Removal of chromium (VI) by acid-washed zero-valent iron under various groundwater geochemistry conditions.
The hexavalent chromium (Cr(VI)) removal capacity of acid-washed zerovalent iron (AW-Fe0) was evaluated under different groundwater geochemistry conditions through column experiments. It was found that each gram of the AW-Fe0 could remove 0.65-1.76 mg of Cr(VI) from synthetic groundwater in the absence of bicarbonate (HCO3-), magnesium and/or calcium ions. Groundwater geochemistry was found to exert various degrees of impact on Cr(VI) removal by the AW-Fe0, in which HCO3- alone gave the mildest impact whereas the copresence of calcium and HCO3- exerted the greatest impact In comparison with the unwashed Fe0, the AW-Fe0 showed a poorer Cr(VI) removal capacity and was also more susceptible to the influence of the dissolved groundwater constituents on Cr(VI) removal,thereby indicating the unsuitability of using AW-Fe0 in permeable reactive barriers for remediation of Cr(VI)-contaminated groundwater. On the AW-Fe0 surface, where the indigenous iron precipitates were almost erased, trivalent chromium including chromium (III) oxides, hydroxides, and oxyhydroxides in irregular strip, chick footmark-liked or boulder-liked forms as well as Cr(III)-Cr(VI) mixed oxides were detected.
Lai
Keith C K
KC
Civil, Architectural and Environmental Engineering Department, University of Texas at Austin, Austin, Texas 78712, USA.
Lo
Irene M C
IM
D001639:Bicarbonates / Q000737:chemistry; D002118:Calcium / Q000737:chemistry; D002857:Chromium / Q000302:isolation & purification*; D007501:Iron / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
D001639:Bicarbonates; D014874:Water Pollutants, Chemical; D002857:Chromium; D007501:Iron; D008274:Magnesium; D002118:Calcium