Toray Industries, Inc.

Masaru Kurihara

Tadahiro Uemura

Tetsuo Watanabe

Yoshio Himeshima

Yukio Nakagawa

Hideo Fujimaki

Noriaki Dokoshi

Tetsuo Inoue

Tatsuo Sasaki

Chiaki Tanaka

Takashi Kubota

Saburo Fujita

Shinichi Yamada

Kuniyasu Shiro

Hideaki Tanisugi

Katsufumi Oto

Naoya Yoda

Hiroyuki Yamamura

Katsunosuke Maeda

Masamitsu Tanimura

Toshihiro Ikeda

Yoichi Shimokawa

Tatsundo Tanaka

Toshiya Yoshi-i

Hiroshi Mochizuki

Hirosuke Yumoto

Soichi Tokizane

Kiyoshi Okada

Akio Kobayashi

Noriho Harumiya

Kojuro Ikeda

This invention relates to an apparatus and method for a multistage reverse osmosis separation which comprises reverse osmosis membrane module units arranged at multistage with a booster pump provided in the concentrate flow channel between reverse osmosis membrane module unit, wherein the total effective reverse osmosis membrane area of a module unit is in the range of 20-80% of that of the preceding module unit. The object of this invention is to provide apparatus and separation method that produce low-concentration solution from high-concentration solution with a high recovery ratio, small energy requirements, and high stability.

Apparatus and method for multistage reverse osmosis separation

Composite membrane

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.

Composite semipermeable membrane, process of producing the same and

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.

Porous membrane and production process thereof

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.

Process for preparation of semipermeable composite membrane

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.

Interfacially synthesized reverse osmosis membrane

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.

The present invention relates to the membrane treatment method for semipermeable membranes, that is, a method wherein it is characterized that not only remarkable improving effect of selective separation performance of semipermeable membranes is obtained but also durability of said improving effect for selective separation performance is improved by means of extremely simple and easy procedures such as said semipermeable membranes are successively brought into contact with very dilute of aqueous solutions including effective substances which are individually water-soluble in due order and for a short time, where said effective water-soluble substances form water-insoluble or very little water-soluble materials thereof fixed on the surface of said semipermeable membranes. The aforesaid remarkable effect is observed especially in the case of semipermeable membranes consisted of cross-linked polymers based of furfuryl alcohol including furfuryl alcohol as an essential monomer component, and polyamides, when, at the same time, the due combination of water-soluble amines and water-soluble aldehyde is employed as said aqueous solutions including effective water-soluble substances.

Membrane treatment method for semipermeable membranes

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.

High performance semipermeable composite membrane and process for

A method of producing a semipermeable membrane comprising a polymeric material based upon a trisisocyanurate structure ##STR1## wherein, R.sub.1, R.sub.2 and R.sub.3 are hydrogen or alkyl radicals containing from 2 to 5 carbon atoms, and at least two of R.sub.1, R.sub.2 and R.sub.3 are alkyl radicals having hydroxyl or glycidyl groups. The membrane has high solute rejection, high flux, excellent high pressure resistance, and high temperature resistance and is a highly useful composite membrane for reverse osmosis. In the method, an aqueous solution containing, for example, a reaction product of Formula I is applied to the surface of a porous substrate and is heated at a temperature of about 100.degree. C. to 190.degree. C. to provide a cross-linked structure including a multiplicity of isocyanurate groups on the porous substrate.

Method of making a reverse osmosis semipermeable membrane

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.

Semipermeable membrane treated with modified vinyl polymer

A method for the selective separation of at least one water-soluble useful material from an aqueous solution by reverse osmosis is provided. The method comprises contacting the aqueous solution under pressure maintained above the osmotic pressure of the aqueous solution with a semipermeable composite membrane. The semipermeable composite membrane comprises a microporous substrate and a barrier layer having about 0.01 to about 0.1 micron thickness and composed of a cross-linked polymeric material having isocyanurate structures of Formula (I) formed on the microporous substrate: ##STR1## wherein each of R.sub.1, R.sub.2 and R.sub.3 is selected from the group consisting of hydrogen, a glycidyl group, and an alkyl radical containing from 2 to 5 carbon atoms, an alkyl radical carrying a functional hydroxyl group and an alkyl radical carrying a functional glycidyl group, with the proviso that at least two of R.sub.1, R.sub.2 and R.sub.3 are glycidyl groups, alkyl radicals carrying functional hydroxyl groups, alkyl radicals carrying glycidyl groups or a combination thereof. The cross-linked polymeric material has ether linkages, ester linkages or a combination thereof connecting the isocyanurate structures to each other.

Reverse osmosis using a composite isocyanurate membrane

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

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Otsu, Japan

Masaru Kurihara