Development of hollow fiber membrane with organic-inorganic composite structure used for water recycle system

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Poly (vinylidene fluoride) (PVDF) hollow fiber membrane was prepared from PVDF/diethyl phthalate system via thermally induced phase separation (TIPS). The melting temperature greatly affected the membrane structure. When the melting temperature was 180℃, spherulite structure due to the polymer crystallization was obtained, while the inter-connected structure (lacy structure) was formed at 150℃. The formation mechanism of the membrane structure was discussed based on the DSC data. The spherulite structure showed the higher water permeability with the lower mechanical strength. On the other hand, the inter-connected structure showed the fairly high strength. The effect of the addition of clay on the membrane performance was also investigated. The addition of clay was useful to form inter-connected structure. The resultant hollow fiber membrane had higher membrane strength and membrane elongation.PVB-TiO_2 composite hollow fiber membranes were prepared via nonsolvent induced phase separation (NIPS) method. Titanium dioxide (TiO_2) particle has the property that makes the surface to be hydrophilic by the irradiation of ultraviolet (UV). Though the water permeability for membranes hardly changed with the addition of TiO_2, the tensile strength and elasticity increased. When PVB concentration is 10wt%, the weight ratio of TiO_2 to PVB changed from 1 to 2. The water permeability increased with the increase of TiO_2 content. Furthermore, for all the membranes, with the elapse of time, the water permeability increased, and it became to be constant after about 15days. On the other hand, tensile strength and elasticity kept constant with the elapse of time. In addition, for PVB-TiO_2 membrane, the water contact angle on the membrane surface decreased after the irradiation of UV, which means that the surface of the composite membrane became to be more hydrophilic.