Preparation, Characterization Of Functionalized Gold Nanoparticles And The Application In Environmental Analysis

Nanosized metal particles have been one of the topics with great current interest, and they continue to attract immense attention due to their fantastic physical, chemical, and biological properties which leading to high potential applications in various fields. Owing to the intrinsic characteristics such as easy of preparation, biocompatibility, stability, high extinction coefficient and highly efficient catalysts, gold nanomaterials have received much more consideration.In view of this, on the basis of the preparation and applications of functionalized gold nanomaterials, the following research was carried out on the previous work:i. focusing on gold nanoparticles special optical properties that the content of herbicide glyphosate could be determined by monitoring with a UV-Vis spectrophotometer; ii. the high catalytic that establish a new, simple and rapid method of preparation Fe3O4@SiO2-Au magnetic nanocomposites with the study on their catalytic activity and reusable ability of the degradation of4-nitrophenol.This dissertation is divided into three chapters, and a brief introduction is as follows:Chapter1This chapter introduces the properties and preparation methods of functionalized gold nanomaterials, and thier application in trace detection and environmental protection.Chapter2In this study, a novel colorimetric method for rapid, sensitive and low-cost detection of glyphosate was developed using the cysteamine-stabilized gold nanoparticles (CS-AuNPs). The CS-AuNPs could be aggregated easily in the presence of glyphosate through electrostatic interaction in acidic medium, resulting in a shift in the surface plasmon band and a consequent color change from red to blue (or purple). Therefore, the content of glyphosate could be determined by monitoring with a UV-Vis spectrophotometer. The detection limit of the present method for glyphosate was5.88×10-8M, with the linear range of0.500～7.00μM.Chapter3A facile approaches was successfully developed for in-situ synthesized Fe3O4@SiO2-Au magnetic nanocomposites (Fe3O4@SiO2-Au MNCs) through inorganic grafting between Sn2+and surface Si-OH and then the linked Sn2+species acted as a reducing reagent to reduce Au3+into AuNPs.The preparation method was simple, economic and fast. Significantly, the as-synthesized Fe3O4@SiO2-Au MNCs displayed both high magnetization and excellent catalytic activity. They showed high performance in catalytic reduction of4-nitrophenol to4-aminophenol with the excess amount of NaBH4. By an external magnet they can be successfully recycled and reused for at least seven times with stable conversion of91%.