US4145281A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Water purification process
Assignee: Monsanto Co
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Filing: 1976-12-20
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Granted: 1979-03-20
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Expires: 1996-12-20
Abstract
Abstract Process for the removal of chromium and zinc corrosion inhibitor compounds from cooling tower blowdown streams, comprising contacting the water of said streams first with a weakly basic anion exchange resin and then with a weakly acidic cation exchange resin.
Inventors
- 👤 Michael F. Weishaar
- 👤 F. Leon Ballard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:02
CPC Classifications
B; B01; B01J; B01J39/00; B01J39/04; B01J39/07
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
61 words
A process for the selective removal of chromate, chromium and zinc ions from water containing total dissolved solids as total hardness of 100-1500 ppm, expressed as CaCo 3 , which comprises contacting said water first with a weakly basic anion exchange resin in a sulfate or chloride form, and then with a weakly acidic cation exchange resin in a sodium form.
Claim 2
Dependent Claim
61 words
A process for the selective removal of chromate, chromium and zinc ions from water containing total dissolved solids as total hardness of 100-1500 ppm, expressed as CaCo 3 , which comprises contacting said water first with a weakly basic anion exchange resin in a sulfate or chloride form, and then with a weakly acidic cation exchange resin in a sodium form.
References Cited (Backward Citations)
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 |