Abstract
In this study, carbon quantum dots (CQDs), which were synthesized from arabica coffee ground-derived activated carbon, have been successfully employed as a fluorescence sensor to detect Fe(3+) ions. CQDs were fabricated using microwave heating for 5-10 min, which emitted vibrant blue light at 455 nm when exposed to excitation at 365 nm. Dynamic light scattering (DLS) analysis revealed that the average size of CQDs was 10.12 nm with a quantum yield of 6.01%. Fluorescence detection was developed for sensing Fe(3+), Pb(2+), and Cr(3+) ions. The addition of the three metal ions resulted in a decrease in the fluorescence (FL) intensity of the CQDs, with the addition of Fe(3+) ions demonstrating a more significant decrease in FL compared to the addition of both Cr(3+) and Pb(2+) ions. The results indicated that the CQDs synthesized from activated carbon of arabica coffee waste performed as a selective fluorescent detector for Fe(3+) ions, with a detection limit of 0.27 μM.