CAREER: Impacts of Incorporated Metals on Dissolution Rates of Minerals

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Certain toxic and radioactive metals, such as lead and radioactive strontium, can cause environmental and health concerns when they are dissolved in surface waters or groundwater. One way to remove or prevent them from entering the environment is to incorporate them into solid minerals, where they can be immobilized for long term storage. However, incorporated metals can directly affect the rate at which these minerals dissolve and thus release contaminants back into the environment. It is not well known which metals are most likely to increase or decrease the rate at which these minerals dissolve, but that information would be helpful for designing more effective remediation strategies. The proposed project will determine how incorporated metals affect mineral dissolution rates and develop a model to better predict the stability and lifetime of minerals precipitated during environmental remediation. The project will also support, train, and promote the retention of a diverse group of undergraduate students through development of a collaborative research experience and inter-college seminar series with students at Queens College and two local community colleges. The research goal of this project is to determine the molecular scale mechanisms that drive differences in dissolution of minerals with incorporated metals as compared to their pure end-member phases. While the thermodynamic solubility of mineral phases can be used to determine the likelihood of dissolution, the rate of dissolution can be equally important, since solubility does not always correlate with reaction rates. Dissolution rates can be predicted using kinetic models, but these are typically parameterized for pure mineral phases rather than for minerals with incorporated metals. In this research plan, overall dissolution rates of minerals with incorporated metals will be measured using batch reactors while surface specific dissolution rates and molecular-scale mechanisms will be measured using atomic force microscopy. These measurements will then be used to parameterize a process-based dissolution model that accounts for molecular-scale attachment and detachment reactions at specific sites on mineral surfaces. The project's educational goals are to introduce non-traditional and diverse transfer students as well as native undergraduate students to collaborative research experiences, and to train future mineral surface geochemists. All students will participate in a summer research experience, attend an inter-college seminar series, and present their findings at an undergraduate research symposium.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.