RUI: SusChEM: Mechanisms of Nanoparticle Aggregation and Corresponding Effects on Metal Sorption, Desorption, and Incorporation Processes

Chapman University, Orange CA

Investigators

Abstract

In this project, funded by the Environmental Chemical Sciences Program in the Division of Chemistry at the National Science Foundation, Professor Christopher Kim of Chapman University is performing research that involves detailed characterization of iron oxyhydroxide nanoparticle aggregates. These characterization studies include batch and real-time metal ion adsorption/desorption experiments and synchrotron-based X-ray spectroscopic methods to improve predictive modeling of metal uptake/retention to nanoscale iron oxyhydroxides. Nanoparticles of inorganic mineral phases are widespread in water-based environmental systems. Natural and synthetic nanoparticles are highly effective in remediation strategies for contaminated waters, such as those that result from metal ore mining activities. This research develops models to predict metal fate and transport in natural waterways. These studies maximize metal retention and reduce metal mobility in contaminated systems. Broader impacts of this work include the creation of independent research opportunities for undergraduate, community college, and high school students (targeting females, under-represented minorities, and low-income populations), providing students with experiences using national synchrotron user facilities, and incorporating new findings in nanoparticle research to the undergraduate curricula in environmental and inorganic chemistry. High school chemistry and environmental science teachers are engaged in the research methods and outcomes through on-campus visits and lesson development. The fate and speciation of metal ion species sorbed to aggregated nanoparticles are largely unknown. Metal sorption to nanoaggregates serves as an important means of natural attenuation and provides considerable potential for the effective remediation of metal-contaminated surface aqueous systems. Specifically, with increasing aggregation state, salinity, and time, metal uptake declines due to loss of reactive surface area but metal retention may increase due to trapping of sorbed ions onto/into the more complex confined aggregate structures. This project advances our understanding of the fundamental processes that control the retention and sequestration of metal ions onto nanoscale iron oxyhydroxide particles and their aggregates. The research impacts the emerging field of environmental nanoscience, particularly the role that nanoscale particles play in the remediation of metal-contaminated sites.