The composite anion exchange membrane includes: a surface layer on a single surface or both surfaces of an anion exchange membrane substrate, in which the above-described surface layer contains a copolymer of a monomer A which is a water-soluble polyfunctional monomer and a monomer B which is a cationic monomer, an anion exchange capacity of the above-described surface layer is 0.05 meq/cm.sup.3 to 0.50 meq/cm.sup.3, and an anion exchange capacity of the above-described anion exchange membrane substrate is 1.0 meq/cm.sup.3 to 5.0 meq/cm.sup.3.

The composite anion exchange membrane includes: a surface layer on a single surface or both surfaces of an anion exchange membrane substrate, in which the above-described surface layer contains a copolymer of a monomer A which is a water-soluble polyfunctional monomer and a monomer B which is a cationic monomer, an anion exchange capacity of the above-described surface layer is 0.05 meq/cm.sup.3 to 0.50 meq/cm.sup.3, and an anion exchange capacity of the above-described anion exchange membrane substrate is 1.0 meq/cm.sup.3 to 5.0 meq/cm.sup.3.

The separations membrane system includes a substrate, a microporous layer, and a selective layer. The microporous layer may be disposed over the substrate. The selective layer may be disposed over the microporous layer, thereby sandwiching the microporous layer between the selective layer and the substrate. The microporous layer includes a thermoplastic material. The selective layer includes a polyamide structure of 2,2-Dimethyl-1,3-propanediamine and/or 1,3,5-Benzenetricarbonyl chloride.

The separations membrane system includes a substrate, a microporous layer, and a selective layer. The microporous layer may be disposed over the substrate. The selective layer may be disposed over the microporous layer, thereby sandwiching the microporous layer between the selective layer and the substrate. The microporous layer includes a thermoplastic material. The selective layer includes a polyamide structure of 2,2-Dimethyl-1,3-propanediamine and/or 1,3,5-Benzenetricarbonyl chloride.

A filtering device is for obtaining a chemical liquid by purifying a liquid to be purified, and has an inlet portion, an outlet portion, a filter A, at least one filter B different from the filter A, and a flow path which includes the filter A and the filter B arranged in series between the inlet portion and the outlet portion and extends from the inlet portion to the outlet portion, in which the filter A includes at least one kind of porous membrane selected from the group consisting of a first porous membrane having a porous base material made of polytetrafluoroethylene and a non-crosslinked coating which is formed to cover the porous base material and contains a perfluorosulfonic acid polymer and a second porous membrane containing polytetrafluoroethylene blended with a perfluorosulfonic acid polymer.

A filtering device is for obtaining a chemical liquid by purifying a liquid to be purified, and has an inlet portion, an outlet portion, a filter A, at least one filter B different from the filter A, and a flow path which includes the filter A and the filter B arranged in series between the inlet portion and the outlet portion and extends from the inlet portion to the outlet portion, in which the filter A includes at least one kind of porous membrane selected from the group consisting of a first porous membrane having a porous base material made of polytetrafluoroethylene and a non-crosslinked coating which is formed to cover the porous base material and contains a perfluorosulfonic acid polymer and a second porous membrane containing polytetrafluoroethylene blended with a perfluorosulfonic acid polymer.

The present invention provides a semipermeable membrane which has resistance to oxidizing agents even in the presence of heavy metals and which, despite this, can have salt-removing performance equal to that of semipermeable membranes having poor resistance to oxidizing agents. A coated semipermeable membrane of the invention includes a semipermeable layer and a polymer layer formed on the semipermeable layer, and the polymer layer includes a polymerization product formed by both condensation of hydrolyzable groups possessed by the following compound (A) and polymerization of the compound (A) with the following compound (B): (A) a silicon compound having a silicon atom, a reactive group including an ethylenically unsaturated group directly bonded to the silicon atom, and a hydrolyzable group directly bonded to the silicon atom; and (B) a compound other than the compound (A), which has both a hydrophilic group and an ethylenically unsaturated group.

The present invention provides a semipermeable membrane which has resistance to oxidizing agents even in the presence of heavy metals and which, despite this, can have salt-removing performance equal to that of semipermeable membranes having poor resistance to oxidizing agents. A coated semipermeable membrane of the invention includes a semipermeable layer and a polymer layer formed on the semipermeable layer, and the polymer layer includes a polymerization product formed by both condensation of hydrolyzable groups possessed by the following compound (A) and polymerization of the compound (A) with the following compound (B): (A) a silicon compound having a silicon atom, a reactive group including an ethylenically unsaturated group directly bonded to the silicon atom, and a hydrolyzable group directly bonded to the silicon atom; and (B) a compound other than the compound (A), which has both a hydrophilic group and an ethylenically unsaturated group.

The present invention refers to a surface coating of commercial polyamide (PA) membranes with graphene oxide (GO) using a technology that involves spin-coating with specific sequence of low and high rotation, interface phenomena provided by a set of materials containing ethyl alcohol in high concentration, as well as morphological characteristics and customized surface chemistry of GO, among other conditions that allow a differentiated technology to obtain an effective coating of GO on PA membrane.

The present invention refers to a surface coating of commercial polyamide (PA) membranes with graphene oxide (GO) using a technology that involves spin-coating with specific sequence of low and high rotation, interface phenomena provided by a set of materials containing ethyl alcohol in high concentration, as well as morphological characteristics and customized surface chemistry of GO, among other conditions that allow a differentiated technology to obtain an effective coating of GO on PA membrane.