Diffusion of volatile organic chemicals in porous media. 1. alcohol/natural zeolite systems

Official URL: http://dx.doi.org/10.1021/ef050095w

The aim of the present paper was to measure the diffusion coefficients, mode of transport, and activation energies of some alcohols into the porous structure of a Turkish natural zeolite. Diffusion coefficients, modes of transport, and activation energies of methanol, ethanol, n-propanol, 2-propanol, and n-butanol into the porous structure of the Turkish Manisa Gördes natural zeolite were measured at 24-28 C. The diffusion coefficients of alcohols were calculated from the slope of graphs of Mt/M versus t1/2. As the molecular weight of the alcohols increased, diffusion coefficients decreased, the activation energy for diffusion increased, and the time necessary to reach equilibrium was increased. The diffusion constants increased linearly with an increase in the temperature. The diffusion of alcohols in the zeolite obeyed the anomalous transport mechanism. Diffusion rate constants remained unchanged as the temperature was increased. With increasing molecular weight of the volatile alcohols, the activation energies also increased. The calculated activation energies of diffusion were 18.3, 46.4, 79.7, 57.3, and 90.1 kJ/mol for methanol, ethanol, n-propanol, i-propanol, and n-butanol, respectively.