Preparation And Adsorption Properties Of Functional Composite Materials Based On Magnetic Nanoparticles

Materials based on magnetic nanoparticles have been widely applied in catalysis,bioseparation and biomedical for their nanostructure and superparamagnetic property.In the past decade, functionalized magnetic materials display potential application inanalytical chemistry including removal of contaminants and sample preparationbefore determination. Therefore, preparation of novel functionalized magneticmaterials and their composites for special applications have aroused extensiveinterests among researchers.In this thesis, several novel functionalized magnetic materials and theircomposites were prepared and used as adsorbents. The details are as follows:(1) Benzenesulfonic acid functionalized magnetic silica nanoparticles (BSAF-Fe3O4@SiO2) were prepared based on three-step reactions of coprecipitation, sol-gelpolymerization and silanization. The prepared materials showed superparamagneticproperty and were used as adsorbenst for extraction glycopeptide antibiotics includingvancomycin (VCM) and norvancomycin (NVCM) from water. The negative chargeson the surface of the BSAF-Fe3O4@SiO2can promote strong electrostatic interactionwith cationic compounds to exhibit selective and efficient extraction capacity. Thehydrophobic interaction between the phenyl groups also plays a supplementary role.In addition, the superparamagnetism induces easy manipulation of the materials underan adscititious magnet.(2) Benzenesulfonic acid functionalized magnetic silica sub-microspheres wereprepared based on three-step reactions of solvothermal reduction, sol-gelpolymerization and silanization. The prepared materials were applied as adsorbentsfor extraction benzimidazole fungicides including carbendazim (MBC) andthiabendazole (TBZ) from fruit juices. The negative charges on the surface of theBSAF-MNPs can promote strong electrostatic interaction with cationic compounds toexhibit selective and efficient extraction capacity. In addition, the adsorbents can besimple and rapidly separated from the aqueous solution by an external magnet.(3) Magnetic Fe3O4@SiO2/Au composites with long-term stability were preparedbased on strong interaction between the primary secondary amine on the surface ofthe Fe3O4microspheres and the Au atoms. The prepared composites combine theparamagnetic property of magnetic nanoparticles, and the unique surface chemicalproperties of gold nanoparticles. They were used as adsorbents for rapid and efficient removal of benzo[a]pyrene (BaP) from aqueous solution was assessed. The sorptionkinetics and isotherms of BaP on the prepared magnetic Fe3O4@SiO2/Au compositeshave been analyzed. The adsorption mechanism between the adsorbent and adsorbatewas also investigated.(4) β-cyclodextrin functionalized magnetic Fe3O4@SiO2/Au composites(Fe3O4@SiO2/Au/β-CD) were prepared via a specific strategy based on the favorablemerits of thiolate group bond Au. The prepared composites combine the paramagneticproperty of magnetic nanoparticles at room temperature, and the unique chiraldiscrimination ability of β-cyclodextrin. They served as chiral magnetic separators forenantioselective separation of mandelic acid (MA) enantiomers. The chiralrecognition mechanism was studied by nuclear magnetic resonance (NMR).(5) The composites of amine functionalized magnetic Fe3O4nanoparticles andmultiwalled carbon nanotubes (Fe3O4/MWCNTs) were synthesized via a one-stepsolvothermal process. The prepared composites combine the magnetic property andamino functionalization of magnetic nanoparticles, and the unique chemicaladsorption properties of carbon nanotubes. They were employed as adsorbents toclean-up the extract of tea samples prior to determination of pesticide residues.Draw a conclusion, based on the application of magnetic nanoparticles inchemical adsorption, various functional magnetic composites were prepared in thiswork for study their adsorption properties.