Filter medium, method for producing filter medium, water treatment module, and water treatment device

A filter medium which uses a liquid containing oil and water as a separation target, and has a channel for the liquid, the medium comprising:

• 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 and are represented by the following formulas (1) to (4),
• wherein, in the formulas (1) and (2), each of Rf1 and Rf2 is a straight-chain or branched perfluoroalkyl group which is the same as or different from each other, and has 1 to 6 carbon atoms, and Rf3 is a straight-chain or branched perfluoroalkylene group which has 1 to 6 carbon atoms;
• in the formulas (3) and (4), each of Rf4, Rf5, and Rf6 is a straight-chain or branched perfluoroalkylene group which is the same as or different from each other, and has 1 to 6 carbon atoms, and Z includes any of an oxygen atom, a nitrogen atom, a CF2 group, and a CF group;
• in the formulas (2) and (4), R is a linking group which is a bivalent organic group;
• and
• in the formulas (1) to (4), X is
• an anion type hydrophilicity imparting group having “—CO2M1”, “—OSO3M1”, “—OP(OH)O2M1”, “—OPO3M12”, “═O2PO2M1”, or “—PO(OH)x(OM1)2-y” (M1 indicates alkali metal, alkaline-earth metal, Mg, and Al, and R1R2R3R4N+;
• R1 to R4 indicate straight chain or branched alkyl groups which are independent from each other, and have hydrogen atoms or 1 to 20 carbon atoms;
• and y indicates an integer of 0 to 2), or
• a cation type hydrophilicity imparting group having “—N+R5R6R7.Cl—”, “—N+R5R6R7.Br—”, “—N+R5R6R7.I—”, “—N+R5R6R7.CH3SO3−”, “—N+R5R6R7.R7SO4−”, “—N+R5R6R7.NO3−”, “(—N+R5R6R7)2CO32−”, or “(—N+R5R6R7)2SO42−” at the termination (R5 to R7 are straight chain or branched alkyl groups which are independent from each other, and have hydrogen atoms or 1 to 20 carbon atoms), or
• an amphoteric type hydrophilicity imparting group having “—N+R8R9(CH2)nCO2—”, a sulfobetaine type of “—N+R8R9(CH2)nSO3−”, an amine oxide type of “—N+R8R9O—”, or a phosphobetaine type of “—OPO3−(CH2)nN+R8R9R10” at the termination (n is an integer of 1 to 5, R8 and R9 indicates an alkyl group having a hydrogen atom or 1 to 10 carbon atoms, and R10 indicates an alkyl group having a hydrogen atom or 1 to 10 carbon atoms or an alkylene group having 1 to 10 carbon atoms).