A green approach for synthesis of highly fluorescent carbon dots from waste engine oil: A strategy for waste to value added products

In this present work, waste engine oil was explored as a precursor for the synthesis of carbon dots (CDs) by hydrothermal route for the first time. The obtained CDs showed excellent water solubility, photostability, bright blue emission under UV light (wavelength 365 nm), pH stability, high quantum yield, and greater biocompatibility. It was thoroughly studied by vital characterization techniques such as HR-TEM, UV–Visible spectroscopy, FTIR, SEM, PSA, Fluorescence spectroscopy with lifetime analysis. The fluorescence of synthesized CDs was quenched by the addition of Fe3+ as it showed excellent selectivity and sensitivity towards Fe3+. The sensing probe showed a good linear response (R2 = 0.9986) with a limit of detection 0.055 μM in the linear range of 0.6–3.3 μM. Due to excellent fluorescence properties of CDs, it have been applied as fluorescent ink for information storage. In addition, CDs coated polymer matrix was made and used for bead-based detection of Fe3+. Finally, the presented system could be considered as an efficient probe for Fe3+ detection and paved a way for efficient utilization of waste into value-added products.