abstract
Motivated by the importance of Hg2+ detection in water due to its harmful effect on the environment and human health, we investigated a recently developed nanocomposite based on carbon dots (CDs) and LAPONITE as an optical chemical sensor using photoluminescence emission. While several studies have reported the Hg2+ detection using CDs' photoluminescence emission, there is a lack of in-depth investigation into the quenching mechanisms involved in turn-off sensors. In this study, we propose a Stern-Volmer analysis at three different temperatures (288, 298, and 303 K). The results indicated selectivity for Hg2+ over that of the other evaluated metal. The optimum detection range for Hg2+ was found to be 1-40 mu M, with limits of detection and quantification of 2.5 and 8.3 mu M, respectively. Using the Stern-Volmer models, we found that static quenching dominates over collisional quenching, possibly due to the complexation between nanocomposite's carboxylate groups and Hg2+. Additionally, the modified Stern-Volmer model, which accounts for the fractional accessibility of the fluorophores by the quenchers, suggests that some parts of the sensor are inaccessible to the quencher.
keywords
HEAVY-METALS; QUANTUM DOTS; WATER; FLUORESCENCE; NANOPARTICLES; LUMINESCENCE; CHEMOSENSOR; MERCURY(II); EMISSION; NITROGEN
subject category
Chemistry
authors
Onishi, BSD; Neto, ANC; Ribeiro, SJL
our authors
Albano Neto Carneiro Neto
Junior ResearcherProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
We would like to thank Brazilian funding agencies, FAPESP, CNPq (grant 383903/2024-6), CAPES, SISFOTON-MCTI (440217/2021-0), the National Institute of Photonics (INFO) and the National Institute of NanoMaterials for Life (NanoVida). This work was developed within the scope of the projects CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020, and LA/P/0006/2020, the LogicALL (PTDC/CTMCTM/0340/2021) financed by national funds through the FCT/MCTES (PIDDAC).