The application of super hydrophobic in oil-water separation technology
1 of the application of membrane separation technology introduction
membrane separation is refers to under the action of a force depends on the selectivity of membrane itself, making some components through the membrane separation and some retained in the body. Separation membrane is the key component of the membrane separation technology, membrane separation is generally a semi-permeable membrane which some components can be trapped by some component in the liquid in the side of the membrane.
membrane separation has lower power consumption; Separation process does not need large temperature variation, so using membrane separation of heat sensitive material separation has a good effect, at the same time operating basic will not occur in the process of phase transition; Separation process of single stage high separation efficiency, flexible operation process is simple, cover an area of an area small, easy to realize automation, etc. There exists a membrane fouling and membrane separation technology, membrane separation efficiency, lower at the same time, the stability of the membrane and solvent resistant ability is limited, the capacity of single membrane separation shortcomings such as limited to a certain extent, restrict the use of it.
2 hydrophobic oil wet membrane application in the oil/water separation
in the mentioned before, the presence of oil in the water main form dissolve oil, emulsified oil, dispersed oil and oil. The main purpose of the oil-water separation is the mixture of emulsified oil, dispersed oil and oil removal. Dispersed oil is not stable in the aqueous phase, through such means as let stand can be converted into the oil in a short time. In the process of separation because of emulsified oil particle size is small, can stable disperse in water phase, is a key problem for oil water separation.
super hydrophobic oil wet membrane due to its differences with water and oil wettability for its application in oil/water separation, first of all, the Chinese Academy of Sciences, a research group in jiang directly onto stainless steel omentum ptfe emulsion preparation into omentum with super hydrophobic super hydrophilic oil properties, the preparation of retinal water contact Angle of about 156 °, the contact Angle of diesel fuel is close to 0 °, in the preparation of water and oil drops on retinal see water droplets to the existence of the stable on the surface of the membrane and the oil droplets within 240 ms through the retina, on the basis of the experiment is proposed adsorption a merge a permeability of oil-water separation mechanism, put forward the application of the retina in the oil/water separation.
Wang use PFAS modified rough stainless steel such as retinal surface preparation of super hydrophobic membrane, and the membrane was developed on the basis of a set of simple separation device, to a mixture of diesel oil and water separation experiments, finally get the oil content in water of 4. 9 wt %, water content in oil of 0. 028wt%。
physi CAL Qin Mou etc. On the basis of previous studies, using spray plasticizing PPS - a high temperature PTFE way of preparation of compound omentum, application in the self-made small plate separation device. The initial oil content is 16. A mixture of 9 wt % after six levels of separation can be up to 16. 12mg/L。 Under the condition of 40 kpa, sun etc. Using the preparation of 0. 4 mm thick membrane demulsification of oil/water emulsion demulsification experiments, can be seen from the experimental results of demulsification after lower oil content of 7 in aqueous solution. 62mg/L。 Combined separation and demulsification process, this paper adopts polytetrafluoroethylene composite omentum of oil-water mixture demulsification first, then to separate the combination of experimental study.
summary 1) This article will PPS and ptfe dispersion in accordance with the different proportion in auxiliary agent, then the suspension layer coating was prepared on stainless steel surface for sintering separation membrane, on the basis of the original preparation improved formula, on the top floor a layer of ptfe sintering defatted film, preparation of hydrophobic membrane demulsification.
( 2) On the preparation of retinal mechanical performance test, the experimental results show that the retinal surface and stainless steel has a good adhesion ability, but also has good hardness. Retinal immersed in 60 days can be seen in the solution with strong corrosive omentum has good chemical stability.
( 3) Through the contact Angle measurement instrument to measure the contact Angle of super hydrophobic separation by 156. 3 °, the contact Angle of membrane demulsification in about 133 °, diesel in super hydrophobic membrane separation and contact Angle on the membranes of the demulsification are close to 0 °, the wettability of larger difference is the foundation of the separation; Through the surface of the scanning electron microscope retinal super hydrophobic membrane surface with micro nanoscale spherical particles, demulsification membrane surface has a fibrous structure drawing.
( 4) Super hydrophobic oil/water separation membrane aperture size on the critical water pressure has obvious influence, along with the aperture and decreases the critical water pressure increasing; For the demulsification process as the film thickness increases its critical water pressure is increased.
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