Chitosan/carbon dots-loaded nanocellulose/layered double hydroxides composite hydrogel for effective detection and removal of iodide ion

To remove iodine, a novel chitosan/carbon dots-loaded nanocellulose/layered double hydroxide composite hydrogel (CCNL) was successfully synthesized to enable the simultaneous detection and removal of the iodide ion (I−). Adsorption experiments revealed that the CCNL exhibited an impressive maximum adsorption capacity of 231.9 mg/g at 25 °C. The adsorption isotherms closely conformed to the Langmuir model, and the adsorption kinetics followed the pseudo-second-order model. The CCNL demonstrated outstanding reusability, maintaining over 89.7 % of its initial adsorption capacity after six cycles. Furthermore, it exhibited remarkable temporal stability, preserving over 91.0 % of its initial adsorption capacity after storage for 15 weeks. In addition, the CCNL exhibited remarkable selectivity and sensitivity in detecting I−, with a low limit of detection (0.09 μg/L) within the linear ranges of 5–150 mg/L and 0.2–1.0 μg/L. Fluorescence quenching was attributed to a dynamic process. Importantly, cost analysis revealed that the cost of the removal of I− per gram using the CCNL was only CNY 0.16 (USD 0.02). This was significantly lower than the cost of removal using activated carbon, which was CNY 3.87 (USD 0.53). This study provides a foundation for the development and production of a long-term, stable, reusable, cost-effective, and multifunctional adsorbent for managing iodide pollution.