Transport Parameters and Heavy Metal Adsorption of a Compacted Lateritic Soil

Abstract

A series of tests were conducted to assess properties of Kor Hong lateritic soil,particularly transport parameters and heavy metal adsorption. Experimental results indicate that thesoil was low plasticity clay with low cation exchange capacity and slightly acidic with pH of 5.5. Thesoil was reddish brown in color due to high iron content. Maximum dry density and optimum watercontent of the soil were 1.7 g/cm3 and 18%, respectively. Freundlich isotherm was found to fit wellwith batch adsorption test results. Heavy metal adsorption capacities of the soil ranked from thehighest were Cr3+, Pb2+, Ni2+, Zn2+, and Cd2+, respectively. Hydraulic conductivity of the soil rangedfrom 4.0x10-8 to 5.0x10-8 cm/s when permeated with deionized water. Long-term hydraulicconductivity test results show that the hydraulic conductivities increased with time when permeatedwith chromium solutions having concentrations greater than 0.001 M. Breakthrough points of heavymetal solutions obtained from column tests were consistent with adsorption capacities obtained frombatch adsorption tests. Diffusion coefficient and retardation factor of the soil were calculated byfitting breakthrough curves with a transport equation. These parameters can be used for calculating athickness of landfill liners.