| Water purification process has been studied and practiced for decades becausecontaminated water, especially those contained organic pollutants, has become aserious concern due to the industrialization and fast development of economy. Whendischarged into environment, these chemicals can be harmful not only to humanhealth but also to natural biological system. Organic pollutants, such as aromatics,phenol and dyes, are the main component of industry wastewater. It has been a mainconcern to remove the pollutants from contaminated water. Activated carbon andzeolites are the most common used industrial adsorbents, however, it’s difficult toseparate them from the reaction agent. Therefore, their applications are limited.Mesoporous materials have attached much attention since they came into being.The large BET surface area and large mesopore volume has made them very popularin catalysis, biological medicine, energy and wastewater treatment. Magnetic propertyis of great interest because it can greatly facilitate the application of parent materials.Some scientists have synthesized magnetic mesoporous materials, which possessedexcellent properties like large surface area and the reusability. Magnetic separation isquick, simple, eco-friendly and considered to be more effective than filtration orcentrifugation. In this paper, we have synthesized several novel core-shell magneticmesoporous materials, aiming to remove pollutants from contaminated water. Wehave also tested their performance in different applications.In Chapter2, we chose FeCl3·6H2O as iron source, ethylene glycol as solvent,NaAc as dispersant, trisodium citrate as stable agent. Through a solvothermal method, we synthesized uniform and monodispersed Fe3O4nanoparticles. Then, after a sol-geland soft-templating process, an inner shell of nonporous silica and an outer shell ofmesoporous silica shell were coated on the magnetic core. The result sample isdesignated as Fe3O4@SiO2@mSiO2. The nanocomposite possessed not only typicalcore-shell structure, but also high surface areas and large pore volumes. When theconcentration of4-NP is relatively low, Fe3O4@SiO2@mSiO2can adsorb4-NP asmuch as possible within a very short time. What’s more, the adsorbent can be recycledsimply through an outer magnet.Heteropoly acids （HPAs）, especially the Keggin-type H3PW12O40, owing to theirsuper strong Br nsted acidity and high photocatalytic property, have attached muchattention in the last decades. However, the major disadvantages of HPAs as catalystslie in their low surface areas and solubility in polar media. In Chapter3, for the firsttime, H3PW12O40was successfully anchored to the surface of amino-functionalizedFe3O4@SiO2@mSiO2microspheres by means of chemical bonding to aminosilanegroups, aiming to remove unwanted organic compounds from aqueous media. Theas-prepared microspheres, designated as Fe3O4@SiO2@mSiO2-NH2-PW, possessunique properties including high magnetization (46.8emu g-1), large BET surface area(135m2g-1), highly open mesopores （5.0nm）, and H3PW12O40loading is calculatedto be16.8%, and as a result, exhibit enhanced performance in degrading dyes underUV irradiation compared with pure H3PW12O40. Additionally, the photocatalyst can beeasily recycled using an external magnetic field without losing the photocatalyticactivity. It may have potential applications in acid catalyzed reactions, and so on.In this thesis, we have synthesized several core-shell magnetic mesoporousnanocomposites, following the idea that structure decides the nature of the material,and nature decides the application of the material. After some efforts to explore andimprove the reaction conditions, we make it possible to optimize the excellentproperties of each component, and overcome the drawbacks of each member at thesame time. These nanocomposites show excellent and stable performance inadsorption and photocatalytic degradation, which made them may have potentialapplications in wastewater treatment, organic catalytic reactions and so on. |
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