| In recent years, carbon nanomaterials have been at the forefront of the field of scientific research. A variety of carbon nanomaterials have emerged, from two-dimensional graphene to the one-dimensional carbon nanotubes and then zero-dimensional fullerenes. Carbon nanomaterials are widely used in many fields, such as optoelectronics, medical, biotechnology, analytical testing and catalysis and so on, due to their superior physical and chemical properties. In this paper, we have established a spectra platform based on carbon nanomaterials for the detection of Al3+, hydrogen peroxide, glucose, and free chlorine. The specific contents of the study are as follows:Part 1:Based on Al (Ⅲ) can enhance Hemin functionalized graphene oxide (H-GO) resonance Rayleigh scattering signal, a novel method for direct determination of Al (Ⅲ) has been established, and this method was successfully applied to detect Al (Ⅲ) in Jialing River water and aspirins samples. Under optimum conditions, the linear regression equation is y= 0.50701+0.98718 C, along with the linear range of 10 nM-6 μM and the detection limit of 0.87 nM. In this work, the reaction mechanism was also investigated by UV-visible spectroscopy, resonance Rayleigh scattering spectroscopy, and infrared spectroscopy. It was found that Al (Ⅲ) does not enhance scattering signal of the graphene oxide and the reduction of graphene, what’s more, EDTA can not quench the scattering signal of Al (Ⅲ)-H-GO system. Based on above phenomena, we can get the conclusion that under this condition, not Al3+, but sol-gel Al (OH) 3 enhanced the scattering signal of H-GO. In addition, the UV-Vis spectra and infrared spectra indicate that the electrons transfer from hemin to GO and then to Al (Ⅲ). In short, the sol-gel Al (OH)3 had affected the surface properties of H-GO.Part 2:Based on graphene quantum dots-Fenton reaction, a hydrogen peroxide and glucose fluorescent sensor has been established. Fe2+ and H2O2 will not quench the fluorescence of graphene quantum dots (GQDs), but Fe+, the product of Fenton reaction, was able to sensitively quench the fluorescence of GQDs. Based on this phenomenon, a new method of indirect fluorescence detection of hydrogen peroxide was established. At the same time, since glucose oxidase is capable of specifically oxidizing glucose to produce hydrogen peroxide, this method can also indirectly detect glucose.In this study, the pH, reaction temperature, and reaction time were optimized; two linear equations were obtained, F-F0= 42.8876 C-1.1229 and F-F0 =7.2123 C+219.5063, corresponding to the linear range of 0.5-6μM and 6-30 μM, respectively, along with detection limit of 0.03μM. Under the same optimum conditions, the detection of glucose also presents two linear ranges, F-F0=26.5506 C+2.4915 and F-F0= 5.7736 C+172.4911, corresponding to the linear range of 1-8 μM and 8-35μM, respectively, along with a detection limit of 0.08μM.Part 3:Mg-doped carbon quantum dots (Mg-CPNs) as a blue fluorescent sensor to detect the free chlorine in tap water. It was found that at pH 6.09 BR buffer solution, the Mg-doped carbon quantum dots can emit stable and moderate blue fluorescence. But in the presence of free chlorine, the fluorescence of Mg-doped carbon quantum dots was rapidly quenched. Based on the above phenomena, a new rapid, sensitive, and selective fluorescent method to detect free chlorine in tap water was established. In this work, the pH, reaction time, and the concentration of Mg-doped carbon quantum dots were optimized. Under optimum conditions, the linear regression equation is F-F0=723.369 C-23.01, corresponding to the linear range of 50 nM-1.75μM and the detection limit of 8 nM. The reason that this system can be used to detect free chlorine may be due to the reaction of strong oxidizing activity of free chlorine and the electron-rich oxygen-containing functional groups on the surface of Mg-doped carbon quantum dots. |
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