Claims
- 1. A process for separating an aqueous mixture into less permeable and more permeable fractions, comprising the steps of:
- a) contacting said aqueous mixture under pressure with a nanofiltration membrane comprising a barrier layer consisting essentially of a polymerizate of one or more first aliphatic monomers having as a molar average A+2 substituents selected from the group consisting of primary and secondary amines with one or more second aliphatic monomers having as a molar average C+2 substituents combinable with primary or secondary amines, A and C being real numbers greater than or equal to zero, the sum of A and C being at least about 0.1 and thus A and C not both being equal to zero simultaneously, said membrane having a steady state flux "a" of at least about 2 gallons per square foot per day when the membrane is challenged at about room temperature and about 225 pounds per square inch trans-membrane pressure difference with fresh, natural, sweet, cheddar cheese whey, said steady state flux "a" determined by fitting the flux "GFD" in gallons per square foot per day through said membrane versus the cumulative volume of liquid "GF" in gallons per square foot passed through said membrane, by a least squares method, to the relationship:
- GFD=a+b exp (-cGF)
- where "a" is the steady state flux in gallons per square foot per day, "a+b" is the extrapolated initial flux rate in gallons per square foot per day, "c" is the exponential degradation rate per cumulative gallons per square foot permeate, and "GF" is the cumulative volume of liquid passed through said membrane in gallons per square foot; and
- b) recovering the liquid passing through the membrane.
- 2. The process of claim 1, wherein the aqueous mixture is milk or an aqueous derivative thereof.
- 3. The process of claim 1, wherein the aqueous mixture is seawater.
- 4. The process of claim 1, wherein the first aliphatic monomer is selected from the group consisting of a cyclohexane diamine, tetraethylene pentamine, ethylene diamine, a diaminopropane, a diaminobutane, a diaminopentane, a diaminohexane, a diaminoheptane, a diaminooctane, a diaminononane, a diaminodecane, diethylene triamine, a dipropylene triamine, a dibutylene triamine, triethylene tetramine, a tripropylene tetramine, a tributylene tetramine, pentaethylene hexamine, a diamino cyclobutane, a diamino cyclopentane, a diamino cycloheptane, a diamino cyclooctane, guanidine, aminoethyl piperazine, an imino bis propyl amine, bis-(p-amino cyclohexyl) methane, N,N'-bis-(3-amino propyl)-1,4-butane diamine, a menthane diamine, 1,4-diamino-2-butanone, a diaminododecane, diamino-2-hydroxy propane, and trisaminoethyl amine.
- 5. The process of claim 1, wherein the first aliphatic monomer is selected from the group consisting of a cyclohexane tricarboxylic acid trihalide, 1,2,3-propane tricarboxylic acid trihalide, 1,2,3,4-butane tetracarboxylic acid tetrahalide, 1,2,4,5-pentane-tetracarboxylic acid tetrahalide, 1,3-cyclohexane dicarboxylic acid halide, and 1,4-cyclohexane dicarboxylic acid halide.
- 6. The process of claim 1, wherein the first aliphatic monomer is a cyclohexane diamine and the second aliphatic monomer is a cyclohexane tricarboxylic acid halide.
- 7. An asymmetric semi-permeable membrane comprising
- a) a porous substrate; and
- b) a barrier layer consisting essentially of a cross-linked polymerizate of
- i) a first aliphatic amine monomer;
- ii) a second aliphatic amine monomer;
- iii) an aliphatic acid chloride monomer,
- wherein the membrane, when challenged at room temperature and at a trans-membrane pressure difference of about 225 pounds per square inch, is characterized by
- sodium chloride rejection of less than 50% in a challenge with water containing 2000 milligrams sodium chloride per liter;
- magnesium sulfate rejection of more than 50% in a challenge with water containing 2000 milligrams magnesium sulfate per liter; and
- a stable non-zero flux in a challenge with whey.
- 8. The membrane of claim 7, wherein the first and second amine monomers are seected from the group consisting of a cyclohexane diamine, tetraethylene pentamine, ethylene diamine, a diaminopropane, a diaminobutane, a diaminopentane, a diaminohexane, a diaminoheptane, a diaminooctane, a diaminononane, a diaminodecane, diethylene triamine, a dipropylene triamine, a dibutylene triamine, triethylene tetramine, a tripropylene tetramine, a tributylene tetramine, pentaethylene hexamine, a diamino cyclobutane, a diamino cyclopentane, a diamino cycloheptane, a diamino cyclooctane, guanidine, aminoethyl piperazine, an imino bis propyl amine, bis-(p-amino cyclohexyl) methane, N,N'-bis-(3-amino propyl)-1,4-butane diamine, a menthane diamine, 1,4-diamino-2-butanone, a diaminododecane, diamino-2-hydroxy propane, and trisaminoethyl amine.
- 9. The membrane of claim 7, wherein the acid halide is selected from the group consisting of a cyclohexane tricarboxylic acid trihalide, 1,2,3-propane tricarboxylic acid trihalide, 1,2,3,4-butane tetracarboxylic acid tetrahalide, 1,2,4,5 -pentane-tetracarboxylic acid tetrahalide, 1,3-cyclohexane dicarboxylic acid halide, and 1,4-cyclohexane dicarboxylic acid halide.
- 10. A membrane according to claim 7 in which said barrier layer consists essentially of a polymerizate of a mixture of a cyclohexane diamine and tetraethylene pentamine with a cyclohexane tricarboxylic acid halide.
- 11. A process for separating a fluid mixture into less permeable and more permeable fractions, said process comprising contacting said fluid mixture under pressure with the barrier layer of a membrane according to claim 7.
- 12. Apparatus for separating a fluid mixture into less permeable and more permeable fractions, said apparatus comprising a membrane according to claim 7 and also comprising means for contacting said fluid mixture under pressure with the barrier layer of said membrane.
Parent Case Info
This application is a continuation of application Ser. No. 08/304,031, now abandoned, filed Sep. 9, 1994, which is a continuation of application Ser. No. 08/063,799, filed May 20, 1993 and now abandoned.
US Referenced Citations (10)
Continuations (2)
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Number |
Date |
Country |
Parent |
304031 |
Sep 1994 |
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Parent |
63799 |
May 1993 |
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