Leaching Characteristics of Heavy Metals (Pb, Cr and Cd)

Abstract

Column flow through leaching experiments reacting heavy metal solution with sand, slit and clay soil samples were performed to study heavy metal attenuation by three soils with different physical, chemical and mineralogical properties. Saturated solute transport experiments were conducted using one small and one large column packed with three different types of soil. This study examined the leaching experiments of three soils in polyvinyl chloride (PVC) column. A column experiment is very useful apparatus that can be used to study the migration and attenuation of heavy metals through a compacted soil column. Prior to testing all three soils were thoroughly characterized for their physical, chemical and mineralogical properties. All soil columns were permeated using laboratory made solution with concentration of heavy metals 500mg/l at pH 5.0. The experiments results were analysed in terms of breakthrough curves. The breakthrough curves shows that the clay sample has better adsorption capacity on heavy metals as compared to sand and silt soils. Less retention means high concentration of heavy metals was detected in the pore fluid. The order of mobility of heavy metals through leaching column experiment in case of sand and silt was Cr>Cd>Pb and in case of clay the order of mobility was Pb>Cd>Cr.
The test results also reflect the influence of soil origin in adsorption of heavy metals, where soil characteristics and surface properties contribute very significantly to the adsorption of heavy metals