US5213660A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Secondary fiber cellulose product with reduced levels of polychlorinated dibenzodioxins and polychlorinated dibenzofurans
Assignee: Paper Technology Foundation Inc
•
Filing: 1991-02-28
•
Granted: 1993-05-25
•
Expires: 2011-02-28
Abstract
Abstract A process for removing PCDD's and PCDF's from cellulose-containing fibers such as waste paper is provided. The process comprises contacting the fibers with supercritical or near supercritical carbon dioxide for a period of time sufficient to extract a substantial portion of the PCDD's and PCDF's without substantially damaging the fibers. Extraction efficiencies of greater than 95% have been achieved with the technique.
Inventors
- 👤 Shafi U. Hossain
- 👤 Carol A. Blaney
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 20:00
CPC Classifications
D; D21; D21C; D21C5/00; D21C5/02; B; B01; B01D; B01D11/00; B01D11/02; B01D11/0203; B01D11/0288; Y; Y02; Y02W; Y02W30/00; Y02W30/50; Y02W30/64
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
77 words
A cellulose-containing product having cellulose-containing secondary fibers originally processed using a chlorine bleaching step on fibers and having levels of polychlorinated dibenzo-p-dioxin and/or polychlorinated dibenzofuran reduced by at least 90% compared to said chlorine bleached fibers and made by the process of contacting said cellulose-containing secondary fibers containing said fibers originally processed using a chlorine bleaching step with carbon dioxide under pressure and temperature conditions such that the carbon dioxide is a supercritical or near supercritical fluid.
Claim 2
Dependent Claim
77 words
A cellulose-containing product having cellulose-containing secondary fibers originally processed using a chlorine bleaching step on fibers and having levels of polychlorinated dibenzo-p-dioxin and/or polychlorinated dibenzofuran reduced by at least 90% compared to said chlorine bleached fibers and made by the process of contacting said cellulose-containing secondary fibers containing said fibers originally processed using a chlorine bleaching step with carbon dioxide under pressure and temperature conditions such that the carbon dioxide is a supercritical or near supercritical fluid.
Claim 3
Dependent Claim
22 words
The cellulose-containing product of claim 1 wherein the pressure is above about 60 atmospheres and the temperature is above about 25° C.
Claim 4
Dependent Claim
22 words
The cellulose-containing product of claim 2 wherein the pressure is above about 73 atmospheres and the temperature is above about 31° C.
Claim 5
Dependent Claim
24 words
The cellulose-containing product of claim 3 wherein the pressure is less than about 300 atmospheres and the temperature is less than about 150° C.
Claim 6
Dependent Claim
31 words
The cellulose-containing product of claim 4 wherein the pressure is between about 80 atmospheres and about 200 atmospheres and wherein the temperature is between about 31° C. and about 90° C.
Claim 7
Dependent Claim
53 words
The cellulose-containing product of claim 1 wherein the supercritical or near supercritical carbon dioxide is flowed through the secondary fibers and wherein the rate of flow is between about 0.01 standard liters per minute per gram of dry secondary fiber and about 10 standard liters per minute per gram of dry secondary fiber.
Claim 8
Dependent Claim
38 words
The cellulose-containing product of claim 6 wherein the rate of flow is between about 0.1 standard liters per minute per gram of dry secondary fiber and about 1.0 standard liters per minute per gram of dry secondary fiber.
Claim 9
Dependent Claim
29 words
The cellulose-containing product of claim 6 wherein the supercritical or near supercritical carbon dioxide is flowed through the secondary fibers for between about one minute and about three hours.
Claim 10
Dependent Claim
29 words
The cellulose-containing product of claim 8 wherein the supercritical or near supercritical carbon dioxide is flowed through the secondary fibers for between about 3 minutes and about one hour.
Claim 11
Dependent Claim
32 words
The cellulose-containing product of claim 1 wherein the ratio of grams of supercritical or near supercritical carbon dioxide to the grams of dry secondary fiber is between about 10 and about 200.
References Cited (Backward Citations)
US3994770A
Cited
US4061566A
Cited
US4048007A
Cited
US4113446A
Cited
US4147624A
Cited
US4263253A
Cited
WO1981000854A1
Cited
WO1981000855A1
Cited
US4543190A
Cited
US4338199A
Cited
US4338199B1
Cited
US4308200A
Cited
US4472442A
Cited
US4466923A
Cited
US4703060A
Cited
US4554170A
Cited
US4550198A
Cited
US4495095A
Cited
US4564458A
Cited
US4728525A
Cited
US4493797A
Cited
US4675198A
Cited
US4594164A
Cited
US4647466A
Cited
US4767634A
Cited
EP0314223A2
Cited
US4956048A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-05-24 | 1996-11-23 | 1997-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-05-24 | 2000-11-23 | 2001-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-05-24 | 2004-11-23 | 2005-05-25 | $7700.00 | Window Closed / Lapsed |