Chemical modification of carbon-coated anodic alumina films and their application to membrane filter

An anodic aluminum oxide film that has uniform and straight nanochannels was exposed to propylene at 800°C, resulting in uniform carbon deposition on the inner-surface of the channels as well as the external surface of the film. The carbon-coated aluminum oxide film was then chemically modified by either fluorination or HNO₃ treatment. The change in channel structure due to the carbon deposition and the subsequent chemical modification was analyzed. Gas permeation behavior through these films was examined by using He and N₂. Furthermore, the films were applied to pervaporation separation of water/ethanol mixture and it was found that water preferentially permeated the fluorinated film. The present study demonstrated that even a membrane whose pore size is as large as 24nm exhibits selectivity in pervaporation.