A systematic study of the oxyanions carbonate, phosphate, arsenate, chromate and sulfate has been undertaken in order to determine mechanisms of adsorption and relative binding energies. A challenge for the computational methodology is to predict enthalpies of adsorption that reproduce observed values. We can constrain surface complexes formed by comparing observed and calculated vibrational spectra; however, the possibility of multiple species forming complicates the issue. We are working to accurately calculate the difference in energy between dissolved oxyanions and those adsorbed onto ferrihydrite. This problem is complicated by the disordered and defect nature of ferrihydrite which makes it difficult to model with great certainty. Work on a better understood surface – rutile (110) – has begun to minimize the complexity caused by the surface of interest so the modeling efforts can focus on the computational approach as a source of error in the adsorption energy calculations.<br/>

Calorimetry, spectroscopy and density functional theory: Oxyanions and ferrihydrite

255th National Meeting (2018)

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