Superhydrophobic Modification Of Polypropylene Hollow Fiber Membrane And Its Application In Membrane Distillation Process

In the context of a wide range of applications of superhydrophobic membrane,exploring superhydrophobic membrane with excellent performance and low cost has certain application value.The preparation process of polypropylene hollow fiber membrane is relatively mature,the cost is lower.However,few reports have been reported on the preparation of superhydrophobic hollow fiber membranes with three-dimensional structure with excellent application prospects in the field of vacuum membrane distillation.In this paper,polypropylene hollow fiber membrane as a matrix,to explore a simple,low cost superhydrophobic modification methods.To widen the application of superhydrophobic surface and polypropylene hollow fiber membrane,accelerate the industrial application of membrane distillation.In this paper,the siloxane was first grafted onto the polypropylene,and then coated by dip-coating combined with phase separation to form a polypropylene coating with a certain degree of roughness and porosity on the surface of the polypropylene hollow fiber membrane.The coated polypropylene hollow fiber membrane was modified with tridecafluorooctyltriethoxysilane to introduce a fluoroalkyl group on the membrane surface.By introducing fluorine on the membrane surface to reduce the membrane free energy.Thus,a polypropylene hollow fiber membrane having superhydrophobicity was obtained.The prepared hollow fiber membrane was characterized by SEM,AFM,FT-IR,XPS and other characterization methods to characterize the surface hydrophobicity,chemical structure,elemental composition and morphology analysis.It was found that the fluoroalkyl groups were successfully introduced into the membrane surface and the roughness of the membrane surface was improved.The superhydrophobic polypropylene hollow fiber membrane was obtained.The effects of the amount of silicone,the number of coating,the concentration of coating solution and the modification time on the preparation of superhydrophobic polypropylene hollow fiber membrane were discussed.Determined the modification process.Finally,the modified superhydrophobic membrane was used in vacuum membrane distillation experiments.The flux,retention and service life of superhydrophobic hollow fiber membranes under different conditions of feed temperature,feed concentration,vacuum degree and long-term operation were discussed.The test results show that the modified superhydrophobic polypropylene hollow fiber membrane in the membrane distillation has a better life than the original membrane,rejection rate than the original film has also been improved.