Green synthesis of fluorescent carbon dots embedded in silanized cellulose nanofibers: A ensitive and ustainable platform for uranium detection and remediation

The rise of uranium ions in groundwater in Northern India has raised serious health concerns, including increased cancer cases. This study introduces a novel solution using a hydrothermal method to synthesize highly fluorescent and stable carbon dots (CDs) from Kalanchoe pinnata. These CDs were embedded in silanized cellulose nanofibers (SCNFs) to create an eco-friendly dual-functional adsorbent and fluorescent probe (SCNFs@CDs) for the remediation of UO₂²⁺ ions. Characterization confirmed the successful integration of CDs, preserving the nanofibrous structure necessary for stability and recovery. SCNFs@CDs demonstrated a strong affinity for UO₂²⁺ ions, even amid competing ions, evidenced by a linear decline in the fluorescence intensity at 360 nm when increasing the concentration, achieving a low limit of detection of 1.64 nM. Adsorption investigation demonstrated pseudo-second order with a maximal adsorption capacity of 196.07 mg g⁻¹, signifying chemisorption. Remarkably, SCNFs@CDs maintained 87 % adsorption efficiency after five cycles of use. Our findings underscore the potential of SCNFs@CDs as an effective, and sustainable solution which can be used both for UO₂²⁺ ions sensing and adsorption from aqueous media, contributing to eco-friendly water purification technologies.