Graphene Quantum Dots with Amine‐Modification: A Smart Fluorescent Probe for Effective Detection of Heavy Metal Ions in Wastewater

In this work, we have developed an optical fluorometric sensor for detection of lead (II) ion (Pb 2+ ) and copper (II) ion (Cu 2+ ) in wastewater using fluorescent amine‐modified graphene quantum dots (a‐GQDs). A simple preparation process, i.e., hydrothermal method is used for the preparation of a‐GQDs. The prepared a‐GQDs emits green luminescence and have an average particle size around 1.26 ± 0.16 nm with uniform distribution. The a‐GQDs utilized for detection of various biologically essential metal ions like Pb 2+ and Cu 2+ ions in aqueous solution using fluorescence‐based spectroscopic technique. Here, UV–visible absorption spectra of a‐GQDs with and without Pb 2+ and Cu 2+ ions, shows no variation in the absorbance of a‐GQDs. Further, lifetime analysis of a‐GQDs shows that lifetime of a‐GQDs changed from 2.02 ns to 1.37 ns in presence of Pb 2+ and 2.02 ns to 1.62 ns in presence of Cu 2+ ions, confirms the dynamic quenching mechanism. The a‐GQDs have detected Pb 2+ and Cu 2+ ions in the linearity range of 2–200 µM and 2–300 µM with limit of detection (LOD) of 1.60 µM and 1.66 µM, respectively. Therefore, this work demonstrates the sustainability of a‐GQDs as a favorable fluorescence (FL) probe that may be used to detect heavy metal ions in wastewater and aqueous solution.