A gas separation membrane includes a composite membrane, the composite membrane including: a gas separation functional layer; and a compound having a composition different from a compound constituting the gas separation functional layer, wherein the presence ratio of the gas separation functional layer at at least one surface of the gas separation membrane is not less than 90% and less than 100%. Provided is a gas separation membrane capable of suppressing damage of the gas separation functional layer during the preparation process of a gas separation membrane module or during the use of a gas separation membrane module even when the gas separation functional layer includes a site having low strength.

An oxygenator having a plurality of porous hollow fiber membranes for gas exchange to treat blood is manufactured by dissolving a silicone compound in an organic solvent having a surface tension of less than 70 dyn/cm to prepare a coating solution, and bringing an inner surface of the hollow fiber membranes into contact with the coating solution under a negative pressure of 50 hPa or more and 150 hPa or less to form a silicone compound-containing coating layer on the inner surface. An antithrombotic polymer compound-containing coat can be provided directly on an outer surface of the hollow fiber membranes.

The present disclosure discloses a preparation method of an organosilica/ceramic composite membrane with a gradient pore structure. The preparation method comprises: (1) selecting a porous ceramic material as a membrane support layer; (2) gradually replacing a solvent with water to prepare zirconium colloidal sols with different particle sizes, and successively coating the prepared zirconium colloidal sols onto a ceramic support from large to small so as to form a membrane transition layer with a gradient pore structure; and (3) catalytically synthesizing an organosilica polymeric sol using hydrochloric acid, coating the prepared organosilica sol onto the preheated transition layer through ultrasonic thermal spraying to undergo heat treatment, so as to prepare the organosilica/ceramic composite membrane with the gradient pore structure. According to the present disclosure, the transition layer with the gradient pore structure is prepared by using the zirconium colloidal sols with different particle sizes. An ultrathin defect-free organosilica separation layer is prepared through ultrasonic thermal spraying. As a result, the obtained organosilica/ceramic composite membrane can be applied to the fields of salt-containing dye wastewater treatment and polypeptide bioactive substance separation.