Extraction of chromium from contaminated soils

A chromium contaminated soil area was studied. in order to recover metals p resent as contaminants in soils, associated to the soil remediation. A leac hing solution of HCl (0,1 M) and NaCl (1,9 M) was used to extract the chrom ium content. The concentration of chromium in the leached solutions was ana lysed. For each contaminated sample, the evolution with time of chromium co ncentrations in leaching solutions was studied. A Langmuir-type model showe d a good fit to experimental data, allowing the determination of the maximu m concentration of chromium that can be reached in the leaching solutions, and the time required to attain a fixed leached concentration of chromium. The influence of natural organic matter content of the soil on the leaching time was evaluated. The results obtained allows to conclude that the natur al organic matter content significantly influences the extraction time, due to the metal complexation by dissolved organic matter present in leaching solutions.