黄瓜前驱体荧光碳量子点的合成及其在铜(II)检测中的应用

以食用黄瓜汁作为前驱体,在较低的温度下利用水热法一步合成了具有荧光性质的碳量子点(简称碳点)。考察了水热反应温度、水热反应时间、溶液pH值对该碳点荧光性能的影响,同时,从盐离子浓度、紫外光照时间以及存放时间这3方面探讨了其光稳定性。结果表明,于水热反应温度为150℃时反应6h,控制溶液酸度为pH12时制备的碳点有较高的荧光量子产率(荧光量子产率3.9%),合成的碳点具有较好的光稳定性。进一步研究发现,Cu²⁺对按照上述方法合成黄瓜汁碳点的荧光强度有明显的猝灭作用,据此建立了一种检测Cu²⁺的新方法。实验表明,Cu²⁺浓度在0.1×10^-6~5.8×10^-6 mol/L范围内与黄瓜汁碳点的荧光猝灭程度呈良好的线性关系,检出限为0.041μmol/L。实验方法用于河水和生活污水中Cu²⁺的测定,测得结果与原子吸收光谱法(AAS)基本一致,相对标准偏差(RSD,n=5)为3.4%~4.3%。

Synthesis of cucumber precursor fluorescent carbon quantum dots and its application in the determination of copper (II)

The carbon quantum dots (CQDs) with fluorescence property were one-step synthesized at low temperature by hydrothermal method using edible fresh cucumber juice as the precursor. The effect of hydrothermal reaction temperature, hydrothermal reaction time and pH of solution on the fluorescence property of CQDs was investigated. Meanwhile, the light stability was discussed from three aspects including salt ion concentration, UV-irradiation time and storage period. The results showed that the prepared CQDs exhibited high fluorescence quantum yield (3.9%) under the following experimental conditions: the hydrothermal reaction temperature was 150℃, the reaction time was 6h, and the pH of solution was controlled at 12. Meanwhile, the CQDs had good light stability. The further study results indicated that Cu²⁺ showed obvious quenching effect on the fluorescence intensity of cucumber juice CQDs prepared above. Hereby a new detection method of Cu²⁺ was established. The concentration of Cu²⁺ in range of 0.1×10^-6-5.8×10^-6 mol/L had good linear relationship with the fluorescence quenching level of cucumber juice CQDs. The detection limit was 0.041μmol/L. The proposed method was applied to the determination of Cu²⁺ in river water and domestic wastewater. The found results were basically consistent with those obtained by atomic absorption spectrometry (AAS). The relative standard deviations (RSD, n=5) were between 3.4% and 4.3%.