Preparation Of Superhydrophobic Composite Hollow Fiber Membrane And Its Application In Brine Separation

The super-hydrophobic surface of membrane can give the membrane better application performance,so it is necessary to explore the conversion of ordinary hydrophobic membranes into super-hydrophobic membranes.In order to improve the low flux and low rejection of the original polypropylene hollow fiber membrane,two methods were used to functionally modify the surface of the membrane to prepare a superhydrophobic polypropylene medium fiber membrane and apply it in vacuum membrane distillation.And related characterization of the modified membrane.The first method is to prepare a fluorine-free porous superhydrophobic polypropylene-based hollow fiber composite membrane using a one-step ultrasonic coating method.A silane coupling agent is used to convert the hydrophilic titanium dioxide into hydrophobic nanoparticles,which are then combined with the polymer to form a coating solution,and the original film is immersed and coated in an ultrasonic environment.The influence of the amount of polymer involved in the compounding,the type and amount of hydrophobic titanium dioxide and the number of coatings on the surface water contact angle of the membrane was discussed,and the best conditions for obtaining a superhydrophobic membrane were finally obtained.The results showed that the amount of PDMS was 3.5 wt%,the content of nano-particle A-Ti O2 was 1.0wt%,the number of coatings was 5,and the contact angle of the modified film reached161°.In vacuum membrane distillation,the super-hydrophobic membrane modified membrane has better anti-wetting performance and anti-fouling performance.The second method is to prepare silica nanoparticles with high hydrophobicity on the surface,place the polyvinylidene fluoride and the nanoparticles in a coagulation bath,and use the suction filter coating method to construct a composite on the surface of the pure polypropylene hollow fiber membrane.Super hydrophobic nano composite coating.The influence of the mass of nanoparticles,coating time and coagulation bath composition on the surface contact angle of the modified membrane was discussed.The results showed that the content of nanoparticles was 1.0 wt%,the coating time was 60 s,and the coagulation bath was isopropanol.The contact angle of the obtained modified film was 161°,and the porosity of the film was larger.In the vacuum membrane distillation application experiment,the original membrane and the superhydrophobic membrane compare the improvement of membrane separation performance.In this paper,a simple coating method is adopted,starting from the two directions of ultrasonic coating preparation of fluorine-free materials and filter coating phase inversion superhydrophobic membranes of fluorine-containing materials,a stable superhydrophobic membrane is prepared,and it is demonstrated in membrane distillation.Better flux and better flux stability,higher rejection rate,better membrane anti-fouling and anti-wetting performance.