Preparation,properties And Application Of Carbon Dots Based On Two Fruits Of Peels

As a new type of carbon nanomaterials,carbon dots(CDs)have remarkable advantages such as excellent photostability,biocompatibility,low cytotoxicity,and easy surface functionalization which makes CDs suitable for fluorescence sensing,biological imaging,catalysis and drug delivery.Carbon dots synthesized from natural biomass as carbon sources have attracted much attention of researchers due to their unique praperties and performance.In this paper,the biomass waste Luochuan Red Fuji apple peed and Guiwei litchi shell were selected as carbon sources,the apple peel carbon dots(Ap-CDs)and litchi shell carbon dots(L-CDS)Were prepared by hydrothermal method,respectively,The chemical composition,structure and optical properties of Ap-CDs and L-CDs were analyzed and studied,and thea their potential application in Fe3+ detection and fluorescent ink was explored.The research contents of this thesis are summerized as follows:(1)Synthesis of Ap-CDs based on Luochuan Red Fuji apple peel and their Fe3+sensing propertyCarbon dots(Ap-CDs)were synthesized by hydrothermal method using Luochuan red Fuji apple peel as carbon source(0.5g/25 mL of water),under the optimized conditions of 18 hrs’ reaction at 200℃,Their chemical composition and structurs were analyzed by transmission electron microscopy(TEM),X-ray diffraction(XRD),Raman spectroscopy,Fourier transform infrared Spectroscopy(FT-IR),X-ray photoelectron spectraseopy(XPS),ultraviolet-visible absorption spectroscopy(UV-Vis),and fluorescence spectroscopy were used to study the fluorescence properties of Ap-CDs.Fluorescence test showed that Ap-CDs emit Luight blue light at 433 nm wavelength under UV irradiation at 350 nm wavelength,with aquantum yield of 9.43%.Meanwhile,the fluorescence intensity of Ap-CDs can be selectively quenched by Fe3+ ions.Adding 0.05-300μM Fe3+ to Ap-CDs,the fluorescence quenching effect of Ap-CDs in the range was linearly related to Fe3+ concentration,and the detection limit was 1.56 μM.Based on this,Ap-CDs fluorescence quenching method was used to determine the concentration of Fe3+ ions in tap water samples.(2)Synthesis of L-CDs based on Guiwei litchi shell carbon dots and their Fe3+sensing propertiesA kind of carbon dots(L-CDs)with strong blue fluorescence emission were prepared by a hydrothermal method using biomass waste Guiwei litchi shell as precursor.The optimal synthesis conditions were explored to be 9 h,180℃ and 0.75 g/25 mL of water.Fluorescence properties test showed that the quantum yield of L-CDs was 7.86%under the optimized conditions.Meanwhile,the fluorescence sensing performance of L-CDs showed that the fluorescence intensity of L-CDs could be quenched(turned off)by Fe3+,and the fluorescence quenching of L-CDs was linearly related to Fe3+concentration in the range of 0-100 μM;then the fluorescence could be recovered(turned on)by glutathione(GSH).Fluorescence recovery of L-CDs/Fe3+showed a linear relationship with glutathione concentration in the range of 080 μM.The detection results of Fe3+and glutathione by L-CDs as "on-off-on" fluorescent sensors were also further investigated.During the process,it was found that compared with other common metal ions,L-CDs had obvious selectivity and detection sensitivity for Fe3+.Therefore,the L-CDs fluorescence quenching method was used to determine the concentration of Fe3+ions in the tap water samples.In addition,due to the strong fluorescent properties of L-CDs,their application in the field of fluorescent ink were estimated.