Synthesis And Performance Evaluation Of Magnetic Carbon Nanomaterial Demulsifier

In the process of extracting crude oil,the mixing of groundwater and the application of water flooding provide conditions for the formation of oil-water emulsions.This is bad for oil production.Therefore,emulsions need to be treated.The most common method of working with emulsions is the use of demulsifiers.Magnetic demulsifier,is a composite demulsifier obtained by compounding other materials or molecules with demulsification ability with magnetic metal oxides such as ferric tetroxide as the core.Compared with traditional chemical demulsifiers,it can be separated from emulsions by magnetic field.Currently,most of the studies have been conducted by compounding ferric tetroxide with chemical demulsifiers.These magnetic demulsifiers showed excellent demulsification and recycling capabilities,however,the chemical demulsifiers contained in magnetic demulsifiers still affect the environment,and the preparation processes are relatively complex.Therefore,it is extremely important to develop a green and environmentally friendly magnetic demulsifier.Aiming at this problem,in this work,carbon nanomaterials were compounded with ferric tetroxide to prepare magnetic carbon nanomaterials demulsifier,and the related characterization and demulsification experiments were carried out.Compared with other magnetic demulsifiers,this magnetic demulsifier preparation process is simple and does not cause pollution to the environment.It has certain guiding significance for the future research of magnetic demulsifiers.Using iron acetylacetonate as iron source,octadecene as reducing agent and oleic acid as surfactant,ferroferric oxide was prepared by solvothermal method.The synthesis temperature was optimized in four temperature gradients during the experiment.The SEM and particle size measurements of these Fe₃O₄ nanoparticles showed that at 170?,the shape of Fe₃O₄nanoparticles are not very uniform and there is a certain agglomeration phenomenon,the particle size is around 476 nm.When the reaction temperature was raised to 200°C,the agglomerated state was relieved but still did not disappear,and the particles became uniform,with a particle size of about 392 nm,and when the temperature was 230°C,the nanoparticles became dispersed while the particles showed a regular spherical shape and the particle size decreased to about 357 nm,and when the temperature continued to rise to 260°C,the Fe3O4magnetic particles became irregular and agglomerated.In addition,the FT-IR and XRD showed that the purity of ferric tetroxide was high and the saturation magnetization intensity was 64.14 emu/g.Three different types of magnetic demulsifiers were synthesized by adding graphene oxide(GO),carbon oxide nanotubes(CNTs),and carbon nanospheres(CNNs)to the preparation of ferric tetroxide in a"one-step"process.Carbon materials were added at 5%,10%,and 15%of the mass of iron acetylacetonate,so that a total of nine experimental emulsion breakers samples were prepared.Taking three magnetic demulsifiers with a carbon material addition of 5%as examples,these magnetic demulsifiers were characterized.The results showed that the particle size of Fe3O4/GO was around 426 nm,Fe3O4/CNTs was around 453 nm,and Fe3O4/CNNs was around 400 nm.Meanwhile,both FT-IR and XRD showed that the magnetic carbon nanomaterial demulsifiers were successfully synthesized,and the saturation magnetization intensity of Fe3O4/GO was 47.28 emu/g,that of Fe3O4/Ox-CNTs was 38.65 emu/g,and that of Fe3O4/CNNs was 51.46 emu/g.A simulated water-in-toluene emulsion was prepared,and the demulsification performance of three magnetic carbon material nanodemulsifiers,Fe3O4/GO,Fe3O4/CNTs and Fe3O4/CNNs,were evaluated.The optimal addition amount of carbon materials was firstly investigated.The demulsification results showed that the magnetic demulsifier with5%addition of carbon material had the best effect and the residual water content was 0.10%for Fe3O4/GO(5%),0.05%for Fe3O4/CNTs(5%)and 0.08%for Fe3O4/CNNs(5%).Then,the effects of demulsifier concentration,demulsification time and demulsification temperature on the residual water content in oil were investigated.The results showed that the dehydration rate was the best when the concentration of demulsifier was 800 ppm,and the demulsification was performed at 25?for 5 min.The recovery experiments showed that after 8 cycles of the demulsifier,the residual moisture content of Fe3O4/GO magnetic demulsifier increased by 0.08%,that of Fe3O4/CNTs magnetic demulsifier increased by0.13%,and that of Fe3O4/CNNs magnetic demulsifier increased by 0.13%.0.14%,which proves that the magnetic carbon material demulsifier have good recovery performance.Finally,in order to prove the ability of the demulsifier to break a variety of water-in-oil emulsions,n-heptane,n-hexane and-20#diesel emulsions were prepared respectively.The results showed that the oil with the addition of Fe3O4/CNNs demulsifier had the smallest residual moisture content.The demulsification mechanism of demulsifier was explored.The lipophilic part in the magnetic demulsifier can"grab"the oil phase,break the relatively stable state of the water-in-oil emulsion,release the small water droplets in the emulsion to coalesce,and break the stability of the oil-water interface.At the same time,the magnetic field increases the chance that the small oil droplets adsorbed on the demulsifier will coalesce and become large oil droplets.