Abstract: A method for operating a reverse osmosis membrane filtration plant having a raw water intake unit, a pre-treatment unit, and a reverse osmosis membrane filtration unit having a reverse osmosis membrane module in this order, the method including: disposing a biofilm formation base material under conditions that reverse osmosis membrane supply water and/or reverse osmosis membrane non-permeated water in the reverse osmosis membrane filtration unit are/is flowed at a linear speed equal to a non-permeated water linear speed in the reverse osmosis membrane module of the reverse osmosis membrane filtration unit; evaluating a biofilm amount on the biofilm formation base material at a frequency of from once a day to once in six months; and controlling the method for operating a reverse osmosis membrane filtration plant based on results of the evaluation.

Abstract: The present invention relates to a surface-treated plastic article including a thin layer composed of a polymer complex on the surface. The surface-treated plastic article can be produced by a treatment with at least one kind of aqueous solutions of polymers having a weight average molecular weight of 200 or more. According to the present invention, the plastic articles, such as contact lenses, having superior transparency, wettability, oxygen permeability, and mechanical properties can be provided.

Abstract: The present invention relates to a surface-treated plastic article including a thin layer composed of a polymer complex on the surface. The surface-treated plastic article can be produced by a treatment with at least one kind of aqueous solutions of polymers having a weight average molecular weight of 200 or more. According to the present invention, the plastic articles, such as contact lenses, having superior transparency, wettability, oxygen permeability, and mechanical properties can be provided.

Abstract: The present invention relates to a surface-treated plastic article including a thin layer composed of a polymer complex on the surface. The surface-treated plastic article can be produced by a treatment with at least one kind of aqueous solutions of polymers having a weight average molecular weight of 200 or more. According to the present invention, the plastic articles, such as contact lenses, having superior transparency, wettability, oxygen permeability, and mechanical properties can be provided.

Abstract: The present invention relates to a surface-treated plastic article including a thin layer composed of a polymer complex on the surface. The surface-treated plastic article can be produced by a treatment with at least one kind of aqueous solutions of polymers having a weight average molecular weight of 200 or more. According to the present invention, the plastic articles, such as contact lenses, having superior transparency, wettability, oxygen permeability, and mechanical properties can be provided.

Abstract: A process of producing a composite semipermeable membrane which includes applying a polyfunctional amine solution and a polyfunctional acid halide solution in a hydrocarbon-based solvent having a flash point of not lower than 10.degree. C. on a surface of a microporous substrate to allow interfacial polycondensation reaction so as to form a cross-linked polyamide-based ultra-thin membrane superposed on the microporous substrate, then blowing a gas on the surface of the ultra-thin membrane so as to evaporate the hydrocarbon-based solvent, which gas has a velocity at the surface of 2-20 m/sec., a temperature of 10.degree.-80.degree. C. that is lower than the flash point of the hydrocarbon-based solvent, and an absolute humidity of not less than 1 g of water per 1 kg of dry gas.

Abstract: A composite membrane excelling in organic solvent resistance, heat resistance and organic vapor resistance is disclosed. The composite membrane of the present invention comprises a porous membrane including as a major constituent a polymer having a repeating unit represented by the formula (I)--Ph--S--Ph--SO.sub.2).sub.n (I)(wherein Ph represents phenyl group, n represents a natural number) and an active layer formed on said porous membrane. The composite membrane of the present invention may be used as a composite membrane for pervaporation, gas separation membrane and as a reverse osmosis membrane.

Abstract: A composite semipermeable membrane which has a high electrolytes rejection even when the concentration of the electrolytes in feed water is very low and even if the pH of feed water is not less than 8 is disclosed. The composite semipermeable membrane of the present invention comprises a microporous substrate and a cross-linked polyamide-based ultra-thin membrane laminated on the microporous substrate, the ultra-thin membrane having a covalently bonded quaternary nitrogen atom.

Abstract: An oxygen scavenger comprises an oxygen absorbent composition and an oxygen permeable film covering the oxygen absorbent composition and including an asymmetric porous membrane whose outer surface portion in the thickness direction of the asymmetric porous membrane is formed as a dense skin layer. Since the dense skin layer is very thin, the oxygen permeability to the oxygen absorbent composition through the oxygen permeable film can be maintained sufficiently high. At the same time, since the dense skin layer has a sufficiently high barrier property as well as a high oxygen permeability, contact of the substances stored in a container with the oxygen absorbent composition can be surely prevented. The substances stored in the container attached with the oxygen scavenger can be prevented from deterioration due to the oxygen present in the container by a high oxygen absorption ability of the scavenger, and maintained in a good or fresh condition for a long term.

Abstract: The present invention relates to a porous membrane which has excellent durability and is useful for ultrafiltration. The porous membrane of the present invention has heterogeneous structure, which consists essentially of a phenylenesulfide-based copolymer of the formula:(Ph--S--Ph--X--).sub.q --(wherein Ph represents phenylene group, X represents --SO.sub.2 -- or --CO--, and g represents an integer from 80-400 which membrane has a dense layer on one or both surfaces of the membrane, the dense layer controlling the separation performance of the membrane, and a porous layer next to the dense layer, which porous layer has a porosity higher than that of the dense layer.

Abstract: Alkyldiamine, 1,3,5-trihydroxybenzene or 1,3-dihydroxybenzene is added as a copolymerization component to a polyfunctional aromatic amine component in the amount of 1-20% by weight with respect to the polyfunctional aromatic amine in producing a composite semipermeable membrane by laminating on a microporous substrate a polyamide formed by interfacial polycondensation between a polyfunctional aromatic amine and a polyfunctional acid halide. The composite semipermeable membrane has improved oxidation resistance while retaining excellent separation selectivity and high permeability of the crosslinked polyamide-based composite semipermeable membrane. The composite semipermeable membrane is used for desalination of brackish and sea water.

Abstract: A process for preparing a semipermeable composite membrane comprising a microporous substrate and an ultra-thin membrane covering the substrate, wherein the ultra-thin membrane comprises a crosslinked piperazine polyamide as a main component and contains a constituent component represented by the following general formula (I): ##STR1## wherein R stands for --H or --CH.sub.3 and n is an integer of from 0 to 3.

Abstract: A semipermeable composite membrane comprising a microporous substrate and an ultra-thin membrane with which the substrate is coated, characterized in that the ultra-thin membrane is composed of a cross-linked aromatic polyamide and the cross-linked aromatic polyamide contains a tri- or higher functional aryl residue having at least two --NH groups. The semipermeable composite membrane has a high solute rejection, high and stable water flux and durability, and thereby may be applicable to various fields.

Abstract: An interfacially synthesized reverse osmosis membrane comprising a microporous substrate and an ultra-thin membrane covering the substrate, wherein the ultra-thin membrane comprises a crosslinked piperazine polyamide as a main component and contains a constituent component represented by the following general formula (1): ##STR1## wherein R stands for --H or --CH.sub.3 and n is an integer of from 0 to 3.

Abstract: A high performance semipermeable composite membrane containing a microporous substrate having a semipermeable membrane on the surface thereof. A composite ultrathin solute rejection barrier is formed on an intermediate transport layer which in turn is formed on a substrate.A mixture of a water soluble organic polymer having reactive amino groups in terminal and/or side chains, together with a monomer or monomeric polyamine is reacted with an agent having a polyfunctional group.

Abstract: A membrane treating agent for rejuvenating and improving a rejection performance of a semipermeable membrane, which contains an effective amount of a modified vinyl polymer having acetoxy groups and at least one group represented by the Formula (I) and/or (II): ##STR1## wherein R is a radical selected from the group consisting of aliphatic, aromatic and heterocyclic radicals having from 1 to 9 carbon atoms, and n is an integer from 1 to 3.Valuable modified vinyl polymers are obtained by reacting a partially saponified vinyl polymer with at least one carboxylic acid such as maleic acid, phthalic acid, succinic acid, butane tetracarboxylic acid and/or acid anhydrides or acid chlorides thereof.

Abstract: A high performance semipermeable composite membrane containing a microporous substrate having a semipermeable membrane on the surface thereof. A composite ultrathin solute rejection barrier is formed on an intermediate transport layer which in turn is formed on a substrate.A mixture of a water soluble organic polymer having reactive amino groups in terminal and/or side chains, together with a monomer or monomeric polyamine is reacted with an agent having a polyfunctional group.

Abstract: Cellulose derivative reverse osmosis membrane containing tetracarboxylic acid and mono- or divalent carboxylic acid.

Abstract: Cellulose derivative reverse osmosis membrane containing tetracarboxylic acid and mono- or divalent carboxylic acid.