Investigation of diffusion and adsorption of water vapor-volatile organic matter mixtures in porous media

ABSTRACT Master Thesis INVESTIGATION OF DIFFUSON AND ADSORPTION OF WATER VAPOR- VOLATELE ORGANIC MATTER MIXTURES IN POROUS MEDIA Mehmet KALENDER University of Fırat Graduate School of Natural and Applied Science Department of Chemical Engineering 2003, Pages 130 In this study, dynamic behaviour of water-miscible (methanol and aceton) and water-immiscible (benzene and toluen) volatile organic compounds in porous soil and zeolite pellets were investigated by the use of single pellet moment technique. For this purpose, an one-sided single pellet adsorption cell was used. Dynamic single pellet experiments were carried out at 1 atm for temperatures ranging from 30 °C to 70 °C by using the pellets having total porosity of 0.49. As a result of interpretation of zeroth moments of tracers studied in soil and zeolite pellets it has been observed that the tracers were adsorbed reversibly. At the first stage of the study, adsorption equilibrium constants and effective diffusivities of tracers in dry media have been calculated by the interpretation of the first absolute moment and second centeral moment for temperatures ranging from 30 °C to 70 °C. The adsorption constants of tracers in both pellets decreased with increasing temperature. Adsorption of xv ^??ii^:;^':tracers decreased in the order of methanol-aceton-benzene-toluene for soil pellet and in the order of methanol-toluene-benzene-aceton for zeolite pellet. Effective diffusivities of tracers in both pellets increased with the increasing temperature. Second part of the experimental studies has been performed by using humidified soil and zeolite pellets. It has been observed that the adsorption equilibrium constant and effective diffusivity values for the tracers used decrease with the increase of relative humidity ratio (at 30 °C). The decrease in both parameters for pellets indicates that the filling of the pores with water obstructed the adsorption and diffusion of tracers. Third part of the experiments was carried out by using partially saturated media with toluene. The experimental results show that the adsorption and diffusion of tracers (methanol and benzene) decrease as the toluene ratios increase in the media. Key Words: Adsorption, Volatile Organic Compounds, Diffusion, Soil Pollution, Moment Technique, Zeolite. XVI