Synlthesis,Characterization Of Fluorescent Carbon Dots And Their Application In Detection Of Mercury Ions

Mercury ion is the most toxic heavy metal pollutant.Because it can lead to severe neurological and psychological diseases,mercury ions have attracted the attention of researchers around the world.For people live in areas where mercury-related industrial activities exist,the risk of inorganic mercury poisoning would be much higher compared with traditional organic mercury food poisoning,owing to the potential contamination of vicinal water system.Urination is one of the main ways of mercury ion metabolism in the human body,thus human urine mercury level can serve as a pre-warning signal of mercury exposure,in case of acute or chronic mercury poisoning.In order to effectively monitor mercury concentration and prevent human mercury poisoning,a versatile mercury ion chemical sensor that can monitor mercury concentration in different aqueous systems and urine is highly desired.In recent years,fluorescent nano-carbon quantum dots?carbon dots for short?as a new chemical sensor have been widely used in the rapid detection of toxic and harmful substances due to their easy synthesis,low cost,good water solubility and optical properties.In this work,we reported a novel fluorimetric chemical sensor based on2,6-pyridinedicarboxylic-acid-derived carbon nanodots?PECDs?,which have been used successfully for sensing Hg²⁺on the basis of photoluminescence quenching.According to structural characterization,PECDs have an average particle size of 5.49 nm.Spectral analyses indicated that the interaction between PECDs and Hg²⁺resulted to fluorescence quenching,and the quenching mechanism was proposed as that the complex formation between PECDs and Hg²⁺was taking place at conjugated-amine chelating position of PECDs,which substantially boosted electrons exciting transition at neogenic conjugated component,and partially suppressed emission at oxygen-related surface groups due to the formation of more favorable non-radiative deactivation pathway,thus causing the phenomenon of fluorescence quenching of carbon dots.The experimental results show that the F/F₀ of carbon dots and Hg²⁺concentration?0.1-10?M,10-100?M?exhibit two good linear relationships,and the detection limit is calculated as low as 75 nM.In the presence of other metal ions,PECDs still exhibited high selectivity to Hg²⁺and strong anti-interference ability.In application,we applied PECDs to the detection of toxic mercury ions in real sample including reservoir water,tap water,and urine samples.The results from all samples showed good recoveries with relative standard deviations of less than 6%.Therefore,we believed PECDs could be used for the determination of the mercury ion in natural water,tap water and urine samples,thus reducing the risk of mercury poisoning of relating residents.