US4166780A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Novel electrolytic process
Assignee: De Nora SpA
•
Filing: 1978-05-16
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Granted: 1979-09-04
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Expires: 1998-05-16
Abstract
Abstract An improved process for the production of halogens and alkali metal hydroxide by electrolysis of aqueous solution of alkali metal halides in a flowing mercury electrolysis cell wherein the salt solutions do not have to purified and to novel amalgam denuders and a mercury electrolytic cell plant without a salt purification step.
Inventors
- 👤 Giuseppe Bianchi
- 👤 Oronzio De Nora
- 👤 Placido M. Spaziante
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:04
CPC Classifications
C; C25; C25B; C25B1/00; C25B1/01; C25B1/34; C25B1/36; C25B1/42
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
97 words
In a process for electrolysis of an aqueous solution of an alkali metal halide in a mercury cathode electrolysis cell to produce halogen and alkali metal hydroxide, the improvement comprising subjecting the amalgam leaving the electrolysis to decomposition by anodic polarization under alkaline conditions to form mercury and an alkali metal hydroxide solution and subjecting the mercury to anodic polarization under acidic conditions in an electrolyte with a counter-electrode maintained at a sufficiently negative potential to remove from the mercury at least a portion of metal impurities contained and recycling the purified mercury to the electrolysis cell.
Claim 2
Dependent Claim
97 words
In a process for electrolysis of an aqueous solution of an alkali metal halide in a mercury cathode electrolysis cell to produce halogen and alkali metal hydroxide, the improvement comprising subjecting the amalgam leaving the electrolysis to decomposition by anodic polarization under alkaline conditions to form mercury and an alkali metal hydroxide solution and subjecting the mercury to anodic polarization under acidic conditions in an electrolyte with a counter-electrode maintained at a sufficiently negative potential to remove from the mercury at least a portion of metal impurities contained and recycling the purified mercury to the electrolysis cell.
Claim 3
Dependent Claim
19 words
The process of claim 1 wherein the electrolyte for the anodic polarization has a pH of 1 to 3.
Claim 4
Dependent Claim
34 words
The process of claim 1 wherein the ratio of the surface area of the mercury in the electrolysis cell and the surface area of the counter-electrode for the anodic polarization is 100 to 10,000.
Claim 5
Dependent Claim
24 words
The process of claim 1 wherein the ratio of the electrolysis current in the electrolysis cell and the anodic polarization is at least 10,000.
Claim 6
Dependent Claim
13 words
The process of claim 1 wherein the alkali metal halide is sodium chloride.
Claim 7
Dependent Claim
62 words
A process of decomposing sodium amalgam comprising subjecting sodium amalgam to decomposition by anodic polarization under alkaline conditions with water to form hydrogen and sodium hydroxide and subjecting the mercury to anodic polarization under acidic conditions in an electrolyte with a counter-electrode maintained at a sufficiently negative potential to remove from the mercury at least a portion of metal impurities contained therein.
Claim 8
Dependent Claim
62 words
A process of decomposing sodium amalgam comprising subjecting sodium amalgam to decomposition by anodic polarization under alkaline conditions with water to form hydrogen and sodium hydroxide and subjecting the mercury to anodic polarization under acidic conditions in an electrolyte with a counter-electrode maintained at a sufficiently negative potential to remove from the mercury at least a portion of metal impurities contained therein.
Claim 9
Dependent Claim
15 words
Th process of claim 6 wherein the pH of the electrolyte is 1 to 3.
Claim 10
Dependent Claim
34 words
The process of claim 6 wherein the mercury at the bottom of the denuder is subjected to anodic polarization in the presence of water at the bottom of the denuder to completely remove sodium.
References Cited (Backward Citations)
US3364128A
Cited
US3562123A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-09-03 | 1983-03-05 | 1983-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-09-03 | 1987-03-05 | 1987-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-09-03 | 1991-03-05 | 1991-09-04 | $7700.00 | Window Closed / Lapsed |