Measurement of adsorption equilibrium and kinetics of water and alcohols on pervaporation membrane top layer pellets by gravimetrical vapor adsorption
Advancing the chemical engineering fundamentals
Membranes and Membrane Science - II (T2-8b)
Keywords: pervaporation, adsorption, diffusion, Langmuir, microbalance
The pervaporative transport through microporous ceramic membranes is governed by adsorption and diffusion processes. Hence, knowledge of both processes allows predicting the membrane’s performance in terms of flux and selectivity. In this study, vapor sorption experiments were carried out with water, methanol and ethanol (single components and mixtures) on a Cahn D-100 microbalance to measure the weight change of calcinated silica membrane top layer pellets exposed to different activities of the components. The composition of the adsorbed vapor is obtained by means of a Turbomass Mass Spectrometer (gas chromatography/mass spectrometry, GC/MS) and a Turbomatrix Headspace Sampler (PerkinElmer). When placing a sample in the Turbomatrix Headspace Sampler and connecting it to the GC/MS, it becomes possible (via an accurate temperature and pressure control) to desorb vapors from the sample and to determine its composition. Adsorption isotherms are correlated to Langmuir adsorption models. Increasing the temperature decreases the sorption capacity of the pellets. Adsorption kinetics are used to derive diffusion and sorption coefficients for both single components and components in a mixture. Focus is on selective sorption and the concentration dependence of the diffusion coefficient. Comparison to previous pervaporation measurements indicates that the vapor adsorption results can be used to predict the pervaporative transport through microporous ceramic membranes.
Presented Wednesday 19, 15:40 to 16:00, in session Membranes and Membrane Science - II (T2-8b).
