Preparation And Applications Of β-Cyclodextrin Modified Core-shell Hybrid Magnetic Nanoparticles

In the past decade, magnetic nanoparticles(MNPs) have received many attentions due to their paramagnetism, large surface-to-volume ratio and the very active surface for immobilization or adsorption of other functional molecules. As a result, these materials show potentials in a wide range of applications. Among them, magnetical nanocatalysts are considerd as the quintessence. They are simply and efficiently removed from reation medium with an external maginitic field to solve the the problems of seperating homogeneous catalysts, which strongly restricts their applications in industry. Compared with the tranditional catalysts, the activity, selectivity and stability of the nanocatalysts are obviously improved by tailoring their size, shape, composition, and electronic structure. Cyclodextrins(CDs) are a family of water-soluble cyclic oligosaccharides produced from degradation of starch by enzyme. As their special interior cavities structure, CDs are frequently used as host molecules in inclusion complexes. All these complexes show good selectivity as similar as enzyme and substrates, which is formed through van der Waals forces, hydrogen bonding, hydrophobic interactions, and the size and shape of the guest molecules. Based on this, we designed the core-shell structure of β-cyclodextrin modified hybrid magnetic nanoparticles to explore its applications on catalytic of benzyl alcohol and adsorption of phenol. The main research contents and conclusions are illustrated as follows:1. A flexible synthetic method, including thermal decomposition, sol-gel process and ring-opening reaction of epoxy group, was successfully developed for the preparation of Fe3O4@SiO2-GPTSCD. The final hybrid nanoparticles were combined with the catalysis of CD and the magnetic separation property of MNPs. Most excitingly, Fe3O4@SiO2-GPTSCD showed the high catalytic activity in the oxidation reaction of benzyl alcohol with sodium hypochlorite and hydrogen peroxide as the oxidant, much more than the pure CD.2. β-cyclodextrin modified hybrid magnetic nanoparticles(Fe3O4@SiO2-h-PAMAM-CD) with a core-shell structure were prepared via the classic hyperbranched polyamidoamine synthesis method, the combination of Michael addition and aminolysis reaction, on the surfaces of silica coatediron oxide nanoparticles. It proved that the adsorptive removal of phenol from aqueous solutions due to host-guest interactions between β-CD and phenol. As a result, there is an approximate linear relationship between absorption and time at the first six hours. Then the adsorption capacity gradually reaches the dynamic balance and the total adsorption quantity is about 0.24μmol. It indicates Fe3O4@SiO2-h-PAMAM-CD is a potential material in the removal of phenol from water.