Effect of kinetics, pH, aqueous speciation and presence of ferrihydrite on vanadium (V) uptake by allophanic and smectitic clays

Andre Baldermann*, Franziska M. Stamm

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Sorption of oxyanions, such as pentavalent vanadium (V(V)), by reactive, poorly crystallized clay minerals and Fe-(hydr)oxides surfaces significantly contributes to the nutrient and pollutant transport in soils. However, only a few studies yet exist, which evaluate and quantify the role of such common soil substituents on V sorption. In this contribution, the uptake of V(V) by allophane with molar Al/Si ratios of 1.5 (ALO-1) and 1.8 (ALO-2) and by montmorillonite-beidellite (MNT-BEI) clays was investigated using kinetic and equilibrium experiments. The effects of pH, V speciation, contact time and presence of 6-line ferrihydrite (FHY) were evaluated at 25 °C. The clayey substrates with(out) FHY were characterized using X-ray diffraction, X-ray fluorescence, high-resolution transmission electron microscopy with energy-dispersive X-ray spectroscopy and selected area electron diffraction and N2-Brunauer-Emmett-Teller physisorption methods. Fast (≥ 15 min) adsorption of V(V) was followed by pseudo-first-order reaction kinetics and progressed through instantaneous diffusion processes at the exterior surface. Subsequently, V(V) transportation and adsorption within the interior substrate, as inferred from Weber-Morris intra-particle diffusion model plots, was observed. The presence of FHY had a positive effect on V(V) adsorption ([V]T = 0.02 mmol/L), which followed in the order MNT-BEI-FHY and MNT-BEI (≥ 95% removal), ALO-1-FHY and ALO-2-FHY (≥ 90% removal), ALO-1 (≥ 70% removal) and ALO-2 (≥ 40% removal) in the pH range from ~6 to ~8. The results of this study demonstrate the high affinity of ferrihydrite as well as allophanic and smectitic clays for V(V) adsorption, suggesting that these components can limit the V mobility in soils over a wide pH range.

Original languageEnglish
Article number121022
JournalChemical Geology
Volume607
DOIs
Publication statusPublished - 30 Sep 2022

Keywords

  • Adsorption
  • Allophane
  • Chemical speciation
  • Ferrihydrite
  • Montmorillonite
  • Vanadium

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

Fields of Expertise

  • Advanced Materials Science

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