Activated persulfate (PS) is a common method used to generate sulfate radicals (SO4•-), a powerful oxidant capable of degrading a broad array of environmental contaminants. The reaction of SO4•- with non-target species (i.e., scavenging), contributes significantly to treatment inefficiency. Radical scavenging in this manner has been quantified for non-target chemical species in the aqueous phase but has never been quantified for solid phase media. Kinetic analysis and laboratory methods were developed to quantify the SO4•- scavenging rate constant (k≡S) for alumina, a naturally occurring mineral in soil and aquifer materials. SO4•- were generated in UV- and thermally-activated persulfate (UV-APS, T-APS) batch systems, and the loss of rhodamine B (RhB) served as an indicator of SO4•- activity. k≡S for alumina was 2.42×104 m-2 s-1 and 2.03×104 m-2 s-1 for UV-APS and T-APS oxidative treatment systems, respectively. At [alumina] >5 g L-1, the reaction of SO4•- with solid phase media increased over the aqueous phase reactions with RhB and aqueous scavengers. SO4•- scavenging by solid surfaces was orders of magnitude greater than reaction with the target compound and scavengers in the aqueous phase, underscoring the significant role of solid surfaces in scavenging SO4•-. This dataset is associated with the following publication: Rusevova Crincoli, K., C. Green, and S.G. Huling. Sulfate Radical Scavenging by Mineral Surfaces in Persulfate-Driven Oxidation Systems: Reaction Rate Constants and Implications. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 54(3): 1955-1962, (2020).

The attached extensive computational chemistry dataset involves detailed electronic structure (density functional theory - DFT) and kinetic calculation (master equation formalism) outputs for the reactions of isoprene and first generation oxidants with the hydroxyl radical. There are a total of 9 tabs in the Excel spreadsheet. The first two tabs provide the potential energy surfaces (PESs) of the isoprene+OH and isopOOH+OH (1st generation oxidant) reactions. The PESs are zero-point energy corrected and obtained at the M062x/maug-cc-pVTZ level of DFT. The third tab provides the reaction barriers for first and second generation 1,5-hydrogen atom shifts for two different isoprene peroxy radical isomers with several different DFT methods. The fourth and fifth tabs provide microcanonical rate constants for the reactions of isoprene and isopOOH with OH respectively. The remaining tabs give the rate constants for the 1,5-H shifts for four different isoprene peroxy radicals. The rate constants are computed using the M062x density functional and an average of 4 different DFT methods given in tab 3 for comparison. The average values are reported as the final rate constants determined by computational methods. This dataset is associated with the following publication: Piletic, I., R. Howell, L. Bartolotti, T. Kleindienst, S. Kaushik, and E. Edney. Multigenerational Theoretical Study of Isoprene Peroxy Radical 1–5-Hydrogen Shift Reactions that Regenerate HOx Radicals and Produce Highly Oxidized Molecules. JOURNAL OF PHYSICAL CHEMISTRY A. American Chemical Society, Washington, DC, USA, 123(4): 906-919, (2019).

Laboratory data supporting "Quantitative constraints on autoxidation and dimer formation from direct probing of monoterpene-derived peroxy radical chemistry" by Zhao, Thornton, and Pye. Abstract: Organic peroxy radicals (RO2) are key intermediates in the atmospheric degradation of organic matter and fuel combustion, but to date, few direct studies of specific RO2 in complex reaction systems exist, leading to large gaps in our understanding of their fate. We show, using direct, speciated measurements of a suite of RO2 and gas-phase dimers from O3-initiated oxidation of α-pinene that ~150 gaseous dimers (C16-20H24-34O4-13) are primarily formed through RO2 cross-reactions, with a typical rate constant of 0.75-2×10-12 cm3 molecule-1 s-1 and a lower-limit dimer formation branching ratio of 4%. These findings imply a gaseous dimer yield that varies strongly with nitric oxide (NO) concentrations, of at least 0.2-2.5% by mole (0.5-6.6% by mass) for conditions typical of forested regions with low to moderate anthropogenic influence (i.e., ≤ 50 ppt NO). Given their very low volatility, the gaseous C16-20 dimers provide a potentially important organic medium for initial particle formation, and alone can explain 5-60% of α-pinene secondary organic aerosol mass yields measured at atmospherically relevant particle mass loadings. The responses of RO2, dimers, and highly-oxygenated multifunctional compounds (HOM) to reacted α-pinene concentration and NO imply that an average ~20% of primary α-pinene RO2 from OH reaction and 10% from ozonolysis autoxidize at 3-10 s-1 and ≥ 1 s-1, respectively, confirming both oxidation pathways produce HOM efficiently, even at higher NO concentrations typical of urban areas. Thus, gas-phase dimer formation and RO2 autoxdiation are ubiquitous sources of low-volatility organic compounds capable of contributing significantly to atmospheric new particle formation and growth. This dataset is associated with the following publication: Zhao, Y., J. Thornton, and H. Pye. Quantitative constraints on autoxidation and dimer formation from direct probing of monoterpene-derived peroxy radical chemistry. PNAS (PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES). National Academy of Sciences, WASHINGTON, DC, USA, 115(48): 12142-12147, (2018).

Recently, we identified seven novel hydroxy-carboxylic acids resulting from gas-phase reactions of isoprene in the presence of nitrogen oxides (NOx), ozone (O3), and/or hydroxyl radicals (OH). In the present study, we provide evidence that hydroxy-carboxylic acids, namely methyltartaric acids (MTA) are: (1) reliable isoprene tracers, (2) likely produced via rapid peroxy radical hydrogen atom(H) shift reactions (autoxidation mechanism) and analogous alkoxy radical H shifts in low and high NOx environments respectively and (3) representative of aged ambient aerosol in the low NOx regime. Firstly, MTA are reliable tracers of isoprene aerosol because they have been identified in numerous chamber experiments involving isoprene conducted under a wide range of conditions and are absent in the oxidation of mono- and sesquiterpenes. They are also present in numerous samples of ambient aerosol collected during the past 20 years at several locations in the U.S. and Europe. Furthermore, MTA concentrations measured during a year-long field study in Research Triangle Park (RTP), NC in 2003 show a seasonal trend consistent with isoprene emissions and photochemical activity. Secondly, an analysis of chemical ionization mass spectrometer (CIMS) data of several chamber experiments in low and high NOx environments show that highly oxidized molecules (HOMs) derived from isoprene that lead to MTAs may be produced rapidly and considered as early generation isoprene oxidation products in the gas phase. Density functional theory calculations show that rapid intramolecular H shifts involving peroxy and alkoxy radicals possess low barriers for methyl-hydroxy-butenals (MHBs) that may represent precursors for MTA. From these results, a viable rapid H shift mechanism is proposed to occur that produces isoprene derived HOMs like MTA. Finally, an analysis of the mechanism shows that autoxidation-like pathways in low and high NOx may produce HOMs in a few OH oxidation steps like commonly detected methyl tetrol (MT) isoprene tracers. The ratio of MTA/MT in isoprene aerosol is also shown to be significantly greater in field versus chamber samples indicating the importance of such pathways in the atmosphere even for smaller hydrocarbons like isoprene. This dataset is associated with the following publication: Jaoui, M., I. Piletic, R. Szmigielski, K.J. Rudzinski, M. Lewandowski, T. Riedel, and T. Kleindienst. Rapid production of highly oxidized molecules in isoprene aerosol via peroxy and alkoxy radical isomerization pathways in low and high NOx environments: Combined laboratory, computational and field studies. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, NETHERLANDS, 775: 145592, (2021).

H2O2_COD_EPA: Measurements of hydrogen peroxide and COD concentrations for water samples from the MEC reactors. MEC_acclimation: raw data for current and voltage of the anode in the MEC reactor. This dataset is associated with the following publication: Sim, J., J. An, E. Elbeshbishy, R. Hodon, and H. Lee. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells. Bioresource Technology. Elsevier Online, New York, NY, USA, 195: 31-36, (2015).

H2O2_COD_EPA: Measurements of hydrogen peroxide and COD concentrations for water samples from the MEC reactors. MEC_acclimation: raw data for current and voltage of the anode in the MEC reactor. This dataset is associated with the following publication: Sim, J., J. An, E. Elbeshbishy, R. Hodon, and H. Lee. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells. Bioresource Technology. Elsevier Online, New York, NY, USA, 195: 31-36, (2015).

Direct oxidative esterification of alcohol via photocatalytic C–H activation has been developed using VO@g-C3N4 catalyst; an expeditious esterification of alcohols occurs under neutral conditions using visible light as the source of energy. This dataset is associated with the following publication: Varma , R., S. Verma, R.B.N. Baig, C. Han, and M. Nadagouda. Oxidative esterification via photocatalytic C-H activation. GREEN CHEMISTRY. Royal Society of Chemistry, Cambridge, UK, 18: 251-254, (2015).

Direct oxidative esterification of alcohol via photocatalytic C–H activation has been developed using VO@g-C3N4 catalyst; an expeditious esterification of alcohols occurs under neutral conditions using visible light as the source of energy. This dataset is associated with the following publication: Varma , R., S. Verma, R.B.N. Baig, C. Han, and M. Nadagouda. Oxidative esterification via photocatalytic C-H activation. GREEN CHEMISTRY. Royal Society of Chemistry, Cambridge, UK, 18: 251-254, (2015).

The TROPESS CrIS-SNPP L2 Peroxyacetyl Nitrate for Reanalysis Stream, Summary Product contains the vertical distribution of the retrieved atmospheric state of peroxyacetyl nitrate (PAN), and formal uncertainties measured by the CrIS instruments on the Suomi-NPP satellite. The reanalysis stream summary product is global for the time period from 2015-12-01 to 2023-05-18. The NASA TRopospheric Ozone and Precursors from Earth System Sounding (TROPESS) project, uses an optimal estimation algorithm, known as the MUlti-SpEctra, MUlti-SpEcies, Multi-SEnsors (MUSES).The data files are written in the netCDF version 4 file format, and each file contains one day of data. The data have a spatial resolution of 14 km (CrIS nadir FOV), and are reported at 16 vertical levels from the surface to 0.1 hPa. The principal investigator for the TROPESS project is Kevin W. Bowman.