Sequestration of arsenate from aqueous solution using 2-line ferrihydrite: Equilibria, kinetics, and X-ray absorption spectroscopic analysis

Woo Chun Lee, Soon Oh Kim, James Ranville, Seong Taek Yun, Sun Hee Choi

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Arsenic(V), as the arsenate (AsO43-) ion and its conjugate acids, has a strong affinity on Fe, Mn, and Al (oxyhydr)oxides and clay minerals. Removal of arsenate from aqueous solution by poorly crystalline ferrihydrite (hydrous ferric oxide) via a combination of macroscopic (equilibria and kinetics of sorption) and X-ray absorption spectroscopic studies was investigated. The removal of arsenate significantly decreased with increasing pH and sorption maxima of approximately 1.994 mmol/g (0.192 molAs/molFe) were achieved at pH 2.0. The Langmuir isotherm is most appropriate for arsenate sorption over the wide range of pH, indicating that arsenate sorption preferentially takes place at relatively homogenous and monolayer sites rather than heterogeneous and multilayer surfaces. The kinetic study demonstrated that arsenate sorption onto 2-line ferrihydrite is considerably fast, and sorption equilibrium was achieved within the reaction time of 2 h. X-ray absorption near-edge structure spectroscopy indicates no change in oxidation state of arsenate following interaction with the ferrihydrite surfaces. Extended X-ray absorption fine structure spectroscopy supports the efficient removal of arsenate by the 2-line ferrihydrite through the formation of highly stable inner-sphere surface complexes, such as bidentate binuclear corner-sharing (2C) and bidentate mononuclear edge-sharing (2E) complexes.

Original languageEnglish
Pages (from-to)3307-3318
Number of pages12
JournalEnvironmental Earth Sciences
Volume71
Issue number8
DOIs
Publication statusPublished - 2014 Apr

Keywords

  • 2-Line ferrihydrite
  • Arsenate
  • Sorption equilibria
  • Sorption kinetics
  • X-ray absorption spectroscopy

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Water Science and Technology
  • Soil Science
  • Pollution
  • Geology
  • Earth-Surface Processes

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