The filter medium is a filter medium which uses a liquid containing oil and water as a separation target, and has a channel for the liquid. The filter medium includes a base constituting the channel, and one or more of nitrogen-containing fluorine compounds which are provided on at least a portion of a surface of the channel. The nitrogen-containing fluorine compound includes an oil-repellency imparting group and any one hydrophilicity imparting group selected from a group consisting of an anion type, a cation type, and an amphoteric type, in a molecule.

The filter medium is a filter medium which uses a liquid containing oil and water as a separation target, and has a channel for the liquid. The filter medium includes a base constituting the channel, and one or more of nitrogen-containing fluorine compounds which are provided on at least a portion of a surface of the channel. The nitrogen-containing fluorine compound includes an oil-repellency imparting group and any one hydrophilicity imparting group selected from a group consisting of an anion type, a cation type, and an amphoteric type, in a molecule.

The filter medium is a filter medium which uses a liquid containing oil and water as a separation target, and has a channel for the liquid. The filter medium includes a base constituting the channel, and one or more of nitrogen-containing fluorine compounds which are provided on at least a portion of a surface of the channel. The nitrogen-containing fluorine compound includes an oil-repellency imparting group and any one hydrophilicity imparting group selected from a group consisting of an anion type, a cation type, and an amphoteric type, in a molecule.

A textile having high fluorine adhesion rate, and excellent water- and oil-repellency can be obtained by a method of producing a treated textile, comprising steps of: (1) preparing a treatment liquid comprising a water- and oil-repellent agent which comprises at least one fluorine-containing compound selected from the group consisting of a fluorine-containing polymer or a fluorine-containing low molecular weight compound, (2) adjusting pH of the treatment liquid to at most 7, (3) applying the treatment liquid to a textile, (4) treating the textile with steam, and (5) washing the textile with water and dehydrating the textile, wherein the treatment liquid comprises a thermally gelling substance.

A textile having high fluorine adhesion rate, and excellent water- and oil-repellency can be obtained by a method of producing a treated textile, comprising steps of: (1) preparing a treatment liquid comprising a water- and oil-repellent agent which comprises at least one fluorine-containing compound selected from the group consisting of a fluorine-containing polymer or a fluorine-containing low molecular weight compound, (2) adjusting pH of the treatment liquid to at most 7, (3) applying the treatment liquid to a textile, (4) treating the textile with steam, and (5) washing the textile with water and dehydrating the textile, wherein the treatment liquid comprises a thermally gelling substance.