S A Nsibande, P B C Forbes
Chemistry Department, Faculty of Natural and Agricultural Sciences, University of Pretoria South Africa
RSC Adv. 2020 Mar 25;10(21):12119-12128. doi: 10.1039/c9ra10153e. eCollection 2020 Mar 24.
Polycyclic aromatic hydrocarbons (PAHs) are potentially harmful pollutants that are emitted into the environment from a range of sources largely due to incomplete combustion. The potential toxicity and carcinogenic effects of these compounds warrants the development of rapid and cost-effective methods for their detection. This work reports on the synthesis and use of graphene quantum dots (GQDs) as rapid fluorescence sensors for detecting PAHs in water. The GQDs were prepared from two sources, graphene oxide (GO) and citric acid (CA) - denoted GO-GQDs and CA-GQDs, respectively. Structural and optical properties of the GQDs were studied using TEM, Raman, and fluorescence and UV-vis spectroscopy. The GQDs were then applied for detection of pyrene in environmental water samples based on a "turn-off-on" mechanism where ferric ions were used for turn-off and pyrene for turn-on of fluorescence emission. The fluorescence intensity of both GQDs was switched on linearly within the 2-10 × 10 mol L range and the limits of detection were found to be 0.325 × 10 mol L and 0.242 × 10 mol L for GO-GQDs and CA-GQDs, respectively. Finally, the potential application of the sensor for environmental water samples was investigated using lake water and satisfactory recoveries (97-107%) were obtained. The promising results from this work demonstrate the feasibility of pursuing cheaper and greener environmental monitoring techniques.
多环芳烃（PAHs）是潜在的有害污染物，主要由于不完全燃烧而从一系列来源排放到环境中。这些化合物的潜在毒性和致癌作用促使人们开发快速且经济高效的检测方法。这项工作报道了石墨烯量子点（GQDs）的合成及其作为检测水中PAHs的快速荧光传感器的应用。GQDs由两种原料制备，氧化石墨烯（GO）和柠檬酸（CA），分别表示为GO-GQDs和CA-GQDs。使用透射电子显微镜（TEM）、拉曼光谱、荧光光谱和紫外可见光谱研究了GQDs的结构和光学性质。然后基于“关-开”机制将GQDs应用于环境水样中芘的检测，其中铁离子用于关闭荧光发射，芘用于开启荧光发射。两种GQDs的荧光强度在2 - 10×10 mol/L范围内呈线性开启，GO-GQDs和CA-GQDs的检测限分别为0.325×10 mol/L和0.242×10 mol/L。最后，使用湖水研究了该传感器在环境水样中的潜在应用，并获得了令人满意的回收率（97 - 107%）。这项工作取得的有前景的结果证明了追求更廉价和更环保的环境监测技术的可行性。
