Diffusion coefficients, modes of transport and activation energies for methanol, ethanol, n-propanol, 2-propanol and n-butanol in the porous structure of Turkish natural zeolite were determined at 24 to 28C. As the molecular weight of the alcohol increased, the diffusion coefficients decreased (table 28), the activation energy for diffusion increased and the time necessary to reach equilibrium increased. The diffusion constants increased linearly with increasing 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 for diffusion were 18.3, 46.4, 79.7, 57.3 and 90.1kJ/mol for methanol, ethanol, n-propanol, i-propanol and n-butanol, respectively. Diffusion of Volatile Organic Chemicals in Porous Media. 1. Alcohol/Natural Zeolite Systems. B.Sakintuna, E.Fakioglu, Y.Yürüm: Energy Fuels, 2005, 19[6], 2219–24

Table 28

Diffusion Coefficients for Alcohols in Natural Zeolite