Détermination du destin des nanoparticules d'argent dans les eaux usées et dans les biosolides en utilisant la microscopie en champ sombre et analyse hyperspectrale
Nanomaterials are a class of emerging and increasingly produced contaminants that are present in increasing concentrations. In complex environmental media, their detection is often complicated by interferences from environmental matrices. The objective of this work was to follow the fate of silver nanoparticles in the wastewaters using enhanced darkfield microscopy (EDM) coupled with hyperspectral imaging (HIS). When coupled with a pixel by pixel analysis, EDM can be used to screen for the presence of nanoparticles, and to locate, identify, and follow their fate in situ. Transformation kinetics of several different silver nanoparticles (40, 80 and 100 nm) with different coatings (citrate and polyvinylpyrrolidone) were analysed in complex media (wastewater, biosolids). Results demonstrated that when spiked into complex systems containing natural organic matter, certain nanoparticles were rapidly transformed (over a period of 2 hours), as shown by a shift in the wavelength attributed to their plasmonic resonance (450 to 570 nm) leading to a decrease in signal intensity of 95%. Based upon complementary results obtained by dynamic light scattering (DLS) and single particle inductively coupled plasma-mass spectrometry (SP-ICP-MS), it was possible to attribute the changes not to particle aggregation or dissolution as much as a change in the nature of the particles due to the adsorption of organic matter on their surface. This memoir will show that the properties of the nanoparticles in complex systems are very different from those in simple systems.
Silver nanoparticles Environment Hyperspectral imaging Darkfield microscopy Single particle inductively coupled plasma-mass spectrometry