CAREER: Developing Quantum Nanogeochemistry for Molecular Studies and Inclusive Education

University Of Iowa, Iowa City IA

Investigators

Abstract

The Environmental Chemical Sciences Program in the Chemistry Division at the National Science Foundation supports the research of Professor Sara E. Mason at the University of Iowa who will direct a project whose ultimate goal is to develop quantum nanogeochemistry as a platform, (1) to provide fundamental understanding of environmental nanoparticle (ENP) structure-reactivity, (2) to merge distinct theories of ENP reactivity, and, (3) to recruit community college (CC) students for training opportunities at the university level. The research strategy is to carry out Density Functional Theory (DFT)-based simulations on two classes of ENPs: Aqueous aluminum hydroxides modeled as Giant Aluminum Polycations (GAPs) and mineral-water interfaces modeled as Periodic Slab Models (PSMs). Reactivity questions that are suited to each model category are identified, and systematic simulation experiments are designed using comparisons to isolate what controls reactivity. The projects are designed to develop atomistic simulations results of both GAPs and PSMs into new conceptual models for ENP reactivity, a goal that will support or dispel existing theories. For this purpose, the distinctions between the models will be exploited, for example, GAPs are ideal models for tracking reactivity with orbital interactions because they are truly nanoparticulate, and fewer electronic states are expected to participate in interfacial bonding. Also, these aluminum hydroxides do not have d electrons, so they have a less complicated electronic structure than similarly structured iron hydroxides. Meanwhile, the PSM geometry is ideal for probing how adsorption-induced long range bond relaxation and relative energetics can be captured in a Bond Valence (BV) framework. Several of the proposed simulations will involve first time calculations, such as the later described DFT + COSMO (conduction-like screening model)+ (delta)H2O (partial explicit hydration) method for simulating the aqueous Al30 (GAP) and deriving surface-specific Hubbard U corrections to accurately model PSMs comprised of strongly correlated mineral oxides. The proposed work will enable improved predictions about the sequestration of aqueous contaminants that could ultimately lead to new water remediation strategies. Each research project will support the training of graduate and undergraduate students, and a major emphasis will be placed on the "Never Too Late to Learn" (NTLL) program and its mission to engage community college students in education and research activities that will extend opportunities to train them as the next generation scientists. Efforts to organize research outcomes into DFT databases that will be reported in the associated Data Management Plan, ensure that the fundamental information obtained from the atomistic simulations will be disseminated to the research community, regardless of any failure to pioneer the proposed conceptual models. The unified research and education plans are suited to principal investigator's strengths, background, and commitment to develop quantum nanogeochemistry as a vital field in environmental chemical science.