Green synthesis of surface-passivated carbon dots from the prickly pear cactus as a fluorescent probe for the dual detection of arsenic(<scp>iii</scp>) and hypochlorite ions from drinking water

Abstract

Efforts were made to develop a simple new approach for the green synthesis of surface-passivated carbon dots from edible prickly pear cactus fruit as the carbon source by a one-pot hydrothermal route. Glutathione (GSH) was passivated on the surface of the CDs to form a sensor probe, which exhibited excellent optical properties and water solubility. The prepared sensor was successfully characterized by UV-visible spectrophotometry, fluorescence spectrophotometry, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The simple sensing platform developed by the GSH-CDs was highly sensitive and selective with a "turn-off" fluorescence response for the dual detection of As³⁺ and ClO^- ions in drinking water. This sensing system exhibited effective quenching in the presence of As³⁺ and ClO^- ions to display the formation of metal complexes and surface interaction with an oxygen functional group. The oxygen-rich GSH-CDs afforded a better selectivity for As³⁺/ClO^- ions over other competitive ions. The fluorescence quenching measurement quantified the concentration range as 2-12 nM and 10-90 μM with the lower detection limit of 2.3 nM and 0.016 μM for the detection of As³⁺ and ClO^- ions, respectively. Further, we explored the potential applications of this simple, reliable, and cost-effective sensor for the detection of As³⁺/ClO^- ions in environmental samples for practical analysis.