[Reaction Kinetics and Impacting Mechanism of Cr(Ⅵ) Removal in Fe-PRB Systems].

Zero-Valent Iron Permeable Reactive Barrier (Fe-PRB) is a competitive and economical in-situ groundwater remediation technology in recent years, and high removal efficiencies of Cr(Ⅵ)-polluted groundwater have been realized. The present study focused on the impacting mechanism of Cr(Ⅵ) removal by Fe-PRB. Environmental condition response was revealed from kinetic view, and kinetic expression describing the removal process was determined. In addition, the effect of groundwater chemical conditions was studied. It was found that calcium had little effect on Cr(Ⅵ) removal. Chloride might influence Cr(Ⅵ) removal through impacting electron transfer, and sulfate/magnesium might influence Cr(Ⅵ) removal through participating in reactions. Bicarbonate might influence Cr(Ⅵ) removal through combined effects of impacting electron transfer and participating in reactions. The results provide method and theory basis for process parameter optimization in Fe-PRB systems.