US4177142A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Mixture of oppositely charged filter aid material
Assignee: Ecodyne Corp
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Filing: 1977-09-27
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Granted: 1979-12-04
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Expires: 1997-09-27
Abstract
Abstract Impurities are removed from a liquid by passing the liquid through an improved filter bed. The filter bed comprises a mixture of oppositely charged particles of filter aid material, the particles normally having a surface charge in aqueous solution. A portion of these particles are treated with a chemical compound to produce a surface charge that is opposite from the normal surface charge. These oppositely charged particles clump in aqueous suspension, and produce a filter bed which is capable of removing suspended particles with very high efficiency, while maintaining a relatively low pressure drop across the filter bed.
Inventors
- 👤 Christopher J. Halbfoster
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:42
CPC Classifications
B; B01; B01D; B01D37/00; B01D37/02; B01D37/03
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
80 words
A method for removing impurities from a liquid comprising: passing said liquid through a filter bed comprising a mixture of oppositely charged particles of filter aid material, said mixture producing a clumping phenomenon, said particles normally all having the same surface charge in aqueous suspension, wherein 5 to 95% of said material has been treated with an electrolyte-type compound that produces a surface charge opposite to said normal surface charge by bonding to the surface of said filter aid material.
Claim 2
Independent Claim
80 words
A method for removing impurities from a liquid comprising: passing said liquid through a filter bed comprising a mixture of oppositely charged particles of filter aid material, said mixture producing a clumping phenomenon, said particles normally all having the same surface charge in aqueous suspension, wherein 5 to 95% of said material has been treated with an electrolyte-type compound that produces a surface charge opposite to said normal surface charge by bonding to the surface of said filter aid material.
Claim 3
Dependent Claim
16 words
The method as defined in claim 1 wherein said particles normally have a negative surface charge.
Claim 4
Dependent Claim
13 words
The method as defined in claim 2 wherein said particles comprise cellulose fibers.
Claim 5
Dependent Claim
24 words
The method as defined in claim 2 wherein said particles comprise cation exchange resin particles in the size range of 60 to 400 mesh.
Claim 6
Dependent Claim
14 words
The method as defined in claim 1 wherein said electrolyte-type compound comprises a polyelectrolyte.
Claim 7
Dependent Claim
66 words
The method as defined in claim 1 further comprising the step of passing said liquid through a mixture of anion and cation exchange resin particles after passing said liquid through said filter aid material, said resin particles being in the size range of about 60 to 400 mesh, said cation exchange resin particles comprising about 5 to 95% by weight of the particles in said mixture.
Claim 8
Dependent Claim
15 words
The method as defined in claim 6 wherein said filter aid particles comprise cellulose fibers.
Claim 9
Dependent Claim
14 words
The method as defined in claim 7 wherein said electrolyte-type compound comprises a polyelectrolyte.
Claim 10
Independent Claim
116 words
A method for removing impurities from a liquid comprising passing said liquid through a bed of oppositely charged particles of filter aid material, said mixture producing a clumping phenomenon said particles normally all having a negative surface charge in aqueous suspension, wherein 5 to 95% of said material has been treated in aqueous suspension with a cationic polyelectrolyte to produce a positive surface charge by bonding to the surface of said filter aid material, and wherein the remainder of said material has been treated in aqueous suspension with a cationic polyelectrolyte and then with an anionic polyelectrolyte to produce a negative surface charge by bonding to said filter aid material previously treated with said cationic polyelectrolyte.
Claim 11
Independent Claim
116 words
A method for removing impurities from a liquid comprising passing said liquid through a bed of oppositely charged particles of filter aid material, said mixture producing a clumping phenomenon said particles normally all having a negative surface charge in aqueous suspension, wherein 5 to 95% of said material has been treated in aqueous suspension with a cationic polyelectrolyte to produce a positive surface charge by bonding to the surface of said filter aid material, and wherein the remainder of said material has been treated in aqueous suspension with a cationic polyelectrolyte and then with an anionic polyelectrolyte to produce a negative surface charge by bonding to said filter aid material previously treated with said cationic polyelectrolyte.
Claim 12
Dependent Claim
13 words
The method as defined in claim 9 wherein said particles comprise cellulose fibers.
Claim 13
Dependent Claim
15 words
The method as defined in claim 9 wherein said particles comprise cation exchange resin particles.
Claim 14
Dependent Claim
64 words
The method as defined in claim 9 further comprising the step of passing said liquid through a mixture of anion and cation exchange resin particles after passing through said filter aid material, said resin particles being in the size range of about 60 to 400 mesh, said cation exchange resin particles comprising about 5 to 95% by weight of the particles in said mixture.
Claim 15
Dependent Claim
13 words
The method as defined in claim 12 wherein said particles comprise cellulose fibers.
Claim 16
Dependent Claim
68 words
An improved filter bed comprising a mixture of oppositely charged particles of filter aid material, said mixture producing a clumping phenomenon, said particles normally all having the same surface charge in aqueous suspension, wherein 5 to 95% of said material has been treated with an electrolyte-type compound that produces a surface charge opposite to said normal surface charge by bonding to said surface of said filter aid material.
Claim 17
Dependent Claim
68 words
An improved filter bed comprising a mixture of oppositely charged particles of filter aid material, said mixture producing a clumping phenomenon, said particles normally all having the same surface charge in aqueous suspension, wherein 5 to 95% of said material has been treated with an electrolyte-type compound that produces a surface charge opposite to said normal surface charge by bonding to said surface of said filter aid material.
Claim 18
Dependent Claim
18 words
The improved filter bed as defined in claim 14 wherein said particles normally have a negative surface charge.
Claim 19
Dependent Claim
15 words
The improved filter bed as defined in claim 15 wherein said particles comprise cellulose fibers.
Claim 20
Dependent Claim
17 words
The improved filter bed as defined in claim 15 wherein said particles comprise cation exchange resin particles.
Claim 21
Dependent Claim
17 words
The improved filter bed as defined in claim 14 wherein said an electrolyte-type compound comprises a polyelectrolyte.
Claim 22
Dependent Claim
68 words
The improved filter bed as defined in claim 14 wherein said filter bed further comprises a layer of ion exchange resin particles beneath said filter aid material, said resin particles comprising a mixture of anion and cation exchange resin particles in the size range of about 60 to 400 mesh, said cation exchange resin particles comprising about 5 to 95% by weight of the particles in said mixture.
Claim 23
Dependent Claim
17 words
The improved filter bed as defined in claim 19 wherein said filter aid particles comprise cellulose fibers.
Claim 24
Dependent Claim
109 words
An improved filter bed comprising: a mixture of oppositely charged particles of filter aid material, said mixture producing a clumping phenomenon, said particles normally all having a negative surface charge in aqueous suspension, wherein 5 to 95% of said material has been treated in aqueous suspension with a cationic polyelectrolyte to produce a positive surface charge by bonding to the surface of said filter aid material, and wherein a second portion of said particles has been treated in aqueous suspension with a cationic polyelectrolyte and then with an anionic polyelectrolyte to produce a negative surface charge by bonding to said filter aid material previously treated with said cationic polyelectrolyte.
Claim 25
Dependent Claim
109 words
An improved filter bed comprising: a mixture of oppositely charged particles of filter aid material, said mixture producing a clumping phenomenon, said particles normally all having a negative surface charge in aqueous suspension, wherein 5 to 95% of said material has been treated in aqueous suspension with a cationic polyelectrolyte to produce a positive surface charge by bonding to the surface of said filter aid material, and wherein a second portion of said particles has been treated in aqueous suspension with a cationic polyelectrolyte and then with an anionic polyelectrolyte to produce a negative surface charge by bonding to said filter aid material previously treated with said cationic polyelectrolyte.
Claim 26
Dependent Claim
15 words
The improved filter bed as defined in claim 21 wherein said particles comprise cellulose fibers.
Claim 27
Dependent Claim
68 words
The improved filter bed as defined in claim 21 wherein said filter bed further comprises a layer of ion exchange resin particles beneath said filter aid material, said resin particles comprising a mixture of anion and cation exchange resin particles in the size range of about 60 to 400 mesh, said cation exchange resin particles comprising about 5 to 95% by weight of the particles in said mixture.
Claim 28
Dependent Claim
17 words
The improved filter bed as defined in claim 23 wherein said filter aid particles comprise cellulose fibers.
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) | 1982-12-03 | 1983-06-04 | 1983-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-12-03 | 1987-06-04 | 1987-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-12-03 | 1991-06-04 | 1991-12-04 | $7700.00 | Window Closed / Lapsed |