Ion exchange of Pb2+ on natural clinoptilolite in fixed bed and batch operations was studied and simple models on experimental data were applied. The operations were conducted at ambient temperature, an initial concentration of 0.01N and at pH4. Paterson's model was used to describe batch kinetics, the Langmuir isotherm was used to correlate equilibrium data and a solid diffusion controlled process was used to describe the fixed bed operation. The evaluated operating capacity was in the range of 0.21 to 1meq/g and the diffusion coefficient was in the range of 7.0 x 10-14 to 5.4 x 10-12m2/s. The experimental results put the basic theory in question. According to these experiments, the capacity and diffusion coefficient in fixed bed systems were flow-dependent and different from those measured in the batch-reactor systems. This could be explained if the type of experimental setup influenced both the equilibrium isotherm and the system behavior.

Modeling of Ion Exchange of Pb2+ in Fixed Beds of Clinoptilolite. V.J.Inglezakis, H.P.Grigoropoulou: Microporous and Mesoporous Materials, 2003, 61[1-3], 273-82