Synthesis,Characterization Of Biomass Carbon Dots And Their Application In Analysis And Detection

Carbon dots are a material similar to metallic quantum dots.They are nanoparticles capable of emitting fluorescence under the excitation of light.The size of cabon dots,which is usually less than ten nanometers,is so small that it has a size effect and thus they exhibit more special features.Some traditional metallic quantum dots,which contain toxic components such as heavy metals,are limited in many applications.In particular,the toxicity of these quantum dots poses a major obstacle to their use in living bodies,because the quantum dots will greatly reduce the activity of the cells and negatively affect the biological tissues.The cost-effective,environmentally-friendly,fluorescent carbon dots show excellent performance,are also compatible with the human body,almost harmless to the organism,and broaden the application of carbon dots.Moreover,carbon dots can be widely used in the field of analysis and detection because of their excellent fluorescence properties,relatively high water solubility,and excellent light stability and chemical stability.Based on the above explanation,this paper mainly carried out the following research:（1）Using the Camellia oleifera husk powder as raw material,the carbon dots were successfully prepared by the one-step hydrothermal method,and carbon dots were characterized.In the preparation process,the preparation conditions of the addition amount,the hydrothermal reaction time and the hydrothermal reaction temperature were optimized.It was found that in 30 m L deionized water,the amount of camellia husk powder was 0.10 g,and hydrothermal reaction temperature was 220°C,the carbon dots had the highest fluorescence intensity.The characterization results indicate that the carbon dots obtained are nearly spherical in shape,mono-dispersed,have an average particle size of 4.7 nm,and hydroxyl,carboxyl,and carbonyl groups on the surface.The maximum excitation wavelength is 353 nm and the maximum emission wavelength is436 nm.The carbon dots also exhibits excitation dependence of emission spectrum,quantum yield of 1.88%,and excellent stability.（2）Using grape skins as raw materials,one-step hydrothermal method was used to prepare carbon dots and carbon dots were characterized.In the preparation process,the preparation conditions of grape skin addition amount,hydrothermal reaction time and hydrothermal reaction temperature were optimized.It was found that in 30 mL deionized water,the added amount of grape skin was 0.05 g,the hydrothermal reaction time was 18 h and the hydrothermal reaction temperature was 200°C,the carbon dots have the highest fluorescence intensity.The characterization results show that the carbon dots obtained have an quasi-spherical shape and good dispersibility.The average particle size is 3.1 nm.Hydroxyl,carboxyl,carbonyl,amino and other groups exist on the surface.The maximum excitation wavelength is 362 nm,and the maximum emission wavelength is 438 nm.The carbon dots also exhibits excitation dependence of emission spectrum,quantum yield of 2.02%,and excellent stability.（3）The Camellia oleifera husk powder carbon dots quenched in the presence of Pb²⁺,and have good selectivity and high sensitivity to Pb²⁺.In the range of 0-10μM Pb²⁺concentration,the fitting linear equation is F₀/F=1.00791+0.01457[Pb²⁺],R²=0.9877,the limit of detection is 136 nM;in the range of Pb²⁺concentration 10-100μM,fitting linear equation is F₀/F=1.11483+0.00464[Pb²⁺],R²=0.9927,and the limit of detection is 63.2 nM.（4）The grape skin carbon dots quenched in the presence of Hg²⁺,and have good selectivity and high sensitivity to Hg²⁺.In the range of Hg²⁺concentration of 0-8μM,the fitting linear equation is F₀/F=0.99967+0.02957[Hg²⁺],R²=0.9926,the limit of detection is 86 nM;in the range of 8-100μM Hg²⁺,the fitting was performed.The linear equation is F₀/F=1.21809+0.0042[Hg²⁺],R²=0.9937,and the limit of detection is 28nM.