Geo-Environmental Assessment of a Micaceous Soil for Its Potential Use as an Engineered Clay Barrier

The ability of the fine fraction of a natural micaceous soil in the Stanleyville area near Perth, Ontario, to retard an acidic waste leachate is examined. Batch and leaching column tests were used to investigate the retention capcity of the natural soil. To investigate the effect of ion competition on adsorption/desorption capacity of the soil, single and multi-components of Pb2+ and Zn2+ were used in batch experiments. The experimental results from column leaching tests were analyzed in terms of adsorption/desorption isotherms, breakthrough curves, and migration profiles of each specific ion in the influent. It was shown that the soil has high adsorption capacity for K+, Pb2+, and Zn2+ as indicated from the concentration profiles of the soil pore fluid with depth during leaching. At the same time, desorption of Na+, Mg2+, and Ca2+ occurred due to ion exchange. The experimental data were analyzed using a phenomenological approach based on nondimensional analysis, analytical solution via Fourier series, and the root time method. The calculated diffusion parameters are presented and compared with the literature.