Scalable application of thin film coating techniques for supported liquid membranes for gas separation made from ionic liquids

• PAN membranes coated with thin layer of ionic liquids and tested for gas transport.
• Thin film coating successfully established by dip coating method.
• Resulting membranes are highly CO2/N2 selective.
• Supported liquid membranes show high stability during numerous pressure cycles.
• Thickness of the ionic liquid layer can be proven by modified Landau-Levich approach.

The application of commercial polyacrylonitrile (PAN) membranes as matrix material for ionic liquids (ILs) for gas separation tasks is reported and morphological characteristics for supported liquid membrane stability are discussed. The compatibility of membrane components was investigated and two thin film coating techniques, dip coating and spin coating, were compared. The dip coating technique has proven to fulfill the requirement of membrane stability, as well as pin-hole free coating and thin coating thickness. The thickness of the ionic liquid layer in the membrane could be assessed by means of a modified Landau-Levich approach. Overall liquid membranes supported by PAN with a narrow pore size distribution achieved remarkably good results especially in combination with 1-ethyl-3-methylimidazolium tetracyanoborate (EMIM TCB) ionic liquid and are showing the way to commercially scalable supported liquid membrane application.

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