A fluorescent GelMA hydrogel with covalently anchored nitrogen-doped carbon dots for efficient adsorption and sensitive detection of Cu(II)

Efficient removal and rapid in situ monitoring of Cu(II) in wastewater are of great importance for aquatic environmental remediation, yet conventional adsorbents generally fail to simultaneously achieve high adsorption capacity and quantitative detection. In this study, a N-doped carbon dot composite hydrogel strategy integrating adsorption and fluorescence sensing was proposed. A three-dimensional hydrogel network rich in N/O-containing functional groups was constructed using gelatin methacryloyl (GelMA), acrylic acid (AAc), acrylamide (AAm), and nitrogen-doped carbon dots (NCDs) were further introduced to fabricate the bifunctional fluorescent composite hydrogel NCDs-GA 1 A 2 gel. This structure not only provided abundant coordination and electrostatic adsorption sites for Cu(II), but also endowed the material with optical responsiveness for fluorescence detection. Batch adsorption experiments showed that the Cu(II) adsorption process followed the pseudo-second-order kinetic model and the Langmuir isotherm model, indicating monolayer chemisorption, with a maximum theoretical adsorption capacity of 203.1 mg·g −1 . After ten adsorption-desorption cycles, the hydrogel retained 86.7% of its initial adsorption capacity, demonstrating favorable regeneration stability. Meanwhile, NCDs-GA 1 A 2 gel could serve as a fluorescent probe for Cu(II), showing a good linear fluorescence response to Cu(II) concentration and a low detection limit of 0.65 μM. Coexisting ion interference experiments further confirmed its excellent selectivity and anti-interference capability. This work provides a facile strategy for developing multifunctional biomass-derived fluorescent hydrogel adsorbents and demonstrates promising application potential for Cu(II) removal and in situ detection in wastewater