Kinetic studies of chromium (VI) binding to carboxylic acid- and methyl ester-functionalized silica/water interfaces important in geochemistry

Hind A. Al-Abadleh, Amanda L. Mifflin, Michael J. Musorrafiti, Franz M. Geiger*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

Real-time kinetic measurements of hexavalent chromium binding to fused silica surfaces functionalized with carboxylic acid and methyl ester terminal groups are performed in situ using resonantly enhanced surface second harmonic generation (SHG) at pH 7 and 300 K. These functional groups were chosen because of their high abundance in humic acids and related biopolymers. Kinetic measurements are conducted in the submonolayer regime using chromate solution concentrations ranging from 1 × 10 -6 to 2 × 10 -5 M. The adsorption rates were analyzed using the standard Langmuir model and the Frumkin-Fowler-Guggenheim model. The desorption kinetics are consistent with a first-order process. These results indicate that hexavalent chromium mobility in carboxylic acid- and ester-rich soil environments increases with decreasing chromate concentrations. Based on the measured half-lives of the adsorbed Cr(VI) species, remobilization of bound hexavalent chromium due to natural or anthropogenic events that lower the chromate concentration in the aqueous phase can occur within minutes.

Original languageEnglish (US)
Pages (from-to)16852-16859
Number of pages8
JournalJournal of Physical Chemistry B
Volume109
Issue number35
DOIs
StatePublished - Sep 8 2005

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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