Modification Of PVDF Membrane By Inorganic Nanoparticles

With the rapid development of membrane separation technology and membrane materials, poly （vinylidene fluoride） （PVDF） membranes already can’t meet the actual needs of human production and living, so they need to be modified. Preparing novel PVDF matrix organic-inorganic composite membranes with new technologies and methods, and realizing multi-functionalization of separation membrane have always attracted increasing attention in the field of membrane science. Compared with neat PVDF membrane, PVDF matrix organic-inorganic composite membranes often combine the advantages of both organic and inorganic materials, and show catalytic characteristic, adsorption characteristic and more excellent separation performance. However, some problems and disadvanatages are still exisited for available organic-inorganic composite membranes. The inorganic nanomaterials are often difficult to disperse homogenously in polymer matrix, resulting in the occurance of defects in membrane. What is worse, the inorganic nanomaterials are easy to leach out during membrane application due to the poor compatibility and interaction between organic and inorganic phases. As a result, membrane performance might gradually degrade in membrane use. These problems limit further development and application of organic-inorganic composite membranes.In this paper, we utilize two strategies to solve the above-mentioned problems. On the one hand, in situ reduction method and co-condensation are used respectively to prepare noble metal nanoparticles and to synthesize thiol functionalized mesoporous silica in pores of modified PVDF membrane, eventually obtaining organic-inorganic composite membranes. This method solves the problem of agglomeration for inorganic nanomaterials （containing noble metal nanoparticles and functionalized mesoporous silica）, increases dispersibility and stability of them in PVDF basis material. On the other hand, allyl functionalized ion interpenetrating mesoporous silica spheres are used to decorate PVDF chains, eventually obtaining PVDF matrix organic-inorganic composite membrane by immersion precipitation phase inversion method. Utilization of interpenetrating network method solves the problem of compatibility between PVDF and mesoporous silica and it of agglomeration for mesoporous silica.An in-situ loaded Pd nanoparticles exhibits high catalytic reactivity and catalytic stability in reduction of 4-nitrophenol after immobilized in PVDF/PMAA blend membrane pores. For well-dispersed Pd nanoparticles, they have not obvious agglomeration.Thiol functionalized mesoporous silica is synthesized by co-condensation method in pores of modified PVDF membrane, finally gaining PVDF-mesoporous SiO2 composite membrane, and adsorption property of the composite membrane for lead ion is researched. The results show that the well-dispersed mesoporous silica spheres do not agglomerate. Besides, the composite membrane shows good adsorption performance for lead ion, repeated use of performance, stability performance and is convenient to reuse.Ion imprinting mesoporous silicas were firstly synthesized by combining ionic imprinting technique and co-condensation method and then were used to decorate PVDF chains, obtaining organic-inorganic composite, which is made into PVDF-IIMSiO2 composite membranes. Finally, the adsorption performance of composite membrane for Cu²⁺ is researched. The experimental results indicate that the composite membrane has excellent adsorption property for Cu²⁺, remarkable reuse and stability perforemance. PVDF-IIMSiO2 composite membrane shows good adsorption selectivity for Cu²⁺.