Facile and Green Fabrication of Carrageenan-Silver Nanoparticles for Colorimetric Determination of Cu2+ and S2-

In the present work, silver nanoparticles (AgNPs) were prepared by a simple and green method using carrageenan as reducing and capping agent. The as-synthesized carrageenan-AgNPs was demonstrated as an effective duel colorimetric sensing for selective and sensitive recognition of Cu2+ and S2-, which could be used to detect these ions with naked eyes. In addition, the possible sensing mechanism was that Cu2+ ions caused serious aggregation of carrageenan-AgNPs, which led to the color change of carrageenan-AgNPs. AgNPs were etched by S2- forming Ag2S, which played an important role in the determination of S2- ions. Furthermore, it has been successfully applied to the determination of Cu2+ and S2- in tap water and lake water, showing its great potential for the analysis of environmental water samples.