The Combination Of Experimental Research On Demulsification And Separation Of Oil-Water Mixture

With serious crisis of global oil resource and freshwater resources reduction, the separation of the oil-water mixture becomes more and more important. This topic takes stainless steel mesh as substrate to make a new type of micro-nanoporous PTFE membrane. This oil-water separation membrane is made by spraying-plasticizing method. The PPS-PTFE composite coating mesh films have high hardness, strong adhesive force and wonderful corrosion resistance. PTFE tape is used to make a kind of micro-nano fiber structure on the surface of the membrane.These composite coating meshes show super-hydrophobic and super-oleophilic properties. Contact angle of this separation membrane is156.3°and the contact angle hysteresis is less than5°for water. Contact angle of demulsification membrane is about130°for water. The oil droplet is spreaded on the surface of this membrane once they meet. The surfaces of the prepared PTFE-PPS composite coating meshes were analyzed through scanning electron microscopy (SEM). It is shown that lots of particles with microscale accumulate on the surface of the mesh film and on these particles find reseaus of nanometer scale and the demulsification membrane has a kind of micro-nano fiber structure on the surface.The demulsification membrane can be applied to the separation of oil-water emulsions.The retentate separated by the mesh film was analyzed through extraction-uv spectrophotometer. As the small demulsification membranes pore size, the membrane flux reduces rapidly at the initial stage and it will be stable after15min. Orthogonal experiment was taken to investigate the operation pressure, membrane thickness and the factors of the initial oil content in water for the impact of demulsification. When the thickness is0.4mm, and pressure difference is40KPa, oil content in permeated water can be reduced to7.9mg/LThe oil-water mixture was taken to be dcmulsificatcd at first and then was separated by five-stage oil-water separator. The impact of the initial oil content and separation time for the pressing of separation was studied. When the thickness is0.3mm, and initial oil content is0.5wt%, oil content in permeated water can be reduced to8.4mg/L. It is harmful to the experiment when the separation pressure is higher than critical pressure. The demulsification is a kind processing of destruction-adsorption-coalescence. The calculated flow rate of5.8×10-4m?s-1is similar to the experimental flow rate of6.25×10-4m?s-1.The superhydrophobic membrane was installed on the improved oil-water separator to test the demulsification performances for water-in-oil emulsions. Water content in permeated oil is measured by using Karl Fischer’s reagent. The change of flux with time was investigated when the operation pressure is2KPa and initial water content is2wt%. The experiment was taken to investigate the operation pressure, membrane pore size and the factors of the initial water content and the experiment time for the impact of demulsification. The superhydrophobic membrane of1300meshes-inch was used to test the separation efficiency. Separation efficiency can be up to99.75%when the operation pressure is2KPa and initial water content is about2wt%and the water content in permeated oil can be reduced to242mg/L...