The Study Of Organic-inorganic Composite Nano-fiber Super-hydrophobic Membrane By Electro-spinning

In recent years, with the continuous progress of science and technology, the technology of super-hydrophobicity has developed rapidly and gradually been used in various fields, such as chemical industry and energy field. In particular, it shows excellent separatio n performance in the field of special water degassing and waste removal, etc., the addition of inorganic substances can further improve the mechanical properties of hydrophobic membrane. However, the super- hydrophobicity still has some drawbacks, such as high cost of preparation, complexity of preparation process, poor stability properties of materials and so on. Considering the special requirement for super-hydrophobic membrane considering deoxidization and decarbonation of boiler water and based on the biomimetic principle of surface roughness and low surface energy, super-hydrophobic organic- inorganic composite nano- fiber membranes were prepared in this paper, providing some theoretical basis for the application of super-hydrophobic membrane in actual industry.SiO₂ nanoparticles with specific particle size by sol- gel method were prepared using tetraethylorthosilicate（TEOS） as the main raw materials, ethanol as dispersing agent, ammonium hydroxide as a catalyst. The effects of temperature, the amount of ethanol, TEOS, water and ammonium hydroxide on the particle size and dispersion conditions were discussed. The particle size and distribution were determined by transmission electron microscope（TEM） and dynamic light scattering（DLS） analyzer. The results indicated that the SiO₂ particle size obviously decreased by the increase of temperature and the amount of ethanol. The particle size increased by the increase of the amount of water and ammonium hydroxide which also improved the dispersion property significantly. SiO₂ particles of three different sizes（90nm, 170 nm, 270nm） were modified by three different coupling agents octyl-triethoxy silane, vinyl- triethoxy silane（A-171）, vinyl-triethoxy silane（A-151）, respectively. Orthogonal experimental method was adopted to investigate the impact of the kinds of coupling agent, temperature, molar ratio of coupling agent and modified silica on the hydrophobicity. Modification effect was analysized by contact angle（CA） measurement, fourier transform infrared spectroscopy（FTIR） and scanning electron microscope（SEM）. The result showed that modified SiO₂ particles was hydrophobic, and SiO₂ particles of 170 nm particle size had the better hydrophobic modification effect.SiO₂/PVDF nanofiber membrane was prepared by electrospinning method after silica particles modified by silane coupling agent and polyvinylidene fluoride（PVDF） was blended. The effect of spinning conditions on the membrane surface contact angle and fiber morphology was studied. The result indicated that the optimal condition was PVDF solution concentration 7%, applied voltage 15 k V, receiving distance 25 cm. When the mass ratio of 90 nm SiO₂ particles and PVDF was 3:1, a super-hydrophobic membrane with CA of 155° was fabricated, which exhibited super-hydrophobicity property.