Evaluation of Electroosmotic Permeability Using Different Models and Investigation of Its Effect on Chromium Removal

Electroosmotic permeability is an important parameter in the electrokinetic remediation (EKR) of heavy-metal-contaminated soil. This study focuses on the applicability of electroosmotic permeability models and the relationship between electroosmotic permeability and heavy metal removal efficiency. The electroosmotic permeability models of ion hydration and the ion hydration–friction model were developed and investigated. Moreover, 11 EKR experiments were conducted in the laboratory to remediate Cr 6+ -contaminated soil. The results showed that the electroosmotic permeability calculated by the H-S model was 3–7 times larger than the measured value, and it was 65–90% of the measured value as calculated by the ion hydration model. However, the ion hydration–friction model, which combined the ion hydration and Spiegler friction theories, predicted the electroosmotic permeability more accurately compared to the H-S and ion hydration models. In addition, the parameters in the ion hydration–friction model were determined easily, meaning that the ion hydration–friction model is of good applicability. The experimental results showed that the soil properties changed and the electroosmotic flow rate decreased when acid was added to the soil, and the Cr 6+ removal efficiency improved.