US4145283A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the purification of waste water
Assignee: Hoechst AG
•
Filing: 1977-12-14
•
Granted: 1979-03-20
•
Expires: 1997-12-14
Abstract
Abstract The waste water being formed upon the preparation of hydroxy aromatics, preferably of resorcinol and β-naphthol, by caustic alkaline melt of the corresponding aryl-sulfonic acids or aryl sulfonates is purified by wet oxidation with oxygen or oxygen-containing gases at temperatures of from about 100° to 370° C. and under a pressure of from about 1 to 300 bars. The COD-decomposition rates amount to about 90% and more. When a hydroxy aromatic is prepared by means of a caustic soda melt, this process provides a sulfate, especially sodium sulfate, which is of sufficient purity for further use without complementary purification stages. The obtention of the pure salt is important for the economy of the process.
Inventors
- 👤 Alwin Topp
- 👤 Klaus Schmiedel
- 👤 Georg Schaeffer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:49
CPC Classifications
C; C01; C01D; C01D5/00; C02; C02F; C02F11/00; C02F11/06; C02F11/08
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
112 words
In a process for the purification of waste water obtained during the preparation of a hydroxy aromatic by caustic alkaline melt of aryl sulfonic acid or aryl sulfonate to form a molten product wherein the molten product is dissolved in water or in an aqueous saline solution, the strongly alkaline liquor obtained is neutralized with sulfur dioxide or sulfuric acid and any precipitating salts and the hydroxy aromatic are separated from the neutralized waste water, the improvement comprising subjecting the neutralized waste water to wet oxidation with oxygen or an oxygen-containing gas at a temperature of rom about 100° to 370° C. under a pressure of from about 1 to 300 bars.
Claim 2
Dependent Claim
112 words
In a process for the purification of waste water obtained during the preparation of a hydroxy aromatic by caustic alkaline melt of aryl sulfonic acid or aryl sulfonate to form a molten product wherein the molten product is dissolved in water or in an aqueous saline solution, the strongly alkaline liquor obtained is neutralized with sulfur dioxide or sulfuric acid and any precipitating salts and the hydroxy aromatic are separated from the neutralized waste water, the improvement comprising subjecting the neutralized waste water to wet oxidation with oxygen or an oxygen-containing gas at a temperature of rom about 100° to 370° C. under a pressure of from about 1 to 300 bars.
Claim 3
Dependent Claim
30 words
The process according to claim 1, which comprises subjecting the waste water obtained upon the preparation of resorcinol by caustic alkaline melt of benzene-1,3-disulfonic acid or benzene-1,3-disulfonate to wet oxidation.
Claim 4
Dependent Claim
30 words
The process according to claim 1, which comprises subjecting the waste water obtained upon the preparation of β-naphthol by caustic alkaline melt of naphthalene-2-sulfonic acid or naphthalene-2-sulfonate to wet oxidation.
Claim 5
Dependent Claim
25 words
The process according to claim 1, which comprises isolating pure sodium sulfate by crystallization and filtration from the waste water submitted to the wet oxidation.
Claim 6
Dependent Claim
47 words
The process according to claim 1 which comprises at least partially recycling a mother liquor obtained by a continuous process of wet oxidation of the waste water and separation of crystallized salts and using the liquor as an aqueous saline solution for the dissolution of the melt.
Claim 7
Dependent Claim
23 words
A process according to claim 5 wherein the process is carried out discontinuously and the aqueous saline solution is reused in another batch.
Claim 8
Dependent Claim
23 words
A process as in claim 1 wherein the oxygen or oxygen-containing gas is at a temperature of from about 180° to 300° C.
Claim 9
Dependent Claim
23 words
A process as in claim 1 wherein the oxygen or oxygen-containing gas is under a pressure of from about 30 to 150 bars.
References Cited (Backward Citations)
US2760992A
Cited
US2665249A
Cited
US2856437A
Cited
US3426083A
Cited
US3907678A
Cited
US4026791A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-03-19 | 1982-09-18 | 1983-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-03-19 | 1986-09-18 | 1987-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-03-19 | 1990-09-18 | 1991-03-20 | $7700.00 | Window Closed / Lapsed |