| “Green development” is one of the important concepts in the 12 th five-year plan of our nation.It is a significant subject to realize demulsification of oil-water emulsion with superhydrophobic composite membrane.Not only is it consistent with the sustainable development idea of recycling limited resources,but also makes positive contribution to environmental protection.In this paper,two types of superhydrophobic composite membranes are successfully made by spraying-plastifying method with two main materials,polytetrafluoroethylene(PTFE)and polyphenyl sulfide(PPS).One type is superhydrophobic stainless steel mesh membrane(500 mesh,800 mesh and 1000 mesh),and the other is superhydrophobic stainless steel porous plate membrane(1?m,5?m,and 10?m).Contact angle of water is characterized between the two superhydrophobic membrane surfaces,and the result is 152.8° and 151.4°,respectively.It is shown that both of the two types of composite membranes have good performance of superhydrophobic property.At the same time,the two types also have good adhesion strength and chemical stability.In order to investigate the demulsification effect of the superhydrophobic composite membrane in oil-water emulsion,single-flow and reflux oil-water emulsion demulsification devices are self-constructed.The core component is the demulsification device with superhydrophobic composite membranes.Determine the amount of oil in the sample by Spectrophotometric method(SY/T 0530-93),and the result shows that the main factors affecting the demulsification efficiency are composite membrane aperture,demulsification flux and oil content in the emulsion.The closer between the composite membrane aperture and oil droplet size is the higher demulsification efficiency is.The larger the demulsification flux is the lower demulsification efficiency is.The higher the oil content in the emulsion is the better performance the demulsification is.The demulsification efficiency of single-plate superhydrophobic stainless steel porous plate membrane is higher than superhydrophobic stainless steel mesh membrane,which is more than 90%.This is related to the more complex channel structure of the stainless steel porous plate,which can increase the fluid turbulence.However,the demulsification stability of superhydrophobic stainless steel mesh membrane is better than superhydrophobic stainless steel porous plate membrane,which can be stable over 80% for a long time.The operating pressure range of superhydrophobic stainless steel porous plate membrane much increases because of its excellent mechanical performance,which is up to 1.0MPa,better than superhydrophobic stainless steel mesh membrane 0.3MPa.The mechanism of oil-water demulsification is analyzed superficially.It is discovered that the very essence of oleophilic superhydrophobic surface is due to the very low surface energy of PTFE and the roughness superhydrophobic structure,which increases the variability in the flow between oil and water in the channel,and makes the better performance of oil-water demulsification.Oversized oil droplets can clog up the channel and reduce the demulsification efficiency,and undersized oil droplets are difficult to contact the channel surface and reduce the demulsification efficiency too.Oil droplets close to the size of the channel are able to complete the process of internal collisions,aggregation,transition and separate in the channel,thus demulsify effectively. |
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