Two birds with one stone: An innovative fluorescent cellulose polyacrylamide-hydrogel modified by born/nitrogen-doped carbon dots with sensitive visual sensing and superior extraction capacity toward Ag+

Since the last decade, water pollution by silver ions (Ag+) has been a serious potential threat to environmental protection and an enormous research effort has been put into the detection and removal of environmental Ag+. Here, we report a novel fluorescent cellulose polyacrylamide-hydrogel (FCPH) modified by boron/nitrogen doped carbon dots (BN-CDs) for sensitive visual detection and efficient extraction of Ag+. In addition, the introduction of BN-CDs in the cross-linking process promotes the formation of 3D network structures with more ionic adsorption sites in FCPH. On the one hand, the FCPH exhibits an excellent sensing performance in the range of 0-300 μM with a limit detection of 51 nM. On the other hand, the adsorption experiments confirm that the FCPH exhibits an excellent Ag+ extraction performance of over 251.4 mg‧g-1, and the adsorption results accord well with the pseudo-second-order model and the Langmuir model. Detailed mechanism characterizations reveal that the excellent adsorption capacity of FCPH is caused by the redox reaction and formation of metal complexes between the surface functional groups of BN-CDs and Ag+ in FCPH. Hence, this work fabricates a bifunctional hydrogel and provides a convenient “two birds with one stone” strategy for the visual sensing and extraction of Ag+.