阅读说明：本技术 可同时实现o/w与w/o乳液高效油水分离的磁性破乳剂的制备方法与应用 (Preparation method and application of magnetic demulsifier capable of simultaneously realizing efficient oil-water separation of O/W and W/O emulsions ) 是由 吕挺 吴艳 张栋 赵红挺 于 2019-09-17 设计创作，主要内容包括：本发明涉及可同时实现O/W与W/O乳液高效油水分离的磁性破乳剂的制备方法与应用。该方法通过水解缩合反应同时将烷基硅烷与氨基硅烷锚定在Fe<Sub>3</Sub>O<Sub>4</Sub>@SiO<Sub>2</Sub>磁性纳米粒子表面,进而赋予磁性粒子优异的界面活性与阳离子特性。该烷基硅氧烷与氨基硅氧烷混合修饰后的磁性粒子可均匀地分散于水相或油相中,当其加入到乳化油水体系中后,在界面活性与静电吸引力的驱动下可高效地吸附到油水界面上,并在磁场作用下迅速分离乳化油滴或水滴,最终可同时实现O/W与W/O乳液中的高效油水分离。本发明得到的磁性纳米材料破乳效率优异,在O/W与W/O乳液油水分离领域有着非常广泛的应用前景。(The invention relates to a preparation method and application of a magnetic demulsifier capable of realizing efficient oil-water separation of O/W and W/O emulsions simultaneously. The method simultaneously anchors alkylsilane and aminosilane to Fe through hydrolytic condensation reaction 3 O 4 @SiO 2 The magnetic nanoparticles have excellent surface activity and cationic property. The magnetic particles modified by mixing the alkyl siloxane and the amino siloxane can be uniformly dispersed in a water phase or an oil phase, and can be efficiently adsorbed on an oil-water interface under the drive of interface activity and electrostatic attraction after being added into an emulsified oil-water system, emulsified oil drops or water drops are rapidly separated under the action of a magnetic field, and finally, efficient oil-water separation in O/W and W/O emulsions can be simultaneously realized. The magnetic nano material obtained by the invention has excellent demulsification efficiency and has very wide application prospect in the field of oil-water separation of O/W and W/O emulsion.)

1. The preparation method of the magnetic demulsifier capable of simultaneously realizing the high-efficiency oil-water separation of O/W and W/O emulsion is characterized by comprising the following steps:

(1) adjusting the pH value of the alcohol-water mixed solution, and controlling the pH value to be 3-12; the mass fraction of water in the alcohol-water mixed solution is 0-40%;

(2) mixing Fe₃O₄@SiO₂Dispersing the magnetic nanoparticles into the alcohol-water mixed solution in the step (1) under the protection of inert gas, then adding a certain amount of aminosiloxane and alkylsiloxane, and promoting the aminosiloxane and the alkylsiloxane to be anchored at Fe at the same time through hydrolytic condensation reaction₃O₄@SiO₂On the surface of the magnetic nanoparticles, a magnetic nano demulsifier which has good water phase and oil phase dispersibility, cationic property and excellent interfacial activity is obtained;

the molar ratio of the alkyl siloxane to the amino siloxane is controlled to be 1:3-3: 1;

the molecular structural formula of the alkyl siloxane is shown as formula A, and the molecular structural formula of the amino siloxane is any one of the following formulas B, C, D:

wherein R is CH₃Or C₂H₅And n is 3-17.

2. The method according to claim 1, wherein the total amount of alkylsiloxane and aminosiloxane is Fe₃O₄@SiO₂8-40% of the mass of the particles.

3. The process according to any one of claims 1 to 2, wherein the reaction temperature of the hydrolytic condensation reaction of the second step is 20 to 80 ℃ and the reaction time is 2 to 48 hours.

4. The production method according to any one of claims 1 to 3, wherein the alcohol in the alcohol-water mixed solution of the step one is one of methanol, ethanol, isopropanol or n-propanol.

5. The production method according to claim 4, wherein the alcohol in the alcohol-water mixed solution is ethanol.

6. The process according to any one of claims 1 to 5, wherein the pH adjusting agent is hydrochloric acid or aqueous ammonia.

7. The method according to any one of claims 1 to 6, wherein in step two Fe₃O₄@SiO₂The preparation method of the magnetic nanoparticles comprises the following steps: FeCl is added₂·4H₂O and FeCl₃·6H₂Dissolving O in hydrochloric acid water solution, then dripping into sodium hydroxide water solution, and reacting to obtain Fe₃O₄Nanoparticles; the sodium silicate solution was then added gradually dropwise to the Fe₃O₄Regulating and stabilizing the pH value of the reaction solution in the nano particle water dispersion liquid to generate SiO₂Coated to Fe₃O₄The surface of the nano-particle is obtained.

8. The method according to claim 7, wherein Fe²⁺With Fe³⁺The molar part ratio of 1:2, the reaction is carried outUnder the protection of inert gas.

9. Use of the magnetic nano demulsifier prepared by the preparation method of any one of claims 1 to 8 in separation of oil and water in O/W emulsion and W/O emulsion.

Technical Field

The invention relates to a method for synthesizing a magnetic nano demulsifier which can be well dispersed in both a water phase and an oil phase, has a cationic characteristic and excellent interfacial activity, and particularly relates to a method for preparing and applying aminosilane and alkylsilane mixed modified magnetic nanoparticles which can realize efficient oil-water separation of a water-in-oil emulsion (W/O emulsion) and an oil-in-water emulsion (O/W emulsion) simultaneously.

Background

With the continuous promotion of petroleum exploitation, storage, transportation and processing, and the continuous development of industries such as machinery, food processing and the like, a large amount of W/O emulsion and O/W emulsion are generated. The moisture and salt content of the W/O emulsion can increase the load on pumps, pipelines and storage tanks, cause corrosion and scaling of metal surfaces, and even cause catalyst poisoning during subsequent processing of oil-based materials. And the discharge of the O/W emulsion not only causes the waste of oil resources, but also causes serious environmental pollution. Therefore, from the viewpoints of effective utilization of resources and environmental protection, the method has great significance for efficient oil-water separation of O/W emulsion and W/O emulsion.

The emulsified oil droplets or water droplets are very stable due to the presence of the surface active substance. In order to separate emulsified oil drops or water drops, various chemical demulsifiers or flocculants are generally added in the industry, so that the oil-water interface property is changed, and oil drops or water drops are promoted to coalesce to realize oil-water separation; however, the process takes a long time and the demulsification efficiency is low. In recent years, many scholars report that filter materials (filter membranes, meshes, fabrics and sponges) with the characteristics of super-hydrophilicity/super-oleophobicity under water can effectively separate emulsified oil drops in a water body, and filter materials with the characteristics of super-hydrophobicity/super-oleophobicity can effectively separate emulsified oil drops in an oil phase, but the filter materials still have the defects of high energy consumption, easiness in pollution, non-lasting effect and the like in practical application.

Fe₃O₄The magnetic nanoparticles are simple to prepare, the surface of the magnetic nanoparticles is easy to modify, and the separation process is simple and flexible, so that the magnetic nanoparticles have a very wide application prospect in the separation of emulsified oil and water. The application of the existing magnetic nano material in emulsified oil-water separation mainly comprises the following two aspects:

(1) application of oil-water separation in O/W emulsion: the magnetic particles were Surface-modified with oleic acid (Energy & Fuels,2014,28, 6172-. The obtained particles have good dispersibility in water, and can migrate from a water phase to the surface of an oil drop, so that oil-water separation of the O/W emulsion is realized under the drive of a magnetic field.

(2) Application of oil-water separation in W/O emulsion: the method adopts ethyl cellulose (Energy & Fuels,2018,32,8078-8089, CN105817057A) and alkyl siloxane (ChemHydrochem, 2015,16,595-600, CN104073287A) to carry out surface modification on magnetic particles, and the obtained particles have good dispersibility in an oil phase and can be transferred to the surface of water drops from the oil phase, thereby realizing rapid demulsification and dehydration of the W/O emulsion under the action of a magnetic field.

Generally speaking, in view of the hydrophobicity and surface negative charge characteristics of most emulsified oil droplets, in order to realize oil-water separation of an O/W emulsion, magnetic particles should have strong hydrophilicity and have certain hydrophobicity or surface positive charge, so that the magnetic particles can be well dispersed in water and migrate from a water phase to the surface of the oil droplets under the promotion of hydrophobic interaction or electrostatic attraction, thereby realizing separation of the emulsified oil droplets. On the contrary, in order to realize the oil-water separation of the W/O emulsion, the magnetic particles have a certain hydrophilicity while having a strong lipophilicity, and the particles can be uniformly dispersed in the oil phase and transferred to the oil-water interface, thereby realizing the separation of emulsified water droplets. In previous studies, alkylsiloxane-modified magnetic particles appeared to separate oil from water for both types of emulsions, but the content was significantly different. When the dosage of the alkyl siloxane is less (CN109096499A, CN105498696A), the hydrophilicity of the alkyl modified particles is stronger, the water phase dispersibility is good, the oil phase dispersibility is poor, and the method is suitable for the oil-water separation of O/W emulsion; when the dosage of the alkyl siloxane is larger (CN104073287A), the lipophilicity of the magnetic particles modified by the alkyl is stronger, the oil phase dispersibility is good, the water phase dispersibility is poor, and the method is suitable for oil-water separation of the W/O emulsion. The amino-modified magnetic particles (CN109350998A, CN104140141A, Applied Surface Science,2017,396: 1604-.

In summary, the currently reported magnetic nanoparticles can only perform oil-water separation on one emulsion, and almost no report about preparation of one magnetic particle that can simultaneously realize efficient oil-water separation of an O/W emulsion and a W/O emulsion is available. In order to realize the efficient oil-water separation of the O/W emulsion and the W/O emulsion at the same time, the magnetic particles are required to have excellent interfacial activity. Certain interfacial activity can be achieved by pure alkyl siloxane anchoring density adjustment, but the regulation window is very narrow; currently, aminosiloxane modification mainly provides amino functional groups on the particle surface, so that the particles possess positive charges, or the aminosiloxane modification is further grafted and modified on the basis of the amino groups on the particle surface, so that good interfacial activity is shown (CN104370333A, CN109251741A, CN107141429A, CN107417922A), and a study on regulating the interfacial activity of the particles by using aminosiloxane and alkylsiloxane modification is not reported yet.

Disclosure of Invention

In order to overcome the defects of the existing magnetic nanoparticles in the field of separation of emulsified oil and water, the invention uses hydrolysis condensation reaction on Fe₃O₄@SiO₂Hydrophobic alkyl silane and relatively hydrophilic amino silane with cationic property are simultaneously introduced into the surface of the nano particle, so that the magnetic nano particle which can be well dispersed in water phase and oil phase and has cationic property and excellent interfacial activity is constructed, and the efficient oil-water separation of O/W emulsion and W/O emulsion can be conveniently realized.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

the invention provides a method for preparing magnetic nanoparticles which can be well dispersed in both an aqueous phase and an oil phase, have cationic characteristics and excellent interfacial activity, and the method comprises the following steps:

(1) adjusting the pH value of the alcohol-water mixed solution, and controlling the pH value to be in a range of 3-12, wherein the mass fraction of water in the alcohol-water mixed solution accounts for 0-40%.

(2) Mixing Fe₃O₄@SiO₂Magnetic nano-meterDispersing the particles into the alcohol-water mixed solution in the step (1) under the protection of inert gas, then adding certain amount of aminosiloxane and alkylsiloxane, and promoting the aminosiloxane and the alkylsiloxane to be anchored in Fe at the same time through hydrolytic condensation reaction₃O₄@SiO₂On the surface of the magnetic nanoparticles, the magnetic nano demulsifier which has good water phase and oil phase dispersibility, cationic property and excellent interfacial activity is obtained.

Further, in the step (2) of the preparation method, the alkyl siloxane is one of molecular structural formulas a, and the aminosiloxane is any one of molecular structural formulas BCD:

r in the structural formula ABCD is CH₃Or C₂H₅And n is 3-17.

In the step (2) of the preparation method, in order to ensure excellent interfacial activity and good dispersibility in the water phase and oil phase of the magnetic nano demulsifier, the total amount of siloxane accounts for Fe₃O₄@SiO₂8-40% of the mass of the magnetic particles, wherein the molar ratio of the alkyl siloxane to the amino siloxane is 1:3-3: 1; with increasing alkyl chain length in the alkylsilane, the proportion of aminosilane used should be increased accordingly to increase the anchoring density of the aminosilane.

In the step (2) of the preparation method, the reaction temperature is controlled to be 20-80 ℃, and the reaction time is 2-48 h.

In the step (1) of the preparation method, the alcohol solvent can be methanol, ethanol, isopropanol or n-propanol, and ethanol is preferably selected in the invention.

In the step (1) of the preparation method, hydrochloric acid or ammonia water is used for adjusting the pH value.

Fe in step (2)₃O₄@SiO₂The magnetic nanoparticles can be prepared by the following method:

FeCl is added₂·4H₂O and FeCl₃·6H₂Dissolving O in hydrochloric acid water solution, and dropwise adding the solution into oxyhydrogenIn sodium hydroxide aqueous solution, Fe is obtained by reaction₃O₄Nanoparticles. Subsequently, sodium silicate solution was gradually added dropwise to Fe₃O₄Regulating and stabilizing the pH value of the reaction solution in the nano particle water dispersion liquid to generate SiO₂Coated to Fe₃O₄On the surface of the nanoparticles, Fe is obtained₃O₄@SiO₂Magnetic nanoparticles.

Further, in the above process, Fe²⁺With Fe³⁺The molar part ratio of the components can be 1:2, and the reactions are carried out under the protection of inert gases.

The product prepared by the method comprises Fe₃O₄@SiO₂Nanoparticles, and anchoring to Fe₃O₄@SiO₂And the silane molecular layer on the outer surface of the nano particle contains an amino group and an alkyl group.

The invention also provides application of the magnetic nano demulsifier in separation of oil and water in O/W emulsion and W/O emulsion. Wherein the pH value of the water phase can be 3-11, and the oil phase can be at least one of gasoline, diesel oil, crude oil, vegetable oil, toluene and n-hexane.

The invention has the beneficial effects that:

the inventors have found that, as a result of intensive studies, in order to promote migration of magnetic particles from an oil phase (or an aqueous phase) to an oil-water interface, the interfacial activity of the particles should be increased as much as possible, and therefore, Fe is required to be used as a material for the magnetic particles₃O₄@SiO₂The particles are modified amphiphatically. Meanwhile, although the electrostatic effect in the W/O emulsion is negligible, the magnetic particles in the O/W emulsion also generate strong electrostatic interaction with oil drops. Since most of the emulsified oil droplets are negatively charged, it is preferable to perform cationic modification on the magnetic particles. For the reasons stated above, the present invention employs both a hydrophobic alkylsiloxane and a relatively hydrophilic aminosiloxane having cationic character versus Fe₃O₄@SiO₂The magnetic nano-particles are subjected to surface modification, and the silane molecular layer structure (alkyl chain length, amino structure and respective anchoring density of two types of silanes) on the surfaces of the magnetic particles is regulated and controlled by changing the using amount and the proportion of the two types of siloxanes, so that the magnetic particles are endowed with excellent interface activity and excellent surface activityCationic character. The magnetic particles modified by mixing alkyl siloxane and amino siloxane can be uniformly dispersed in a water phase or an oil phase, and can be efficiently adsorbed on an oil-water interface under the drive of interface activity and electrostatic attraction after being added into an emulsified oil-water system, emulsified oil drops or water drops are rapidly separated under the action of a magnetic field, and finally, efficient oil-water separation in O/W and W/O emulsions can be simultaneously realized. The particles can be recycled after being washed and regenerated.

Drawings

FIG. 1 is a schematic diagram of the preparation of the magnetic nano demulsifier having cationic characteristics and excellent interfacial activity according to the present invention, wherein the alkylsilane is Octyltrimethoxysilane (OTMS) for example, and the aminosilane is N-aminoethyl-gamma-aminopropyltrimethoxysilane (AEAPTMS) for example.

Detailed Description

The present invention will be described in detail below with reference to specific synthetic examples and examples.