TY - JOUR ID - 10.1016/j.jes.2019.11.011 TI - Water chemistry influences on long-term dissolution kinetics of CdSe/ZnS quantum dots AU - Pooya Paydary AU - Philip Larese-Casanova VL - 32 IS - 4 PB - SP - 216 EP - 233 PY - JF - Journal of Environmental Sciences JA - J. Environ. Sci. UR - http://www.jesc.ac.cn/jesc_en/ch/reader/view_abstract.aspx?file_no=S1001074219333613&flag=1 KW - Quantum dots;CdSe/ZnS;Dissolution kinetics;Shrinking particle model;Size exclusion chromatography;Inductively coupled plasma mass spectrometry AB - Widespread usage of engineered metallic quantum dots (QDs) within consumer products has evoked a need to assess their fate within environmental systems. QDs are mixed-metal nanocrystals that often include Cd2+ which poses a health risk as a nanocrystal or when leached into water. The goal of this work is to study the long-term metal cation leaching behavior and the factors affecting the dissolution processes of mercaptopropionic acid (MPA) capped CdSe/ZnS QDs in aphotic conditions. QD suspensions were prepared in different water conditions, and release of Zn2+ and Cd2+ cations were monitored over time by size exclusion chromatography-inductively coupled plasma-mass spectrometry. In most conditions with dissolved O2 present, the ZnS shell degraded fairly rapidly over ~1 week, while some of the CdSe core remained up to 80 days. Additional MPA, Zn2+, and Cd2+ temporarily delayed dissolution, indicating a moderate role for capping agent detachment and mineral solubility. The presence of H2O2 and the ligand ethylenediaminetetraacetate accelerated dissolution, while NOM had no kinetic effect. No dissolution of CdSe core was observed when O2 was absent or when QDs formed aggregates at higher concentrations with O2 present. The shrinking particle model with product layer diffusion control best describes Zn2+ and Cd2+ dissolution kinetics. The longevity of QDs in their nanocrystal form appears to be partly controlled by environmental conditions, with anoxic, aphotic environments preserving the core mineral phase, and oxidants or complexing ligands promoting shell and core mineral dissolution. ER -