In-Situ Preparation of Supported Liquid Membranes Using Inorganic Supports and Non-Volatile Liquids
Advancing the chemical engineering fundamentals
Membranes and Membrane Science - II (T2-8b)
Keywords: Supported Liquid Membrane, In-Situ Preparation, Inorganic Support, Non-Volatile, Liquid Layer Optimization
Supported Liquid Membranes (SLM) consist of a mesoporous support and a liquid, which is immobilized in the support due to capillary and interfacial forces. Although liquid membranes have been of interest in research for more than thirty years, only few industrial applications have been put into practice. This can clearly be related to the lacking mechanical and long term stability of the membrane configurations. In literature mainly combinations of an organic support and a volatile organic liquid are found. These systems suffer from evaporation of the liquid phase and the chemically or thermally provoked change of the support’s properties like pore size and wettability. Novel materials like chemically and thermally inert inorganic supports and non-volatile ionic liquids or liquid molten salts can overcome these stability problems.
Since the permeability of membranes is reversely proportional to the thickness of a membrane, a minimum thickness would be required to reach maximum permeability. This changes if the SLM concept is combined with a facilitated transport concept using carrier species. These species reversibly react with a permeating component of a mixture and enhance the selectivity of the membrane. The time for reversible reaction with a desired component competes with the time for diffusion of undesired components. Hence an optimum membrane thickness with respect to the carrier is required.
In contrast to organic supports of defined small thickness inorganic supports are mostly available with thickness greater than 200 µm, being unfavourable for non-carrier mediated transport membranes. On the other hand a method for adjustment of the membrane thickness allows for preparation of SLM with optimized thickness for carrier mediated transport.
In our current work we have developed a method for in-situ-preparation of SLM inside a module already installed in a gas separation process allowing for adjustment of the membrane thickness within an asymmetric capillary inorganic support. This in-situ preparation leads one step further to industrial application, since the membrane preparation takes place after mounting the support to the module. Even water and oxygen sensitive liquids can be employed as membrane phase in an easy way in contrast to complex manual preparation in glove-boxes. The method is based on a model accounting for the wetting kinetics of the support. Since this model is formulated in a dimensionsless way, results can be transferred to different membrane-liquid configurations.
Presented Wednesday 19, 16:00 to 16:20, in session Membranes and Membrane Science - II (T2-8b).
