Surface complexation of carboxylate adheres Cryptosporidium parvum oocysts to the hematite-water interface

Xiaodong Gao, David W. Metge, Chittaranjan Ray, Ronald W. Harvey, Jon Chorover

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

The interaction of viable Cryptosporidium parvum öocysts at the hematite (α-Fe2O3)-water interface was examined over a wide range in solution chemistry using in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Spectra for hematite-sorbed öocysts showed distinctchangesin carboxylate group vibrations relative to spectra obtained in the absence of hematite, indicative of direct chemical bonding between carboxylate groups and Fe metal centers of the hematite surface. The data also indicate that complexation modes vary with solution chemistry. In NaCl solution, öocysts are bound to hematite via monodentate and binuclear bidentate complexes. The former predominates at low pH, whereas the latter becomes increasingly prevalent with increasing pH. In a CaCl2 solution, only binuclear bidentate complexes are observed. When solution pH is above the point of zero net proton charge (PZNPC) of hematite, öocyst surface carboxylate groups are bound to the mineral surface via outer-sphere complexes in both electrolyte solutions.

Original languageEnglish (US)
Pages (from-to)7423-7429
Number of pages7
JournalEnvironmental Science and Technology
Volume43
Issue number19
DOIs
StatePublished - Oct 1 2009

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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