Mechanism of arsenate coprecipitation at the solid/liquid interface of ferrihydrite: A perspective review

Chiharu Tokoro, Masakazu Kadokura, Tatsuya Kato

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Arsenate (As(V)) is a toxic element in acid mine drainage and has to be removed during the neutralization process. Coprecipitation with ferrihydrite is the main mechanism for As(V) removal from acid mine drainage. To improve treatment efficiency, a quantitative understanding of the coprecipitation mechanism is required. Coprecipitation can incorporate more As(V) into ferrihydrite than adsorption. The results of XRD (X-ray Diffraction) and XANES (X-ray Adsorption Near Edge Structure) analysis confirmed that the formation of poorly crystalline ferric arsenate increased when the initial As/Fe molar ratio increased in the coprecipitation with ferrihydrite. EXAFS (Extended X-ray Adsorption Fine Structure) analysis at the iron K-edge showed that the proportion of octahedral structures in ferrihydrite increased when the initial As/Fe molar ratio increased. Moreover, EXAFS analysis at the arsenic K-edge, assuming three kinds of surface complexes for the As–Fe bond, revealed that the coordination number for As–Fe with an atomic distance of 2.85 × 10−10 m increased and that for As-Fe with an atomic distance of 3.24 × 10−10 m decreased as the initial As/Fe molar ratio increased. Thus, for more efficient wastewater treatment, active control of coprecipitation phenomena according to mechanistic details is essential.

Original languageEnglish
Pages (from-to)859-866
Number of pages8
JournalAdvanced Powder Technology
Volume31
Issue number2
DOIs
Publication statusPublished - 2020 Feb

Keywords

  • EXAFS
  • Local structure
  • Octahedral structure
  • Tetrahedral structure
  • XAFS

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Mechanics of Materials

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