Monitoring and removal of trace heavy metal ions via fluorescence resonance energy transfer mechanism: In case of silver ions

Abstract The heavy metal ions pollution has attracted tremendous attention owing to their cumulative effect in organs. In this work, ZnS coated upconversion nanoparticles (denoted as UCNPs@ZnS) has been fabricated and firstly used as dual-functional fluorescence probe for simultaneously removal of heavy metals such as Ag+, Cu2+ or Hg2+ and detection of these ions residual in aqueous solution.. The upconversion fluorescence intensity of the UCNPs@ZnS suspension solution was quenched gradually with the addition of the Ag+, Cu2+ or Hg2+ aqueous solution, which is attributed to the formation of highly insoluble metal sulfides with narrower band-gap with enhanced fluorescence resonance energy transfer (FRET) efficiency. 3.98 µmol Ag+ can be removed completely in presence of 1 mg UCNPs@ZnS core-shell nanoparticles. In addition, removal amount of Ag+ is proportional to the changes of the upconversion fluorescence intensity of the UCNPs@ZnS core-shell nanoparticles suspension solution. Therefore, this work could be extended to monitor and remove these heavy metal ions whose sulfides are less soluble than ZnS.