Patent US4285819A successfully refreshed from Google Patents.
US4285819A
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US
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Functional magnetic microspheres
Assignee: California Institute of Technology
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Filing: 1980-01-28
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Granted: 1981-08-25
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Expires: 2000-01-28
Abstract
Abstract Functional magnetic particles are formed by dissolving a mucopolysaccharide such as chitosan in acidified aqueous solution containing a mixture of ferrous chloride and ferric chloride. As the pH of the solution is raised magnetite is formed in situ in the solution by raising the pH. The dissolved chitosan is a polyelectrolyte and forms micelles surrounding the granules at pH of 8-9. The chitosan precipitates on the granules to form microspheres containing the magnetic granules. On addition of the microspheres to waste aqueous streams containing dissolved ions, the hydroxyl and amine functionality of the chitosan forms chelates binding heavy metal cations such as lead, copper, and mercury and the chelates in turn bind anions such as nitrate, fluoride, phosphate and borate.
Inventors
- 👤 Shiao-Ping S. Yen
- 👤 Alan Rembaum
- 👤 Robert F. Landel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 01:01
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/44; B; B03; B03C; B03C1/00; B03C1/005; B03C1/01; C; C02; C02F; C02F1/00; C02F1/28; C02F1/288; C02F1/48; C02F1/488; C02F1/52; C02F1/5272; C02F1/68; C02F1/683
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
46 words
A composition comprising functional magnetic microsphere particles having a diameter from 100 angstroms to 1000 microns consisting essentially of: magnetic granules having a diameter less than 50 angstroms containing a coating of a water insoluble chitosan, said particles containing at least 0.1% by weight of metal.
Claim 2
Dependent Claim
46 words
A composition comprising functional magnetic microsphere particles having a diameter from 100 angstroms to 1000 microns consisting essentially of: magnetic granules having a diameter less than 50 angstroms containing a coating of a water insoluble chitosan, said particles containing at least 0.1% by weight of metal.
Claim 3
Dependent Claim
19 words
A composition according to claim 1 in which the chitosan has a degree of polymerization for 500 to 1500.
Claim 4
Dependent Claim
12 words
A composition according to claim 2 in which the granules comprise magnetite.
Claim 5
Dependent Claim
23 words
A composition according to claim 1 in which the particles are in the form of chitosan microspheres containing a dispersion of magnetite granules.
Claim 6
Dependent Claim
26 words
A composition according to claim 1 in which the microspheres contain from 1 to 25% metal and have a diameter from 500 angstroms to 1 micron.
Claim 7
Independent Claim
63 words
A method of removing ions from aqueous solution comprising the steps of: adding functional magnetic particles to the solution; said particles comprising a dispersion of at least 0.1% by weight magnetic granules in a chitosan microsphere having a diameter from 100 angstroms to 1000 angstroms; binding heavy metal ions to the particles to form chelates; and magnetically separating the particles from the solution.
Claim 8
Independent Claim
63 words
A method of removing ions from aqueous solution comprising the steps of: adding functional magnetic particles to the solution; said particles comprising a dispersion of at least 0.1% by weight magnetic granules in a chitosan microsphere having a diameter from 100 angstroms to 1000 angstroms; binding heavy metal ions to the particles to form chelates; and magnetically separating the particles from the solution.
Claim 9
Dependent Claim
24 words
A method according to claim 6 in which the ions are heavy metal ions that form chelate complexes with the coating on the particles.
Claim 10
Dependent Claim
20 words
A method according to claim 6 further including the step of binding anions from the solution to the chelate complexes.
Claim 11
Independent Claim
65 words
A method of forming functional magnetic particles comprising the steps of: dissolving a mixture of ferrous chloride and ferric chloride in water; adjusting the pH of the solution to a pH of 1 to 3; dissolving a mucopolysaccharide in the solution; raising the pH to above 7 to form micelles of the mucopolysaccharide containing granules of magnetite; and precipitating the mucopolysaccharide on the magnetite granules.
Claim 12
Independent Claim
65 words
A method of forming functional magnetic particles comprising the steps of: dissolving a mixture of ferrous chloride and ferric chloride in water; adjusting the pH of the solution to a pH of 1 to 3; dissolving a mucopolysaccharide in the solution; raising the pH to above 7 to form micelles of the mucopolysaccharide containing granules of magnetite; and precipitating the mucopolysaccharide on the magnetite granules.
Claim 13
Dependent Claim
14 words
A method according to claim 9 in which the mucopolysaccharide is a glucosamine polysaccharide.
Claim 14
Dependent Claim
12 words
A method according to claim 10 in which the polysaccharide is chitosan.
Claim 15
Dependent Claim
32 words
A method according to claim 10 in which the particles are in the form of microspheres containing from 0.1 to 90% iron and have a diameter from 100 angstroms to 1000 microns.
Claim 16
Dependent Claim
26 words
A method according to claim 12 in which the microspheres contain from 1 to 25% metal and have a diameter from 500 angstroms to 1 micron.
Claim 17
Dependent Claim
17 words
A method according to claim 13 in which the magnetite granules have a diameter below 50 angstroms.
Claim 18
Dependent Claim
19 words
A method according to claim 14 in which the chitosan has a degree of polymerization from 500 to 1500.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-08-24 | 1985-02-23 | 1985-08-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-08-24 | 1989-02-23 | 1989-08-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-08-24 | 1993-02-23 | 1993-08-25 | $7700.00 | Window Closed / Lapsed |