Patent US3658674A successfully refreshed from Google Patents.
US3658674A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for demineralization of water
Assignee: Standard Oil Co
•
Filing: 1970-02-13
•
Granted: 1972-04-25
•
Expires: 1990-02-13
Abstract
Abstract The invention described herein is a process for the purification of carbon. That process provides for the treatment of carbon with hydrofluoric acid, or a mixture of hydrofluoric acid and nitric acid, followed in each case by treatment with hot aqueous hydrochloric acid. The carbon thus purified is notably effective for use as electrode material in a demineralization cell, i.e., one used for the demineralization of water.
Inventors
- 👤 James L Benak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:45
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/48; B; B01; B01J; B01J47/00; B01J47/02; B01J47/06; B01J47/08; C01; C01B; C01B32/00; C02F1/46; C02F1/461; C02F1/46104; C02F1/46109; C02F1/469; C02F1/4691; C02F2001/46133
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
140 words
A process for the demineralization of water containing calcium sulfate ions comprising the steps of: A. passing the water successively through a plurality of carbon electrodes wherein the carbon has been treated to remove substantially all of the graphitoidal silicon and ash present in the carbon by means of a. immersing the carbon in a mixture of concentrated aqueous hydrofluoric acid and aqueous nitric acid, b. transferring the carbon to aqueous hydrochloric acid and boiling, c. rinsing the carbon with water, d. drying the carbon substantially free of water, e. rinsing the dried carbon with aqueous hydrochloric acid, f. rinsing the carbon with boiling water, and g. finally drying to substantially completely remove water; aNd B. imposing opposite electrical charges on adjacent carbon electrodes to attract the calcium sulfate as ions to the surface between an electrode and the water.
References Cited (Backward Citations)
US982704A
Cited
US1603298A
Cited
US2773025A
Cited
US2864750A
Cited
US3379637A
Cited
US3458415A
Cited
US3515664A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-04-25 | 1975-10-25 | 1976-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-25 | 1979-10-25 | 1980-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-25 | 1983-10-25 | 1984-04-25 | $7700.00 | Window Closed / Lapsed |