Data for: Rates and Products of Oxidation of Ferrous Iron in Trioctahedral Smectites

Description

Data package for manuscript "Rates and Products of Oxidation of Ferrous Iron in Trioctahedral Smectites", by Robert J. Kupper, Nanqing Zhou, Clara S. Chan, Aaron Thompson, Jeffrey G. Catalano. The manuscript will be submitted to Geochimica et Cosmochimica Acta. This dataset contains sample characterization and oxidation kinetics results for two synthetic, Fe(II)-bearing trioctahedral smectites. Both clay minerals were suspended in media solution and then exposed to a series of oxidants: dissolved oxygen equilibrated with 21% O2, dissolved oxygen equilibrated with 2% O2, 5 mmol/L nitrite, or an excess of hydrogen peroxide. The post-reaction solids were characterized by powder X-ray diffraction and Mossbauer spectroscopy. The file "Kupper2022_XRD_data.csv" contains powder X-ray diffraction patterns of moderate-iron trioctahedral smectite [Ca0.17(FeII1.59Mg0.78FeIII0.12Al0.33)(Si3.58Al0.42)O10(OH)2] and high-iron trioctahedral smectite [Ca0.20(FeII2.16Mg0.26FeIII0.19Al0.24)(Si3.48Al0.52)O10(OH)2]. "Unaltered" indicates the initial, synthesized clays. The other labels indicate samples reacted with the specified oxidant: 21% O2, 2% O2, 5 mmol/L dissolved nitrite, and an excess of hydrogen peroxide (H2O2). These data appear in Figures 1, 5, and 6 in the associated manuscript. The folder "Kupper2022_Mossbauer_data" contains the Mossbauer spectra of moderate-iron trioctahedral smectite and high-iron trioctahedral smectite. "Unaltered" indicates the initial, synthesized clays. The other labels indicate samples reacted with the specified oxidant: 21% O2, 2% O2, 5 mmol/L dissolved nitrite, and an excess of hydrogen peroxide (H2O2). The subfolders labeled 295K, 13K, and 5K indicate the temperature in Kelvin at which data were collected. These data appears in Figures 2, 8, and 9 in the associated manuscript. The file "Kupper2022_OxidationKinetics_data.csv" contains data on solid phase Fe(II)/Total Fe in the moderate-iron trioctahedral smectite and high-iron trioctahedral smectite as a function of time in hours during reaction with 21%O2, 2%O2, or 5 mmol/L nitrite. Oxidation-free control data are also provided. These data appear in Figures 3, 4, and S3 in the associated manuscript. The file "Kupper2022_ModIron_Nitrite_data.csv" contains dissolved nitrite concentrations during the experiments with the moderate-iron smectite. These data appear in Figure S2 in the associated manuscript. The folder "Kupper2022_Oxygen_data" contains dissolved oxygen concentrations (in umol/L) and temperature as a function of time for the oxidation experiments with the moderate- and high-iron smectite reacted with 21% or 2% O2. These data appear in Figure S1 in the associated manuscript. The file "Kupper2022_EXAFS_data.csv" contains the XAFS spectra of the moderate- and high-iron smectites upon synthesis and after exposure to 21% O2 or H2O2.

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