Characterization of Chromium in Contaminated Soil Studied by SEM, EDS,XRD and Mossbauer Spectroscopy

Abstract

Chromium is important from the environmental point of view since its behavior and toxicity properties depend on its oxidation states. The Cr(VI) concentration in wells of Buenavista, Guanajuato, Mexico, is higher than the permissible level of it for drinking water, 0.05mg/L. The objective of this research was to determine the elution of chromium with deionized water from contaminated soil samples and to determine the oxidation state of Fe, which is an element that can limit the mobility of chromium. These results will be considered in a pump and treat remediation scheme for this site. Chromium contaminated soil samples were obtained from an industrial area of Leon, Guanajuato, Mxico. O, Na, Mg, K, Al, Si, Ca, Cr and Fe were found in the chemical analysis by EDS of the contaminated samples. In the soluble species only O, Na, S, Ca and Cr were found. The oxidation state of iron was determined by Mssbauer spectroscopy (MS) in the soil contaminated with chromium, in the soil washed with deionizer water and also in the soluble samples. CaCrO 4 was found in the soluble fraction, as a single crystalline phase by XRD. MS indicated that at least two iron species were present, one insoluble and the other sparingly soluble.