Based On Ionic Liquid Carbon Quantum Dots Preparation And Testing Applications

Carbon quantum dots have attracted much attention in fluorescence detection due to their excellent biocompatibility,good environmental compatibility,low toxicity,simple preparation,low cost,and excellent fluorescence properties.In order to explore a fluorescent probe material applied in the field of environmental detection,this article studied the physical,chemical,and optical properties of carbon quantum dots prepared based on low eutectic ionic liquids and biomass carbon source materials.The application of carbon quantum dots in the detection of heavy metal ions in water and food additives was explored.The specific content is as follows:1)Glycolic acid proline carbon quantum dots for specific detection of Fe³⁺were prepared using ionic liquid（Ionic Liquid）as a carbon source,and the effects of pH and time period on the stability of carbon quantum dots were investigated.Glycolic acid proline CQDs are pH independent fluorescent carbon quantum dots that are not affected by pH and exhibit stable fluorescence properties within 60 days.The fluorescence quantum yield of glycolic acid proline CQDs is 17.5%,and the fluorescence quenching rate of Fe³⁺is 98.37%.The fluorescence quenching effect is significant.Within the corresponding concentration range,the detection limit for Fe³⁺can be as low as 0.001nmol·L^-1,achieving trace detection of Fe³⁺.2)Glycolic acid-proline-grape skin carbon quantum dots（ILB-CQDs）were prepared by hydrothermal method by using grape skin biomass as the carbon source and modified by glycolic acid-proline ionic liquid.The ILB-CQDs in this work increased the fluorescence quantum yield of carbon quantum dots in biomass grape skins from 2.4%to26.7%.Compared with glycolic acid-proline carbon quantum dots,which can only specifically detect Fe³⁺,ILB-CQDs can not only specifically detect Fe³⁺through fluorescence enhancement effect,but also specifically detect Pd²⁺through fluorescence quenching effect,so as to achieve specific detection of two metal ions.The fluorescence enhancement rate of ILB-CQDs to Fe³⁺was 48.40%,and the fluorescence quenching rate of ILB-CQDs to Pd²⁺was 85.79%.In the corresponding concentration range,the linear detection limit of Fe³⁺is 0.001 nmol·L^-1,Pd²⁺linear detection limit of 0.23μmol·L^-1。It can meet the trace detection of Fe³⁺and Pd²⁺in the water environment,and ILB-CQDs can be recycled 4-5 times.3)Glycolic acid xylitol chestnut skin carbon quantum dots（GXC-CQDs）were prepared by hydrothermal method using chestnut skin biomass as a carbon source and modified with glycolic acid xylitol ionic liquid.Explore the application of low eutectic ionic liquid modified biomass carbon quantum dots in the detection of food additive sodium benzoate.GXC-CQDs have excellent time and pH stability,and can specifically detect sodium benzoate with a fluorescence quenching rate of 71.6%.Within the corresponding concentration range,the detection limit of sodium benzoate can be as low as 0.7 mmol·L^-1,it has a good detection effect and meets the testing requirements of sodium benzoate in food now.