The purpose of this project is to fabricate different types of core-shell nanoparticles for effective detection and adsorption of metal ion as well as emerging pollutants in the environment. The sensing elements were immobilized onto the surface of core-shell nanoparticles by surface modification techniques, and thus can be used for high-throughput and rapid analysis of contaminants in small or trace amounts of samples. TEM and XRPD results show that co-precipitation is a suitable method for fabrication of magnetite (Fe3O4) at around 8 nm. The microstructures and particle sizes of Fe3O4/SiO2 nanoparticles are found to be controlled by several sol-gel parameters. The optimized condition for fabrication of Fe3O4/SiO2 core-shell nanoparticles were: [TEOS], 0.05M, [NH4OH], 0.15M, and H2O/TEOS ratio, 180. In addition, the use of self-assembled monolayer techniques with THPC/formaldehyde reduction methods can successfully coat gold nanoparticles onto the surface of SiO2, which possess novel optical properties for metal ion detection. Results of superconducting quantum interference device (SQUID) showed that the Fe3O4/SiO2/Au core-shell nanoparticles were superparamagnetic nanomaterials. However, the saturation magnetization decreased upon increasing the thickness of shell layer. The value of saturation magnetization for Fe3O4, Fe3O4/SiO2, and Fe3O4/SiO2/Au nanoparticles were 53.84, 12.1 and 2.21 emu/g, respectively. The detection limits for Cu(II) and Cd(II) by MPA-modified Fe3O4/SiO2/Au core-shell nanoparticles was about 0.5 ppm with the dynamic range of 2-3 orders of magnitude. The developed core-shell nanoparticles have less sensitivity toward Ni(II) detection with linear range of 5-100 mg/L. In addition to Fe3O4/SiO2/Au nanoparticles, both bulk polymerization and precipitation polymerization were used to fabricate molecularly imprinting polymers (MIP), which can be detection emerging pollutants. The MIP fabricated with by bulk polymerization method has high selectivity and binding capacity towards -estradiol. The maximum adsorption capacity can be up to 0.799 mg/g. In addition, the particle sizes of MIPs fabricated from precipitation polymerization, ranging from 178 to 2472 nm, which can be easily controlled by changing the ratios of cross linker-to-monomer. Results of SEM, IR, EDS, and SQUID analyses showed that Fe3O4/SiO2/MIP was still a superparamagenetic material. The saturation magnetization at 300 K was 0.34 emu/g, which can be recovered simply by magnetic force. In addition, the equilibrium of organic adsorption by Fe3O4/SiO2/MIP can be achieved within 2-5 h. The adsorbed amounts of acetaminophen and estradiol can be up to 0.243 and 1.07 mg/g-MIP, respectively.

Core-shell nanocomposite materials, Molecularly imprinting polymers (MIPs), Emerging pollutants, heavy metals, nanosensing system, adsorption