Chromate Reduction and Remediation Utilizing the Thermodynamic Instability ofZero-Valence State Iron

摘要

The study examines the reaction kinetics for redox potential change and chromatereduction in stirred batch reactor systems (SBRs) containing a simulated groundwater in the presence and absence of natural aquifer material, using iron filings as the zero-oxidation state chemical. Column experiments were also utilized to evaluate reductive capacity and the potential for chromate breakthrough. Continuous tracking of the system chemistry, including redox potential, pH, and the concentrations of the chemical species of interest was performed for both types of experiments. Mathematical evaluations of the rates of changes in the SBRs were performed to determine the pseudo-reaction orders with respect to the electron, (measured as redox, or Eh) and chromate, as well as the reaction rates. Results indicate rapid changes in Eh from positive to highly negative values upon introduction of Fe metal to these systems, both in the presence and absence of aquifer material. (Copyright (c) Water Environment Federation 1994.)