# US 4,392,960 A · Process for the removal of urea from aqueous solutions

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- Number: US 4,392,960 A
- Document ID: US4392960A
- Status: Granted
- Kind: A
- Application number: 05/652,812
- Filed: 1976-01-27
- Granted: 1983-07-12
- Earliest claimed: 1975-01-27
- Assignees: A. T. Ramot Plastics Ltd.
- Inventors: Menahem A. Kraus; Moshe A. Frommer; Mara Nemas; Rodika Gutman
- Web page: https://patentgrep.com/patent/US4392960A

## CPC

- B01D 71/56: Polyamides, e.g. polyester-amides
- A61M 1/3679: {by absorption (A61M1/3675 takes precedence)}
- B01D 67/0006: {by chemical reactions (in-situ polymerisation, polycondensation, cross-linking or reaction for manufacturing composite membranes B01D69/125)}
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}

## Abstract

A process for the removal of urea from an aqueous solution containing same, which comprises subjecting the solution to reverse osmosis through a polymeric membrane prepared from a polymer of the formula --(--A--X--).sub.n wherein A designates an aromatic moiety and X designates a bivalent linking group, the aromatic moiety A being chosen from the group consisting of phenyl, biphenyl, naphthyl, and mixtures of such moieties; and such moieties connected by means of linkages selected from --O--, --SO.sub.2 --, --SO--, --NH--, --CH.sub.2 --, and --PO(R) (wherein R is alkyl); mixtures of aromatic and aliphatic chains of not more than 6 carbon atoms which do not constitute above 40 mole-% of the A-groups; mixtures of aromatic and alicyclic moieties wherein the alicyclic moieties do not constitute more than 50 mole-% of the A-groups; mixtures of aromatic and heterocyclic moieties, wherein said A moieties are optionally substituted by one or more substituents selected from the group consisting of alkyl of up to 4 carbon atoms, alkoxy of up to 4 carbon atoms, amino, dialkylamino, hydroxy, carboxy, carboxamido and sulfonic acid; the group X being selected from amido (--NH--CO--), substituted amido (--NR--CO--) wherein R is lower alkyl, provided that the substituted amido groups do not constitute more than 50 mole-% of the X groups; hydrazido (--CO--NH--NH--CO--), ureido (--NH-- CO--NH--), semicarbazido (--NH--CO--NH--NH--CO--), sulfonamido (--SO.sub.2 --NH--), and phosphoramido of the formula --CO--NH--Ar--NH--PO(NHAr)--NH--Ar--NH--CO and mixtures of the above linking groups, and wherein n is about 80 to 300, and devices for the hyperfiltration of urea-containing aqueous solutions, whenever based on the above process and on membranes defined above.

## Claims

### Claim 1

A process for the removal of urea from an aqueous solution containing same, wherein a removal equivalent to a rejection of at least 60% from a urea concentration of 5,000 ppm and at 600 psi operating pressure is achieved, which comprises subjecting the solution to reverse osmosis through a polymeric membrane produced from a polymer obtained by the polymerization of m-phenylenediamine, 3,3'-diamino-N,N',N"-triphenyl phosphoric triamide and isophthaloyl chloride.