Diffusion of metals in geosynthetic clay liners Available to Purchase

The potential for using geosynthetic clay liners (GCLs) to mitigate metal mobility is dependent, in part, on consideration of its effectiveness as a diffusive barrier. In this context, laboratory-measured diffusion coefficients and supporting sorption data for metals (Al, As, Cd, Cu, Fe, K, Mg, Mn, Ni, Sr, Zn) are reported for the following four cases where a GCL might serve as an effective barrier material to metals and metalloids: acidic rock drainage, gold mine tailings, lime-treated mine effluent, and municipal solid waste. The average diffusion coefficients for Cu, Cd, Zn, Fe and Ni covered a narrow range from 0.67 × 10⁻¹⁰ to 0.89 × 10⁻¹⁰ m²/s. The diffusion coefficients for As, Al, Mg, Mn and Sr were in the range D = 0.80 × 10⁻¹⁰ to D = 1.6 × 10⁻¹⁰. The diffusive movement of other more common inorganic ions such as Ca, Na, S (SO₄) and Cl are also considered, as well as the impact of pH, Eh and speciation on metal mobility in GCLs.