| Carbon quantum dots as a new with Carbon as the main body of the fluorescent nanomaterials, because of its unique optical characteristics, cell advantages of low toxicity, the synthetic of low price becoming a hot spot popular in scholars studies, the carbon quantum dots widely applied in the fields of medical imaging, chemical testing, industrial waste, biomarkers and so on. This thesis mainly synthesis of CQDs by microwave method, and discusses its application in monitoring environmental heavy metal ions in water analysis. Specific research contents include the following three parts:(1) The experiment with glucose as the carbon material, rapid microwave heating synthesized water-soluble fluorescence carbon quantum dots. The surface with affluent carboxyl and hydroxyl groups, with the aid of the fluorescence CQDs and studied the environment between the heavy metal cadmium ion fluorescence quenching effect. Found in the pH=4.00 acetic acid sodium acetate buffer solution(HAc-NaAc), the system of the intensity of fluorescence quenching and had good linear relationship of cadmium ion concentration, the equation of linear regression is ?F=0.1598 c+8.1781, the correlation coefficient is 0.9982, the detection limit is 0.50 μg/L, with high selectivity and sensitivity, the operation is simple, rapid, and has been successful used in detetion of trace cadmium in water environment, the results are satisfied.(2)D-fructose as the main body of the carbon, L-lysine as modifier, step the microwave CQDs with strong fluorescence properties. Fluorescence performance under optimum synthesis condition was studied the influence of factors, with the help of X-ray diffraction(XRD), Fourier transform infrared spectrum(FTIR), Ultraviolet-visible absorption spectrum and Fluorescence spectrum characterization method for characterizing the structure and optical properties of CQDs, found that the blue color of CQDs surface with affluent carboxyl and hydroxyl groups, emission wavelength depends on the excitation wavelength and has strong hydrophilicity. Also discussed the surfactant, common ions, oxidant, reductant, pH and temperature influence on carbon quantum dots fluorescent properties, found that the addition of silver ion make the CQDs intensity of obvious fluorescence quenching phenomenon, and silver ion solution at 5.00-100.00ug/L concentration range with CQDs good linear relation with the intensity of fluorescence quenching, on this basis, established the detection of the silver ion solution method, successful application in environmental water samples the determination of silver.(3)Explores the ascorbic acid as the carbon source, using microwave heating method to synthesize water-soluble CQDs, using electron transmission microscope(TEM), Ultraviolet-visible absorption spectra, Fluorescence spectra, Fourier infrared spectrum(FTIR) and X-ray diffraction(XRD), found that the CQDs size uniform, has a strong fluorescence, at the same time found that the addition of Cr(Ⅵ) can make a strong fluorescence carbon quantum dots of fluorescence signal significantly quenched, and Cr(Ⅵ) in 2.00-71.00 ug/L concentration range and the system had good linear relationship fluorescence intensity, the equation of linear regression is ?F=9.5792 c +1.1719, the correlation coefficient is 0.9968, the detection limit is 2.90 ng/L. This method has been successful used in detetion of Cr(Ⅵ) in industrial water, the results are satisfied. Using uv-visible absorption spectrum, the relationship between fluorescence quenching degree and temperature of Cr(Ⅵ) and CQDs probes into the possible mechanism of the interaction. |
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