Mathematical prediction of lead removal from carbonate-rich illite

The interaction between heavy metal contaminants and surface forces associated with the reactive surfaces of soil particles was studied with the aim of developing an analytical tool that would permit the prediction of heavy metal and soil sorption–desorption phenomena. The predictive model developed in this study considers the energy of the interaction developed between a lead contaminant and illitic soil. Since these energy calculations include both inner and outer sphere complexes, energy balance requirements can be realistically evaluated with respect to environmental mobility. For a comparison between the calculated values obtained from the predictive model and experimentally obtained measurements, laboratory batch equilibrium tests and electro–kinetic tests were used. These were concerned with the sorption–desorption determination of illitic soil samples with the lead contaminant in the form of a lead nitrate solution. The force balance of lead ions indicates that lead ions in the so-called Stern layer, i.e. the first two layers of a water molecule, are non-removable. Good correlations between calculated and measured values were obtained.