Abstract:
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, i.e. 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 6 mol L 1 range and the limits of detection were found to be 0.325
10 6 mol L 1 and 0.242 10 6 mol L 1 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.
