The Preparation Of Graphene-based Composites And Graphene Quantum Dots For Analysis Of Some Environmental Pollutants Of Phenol Compounds

Graphene is a novel nanomaterials with a two dimensional sheet of sp2-hybrbridized carbon atomspacked in a hexagonal lattice. Since the first report about its synthesis, graphene has the advantages ofcharged carrier mobility and mechanical strength. Therefore, various synthesis approaches have beenestablished, however, the reduction of graphene oxide is a common methods one of the most active researchtopic has drawn attention in many field, including: spaceflight, chemistry, biology, physics, pharmaceuticaland environment protection, because of the fascinating properties of graphene, such as high surface area,high thermal conductivity, using graphene oxide as the starting material to produce graphene has turned outto be an efficient and economic process for mass production. However, there is still existed someimperfection when the graphene is submitted to the practical application. For this problem, graphene surfacemultifunctional, formed by the noncovalent attachment taking advantages of both the superior properties ofgraphene and the functionalizing molecules, have been great importance in application field.During the further research of the graphene, the researcher found that graphene quantum dots (GQDs)are small graphene fragments. Compared with the graphene, its property of electronic transport, photologyand toxicity is much different. Thus, the study on GQDs has attracted considerable attention from boththeoretical scientific communities and synthesis procedure. However, there is few report about its applicationin quantitative analysis in food and environment samples.To exploreing the potential application of the novel carbon nanocomposites in quantitative analysis, inthis paper, graphene-based composite materials and GQDs were investigated. The detection method ofcommon environment pollutants phenolic compounds were built combined with the mimetic enzyme catalystspectrophotometric, resonance light scattering and fluorescence quenching technique. In addition, a simpleand rapid analytical method for the diction the homologue phenolic compounds was established by combinedwith the chemometrics. The thesis is summaried as follows:Chapter one: It was simple reviewed the synthetic method of graphene nanocomposite and GQDs, andthe development of the new nanocomposite has been investigated in some fields. Besides, a briefintroduction of experimental theory and reaction mechanism, and the novel materials combined with thespectrophotometry used in the quantitative qnqlysis were given.Chapter two: A hemin-graphene hybrid nanosheets (H-GNs) through the-interaction weresynthesized by a wet-chemical method. And the morphology image of the materials were carried out byUV-vis spectrum, Atomic force microscope (AFM), Scanning electron microscopy (SEM) and X-rayspectroscopy (EDS) methods. This new material possesses the particular advantage of both hemin andgraphene and exhibits three interesting properties.1. they are quite solubale in water, and are more stablethan either hemin or graphene;2. they also mimic the activity of the peroxidase enzyme,3. catalysts for theoxidation of phenols to form different quinone-imine colored products, which facilitate spectroscopicqualitative detection;4. For the simultaneous analysis of the three analytes-pyrocatechol, resorcin andhydroquinone through combined to the chemometric. Chapter three: An important aspect of the method involved the use of GQDs, which were initiallyobtained from the pyrolysis of citric acid dissolved in aqueous solutions. The atomic force microscope (AFM)images, UV-vis spectrum and Fourier transform infrared spectra (FT–IR) were used to characterized. A novel,highly selective resonance light scattering (RLS) method was researched and developed for the analysis ofphenol in different types of industrial water. A trace amounts of phenol were detected over the linear rangesof6.0010-8M–2.1610-6M and2.4010-6M–2.8810-5M with a detection limit of2.2010-8M. Inaddition, three different spiked waste water samples and two untreated lake water samples were analysed forphenol. Thus, the proposed method was successed used to dection the water samples, which not have anypretreatment procedure.Chapter four: From the perspective of the unique fluorescence of graphene quantum dots, an efficientmethod for the trace amount of hydroquinone detection in water samples by using GQDs as fluorescentprobe has been developed. The fluorescence quenching during the benzoquinone was increased, which viahorseradish peroxidase catalyzed oxidation of hydroquinone. In the optimum condition, good linear rangeand the low detection limit of8.410-8M were obtained. A simple method for rapid determination ofhydroquinone was obtained.With aid of the new nanocomposites, the sensitive and simple spectroscopy method for the detectionphenolic compounds was built. A good channel of environmental pollutants analysis could be establishedthrough combined the nanocomposites.