Preparation Of Superhydrophilic Composite Filter Membranes And Study On Its Separation Performance Of Oil In Water Emulsions

In recent years,the frequency of diseases caused by high blood lipid levels had been increasing,seriously affecting physical health.The membrane separation method for oil-water separation could be used as a primary application in the process of separating blood lipids from hyperlipidemic blood in the medical field.In this thesis,the modified foam titanium and Co Mn O₃/Ti O₂ stainless steel mesh were prepared by hydrothermal method and pull impregnation method,and applied to the separation of oil-water mixture and emulsion.On this basis,the separation effect of the filter membrane on pseudolipidemia and pig blood was further explored.Using one-step hydrothermal method to form titanium dioxide micro nanostructures on the surface of foam titanium,and the using of fluorine would further form Ti-O-F groups.The surface wettability of modified foam titanium was superhydrophilic,and the underwater performance was superoleophobic with low oil adhesion.The underwater oil contact angle was 159°.After the modified foam titanium was soaked in acid,alkali and salt environment,the underwater oil contact angle decreased slightly,but it could maintain the underwater superoleophobic,and the sliding angle increased slightly.After 6 months of long-term storage,the wettability and separation efficiency of modified foam titanium were basically unchanged.Under the action of gravity alone,the separation efficiency of modified foam titanium for four types of oil-water mixtures,namely,n-hexane,vegetable oil,xylene and petroleum ether,was more than 98%,and 20 consecutive separations could be achieved with the separation efficiency still more than 96%.During the continuous separation process,cleaning the filter membrane resulted in a decrease in separation efficiency of only about 2%.The titanium dioxide on the surface of foam titanium could be modified by ultraviolet irradiation,which could effectively remove the residual oil phase on the surface after separation,and made the surface become superhydrophilic again.Co Mn O₃/Ti O₂ composite coatings were deposited on the surface of stainless steel mesh using hydrothermal method,pull-up impregnation method,and annealing.The composite coated stainless steel mesh transforms into superhydrophilic and superoleophobic underwater,with an underwater oil contact angle of approximately156°,exhibiting low oil adhesion and a sliding angle of less than 5°.The Co Mn O₃/Ti O₂SSM single piece filter membrane could withstand an oil phase pressure of about 0.9k Pa.The separation efficiency of the filter membrane for n-hexane,petroleum ether,n-heptane,and mixed oil was greater than 98%.After 20 consecutive separations,the efficiency decreases by about 3%.The acid,alkali,and salt environment had a small impact on the separation efficiency of the filter membrane,with separation efficiency greater than 95%.Under a load of 1.25 k Pa and friction of 30 cm,the underwater oil droplet contact angle of the filter membrane decreased from 156°to 148°,and the sliding angle increased by 15°.Co Mn O₃/Ti O₂ SSM still exhibited stable superhydrophilicity after 6 months of storage.Emulsions of n-hexane,n-heptane,petroleum ether,xylene,unsaturated fat acid and other common organic solvents were prepared by ultrasonic cleaner,and their emulsions were observed and analyzed.The prepared emulsion maintains a stable emulsified state within 24 hours.The emulsion was separated by modified foam titanium and Co Mn O₃/Ti O₂ SSM.The modified foam titanium had poor separation effect on the emulsion due to the substrate preparation process,and could only be used as the primary separation method in the separation process;The efficiency of Co Mn O₃/Ti O₂ SSM for emulsion separation could reach 99%and could be repeatedly separated.After 20 consecutive separations,the efficiency decreased to 90%.Meanwhile,Co Mn O₃/Ti O₂ SSM had a certain separation efficiency for blood lipids.When the modified foam titanium was overlapped with Co Mn O₃/Ti O₂ SSM,the separation efficiency for triglycerides,cholesterol and low-density lipoprotein was30.4%,13.7%and 36.1%.In conclusion,the modified foam titanium and Co Mn O₃/Ti O₂ SSM had the advantages of simple process,low cost,high efficiency,high mechanochemical strength and environmental friendliness.They had a good separation effect on oil-water mixture and emulsion,and had a certain separation efficiency for simulated blood lipids and pig blood,providing a research foundation for subsequent lipid separation research.The thesis has 52 figures,11 tables,and 114 references.