GEOC 22 |
| Giehyeon Lee, Environmental Science and Engineering, California Institute of Technology, MS 138-78, 1200 E. California Blvd., Pasadena, CA 91125 and Janet G. Hering, Environmental Science and Engineering, California Institute of Technology, 1200 E. California Blvd, MS 138-78, Pasadena, CA 91125. |
| Under oxidative conditions, the dissolution of Cr(OH)3 releases Cr(VI) into solution, which may subsequently adsorb onto the residual solid. The effect of Cr(VI) sorption on the oxidative dissolution of Cr(OH)3 by a strong oxidant, HOCl/OCl-, was examined in batch experiments at pH 2 and 9. At pH 9, linear dissolution was observed in the presence of the oxidant at a rate of 0.0017 μmol/m2s. In contrast, under oxidizing conditions at pH 2, the rate of Cr release decreased rapidly with time. This effect of pH on oxidative dissolution rates corresponds to the pH dependence of Cr(VI) sorption onto Cr(OH)3, which increased with decreasing pH reaching a maximum sorption density of 302 μmol/g at pH 3. Thus, it appears that sorption of Cr(VI) onto Cr(OH)3 inhibits further dissolution of the solid, presumably by blocking surface sites. |
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Chemistry of Metals in Terrestrial and Aquatic Systems
8:10 AM-11:30 AM, Monday, March 29, 2004 Marriott -- Marquis NE, Oral
Division of Geochemistry |