Fabrication And Application Of Inorganic Porous Materials With Special Aggregative States

The inorganic porous materials as a classic functional material have been widelyused in the fields of catalysis, adsorption and ion exchange, etc. With the developmentof technology and interdisciplinary research, applications of inorganic porousmaterials are rapidly developed and show attractive prospect in the fields of optical,electrical, magnetic, interface science, life science, environmental protection, etc.However, inorganic porous materials with special aggregative states, such as fibers,films, core-shell capsules are generally necessary to fulfill the need for theseapplications. Therefore, the synthesis of inorganic porous materials with specialaggregation states to meet the needs of these emerging applications is pretty necessaryand has become one of the hot research areas of inorganic porous materials. Underthis research background, the present dissertation is dedicated to develop newfabrication strategies and applications of porous inorganic materials with specialaggregation states, and the primary contents of the dissertation are listed as follows:We fabricated zeolite-coated steel meshes with superamphiphilicity inair/solid/liquid three-phase system and superoleophobicity under water, and exploredtheir applications in oil/water separation for the first time. Water can permeatethrough the superhydrophilicity film quickly only driven by gravity, and oils can isarchitected be retained above the superoleophobicity film underwater. Such specialwettability based on the micro/nanoscale hierarchical rough surface formed by c-axesoriented MFI-type zeolite crystals and the existence of abundant Si-OH. Moreimportantly, such films are highly stable under various harsh conditions, such as acidand concentrated salt, etc., which makes it an ideal candidate for applications inindustry and everyday life, such as the oil retention barrier of industrial outlet sewer pipes, oil fences for oil spill accidents, separation of living waste oil, etc. Furthermore,multi-functional devices with smart surface could be designed that may possessperformances of ion exchange, catalysis and separation simultaneously by combiningthe inherent structural characteristics of zeolites as well as their special wettability.We demonstrated flexible inorganic nanofibrous membranes with mesoporous forthe first time. Such SiO2-TiO2composite porous nanofibrous membranes (STPNMs)with hierarchical porous structure can be fabricated in large scale by anenergy-efficient, low cost electrospinning process. We found that with the increase oftitanium doping, the flexibility of the composite fibers can be significantly improvedand the mesopore structure in composite fibers tends to be wormlike. Whileincreasing the amount of doping titanium to an Si/Ti molar ratio of6, the flexibility ofthe nanofibrous membranes is close to common paper. In water purificationexperiments the composite fibrous membranes exhibit excellent adsorption capacityand permeability owing to their hierarchical porous structure (interfiber-macroporous,intrafiber-mesoporous) and the ultra-fast water spreading property. Because of thesuperior chemical and thermal stability, such membranes can be simply regeneratedby calcination. Therefore, composite fibrous membranes hold great promise for theadsorption of organic contaminants in wastewater.A multi-channel coaxial electrospinning method was employed to fabricateTiO2/silicalite-1composite fibers with a multi-channel cavity structure, and thephotocatalysis activities of composite fibers were evaluated by photodegradation testof methylene blue dye aqueous solution. The introduction of zeolites greatly increasesthe surface area and adsorption capacity of the fibers, which can concentrate reactantsto catalyst more effectively. Meanwhile, macroporous channels increasephotoabsorption efficiency and allow efficient diffusion of reactant molecules.Compared with pure TiO2fibers prepared by electrospinning and commercial P25, thezeolite/TiO2composite fibers exhibited the highest catalytic efficiency. Furthermore, our work demonstrated a simple and universal strategy to assemble nanoparticles intocomplex multi-channel cavity structure in one step, which provides a new way toeasily assemble nanoparticle aggregates with complex structures.