Rates of Dissolution of Quantum Dots Influenced by Organic Ligands

Presenter: Annie Ikemoto

Research Category: Engineering and Technology

Quantum dots (QDs) are mixed-mineral nanocrystals (approximately 2-10 nm) that are a common component in many consumer products because of their desirable physical and chemical properties. Some examples include display screens, optical devices, and other electrical products. However, QDs can find their way into the environment through product disposals in landfills or manufacturing waste streams. The problem that needs to be considered, and what this project aims to help answer, is how QDs behave over time in the environment. Recent findings have shown that QDs may dissolve when exposed to water, and studies have shown that QDs can induce toxic effects to aquatic organisms. However, there is still limited data about the overall environmental and health impacts of QDs.

To determine the stability and longevity of QDs in the environment, the conditions in landfill leachate (water drained after contact with solid waste that could contain QDs) were mimicked. This was done by creating different types of organic ligand solutions at one pH and exposing these solutions to QDs (CdSe/ZnS). Multiple samples of the ligand/QD solution were tested over time using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to measure the level of QDs in the solution. The rate of dissolution of the QDs overtime was calculated from the measured samples. The data presented will show what properties of organic ligands determines the rate of dissolution of QDs (for example, the equilibrium constant, number of attachments, or size of the ligand).