 200 g of ethanol solution, heat to 60°C, add 27.2 g of ethyl orthosilicate and perform a first stirring for 1.5 h. After separation and drying, obtain particles I-4; wherein the weight ratio of Fe3O4 particles to silicon source is 1:0.8.

[0148] S2. Weigh 50 g of the above-mentioned particles I-4 and add them to 200 g of a paraffin / water mixed solution at 90° C., where the ratio of paraffin to water is 1:5, and perform a second stirring, the second stirring time being 45 minutes; forming a stable paraffin-in-water emulsion, wherein the amount of particles I-4 is 25 parts by weight relative to 100 parts by weight of the mixed solution.

[0149] S3, to the product of step S2, 1.75g of (3-acrylamidopropyl) triethoxysilane was added to carry out a first grafting reaction, the first grafting reaction time was 3h, the first grafting reaction temperature was 90°C, 1.4g of potassium persulfate and 0.7g of ethylene thiourea were added, and then 122.5g of an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid (wherein the mass of 2-acrylamido-2-methylpropanesulfonic acid was 61.25g) was added dropwise to carry out a first polymerization reaction, and the polymerization reaction was carried out. The reaction temperature is 90° C., the polymerization reaction time is 2 hours, and the magnetic particles are separated by an external magnetic field. The particles are dried in a natural state, washed with a large amount of water, and then vacuum-dried to obtain particles II-4; wherein, the weight ratio of particles I-4 to the first silane coupling agent is 1:0.035, the weight ratio of the first silane coupling agent to 2-acrylamido-2-methylpropanesulfonic acid is 1:35, and the weight ratio of the first silane coupling agent, the water-soluble initiator, and the water-soluble promoter is 1:0.8:0.4.

[0150] S4, weighing 30g of the above particles II-4, added to 200g of xylene, uniformly dispersed, at 75 ° C, added 1.29g of vinyltriethoxysilane for a second grafting reaction, the second grafting reaction time is 2h, 1.032g of azobisisobutyronitrile and 0.645g of dodecyl mercaptan were added, and then 103.2g of a xylene solution of styrene (wherein the mass of styrene was 51.6g) was added dropwise to carry out a second polymerization reaction, and the polymerization reaction temperature was 0.147°C. The temperature was 75° C., the polymerization reaction time was 2.5 h, the particles were separated by an external magnetic field, washed with a large amount of xylene, and vacuum-dried at 50° C. to obtain oligomer microsphere particles A4; wherein the weight ratio of particles II-4 to the second silane coupling agent was 1:0.043, the weight ratio of the second silane coupling agent to the oil-soluble monomer was 1:40, and the weight ratio of the second silane coupling agent, the oil-soluble initiator, and the oil-soluble accelerator was 1:0.8:0.5.

[0151] Based on the total mass of the oligomer microsphere particles A4, the content of the nanoparticles is 42.05wt%, the content of the intermediate layer is 33.65wt%, the content of the oligomer represented by formula I (m is 8) is 10.23wt%, and the content of the oligomer represented by formula II (q is 5) is 14.07wt%.

[0152] Example 5

[0153] S1. Add 40 g of Fe3O4 particles to 200 g of ethanol solution, heat to 35°C, add 36 g of ethyl orthosilicate and perform a first stirring for 3 hours. After separation and drying, obtain particles I-5; wherein the weight ratio of Fe3O4 particles to silicon source is 1:0.9.

[0154] S2. Weigh 60 g of the above-mentioned particles I-5 and add them to 200 g of a paraffin / water mixed solution at 80° C., where the ratio of paraffin to water is 1:5, and perform a second stirring, the second stirring time being 60 min; forming a stable paraffin-in-water emulsion, wherein the amount of particles I-5 is 30 parts by weight relative to 100 parts by weight of the mixed solution.

[0155] S3. Add 3 g of (3-acrylamidopropyl)triethoxysilane to the product of step S2 for a first grafting reaction, wherein the first grafting reaction time is 4 h and the first grafting reaction temperature is 80° C., add 2.1 g of potassium persulfate and 0.6 g of ethylene thiourea, and then dropwise add 240 g of an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid (wherein the mass of 2-acrylamido-2-methylpropanesulfonic acid is 120 g) for a first polymerization reaction, wherein the polymerization reaction temperature is 80° C. and the polymerization reaction time is 1 h. Separate the magnetic particles using an external magnetic field, dry them in a natural state, wash them with a large amount of water, and then vacuum dry them to obtain particles II-5; wherein the weight ratio of particles I-5 to the first silane coupling agent is 1:0.05, the weight ratio of the first silane coupling agent to 2-acrylamido-2-methylpropanesulfonic acid is 1:40, and the weight ratio of the first silane coupling agent, the water-soluble initiator, and the water-soluble promoter is 1:0.7:0.2.

[0156] S4, weighing 24g of the above-mentioned particles II-5, added to 300g of xylene, uniformly dispersed, at 70°C, 1.2g of vinyltriethoxysilane was added for a second grafting reaction, the second grafting reaction time was 4h, 0.96g of azobisisobutyronitrile and 0.42g of dodecyl mercaptan were added dropwise, and a xylene solution of styrene (wherein the mass of styrene was 60g) was added dropwise to carry out a second polymerization reaction, the polymerization reaction temperature was 70°C, the polymerization reaction time was 3h, and the particles were separated by an external magnetic field, then washed with a large amount of xylene, and the particles were vacuum dried at 50°C to obtain oligomer microsphere particles A5; wherein the weight ratio of particles II-5 to the second silane coupling agent was 1:0.05, the weight ratio of the second silane coupling agent to the oil-soluble monomer was 1:50, and the weight ratio of the second silane coupling agent, the oil-soluble initiator and the oil-soluble promoter was 1:0.8:0.35.

[0157] Based on the total mass of the oligomer microsphere particles A5, the content of the nanoparticles is 32.38wt%, the content of the intermediate layer is 29.14wt%, the content of the oligomer represented by formula I (m is 10) is 14.70wt%, and the content of the oligomer represented by formula II (q is 10) is 23.78wt%.

[0158] Example 6

[0159] The process was carried out in the same manner as in Example 3, except that in step S3, 2.025 g of (3-acrylamidopropyl)triethoxysilane was added to produce oligomer microsphere particles A6. The weight ratio of particles I-3 to the first silane coupling agent was 1:0.045, the weight ratio of the first silane coupling agent to 2-acrylamido-2-methylpropanesulfonic acid was 1:21.8, and the weight ratio of the first silane coupling agent, water-soluble initiator, and water-soluble accelerator was 1:0.39:0.19.

[0160] Based on the total mass of the oligomer microsphere particles A6, the content of the nanoparticles is 39.67wt%, the content of the intermediate layer is 27.76wt%, the content of the oligomer represented by formula I (m is 8) is 11.93wt%, and the content of the oligomer represented by formula II (q is 4) is 20.64wt%.

[0161] Example 7

[0162] The process was carried out in the same manner as in Example 3, except that 4.05 g of (3-acrylamidopropyl)triethoxysilane was added in step S3 to produce oligomer microsphere particles A7. The weight ratio of particles I-3 to the first silane coupling agent was 1:0.09, the weight ratio of the first silane coupling agent to 2-acrylamido-2-methylpropanesulfonic acid was 1:10.9, and the weight ratio of the first silane coupling agent, water-soluble initiator, and water-soluble accelerator was 1:0.19:0.09.

[0163] Based on the total mass of the oligomer microsphere particles A7, the content of the nanoparticles is 34.81wt%, the content of the intermediate layer is 24.36wt%, the content of the oligomer represented by formula I (m is 8) is 20.94wt%, and the content of the oligomer represented by formula II (q is 4) is 19.89wt%.

[0164] Example 8

[0165] The process was carried out in the same manner as in Example 3, except that 1.128 g of vinyltriethoxysilane was added in step S4 to produce oligomer microsphere particles A8. The weight ratio of particles II-3 to the second silane coupling agent was 1:0.047, the weight ratio of the second silane coupling agent to the oil-soluble monomer was 1:52, and the weight ratio of the second silane coupling agent, oil-soluble initiator, and oil-soluble accelerator was 1:0.52:0.3.

[0166] Based on the total mass of the oligomer microsphere particles A8, the content of the nanoparticles is 39.50wt%, the content of the intermediate layer is 27.64wt%, the content of the oligomer represented by formula I (m is 7) is 6.48wt%, and the content of the oligomer represented by formula II (q is 3) is 26.38wt%.

[0167] Example 9

[0168] The same method as in Example 3 was followed, except that 0.24 g of vinyltriethoxysilane was added in step S4 to produce oligomer microsphere particles A9. The weight ratio of particles II-3 to the second silane coupling agent was 1:0.01, the weight ratio of the second silane coupling agent to the oil-soluble monomer was 1:245, and the weight ratio of the second silane coupling agent, oil-soluble initiator, and oil-soluble accelerator was 1:2.45:1.4.

[0169] Based on the total mass of the oligomer microsphere particles A9, the content of the nanoparticles is 49.95wt%, the content of the intermediate layer is 34.96wt%, the content of the oligomer represented by formula I (m is 7) is 8.19wt%, and the content of the oligomer represented by formula II (q is 4) is 6.90wt%.

[0170] Example 10

[0171] The process was carried out in the same manner as in Example 3, except that in step S3, 50.4 g of 2-acrylamido-2-methylpropanesulfonic acid was added to prepare oligomer microsphere particles A10, wherein the weight ratio of the first silane coupling agent to the 2-acrylamido-2-methylpropanesulfonic acid was 1:40.

[0172] Based on the total mass of the oligomer microsphere particles A10, the content of the nanoparticles is 41.93wt%, the content of the intermediate layer is 29.36wt%, the content of the oligomer represented by formula I (m is 11) is 7.71wt%, and the content of the oligomer represented by formula II (q is 4) is 21wt%.

[0173] Example 11

[0174] The process was carried out in the same manner as in Example 3, except that in step S3, 12.6 g of 2-acrylamido-2-methylpropanesulfonic acid was added to obtain oligomer microsphere particles A11. The weight ratio of the first silane coupling agent to the 2-acrylamido-2-methylpropanesulfonic acid was 1:100.

[0175] Based on the total mass of the oligomer microsphere particles A11, the content of the nanoparticles is 44.98wt%, the content of the intermediate layer is 31.49wt%, the content of the oligomer represented by formula I (m is 2) is 2.06wt%, and the content of the oligomer represented by formula II (q is 4) is 21.47wt%.

[0176] Example 12

[0177] The process was carried out in the same manner as in Example 3, except that in step S4, 134.4 g of a xylene solution of p-dodecylstyrene (wherein the mass of p-dodecylstyrene was 67.2 g) was added to prepare oligomer microsphere particles A12, wherein the weight ratio of the second silane coupling agent to the oil-soluble monomer was 1:80.

[0178] Based on the total mass of the oligomer microsphere particles A12, the content of the nanoparticles is 40.53wt%, the content of the intermediate layer is 28.37wt%, the content of the oligomer represented by formula I (m is 7) is 6.65wt%, and the content of the oligomer represented by formula II (q is 5) is 24.45wt%.

[0179] Example 13

[0180] The process was carried out in the same manner as in Example 3, except that in step S4, 33.6 g of a xylene solution of p-dodecylstyrene (wherein the mass of p-dodecylstyrene was 16.8 g) was added to obtain oligomer microsphere particles A13, wherein the weight ratio of the second silane coupling agent to the oil-soluble monomer was 1:20.

[0181] Based on the total mass of the oligomer microsphere particles A13, the content of the nanoparticles is 46.53wt%, the content of the intermediate layer is 32.56wt%, the content of the oligomer represented by formula I (m is 7) is 7.63wt%, and the content of the oligomer represented by formula II (q is 2) is 13.28wt%.

[0182] Example 14

[0183] The process was carried out in the same manner as in Example 3, except that in step S2, the second temperature was 95° C., thereby obtaining oligomer microsphere particles A14.

[0184] Based on the total mass of the oligomer microsphere particles A14, the content of the nanoparticles is 44.25wt%, the content of the intermediate layer is 26.38wt%, the content of the oligomer represented by formula I (m is 4) is 4.43wt%, and the content of the oligomer represented by formula II (q is 4) is 24.94wt%.

[0185] Example 15

[0186] The process was carried out in the same manner as in Example 3, except that in step S2, the second temperature was 65° C., thereby obtaining oligomer microsphere particles A15.

[0187] Based on the total mass of the oligomer microsphere particles, the content of the nanoparticles is 48.51wt%, the content of the intermediate layer is 20.44wt%, the content of the oligomer represented by formula I (m is 9) is 7.48wt%, and the content of the oligomer represented by formula II (q is 4) is 23.57wt%.

[0188] Comparative Example 1

[0189] The process was carried out in the same manner as in Example 3, except that step S3 was not performed to obtain oligomer microsphere particles D1.

[0190] Based on the total mass of the oligomer microsphere particles, the content of the nanoparticles is 38.53 wt %, the content of the intermediate layer is 26.97 wt %, the content of the oligomer represented by formula I is 0 wt %, and the content of the oligomer represented by formula II (q is 5) is 34.50 wt %.

[0191] Comparative Example 2

[0192] The process was carried out in the same manner as in Example 3, except that in step S3, an equal amount of acrylic acid was used to replace 2-acrylamido-2-methylpropanesulfonic acid, to obtain oligomer microsphere particles D2.

[0193] Based on the total mass of the oligomer microsphere particles (, the content of the nanoparticles is 44.32wt%, the content of the intermediate layer is 31.03wt%, the content of the oligomer represented by formula I (m is 10) is 3.29wt%, and the content of the oligomer represented by formula II (q is 4) is 21.36wt%.

[0194] Comparative Example 3

[0195] The process was carried out in the same manner as in Example 3, except that step S4 was omitted and the surface of the particles contained paraffin wax, thereby obtaining oligomer microsphere particles D3.

[0196] Based on the total mass of the oligomer microsphere particles, the content of the nanoparticles is 34.08wt%, the content of the intermediate layer is 23.86wt%, the content of the oligomer represented by formula I (m is 7) is 5.59wt%, and the content of the oligomer represented by formula II is 0wt%.

[0197] In Comparative Example 3, since step S4 was not performed, the surface of the obtained oligomer microsphere particles was still partially coated with paraffin wax. Based on the total mass of the oligomer microsphere particles, the content of the coated paraffin wax was 36.47 wt %.

[0198] Comparative Example 4

[0199] The process was carried out in the same manner as in Example 3, except that in step S4, an equal mass of methyl methacrylate was used instead of p-dodecylstyrene to prepare oligomer microsphere particles D4.

[0200] Based on the total mass of the oligomer microsphere particles, the content of the nanoparticles is 46.05wt%, the content of the intermediate layer is 32.23wt%, the content of the oligomer represented by formula I (m is 7) is 7.56wt%, and the content of the oligomer represented by formula II (q is 5) is 14.16wt%.

[0201] Comparative Example 5

[0202] The process was carried out in the same manner as in Example 3, except that in step S3, an equal amount of Si-69 was used instead of (3-acrylamidopropyl)triethoxysilane to obtain oligomer microsphere particles D5.

[0203] Based on the total mass of the oligomer microsphere particles, the content of the nanoparticles is 44.72 wt %, the content of the intermediate layer is 31.30 wt %, the content of Si-69 is 1.32 wt %, and the content of the compound represented by formula II is 22.66 wt %.

[0204] In Comparative Example 5, Si-69 does not contain a polymerizable double bond and cannot be further grafted with acrylamide. Therefore, the core-shell particle D3 does not contain the oligomer structure represented by Formula I, and only contains the structure of Si-69.

[0205] Table 1

[0206]

[0207] * - refers to the content of grafted Si-69 on the core-shell particles.

[0208] The sizes of the prepared oligomer microsphere particles are shown in Table 1.

[0209] Table 1

[0210]

[0211]

[0212] Test Case

[0213] 1 g of each oligomer microsphere prepared in each of the examples and comparative examples was weighed and added to 100 mL of oily wastewater. After ultrasonic vibration for 5 minutes, the solution was placed in a magnetic field (magnetic field strength of 1170-1210 mT). Under the force of the magnetic field, the oligomer microspheres adsorbed oil droplets underwent directional migration and were filtered after stabilization. The oil contents before and after separation were measured as C1 and C2, respectively, according to SY / T0530-2011, Determination of Oil Content in Oilfield Produced Water - Spectrophotometry. The oil removal rate (%) was calculated using the formula: (1-C2 / C1) × 100%.

[0214] The sewage treatment performance of oligomer microsphere particles is shown in Table 2.

[0215] Table 2

[0216]

[0217] It can be seen from the results in Table 1 and Table 2 that, compared with the comparative example, when the oligomer microsphere particles prepared in the embodiment of the present invention are used to treat oily wastewater, the oil removal rate can be significantly improved.

[0218] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. An oligomer microsphere particle, characterized in that: The oligomer microsphere particles include a core portion, an intermediate layer portion, and a shell portion, wherein the core portion comprises nanoparticles, the intermediate layer portion comprises silicon dioxide, and the shell portion comprises the oligomer represented by formula I and the oligomer represented by formula II; wherein R and R' are each independently selected from -OCH2CH3 or -OCH3, x is 1-3, k is an integer of 1-5, and m is an integer of 4-12. R1 is H or a C6-C15 alkyl group, y is 1-3, and q is an integer of 4-12.

2. The oligomer microsphere particles according to claim 1, wherein R and R' are each independently -OCH2CH3, k is an integer of 1-3, m is an integer of 4-8, Preferably, R1 is H, a C8 alkyl group or a C12 alkyl group, and q is an integer of 4-8.

3. The oligomer microsphere particles according to claim 1 or 2, wherein Based on the total mass of the oligomer microsphere particles, the content of the nanoparticles is 32-57 wt%, the content of the intermediate layer is 22-34 wt%, the content of the oligomer represented by formula I is 2.5-15 wt%, and the content of the oligomer represented by formula II is 14-27 wt%; Preferably, based on the total mass of the oligomer microsphere particles, the content of the nanoparticles is 40-53wt%, the content of the intermediate layer is 25-34wt%, the content of the oligomer represented by formula I is 5-11wt%, and the content of the oligomer represented by formula II is 14-22wt%.

4. The oligomer microsphere particles according to claim 1, wherein: The particle size of the oligomer microsphere particles is 300-800 nm, preferably 400-600 nm; Preferably, the particle size of the nanoparticles is 100-400 nm, preferably 200-300 nm.

5. The oligomer microsphere particles according to any one of claims 1 to 4, wherein The nanoparticles are selected from at least one of a metal element, a metal alloy and a metal oxide, and are preferably ferrosoferric oxide.

6. A method for preparing oligomer microsphere particles, characterized in that: The method comprises: (1) synthesizing silica in situ on the surface of the nanoparticles under a first stirring condition at a first temperature to obtain particles I; (2) heating to a second temperature, adding particles I to a mixed solution of paraffin and water, and forming an oil-in-water emulsion under a second stirring condition; (3) adding a first silane coupling agent to the emulsion of step (2) to carry out a first grafting reaction on the particle I; and then adding 2-acrylamido-2-methylpropanesulfonic acid in the presence of a water-soluble initiator and a water-soluble promoter to carry out a first polymerization reaction to obtain particles II; (4) removing the paraffin on the surface of particle II, adding a second silane coupling agent, and performing a second grafting reaction; in the presence of an oil-soluble initiator and an oil-soluble promoter, adding an oil-soluble monomer, performing a second polymerization reaction, and separating to obtain the oligomer microsphere particles; Wherein, the first silane coupling agent is selected from acrylamide silane coupling agents; The second silane coupling agent is selected from vinyl silane coupling agents.

7. The preparation method according to claim 6, wherein The step (1) comprises: the step of synthesizing silicon dioxide in situ comprises: mixing nanoparticles with a silicon source in the presence of an alcohol solvent; Preferably, the alcohol solvent is selected from at least one of methanol, ethanol, n-butanol, isobutanol and propylene glycol; Preferably, the silicon source is selected from ethyl orthosilicate and / or butyl orthosilicate; Preferably, the nanoparticles are selected from at least one of a metal element, a metal alloy and a metal oxide, and are preferably ferrosoferric oxide; Preferably, the weight ratio of the nanoparticles to the silicon source is 1:0.4-0.9, preferably 1:0.5-0.

8.

8. The preparation method according to claim 6 or 7, wherein In step (2), the amount of the particles I is 8-20 parts by weight, preferably 10-18 parts by weight, relative to 100 parts by weight of the mixed solution of paraffin and water.

9. The preparation method according to any one of claims 6 to 8, wherein In step (3), the first silane coupling agent is selected from (3-acrylamidopropyl)triethoxysilane and / or (3-acrylamidoethyl)triethoxysilane, preferably (3-acrylamidopropyl)triethoxysilane; Preferably, the water-soluble initiator is selected from potassium persulfate and / or ammonium persulfate; Preferably, the water-soluble promoter is selected from tetramethylethylenediamine and / or ethylenediamine; Preferably, the weight ratio of the particles I to the first silane coupling agent is 1:0.01-0.05, preferably 1:0.02-0.035; Preferably, the weight ratio of the first silane coupling agent to the 2-acrylamido-2-methylpropanesulfonic acid is 1:20-40, preferably 1:25-35; Preferably, the weight ratio of the first silane coupling agent, the water-soluble initiator and the water-soluble promoter is 1:0.4-0.8:0.2-0.5, preferably 1:0.6-0.8:0.3-0.

5.

10. The preparation method according to any one of claims 6 to 9, wherein In step (4), the specific steps of removing the paraffin on the surface of the particles II include: dispersing the particles II in an oil-soluble solvent to remove the paraffin coated on the particles II; Preferably, the oil-soluble solvent is selected from at least one of xylene and / or toluene; Preferably, the second silane coupling agent is selected from vinyltriethoxysilane and / or vinyltrimethoxysilane; Preferably, the oil-soluble initiator is selected from azobisisobutyronitrile and / or benzoyl peroxide; Preferably, the oil-soluble promoter is selected from dodecyl mercaptan and / or tert-dodecyl mercaptan; Preferably, the oil-soluble monomer is selected from at least one of styrene, octylstyrene, p-dodecylstyrene and p-aminostyrene, preferably at least one of styrene, octylstyrene and p-dodecylstyrene; Preferably, relative to 100 parts by weight of the oil-soluble solvent, the amount of the particles III is 5-20 parts by weight, preferably 5-15 parts by weight; Preferably, the weight ratio of the particles II to the second silane coupling agent is 1:0.02-0.05, preferably 1:0.025-0.045; Preferably, the weight ratio of the second silane coupling agent to the oil-soluble monomer is 1:40-80, preferably 1:40-70; Preferably, the weight ratio of the second silane coupling agent, the oil-soluble initiator and the oil-soluble promoter is 1:0.4-0.9:0.2-0.5, preferably 1:0.45-0.8:0.3-0.

45.

11. The preparation method according to any one of claims 6 to 10, wherein: The first temperature is 35-65°C, preferably 45-60°C, and the first stirring time is 1-3h, preferably 1.5-2.5h; Preferably, the second temperature is 80-95°C, preferably 80-90°C, and the second stirring time is 35-60min, preferably 40-50min; Preferably, the first grafting reaction is carried out at a third temperature, which is 80-95° C., preferably 80-90° C., and the first grafting reaction time is 1-5 hours, preferably 1.5-3.5 hours; Preferably, the conditions of the first polymerization reaction include: the first polymerization reaction temperature is 80-95°C, preferably 80-90°C, the first polymerization reaction time is 1-3h, preferably 1-2h; Preferably, the removal of the paraffin coated on the particles III is performed at a fourth temperature, which is 70-90° C., preferably 75-85° C.; Preferably, the conditions of the second grafting reaction include: the temperature of the second grafting reaction is 70-90°C, preferably 75-85°C, and the time of the second grafting reaction is 1-4h, preferably 1.5-2.5h; Preferably, the conditions of the second polymerization reaction include: the temperature of the second polymerization reaction is 70-90° C., preferably 75-85° C., and the time of the second polymerization reaction is 1-3 hours, preferably 1.5-2.5 hours.

12. The oligomer microsphere particles prepared by the preparation method according to any one of claims 6 to 11.

13. Use of the oligomer microsphere particles according to any one of claims 1 to 5 or 12 in oil-water separation of oily wastewater.

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