Environmental Hg vapours adsorption and detection by using functionalized gold nanoparticles network

Adsorption and detection of environmental total gaseous mercury (TGM) was studied by using gold nanoparticles (AuNPs) on purpose functionalized with dithiol ligands, i.e. Biphenyl-4,4′-dithiol (BI) or p-Terphenyl-4,4′′-dithiol (TR), suitable for nanoparticles based network formation. AuNPs-BI and AuNPs-TR with size 6-8 nm were deposited onto quartz fibres and used as adsorbent materials for the detection of TGM, both indoor for adsorption studies, at defined concentrations (~4.5 ng m-3 Hg), and outdoor, at the vapour mercury concentration of the environmental countryside (~1.5 ng m-3 Hg). The role of relative humidity (RH) in the absorption process has been observed. A high Hg adsorption capability, also when exposed to sub ppb concentration, has been observed. A cold vapour atomic fluorescence spectroscopy (CVAFS) detector was used to determine gaseous mercury concentrations lower than 2 ng m-3, with a robust and reproducible procedure. Moreover, the use of quartz fibres substrate covered with AuNPs-BI or AuNPs-TR, and used for more than thirty times during the experiments, makes them competitive in the use in large-scale measurement campaigns.