Surface complexation of carboxylate adheres Cryptosporidium parvum oocysts to the hematite-water interface.
The interaction of viable Cryptosporidium parvum oocysts at the hematite (alpha-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 oocysts showed distinct changes in 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. InNaCl solution, oocysts 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, oocyst surface carboxylate groups are bound to the mineral surface via outer-sphere complexes in both electrolyte solutions.
Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona 85721, USA.
Xiaodong
X
Gao
David W
DW
Metge
Chittaranian
C
Ray
Ronald W
RW
Harvey
Jon
J
Chorover
D000818:Animals; D002264:Carboxylic Acids / Q000737:chemistry*; D002448:Cell Adhesion / Q000187:drug effects; D016785:Cryptosporidium parvum / Q000502:physiology*; D005290:Ferric Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D033661:Oocysts / Q000502:physiology; D013499:Surface Properties; D014867:Water / Q000737:chemistry* / Q000469:parasitology; D018508:Water Purification / Q000379:methods
D002264:Carboxylic Acids; D005290:Ferric Compounds; D014867:Water; C000499:ferric oxide