Date of Completion

Spring 5-1-2015

Thesis Advisor(s)

Chad Johnston

Honors Major

Environmental Engineering




In soils, the spread of toxic organic anions through groundwater can be partially mitigated by the formation of inner- and outer-sphere complexes with aluminum (hydr)oxides. In current practice, a constant soil-water partition coefficient is used to describe the relative quantity of sorbed compound to that in solution. However this method is empirical and site-specific. In order to establish a thermodynamically relevant sorption model, sorption reactions between many mineral phases and organic compounds must be characterized. While there exists a wealth of research quantifying the sorption potential of ferric oxide mineral phases, there remains a gap in knowledge of these parameters for aluminum oxides. In this study, the energy of outer-sphere complexation reactions will be calculated based on electrostatic and van der Waals interactions between gibbsite (Al(OH)$_3$) and the benzoate compounds using LAMMPS molecular dynamics software. To achieve this objective, adsorption energies have been calculated for benzoate ions with the follwing para-substituted functional groups: nitro-, chloro-, methoxy-, methyl-, and amine-. This research is an advancement of an ongoing effort to develop a thermodynamically relevant adsorption model.

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Engineering Commons