US4708805A
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US
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Barium sulfate removal and anti-deposition compositions and process of use therefor
Assignee: Corpex Technologies Inc
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Filing: 1986-11-24
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Granted: 1987-11-24
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Expires: 2006-11-24
Abstract
Abstract The invention provides a process for the sequestration of barium sulfate scale and barium sulfate sequestrant compositions therefor comprising an aqueous solution of citric acid (CA), a polycarbazic acid (PA), and an alklyenepolyaminopolycarboxylic acid (APAPCA), the weight ratio of CA to APAPCA being in the range from about 0.5 to 1 to about 11 to 1 and the weight ratio of PCA to APAPCA being in the range from about 0.002 to about 0.2, wherein the polycarbazic acid has the formula (R) 2 --N--[CH 2 CH 2 N(R)] m --R where R is the group CH 2 --CO--NH--NH--COOH and m is 0 or an integer from 1 to about 4, and wherein the APAPCA has the formula (HOOC--CH 2 ) 2 --N--[CH 2 --CH 2 --N(CH 2 --COOH)] n --CH 2 COOH where n is an integer from 1 to about 4. The preferred aqueous sequestering solution has a pH in the range from about 9.5 to about 14, said pH being provided by a base selected from the group consisting of potassium hydroxide, potassium carbonate, and mixtures thereof.
Inventors
- 👤 Thomas F. D'Muhala
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 01:07
CPC Classifications
C; C02; C02F; C02F5/00; C02F5/08; C02F5/10; C02F5/12
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
70 words
A composition for sequestration of barium sulfate comprising citric acid, a polycarbazic acid, and an alkylenepolyaminopolycarboxylic acid, wherein the weight ratio of said citric acid to said alkylenepolyaminopolycarboxylic acid is in the range from about 0.5 to 1 to about 11 to 1, and wherein the weight ratio of said polycarbazic acid to said alkylenepolyaminopolycarboxylic acid is in the range from about 0.002 to 1 to about 0.2 to 1.
Claim 2
Dependent Claim
70 words
A composition for sequestration of barium sulfate comprising citric acid, a polycarbazic acid, and an alkylenepolyaminopolycarboxylic acid, wherein the weight ratio of said citric acid to said alkylenepolyaminopolycarboxylic acid is in the range from about 0.5 to 1 to about 11 to 1, and wherein the weight ratio of said polycarbazic acid to said alkylenepolyaminopolycarboxylic acid is in the range from about 0.002 to 1 to about 0.2 to 1.
Claim 3
Dependent Claim
73 words
The composition of claim 1 wherein said polycarbazic acid has the formula (R) 2 --N--[CH 2 --CH 2 --N(R)] m --R where R is the group CH 2 --CO--NH--NH--COOH and m is 0 or an integer from 1 to about 4, and wherein said alkylenepolyaminopolycarboxylic acid has the formula (HOOC--CH 2 ) 2 --N--[CH 2 --CH 2 --N(CH 2 --COOH)] n--CH 2 --COOH where n is an integer from 1 to about 4.
Claim 4
Dependent Claim
18 words
The composition of claim 2 wherein m is 0 or 1 and wherein n is 1 or 2.
Claim 5
Dependent Claim
53 words
The composition of claim 3 wherein said weight ratio of citric acid to said alkylenepolyaminopolycarboxylic acid is in the range from about 0.5 to about 3.5 and wherein said weight ratio of said polycarbazic acid to said alkylenepolyaminopolycarboxylic acid is in the range from about 0.01 to 1 to about 0.10 to 1.
Claim 6
Dependent Claim
99 words
The composition of claim 4 wherein m =1 or said polycarbazic acid is a mixture of polycarbazic acids wherein m is 0 and 1, the weight ratio of said polycarbazic acid wherein m is 0 to said polycarbazic acid wherein m is 1 being in the range from about 0 to 1 to about- 1 to 1, and wherein said alkylenepolyaminopolycarboxylic acid is ethylenediaminetetraacetic acid or a mixture of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid, the weight ratio of said diethylenetriaminepentaacetic acid to said ethylenediaminetetraacetic acid being in the range from about 0 to 1 to about 3 to 1.
Claim 7
Dependent Claim
95 words
The composition of claim 4 wherein m=1 or said polycarbazic acid is a mixture of polycarbazic acids wherein m is 0 and 1, the weight ratio of said polycarbazic acids wherein m is 0 to said polycarbazic acid wherein m is 1 being in the range from about 0 to 1 to about 1 to 1, and wherein said alkylenepolyaminopolycarboxylic acid is a mixture of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid, the weight ratio of said diethylenetriaminepentaacetic acid to said ethylenediaminetetraacetic acid being in the range from about 0.5 to 1 to about 1.5 to 1.
Claim 8
Dependent Claim
47 words
The composition of claims 3, 4, 5, or 6 which contains sufficient water and base to provide a solution having a pH in the range from about 9.5 to about 14, said base being selected from the group consisting of potassium hydroxide, potassium carbonate, and mixtures thereof.
Claim 9
Dependent Claim
101 words
A process for solubilizing barium sulfate which comprises contacting said barium sulfate at a temperature of at least 82° C. with an aqueous solution of a sequestrant mixture comprising citric acid and ethylenediaminetetraacetic acid having a weight ratio of citric acid to ethylenediaminetetraacetic acid in the range from about 2 to 1 to about 7.33 to 1, said aqueous solution having a pH in the range from about 9.5 to about 14, said pH being obtained by neutralization of said sequestrant mixture with an excess of a base selected from the group consisting of potassium hydroxide, potassium carbonate, and mixtures thereof.
Claim 10
Dependent Claim
101 words
A process for solubilizing barium sulfate which comprises contacting said barium sulfate at a temperature of at least 82° C. with an aqueous solution of a sequestrant mixture comprising citric acid and ethylenediaminetetraacetic acid having a weight ratio of citric acid to ethylenediaminetetraacetic acid in the range from about 2 to 1 to about 7.33 to 1, said aqueous solution having a pH in the range from about 9.5 to about 14, said pH being obtained by neutralization of said sequestrant mixture with an excess of a base selected from the group consisting of potassium hydroxide, potassium carbonate, and mixtures thereof.
Claim 11
Dependent Claim
41 words
A process for solubilizing barium sulfate which comprises contacting said barium sulfate with an aqueous solution of the composition of claim 3, 4, 5, or 6, said aqueous solution having a pH in the range from about 9.5 to about 14.
Claim 12
Dependent Claim
61 words
A process for solubilizing barium sulfate which comprises contacting said barium sulfate with an aqueous solution of the composition of claim 3, 4, 5, or 6, said aqueous solution having a pH in the range from about 9.5 to about 14, said pH eing provided by a base selected from the group consisting of potassium hydroxide, potassium carbonate, and mixtures thereof
Claim 13
Dependent Claim
42 words
A process for preventing the formation of barium sulfate scale deposits in an aqueous system containing barium ions and sulfate ions which comprises adding to said aqueous system a precipitation inhibiting amount of the composition of claim 3, 4, 5, or 6.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-11-23 | 1991-05-25 | 1991-11-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-23 | 1995-05-25 | 1995-11-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-23 | 1999-05-25 | 1999-11-24 | $7700.00 | Window Closed / Lapsed |