Carbon dot-functionalized macroporous adsorption resin for bifunctional ultra-sensitive detection and fast removal of iron(III) ions.

Heavy metal pollution has spread around the world with the development of industry, posing a major threat to human health. It is urgent to design and fabricate bifunctional materials for detection and adsorption of heavy metal ions. Herein, poly(glycidyl methacrylate-<i>co</i>-ethylene glycol dimethacrylate) microspheres, a kind of common macroporous adsorption resin (MAR), were employed as the matrix, and carbon dots (CDs) with excellent optical properties were grafted onto the surface of MAR by surface-initiated atom transfer radical polymerization (SI-ATRP) and photo-initiated "thiol-yne" click chemistry. The synthesized MAR@poly(PA)@CD could produce fluorescence quenching with Fe³⁺. A simple fluorescence spectrometric method for detection of Fe³⁺ was established. The fluorescence intensity of MAR@poly(PA)@CD decreased linearly with the concentration of Fe³⁺ in the range of 0-70 nmol L^-1, with a limit of detection (LOD) of 6.6 nmol L^-1, which had the potential for trace detection. In addition, after SI-ATRP modification, many adsorption sites were generated on the surface of MAR, and the adsorption capacity for Fe³⁺ was 23.8 mg g^-1. Isothermal and kinetic adsorption experiments were more consistent with the Langmuir model (<i>r</i> = 0.9992) and pseudo-second-order model (<i>r</i> = 0.9902), indicating that the adsorption was monolayer adsorption and chemical adsorption, respectively. MAR@poly(PA)@CD with dual functions of detecting and adsorbing Fe³⁺ was successfully prepared, showing great application prospects in the environmental field.