Modeling of heavy metal removal dynamics in clinoptilolite packed beds

The study of heavy metal removal, ion-exchange equilibrium and column dynamics was investigated using a clinoptilolite-rich tuff from Ukraine (Sokirskoe) and Slovakia (Nizny Hrabovec). The Equilibrium-Dispersive and Lumped-Kinetic models were developed for simulation of concentration profiles in an ion-exchange column. The mass balance equations were coupled with conventional sorption two-parameter equilibrium models (the Langmuir, competitive Langmuir and thermodynamic equilibrium models) as well as initial and boundary conditions. The ion-exchange breakthrough curves in the clinoptilolite column, obtained for single- and multi-component systems, were compared with the results predicted by the proposed models. The best approximation of real conditions was achieved using the Lumped-Kinetic model supplemented with the thermodynamic isotherm. Then these models were used to predict the concentration profile for a larger column, and the calculated results agreed well with experimental data.