Effects of C/Mn Ratios on the Sorption and Oxidative Degradation of Small Organic Molecules on Mn-Oxides
Journal Article
·
· Environmental Science and Technology
- North Carolina State University, Raleigh, NC (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Argonne National Laboratory (ANL), Lemont, IL (United States)
- University of Delaware, Newark, DE (United States)
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
We report manganese (Mn) oxides have a high surface area and redox potential that facilitate sorption and/or oxidation of organic carbon (OC), but their role in regulating soil C storage is relatively unexplored. Small OC compounds with distinct structures were reacted with Mn(III/IV)-oxides to investigate the effects of OC/Mn molar ratios on Mn–OC interaction mechanisms. Dissolved and solid-phase OC and Mn were measured to quantify the OC sorption to and/or the redox reaction with Mn-oxides. Mineral transformation was evaluated using X-ray diffraction and X-ray absorption spectroscopy. Higher OC/Mn ratios resulted in higher sorption and/or redox transformation; however, interaction mechanisms differed at low or high OC/Mn ratios for some OC. Citrate, pyruvate, ascorbate, and catechol induced Mn-oxide dissolution. The average oxidation state of Mn in the solid phase did not change during the reaction with citrate, suggesting ligand-promoted mineral dissolution, but decreased significantly during reactions with the other compounds, suggesting reductive dissolution mechanisms. Phthalate primarily sorbed on Mn-oxides with no detectable formation of redox products. Mn–OC interactions led primarily to C loss through OC oxidation into inorganic C, except phthalate, which was predominantly immobilized in the solid phase. Together, these results provided detailed fundamental insights into reactions happening at organo–mineral interfaces in soils.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Argonne National Laboratory (ANL), Lemont, IL (United States)
- Sponsoring Organization:
- USDOE; USDOE Laboratory Directed Research and Development (LDRD) Program; US Department of Agriculture (USDA)
- Grant/Contract Number:
- AC05-00OR22725; AC02-06CH11357
- OSTI ID:
- 1906561
- Journal Information:
- Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: xx Vol. xx; ISSN 0013-936X
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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