Converting Plastic Waste into Functional Carbon Nanodots for the Selective Detection of Iron and Mercury Ions

Converting plastic waste into valuable materials is crucial for reducing environmental pollution, conserving resources, and promoting sustainability by transforming waste into useful products that contribute to a circular economy. This study introduces a novel method for transforming harmful polyethylene terephthalate (PET) plastic waste into useful fluorescent carbon nanodots (PPET-CDs), addressing environmental waste management challenges and the demand for advanced nanomaterials. The PPET-CDs emit bright blue emission at 400 nm with excitation at 350 nm. PPET-CDs were characterized using common microscopic and spectroscopic methods. The sizes of the PPET-CDs were around 25 nm and had spherical shapes. Unlike conventional approaches, this method yields carbon nanodots with precise blue emission properties and achieves selective, highly sensitive detection of Fe²⁺ and Hg²⁺ ions, presenting an innovative application for heavy metal sensing. With excellent linearity between 5 and 50 µg/mL and coefficient of determination (R² ≥ 0.987) for Fe³⁺ ions and (R² ≥ 0.988) for Hg²⁺ ions. The proposed sensors allow 2.14 and 2.92 µM as LOD for Fe³⁺ and Hg²⁺, respectively, with relative standard deviations for both below 2%. These novel PPET-CDs show superior performance in sensor technology, paving the way for sustainable, high-value applications of plastic waste.