Extraction of chromium from contaminated soils

A chromium contaminated soil area was studied. in order to recover metals present as contaminants in soils, associated to the soil remediation. A leaching solution of HCl (0,1 M) and NaCl (1,9 M) was used to extract the chromium content. The concentration of chromium in the leached solutions was analysed. For each contaminated sample, the evolution with time of chromium concentrations in leaching solutions was studied. A Langmuir-type model showed a good fit to experimental data, allowing the determination of the maximum 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 natural organic matter content significantly influences the extraction time, due to the metal complexation by dissolved organic matter present in leaching solutions.