Effect of Coexisting Competitive Anions on Adsorption to Various Soils by Soil and Underground Water Contamination Metals

Soil contamination by toxic anions has become a serious problem, because of their persistence for a longtime and their diffusion into underground water. In this study, the adsorption equilibria for three hazardous anions of As(V), Se(IV), and Cr(VI) were investigated in a wide concentration range for four types of soilunder the condition of coexisting of competitive anions. The adsorption amount of toxic anions was altered by 20∼40 fold depending on the type of soil, Ando soil, Brown Forest soil >> Glay Upland soil> Terrestrial Rego soil. Metal anion adsorption was hindered by coexisting anions, particularly hydroxide ion, and competitive adsorption could be quantitatively expressed using the multiple isotherm equation proposed in this study. From the quantitative investigation analysis, the effect of the concentration change in liquid phase did not depend on the type of soil, but could be approximated by a constant for each anion. On the basis of experimental results, the behavior of the toxic metal anions in contaminated soils could be estimated by examining the adsorption isotherms for the soils and its pH dependence.