▎ 摘　　要

NOVELTY - A separation membrane for oil and water separation, comprises porous substrate layer and active layer arranged over at least a portion of the substrate layer, where the active layer comprises a hydrophilic agent and a superhydrophilic agents. USE - A separation membrane for separating low water content oil and water mixtures, such as oil and water mixtures comprising less than 30 wt.% water, used in drainage device, i.e. drain valve for fuel tank of an automotive product or any of its component (all claimed). Can be used in fuel tanks of aircrafts, ships and boats, and other hydrocarbon-based transportation. ADVANTAGE - The separation membrane effectively separates the oil and water from the fuel in the fuel tank of the transport vehicle e.g. marine or aviation vehicle fuel tank, thus preventing water ingress into the fuel tanks, and reducing the amount of fuel being carried and further wastes energy carrying the undesired water, and hence preventing damage and corrosion to the engine and/or the whole system, resulting in more severe outcomes such as ice formation at high altitude, which may cause engine failure when the ice enters the engine system, and potentially resulting in a forced landing or crash. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) production of separation membrane which involves (a) optionally, preparing a substrate by treating the substrate with physical rinsing, chemical treatment, radiation treatment, plasma treatment, and/or thermal treatment, (b) optionally, contacting the substrate with an intermediate layer coating composition to form an intermediate layer, (c) contacting the substrate with a coating composition comprising a hydrophilic agent or its precursor, and optionally further comprising a superhydrophilic agent or its precursor, to form an active layer, (d) optionally, drying the active layer, (e) optionally, contacting the active layer with an intermediate layer coating composition to form an intermediate layer, (f) if a superhydrophilic agent is not contacted with the substrate in step (c), contacting the coated substrate with a coating composition comprising a superhydrophilic agent or its precursor to form a further active layer, and (g) optionally, drying the further active layer; (2) use of a coating composition comprising a superhydrophilic agent or its precursor in the manufacture of a separation membrane; and (3) fuel tank comprising a drain valve which comprises the membrane.