US4828701A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature-sensitive method of size-selective extraction from solution
Assignee: University of Minnesota System
•
Filing: 1987-12-08
•
Granted: 1989-05-09
•
Expires: 2007-12-08
Abstract
Abstract A separation method utilizing the ability of temperature-sensitive cross-linked polymer gels to selectively extract solvent from a solution of a macromolecular material. A feed solution containing macromolecules is added to a small amount of gel. The gel swells to absorb the low molecular weight solvent, but it cannot absorb the macromolecules. The raffinate, which is now a concentrated macromolecular solution, is drawn off. To regenerate, the filtered gel is warmed, so that its volume decreases sharply. This suddenly decreased volume occurs because the gel is near a critical point. The solvent is removed from the shrunken gel. The temperature of the gel is then lowered; more feed solution is added; and the cycle is begun again.
Inventors
- 👤 Edward L. Cussler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:41
CPC Classifications
B; B01; B01D; B01D15/00; B01D15/08; B01D15/26; B01D15/34; B01D15/38; B01D15/3861; B01D15/3876
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
106 words
A method for selectively extracting low molecular weight solvents from solution of higher molecular weight solutes which comprises: a. mixing a solution containing a low molecular weight solvent and a higher molecular weight solute with a cross-linked polymer gel selected from the group consisting of N-substituted polyacrylamides and copolymers of N-substituted acrylamide; b. swelling the gel to absorb a portion of the solvent from the solution by substantially maintaining the temperature of the gel at a preselected temperature slightly below the lower critical solution temperature of the gel, to yield a concentrated solution of the solute; and c. separating the concentrated solution from the swollen gel.
Claim 2
Independent Claim
106 words
A method for selectively extracting low molecular weight solvents from solution of higher molecular weight solutes which comprises: a. mixing a solution containing a low molecular weight solvent and a higher molecular weight solute with a cross-linked polymer gel selected from the group consisting of N-substituted polyacrylamides and copolymers of N-substituted acrylamide; b. swelling the gel to absorb a portion of the solvent from the solution by substantially maintaining the temperature of the gel at a preselected temperature slightly below the lower critical solution temperature of the gel, to yield a concentrated solution of the solute; and c. separating the concentrated solution from the swollen gel.
Claim 3
Dependent Claim
56 words
The method of claim 1 further comprising: d. warming the gel to a temperature slightly above the lower critical solution temperature of the swollen gel, so that the gel undergoes a phase change and shrinks to a reduced volume, and releases most of the absorbed solvent; and e. separating the solvent from the reduced volume gel.
Claim 4
Dependent Claim
76 words
The method of claim 2 wherein the concentrated solution of the solute is further concentrated by: a. admixing the concentrated solution with the reduced volume gel and maintaining the mixture at a temperature slightly below the lower critical solution temperature of the gel, to swell the gel and to absorb a further portion of the solution by the gel to yield a further concentrated solution; and b. separating the further concentrated solution from the swollen gel.
Claim 5
Dependent Claim
23 words
The method of claim 2, wherein the gel is of polyisopropyl acrylamide crosslinked with methylene bis-acrylamide and is swollen at about 25°-32° C.
Claim 6
Dependent Claim
23 words
The method of claim 4 wherein the volume of the reduced volume gel is about 10% of the volume of the swollen gel.
Claim 7
Dependent Claim
23 words
The method of claim 2 wherein the gel is a copolymer of poly(N,N-diethylacrylamide) and sodium methacrylate and is swollen at about 25°-55° C.
Claim 8
Dependent Claim
23 words
The method of claim 6 wherein the volume of the reduced volume gel is about 5% of the volume of the swollen gel.
References Cited (Backward Citations)
US3386912A
Cited
US3721621A
Cited
US3658745A
Cited
US3817379A
Cited
US3925017A
Cited
US3968093A
Cited
US4555344A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-05-08 | 1992-11-07 | 1993-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-08 | 1996-11-07 | 1997-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-08 | 2000-11-07 | 2001-05-09 | $7700.00 | Window Closed / Lapsed |