Phosphate competition with arsenate on poorly crystalline iron and aluminum (hydr)oxide mixtures

Abstract

Phosphate competes with arsenate for sorption sites on poorly crystalline iron and aluminum (hydr) oxides. The competition has implications e.g. for the management of arsenic-contaminated soil and water. Phosphate competition with arsenate on mixed phases containing both iron and aluminum (hydr) oxides has rarely been investigated. Here, the phosphate competition with arsenate on mixtures of poorly crystalline aluminum hydroxide (Alhox) and ferrihydrite (Fh), was investigated in batch experiments at pH 6.5. X-ray absorption spectroscopy (XAS) was performed on the phosphorus and arsenic K edges, which offered a unique insight in the partitioning of arsenate and phosphate on mixed Alhox-Fh sorbents. Under the studied conditions the sorption capacity of the mixed sorbents (per mol Al or Fe) increased at higher Alhox to Fh ratios. The XAS measurements provided direct evidence that phosphate competed more effectively with arsenate for sorption sites on Alhox than on Fh. For example, in a mixture with 50% of both sorbents and with similar additions of arsenate and phosphate, 71% of the oxyanions adsorbed on Fh and 46% on Alhox were arsenate. Consequently, phosphate may mobilize arsenate more easily from mixed iron-aluminum matrices that are rich in aluminum. (C) 2020 The Authors. Published by Elsevier Ltd.

Keywords

Arsenate; Phosphate; Sorption; Iron (hydr)oxide; Aluminum hydroxide; X-ray absorption spectroscopy

Published in

Chemosphere
2020, volume: 255, article number: 126937
Publisher: PERGAMON-ELSEVIER SCIENCE LTD

SLU Authors

• Tiberg, Charlotta

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Eriksson, Ann Kristin

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Gustafsson, Jon-Petter

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Sjöstedt, Carin

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

Global goals (SDG)

SDG3 Good health and well-being
SDG6 Clean water and sanitation

UKÄ Subject classification

Water Treatment

Publication identifier

• DOI: https://doi.org/10.1016/j.chemosphere.2020.126937

Permanent link to this page (URI)

https://res.slu.se/id/publ/106555