One-step Preparation Of Magnetized Demulsifier And Its Demulsification Performance

Most of the output liquids produced in oil fields are in the form of water-in-oil emulsion.The emulsified water contained in the crude oil emulsion not only causes the serious corrosion of pipelines,but also have a significant impact on refining.Therefore,it is necessary to demulsify and dehydrate crude oil emulsion by using demulsifiers.At present,magnetic nanoparticles have raised a lot of interests as they can response to the external magnetic field,which means that they can be separated from complex multiphase system and reused easily.Given this significant property,there are a lot of papers reporting the preparation of magnetic demulsifiers through combing the magnetic nanoparticles with those compounds that possess demulsifying properties.However,those papers reporting how to prepare different magnetic demulsifers mainly focus on the combination of ferriferrous oxide and distinct functionalized compounds without paying attention to the morphologies of magnetic demulsifiers.In fact,it has been shown that the magnetic functional nanoparticles with different morphologies possess different optical,magnetic,interfacial and catalytic properties,causing different applications in different fields.Besides,the methods of preparing magnetic demulsifiers are too complicated at present,which means their further applications in practical industries have been limited at the large extent.Therefore,the purpose of this paper is to investigate how the morphology of magnetic demulsifiers influences their demulsification ability,and to simplify the experimental preparation method to improve their ability of practical application at the same time.In the first part of this paper,three different kinds of magnetic demulsifiers showing different morphologies,including triangle-shaped(TF NPs),octahedron-shaped(OF NPs)and truncated octahedron-shaped(TOF NPs),were prepared by solvothermal method by using block polyether,oleic acid and iron acetylacetone as raw materials.By using scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),infrared spectroscopy(IR),thermogravimetric analysis(TGA)and the superconducting quantum interference device(SQUID),the morphologies and surface properties of these products were analyzed,and their demulsification properties were evaluated by using water/cyclohexane simulated emulsion.It is found that the demulsification ability of TOF NPs is the best.Through dynamic interfacial tension and interfacial viscoelastic experiments,the diffusion coefficients D0 and D∞ of three magnetized demulsifiers in the initial and late diffusion stages of demulsification process are calculated.The change of elastic modulus of water/cyclohexane interface reveals the reason why TOF NPs has the best demulsification ability.In the second part of this paper,the preparation method of magnetized demulsifier was optimized.The morphology of the obtained modified magnetic demulsifer(PEMN),prepared by one-step method,was similar to that of TOF NPs.The surface of this demulsifier contains higher content of surface modification agents and its size was smaller than that of TOF NPs.The demulsification ability of PEMN toward crude oil emulsion was investigated.After using confocal microscope to observe how the emulsified water droplets changed during the demulsification process,it was determined that PEMN could absorb on the oil-water interface during the demulsification process,thus reducing the stability of the water droplets,promoting the aggregation of water droplets,and finally realizing the separation of oil and water phases.