US3979286A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removal of heavy metal ions from aqueous solutions with insoluble cross-linked-starch-xanthates
Assignee: United States Department of Agriculture
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Filing: 1974-10-16
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Granted: 1976-09-07
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Expires: 1994-10-16
Abstract
Abstract An insoluble-starch-xanthate composition is prepared which is capable of removing most heavy metal ions from aqueous solutions. Concentrations of heavy metal ions contained in several industrial effluents were reduced to below the most stringent aqueous discharge limits.
Inventors
- 👤 Robert E. Wing
- 👤 William M. Doane
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:46
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/28; C02F1/286
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
111 words
A process of removing heavy metal ions from aqueous solutions comprising contacting heavy metal ions in aqueous solutions with an amount of a water-insoluble crosslinked-starch-xanthate, wherein said crosslinked-starch-xanthate has been prepared by first crosslinking starch with a crosslinking reagent and subsequently xanthating the crosslinked starch by reacting the same with carbon disulfide, and wherein said crosslinked-starch-xanthate has a degree of crosslinking (DCL) such that said crosslinked-starch-xanthate exhibits a degree of swelling in water at 95° C. of from 65% to 450%, said amount of crosslinked-starch-xanthate being such that the molar ratio of the xanthate moiety to metal ions is about 1:1, and removing said heavy metal ions from said aqueous solution.
Claim 2
Dependent Claim
111 words
A process of removing heavy metal ions from aqueous solutions comprising contacting heavy metal ions in aqueous solutions with an amount of a water-insoluble crosslinked-starch-xanthate, wherein said crosslinked-starch-xanthate has been prepared by first crosslinking starch with a crosslinking reagent and subsequently xanthating the crosslinked starch by reacting the same with carbon disulfide, and wherein said crosslinked-starch-xanthate has a degree of crosslinking (DCL) such that said crosslinked-starch-xanthate exhibits a degree of swelling in water at 95° C. of from 65% to 450%, said amount of crosslinked-starch-xanthate being such that the molar ratio of the xanthate moiety to metal ions is about 1:1, and removing said heavy metal ions from said aqueous solution.
Claim 3
Dependent Claim
32 words
A process as described in claim 1 wherein the crosslinked-starch-xanthate has the following general structure: ##STR5## where R = -H or ##STR6## ##STR7## where n = 1, 2, or 3; or ##STR8##
Claim 4
Dependent Claim
20 words
A process as described in claim 1 wherein the crosslinked-starch-xanthate exhibits a degree of swelling of from 65% to 75%.
Claim 5
Dependent Claim
21 words
A process as described in claim 1 wherein the crosslinked-starch-xanthate has a xanthate degree of substitution of from 0.1 to 1.
References Cited (Backward Citations)
US3834984A
Cited
US3763060A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-09-07 | 1980-03-08 | 1980-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-07 | 1984-03-08 | 1984-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-07 | 1988-03-08 | 1988-09-07 | $7700.00 | Window Closed / Lapsed |