title: Sulfate radical oxidation of aromatic contaminants: a detailed assessment of density functional theory and high-level quantum chemical methods.
abstract: Advanced oxidation processes that utilize highly oxidative radicals are widely used in water reuse treatment. In recent years, the application of sulfate radical (SO4˙-) as a promising oxidant for water treatment has gained increasing attention. To understand the efficiency of SO4˙-in the degradation of organic contaminants in wastewater effluent, it is important to be able to predict the reaction kinetics of various SO4˙--driven oxidation reactions. In this study, we utilize density functional theory (DFT) and high-level wavefunction-based methods (including computationally-intensive coupled cluster methods), to explore the activation energies of SO4˙--driven oxidation reactions on a series of benzene-derived contaminants. These high-level calculations encompass a wide set of reactions including 110 forward/reverse reactions and 5 different computational methods in total. Based on the high-level coupled-cluster quantum calculations, we find that the popular M06-2X DFT functional is significantly more accurate for OH-additions than for SO4˙-reactions. 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 M06-2X functional, particularly for water oxidation reactions that involve SO4˙-and other inorganic species.
authors.affiliation: Department of Chemical & Environmental Engineering, University of California-Riverside, Riverside, California, USA. haizhou@engr.ucr.edu.
authors.forename: Sangavi
authors.initials: S
authors.lastname: Pari
authors.affiliation: Department of Chemical & Environmental Engineering, University of California-Riverside, Riverside, California, USA. haizhou@engr.ucr.edu.
authors.forename: Inger A
authors.initials: IA
authors.lastname: Wang
authors.affiliation: Department of Chemical & Environmental Engineering, University of California-Riverside, Riverside, California, USA. haizhou@engr.ucr.edu.
authors.forename: Haizhou
authors.identifier: http://orcid.org/0000-0003-4194-2566
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Chemical & Environmental Engineering, University of California-Riverside, Riverside, California, USA. haizhou@engr.ucr.edu and Materials Science & Engineering Program, University of California-Riverside, Riverside, California, USA. bryan.wong@ucr.edu.
authors.forename: Bryan M
authors.identifier: http://orcid.org/0000-0002-3477-8043
authors.initials: BM
authors.lastname: Wong
mesh_terms: D007700:Kinetics; D008956:Models, Chemical; D010084:Oxidation-Reduction; D013431:Sulfates / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D013431:Sulfates; D062065:Wastewater; D014874:Water Pollutants, Chemical; C069025:sulfate radical