US3956121A
Expired / Lapsed
US
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Process for the precipitation of heavy metal ion-polycarboxylate complexes
Assignee: Evonik Operations GmbH
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Filing: 1974-11-11
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Granted: 1976-05-11
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Expires: 1994-11-11
Abstract
Abstract A process for precipitating heavy metal ion-polycarboxylate complexes from solution, said process comprising adding to a solution containing at least one of said complexes an aqueous solution of a water soluble aluminum salt, the anion of which does not form any water soluble complexes with said heavy metal ions to be precipitated or optionally such anion-heavy metal complexes having a stability constant, expressed as their decadic logarithm, of less than 2; wherein 0.9 to 1.8 moles of aluminum ions are employed per equivalent of polycarboxylate; and adjusting the pH of the resulting reaction mixture to about 6.5 to about 9.0 with an alkali metal carbonate.
Inventors
- 👤 Heinz Haschke
- 👤 Helmut Knorre
- 👤 Gerhard Morlock
- 👤 Gerhard Pohl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:35
CPC Classifications
C; C02; C02F; C02F9/00; C02F1/00; C02F1/52; C02F1/5236; C02F1/001; C02F1/66; C02F2101/00; C02F2101/10; C02F2101/20; C02F2101/30; C02F2101/303
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
178 words
A process for precipitating heavy metal ion-polycarboxylate complexes from an aqueous metal processing effluent said process comprising adding to said aqueous effluent containing at least one of said complexes an aqueous solution of a water soluble aluminum salt, wherein the anion of said salt does not form any water soluble complexes with said heavy metal ions to be precipitated or does form such anion-heavy metal complexes having a stability constant, expressed as their decadic logarithm, of less than 2; wherein the aluminum salt is added in an amount corresponding to 0.9 to 1.8 moles of aluminum ions per equivalent of polycarboxylate; adjusting the pH of the resulting reaction mixture to about 6.5 to about 9.0 with an alkali metal carbonate; and further wherein said heavy metal ions are selected from the group consisting of zinc, cadmium, copper, nickel, cobalt, iron and chrome; and said polycarboxylate has a mean degree of polymerization of about 5 to about 500, said polycarboxylate being selected from the group consisting of poly(aldehydocarboxylates), poly(hydroxycarboxylates) and poly(hydroxyaldehydocarboxylates); and separating the resulting precipitate from said solution.
Claim 2
Dependent Claim
178 words
A process for precipitating heavy metal ion-polycarboxylate complexes from an aqueous metal processing effluent said process comprising adding to said aqueous effluent containing at least one of said complexes an aqueous solution of a water soluble aluminum salt, wherein the anion of said salt does not form any water soluble complexes with said heavy metal ions to be precipitated or does form such anion-heavy metal complexes having a stability constant, expressed as their decadic logarithm, of less than 2; wherein the aluminum salt is added in an amount corresponding to 0.9 to 1.8 moles of aluminum ions per equivalent of polycarboxylate; adjusting the pH of the resulting reaction mixture to about 6.5 to about 9.0 with an alkali metal carbonate; and further wherein said heavy metal ions are selected from the group consisting of zinc, cadmium, copper, nickel, cobalt, iron and chrome; and said polycarboxylate has a mean degree of polymerization of about 5 to about 500, said polycarboxylate being selected from the group consisting of poly(aldehydocarboxylates), poly(hydroxycarboxylates) and poly(hydroxyaldehydocarboxylates); and separating the resulting precipitate from said solution.
Claim 3
Dependent Claim
25 words
Process according to claim 1 in which said heavy metal ion is selected from the group consisting of zinc, cadmium, copper, nickel and chromium ions.
Claim 4
Dependent Claim
18 words
Process according to claim 1 in which the mean degree of polymerization is about 10 to about 300.
Claim 5
Dependent Claim
18 words
Process according to claim 3 in which the mean degree of polymerization is about 15 to about 100.
Claim 6
Dependent Claim
121 words
Process according to claim 1 in which the polycarboxylate consists of: ##EQU3## wherein U equals about 12 to about 47; V equals about 1 to about 25; W equals 0 to about U; Y equals 100-(U+V+Z); Z equals 0 to about 20; A signifies an alkali metal, hydrogen or ammonium ion; R 1 signifies hydrogen, methyl, hydroxymethyl, ethyl, chlorine or bromime; R 2 and R 4 are the same or different and signify hydrogen or hydroxymethyl; R 3 and R 5 are the same or different and signify hydrogen, methyl or ethyl; and whereby when W is greater than 0.3.U, the quotient of basic mole percent carboxyl or carboxylate groups to basic mole percent hydroxyl groups lies between 2 and 16.
Claim 7
Dependent Claim
80 words
Process according to claim 5 in which U equals about 10 to about 30; V equals about 1 to about 25; W equals about 0.3.U to about U; A signifies a sodium or hydrogen ion; R 1 signifies hydrogen or hydroxymethyl; R 3 and R 5 are hydrogen; and wherein when W is greater than 0.3 U, the quotient of basic mole percent carboxyl or carboxylate groups to basic mole percent hydroxyl groups lies between about 2 and about 9.
Claim 8
Dependent Claim
32 words
Process according to claim 6 in which V equals 1 to about 10; W equals about 0.5.U to about U; Z equals 0; and the quotient is about 3 to about 8.
Claim 9
Dependent Claim
20 words
Process according to claim 1 in which said aluminum salt is aluminum chloride, aluminum sulfate, aluminum nitrate or aluminum acetate.
Claim 10
Dependent Claim
17 words
Process according to claim 1 in which the aluminum salt is a salt of an inorganic acid.
Claim 11
Dependent Claim
21 words
Process according to claim 1 in which the aqueous solution of the water soluble aluminum salt comprises about 0.2-4 moles Al/liter.
Claim 12
Dependent Claim
15 words
Process according to claim 1 in which the pH is about 7.0 to about 8.9.
Claim 13
Dependent Claim
15 words
Process according to claim 1 in which the pH is about 7.3 to about 8.7.
Claim 14
Dependent Claim
27 words
Process according to claim 1 in which the alkali metal carbonate is in an aqueous solution having a concentration of about 0.1 molar to a saturated solution.
Claim 15
Dependent Claim
14 words
Process according to claim 13 in which the alkali metal carbonate is sodium carbonate.
Claim 16
Dependent Claim
26 words
Process according to claim 1 in which a precipitate is obtained, and the precipitate is separated from the reaction mixture by filtration or sedimentation and decantation.
Claim 17
Dependent Claim
27 words
Process according to claim 1 in which said aluminum salt is Al(OH) x Cl 3 -x , wherein x is larger than zero but less than 3.
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) | 1979-05-11 | 1979-11-10 | 1980-05-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-11 | 1983-11-10 | 1984-05-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-11 | 1987-11-10 | 1988-05-11 | $7700.00 | Window Closed / Lapsed |