Enhanced Detection and Absorption of Fe3+ Ions Using Robust Fluorescent Hydrogels Incorporating Carbon Dots and Amphiphilic Polyurethane

Nanocomposites incorporating carbon dots (CDs) and polymers have gained significant attention for various applications, including heavy metal ion detection. This study presents a novel composite that integrates CDs with amphiphilic polyurethane (PU) for enhanced fluorescence detection and absorption of Fe³⁺ ions in wastewater. The resulting nanocomposites exhibit superior mechanical stability, high sensitivity, and selectivity for Fe³⁺, with a remarkable 10 3 -fold enhancement in the limit of detection (LOD) for Fe³⁺ (from 0.38   µM to 0.98   nM) compared to CDs in solution. This enhancement is attributed to the interaction between the functional groups on the CDs and the polyethylene glycol segments of the PU matrix, leading to a red shift in fluorescence emission and improved stability. Additionally, the composite hydrogels show a 4.2-fold increase in Fe³⁺ absorption capacity compared to pure PU, due to the formation of stable complexes between the CDs and Fe³⁺ ions. Mechanistic insights into the absorption process are discussed using various modeling approaches. This hybrid fluorescent hydrogel platform presents a portable, cost-effective solution for Fe³⁺ detection and absorption in wastewater, with potential applications in bio-imaging, light-emitting diodes, and anti-counterfeiting.