Sulfate radicals are strong short-lived oxidants that can be generated when persulfate reacts with transition metal oxides during in situ chemical oxidation of contaminated groundwater. These specific chemical reactions involve a series of complex steps and play a vital role in the operation of remediation systems. In order to control sulfate production and, hence, improve the overall efficiency of these processes, we require a detailed theoretical understanding of reaction mechanisms at the quantum molecular level. To this end, we have used both density functional theory (DFT) calculations and high-level wavefunction-based calculations at the coupled-cluster singles and doubles with perturbative triples (CCSD(T)) level of theory to elucidate the activation energies and, hence, their reaction rates of sulfate radical generation. Most importantly, we highlight some of the limitations and deficiencies of other computational methods, and we recommend the use of high-level quantum calculations to spot-check environmental chemistry reactions that may lie outside the training set of the DFT methods, particularly for water oxidation reactions that involve sulfate and other inorganic species.

Sulfate radical oxidation of aromatic contaminants: A detailed assessment of density functional theory and high-level quantum chemical methods

254th National Meeting (2017)

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