Bifunctional Composite Films Embedded with Plastic Waste-Derived Carbon Quantum Dots for Synergistic Uranium Detection and Enrichment

Increasing energy demand and the urgent need to decrease global carbon emissions have shifted the focus to nuclear power generation, with uranium as a prime resource. Additionally, the rising challenge of plastic waste demands its transformation into useful materials. Hence, we have developed a sustainable method of valorizing waste plastic into functional materials for synergistic uranium detection and enrichment. Waste polyethylene (PE) plastic bag-derived carbon quantum dots (PLCDs) with excellent photostability were synthesized, and their composite film (PLCD-COF-CS) was fabricated with chitosan (CS) and urethane-linked covalent organic framework (COF). The nitrogen-rich porous COF was constructed by a sonochemical approach. PLCDs, COF, and PLCD-COF-CS were well-characterized to study their size, morphology, optical properties, microstructure, and porosity. The visual and photoluminescence (PL) studies showed the selective and ultratrace uranium detection ability of PLCDs and PLCD-COF-CS. The LOD values of 10.9 pM and 18.5 pM were observed for PLCD and PLCD-COF-CS, respectively toward uranium detection, which is much lower than U.S. Environmental Protection Agency standards for maximum permissible uranium contamination, set at 60 μM in drinking water. Further, PLCD-COF-CS demonstrated excellent uranium enrichment performance with an elevated capacity of 1271 mg g–1. Through this, we envisage a combinatorial approach to uranium detection and extraction using plastic waste-derived nontoxic and economical materials, which was also validated against seawater samples.