動電学的土壌浄化における弱酸の濃度分布解析

抄録

Restoration of contaminated soils to environmentally acceptable condition is important. Contaminants are primarily concentrated in the fine-grained soil fraction (i. e., silt and clay) and are not strongly retained on the coarse-grained particles (i. e. sand). Various methods currently used have advantages and limitations in remediating contaminants in soils. In fact, most successful in-situ remediation technologies are restricted to soils with relatively high hydraulic conductivities (silt and sand) and can not be used for fine-grained deposits. One of the newer techniques in soil remediation is a method based on electrokinetic phenomena in soils. Electrokinetic soil remediation is an effective in-situ separation and removal technique used for extraction of heavy metals and some organic compounds from fine-grained soils. The technology uses electricity to affect chemical concentrations and water flow through the pores of soils. However, the effect of the soil properties such as tortousity, permeability and pH on the distribution behavior of pollutants are not elucidated. Therefore, in the present study, the effect of the soil properties on the distributions of weak acids (acetic acid and phenol) in the electrokinetic processing of fine-grained soils are investigated. An analytical model, based on the Nernst-Planck equations, is presented to evaluate the effect of soil properties on the distributions of pH and weak acids and the results obtained in this study are summarized as follows: The distribution behaviors of acetic acid and phenol in close to the cathode are significantly different. The movement rate of acetic acid and phenol toward the cathode are faster with a decrease in the initial pH of soil and it is proportional to the acidification rate of soil. Soil properties such as tortousity and permeability significantly affect the remediation progress.