Vanadate Retention by Iron and Manganese Oxides

Macon J Abernathy; Michael V Schaefer; Roxana Ramirez; Abdi Garniwan; Ilkeun Lee; Francisco Zaera; Matthew L Polizzotto; Samantha C Ying

doi:10.1021/acsearthspacechem.2c00116

Vanadate Retention by Iron and Manganese Oxides

ACS Earth Space Chem. 2022 Aug 18;6(8):2041-2052. doi: 10.1021/acsearthspacechem.2c00116. Epub 2022 Aug 5.

Authors

Macon J Abernathy¹, Michael V Schaefer², Roxana Ramirez³, Abdi Garniwan³, Ilkeun Lee⁴, Francisco Zaera⁴, Matthew L Polizzotto⁵, Samantha C Ying^{3

6}

Affiliations

¹ Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
² Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, United States.
³ Environmental Sciences Department, University of California-Riverside, Riverside, California 92521, United States.
⁴ Department of Chemistry, University of California-Riverside, Riverside, California 92521, United States.
⁵ Department of Earth Sciences, University of Oregon, Eugene, Oregon 97403, United States.
⁶ Environmental Toxicology Graduate Program, University of California-Riverside, Riverside, California 92521, United States.

Abstract

Anthropogenic emissions of vanadium (V) into terrestrial and aquatic surface systems now match those of geogenic processes, and yet, the geochemistry of vanadium is poorly described in comparison to other comparable contaminants like arsenic. In oxic systems, V is present as an oxyanion with a +5 formal charge on the V center, typically described as H _x VO₄ ^(3-x)-, but also here as V(V). Iron (Fe) and manganese (Mn) (oxy)hydroxides represent key mineral phases in the cycling of V(V) at the solid-solution interface, and yet, fundamental descriptions of these surface-processes are not available. Here, we utilize extended X-ray absorption fine structure (EXAFS) and thermodynamic calculations to compare the surface complexation of V(V) by the common Fe and Mn mineral phases ferrihydrite, hematite, goethite, birnessite, and pyrolusite at pH 7. Inner-sphere V(V) complexes were detected on all phases, with mononuclear V(V) species dominating the adsorbed species distribution. Our results demonstrate that V(V) adsorption is exergonic for a variety of surfaces with differing amounts of terminal -OH groups and metal-O bond saturations, implicating the conjunctive role of varied mineral surfaces in controlling the mobility and fate of V(V) in terrestrial and aquatic systems.