U.S. patent application number 10/315589 was filed with the patent office on 2004-06-10 for catalyst ink.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Hanson, Eric Joseph, Mekala, David Robert, Velamakanni, Bhaskar V..
Application Number | 20040107869 10/315589 |
Document ID | / |
Family ID | 32468741 |
Filed Date | 2004-06-10 |
United States Patent
Application |
20040107869 |
Kind Code |
A1 |
Velamakanni, Bhaskar V. ; et
al. |
June 10, 2004 |
Catalyst ink
Abstract
A catalyst ink is provided, comprising: 25-95% by weight water;
1-50% by weight of at least one solid catalyst, typically a highly
dispersed platinum catalyst; 1-50% by weight of at least one
polymer electrolyte in acid (H.sup.+) form; and 1-50% by weight of
at least one polar aprotic organic solvent. The catalyst ink
typically has a viscosity at 1 sec.sup.-1 of 10 Pa.multidot.sec or
less. The catalyst ink typically does not ignite spontaneously when
dried to completion in air at a temperature of 80.degree. C. or
greater. The catalyst ink may be used in the fabrication of
membrane electrode assemblies for use in fuel cells.
Inventors: |
Velamakanni, Bhaskar V.;
(Woodbury, MN) ; Mekala, David Robert; (Maplewood,
MN) ; Hanson, Eric Joseph; (Hudson, WI) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
32468741 |
Appl. No.: |
10/315589 |
Filed: |
December 10, 2002 |
Current U.S.
Class: |
106/31.92 ;
204/282; 429/492; 429/524 |
Current CPC
Class: |
H01M 4/8668 20130101;
Y02E 60/50 20130101; H01M 4/92 20130101; H01M 8/1004 20130101; C09D
11/03 20130101 |
Class at
Publication: |
106/031.92 ;
429/040; 204/282 |
International
Class: |
C09D 011/00; H01M
004/86 |
Claims
We claim:
1. A catalyst ink comprising: a) 25-95% by weight water; b) 1-50%
by weight of at least one solid catalyst; c) 1-50% by weight of at
least one polymer electrolyte in acid (H.sup.+) form; and d) 1-50%
by weight of at least one polar aprotic organic solvent.
2. The catalyst ink according to claim 1 wherein said solid
catalyst is a highly dispersed platinum catalyst.
3. The catalyst ink according to claim 2 wherein said polar aprotic
organic solvent has a standard boiling point of at least 80.degree.
C.
4. The catalyst ink according to claim 2 wherein said polar aprotic
organic solvent is selected from the group consisting of:
dimethylsulfoxide (DMSO), N,N-dimethyacetamide (DMA), ethylene
carbonate, propylene carbonate, dimethylcarbonate,
diethylcarbonate, N,N-dimethylformamide (DMF),
N-methylpyrrolidinone (NMP), dimethylimidazolidinone, acetonitrile,
butyrolactone, hexamethylphosphoric triamide, isobutyl methyl
ketone, and sulfolane.
5. The catalyst ink according to claim 2 wherein said polar aprotic
organic solvent is selected from the group consisting of: N-methyl
pyrrolidinone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide,
dimethylsufoxide (DMSO) and acetonitrile.
6. The catalyst ink according to claim 2 wherein said polar aprotic
organic solvent is N-methyl pyrrolidinone (NMP).
7. The catalyst ink according to claim 2 wherein said polymer
electrolyte is highly fluorinated.
8. The catalyst ink according to claim 7 wherein said polymer
electrolyte contains no arylene units in the polymer backbone.
9. The catalyst ink according to claim 2 comprising 50-80%
water.
10. The catalyst ink according to claim 2 comprising 10-20% of said
solid catalyst.
11. The catalyst ink according to claim 2 comprising 1-10% of said
polymer electrolyte in acid (H.sup.+) form.
12. The catalyst ink according to claim 2 comprising 5-15% of said
polar aprotic organic solvent.
13. The catalyst ink according to claim 2 having a viscosity at 1
sec.sup.-1 of 10 Pa.multidot.sec or less.
14. The catalyst ink according to claim 2 having a viscosity at 1
sec.sup.-1 of 1.0 Pa.multidot.sec or less.
15. The catalyst ink according to claim 2 wherein said catalyst ink
does not ignite spontaneously when dried to completion in air at a
temperature of 80.degree. C. or greater.
16. The catalyst ink according to claim 2 wherein said catalyst ink
does not ignite spontaneously when dried to completion in air at a
temperature of 110.degree. C. or greater.
17. The catalyst ink according to claim 2 wherein said catalyst ink
does not ignite spontaneously when dried to completion in air at a
temperature of 140.degree. C. or greater.
18. A catalyst ink comprising: a) 25-95% by weight water; b) 1-50%
by weight of at least one highly dispersed platinum catalyst; c)
1-50% by weight of at least one polymer electrolyte in acid
(H.sup.+) form; and d) 1-50% by weight of at least one second
solvent which is not water; wherein said catalyst ink has a
viscosity at 1 sec.sup.-1 of 10 Pa.multidot.sec or less, and
wherein said catalyst ink does not ignite spontaneously when dried
to completion in air at a temperature of 80.degree. C. or
greater.
19. The catalyst ink according to claim 18 wherein said second
solvent has a standard boiling point of at least 80.degree. C.
20. The catalyst ink according to claim 18 wherein said second
solvent is selected from the group consisting of: dimethylsulfoxide
(DMSO), N,N-dimethyacetamide (DMA), ethylene carbonate, propylene
carbonate, dimethylcarbonate, diethylcarbonate,
N,N-dimethylformamide (DMF), N-methylpyrrolidinone (NMP),
dimethylimidazolidinone, acetonitrile, butyrolactone,
hexamethylphosphoric triamide, isobutyl methyl ketone, and
sulfolane.
21. The catalyst ink according to claim 18 wherein said second
solvent is selected from the group consisting of: N-methyl
pyrrolidinone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide,
dimethylsufoxide (DMSO) and acetonitrile.
22. The catalyst ink according to claim 18 wherein said second
solvent is N-methyl pyrrolidinone (NMP).
23. The catalyst ink according to claim 18 wherein said polymer
electrolyte is highly fluorinated.
24. The catalyst ink according to claim 23 wherein said polymer
electrolyte contains no arylene units in the polymer backbone.
25. The catalyst ink according to claim 18 comprising 50-80%
water.
26. The catalyst ink according to claim 18 comprising 10-20% of
said solid catalyst.
27. The catalyst ink according to claim 18 comprising 1-10% of said
polymer electrolyte in acid (H.sup.+) form.
28. The catalyst ink according to claim 18 comprising 5-15% of said
second solvent.
29. The catalyst ink according to claim 18 having a viscosity at 1
sec.sup.-1 of 1.0 Pa.multidot.sec or less.
30. The catalyst ink according to claim 18 wherein said catalyst
ink does not ignite spontaneously when dried to completion in air
at a temperature of 110.degree. C. or greater.
31. The catalyst ink according to claim 18 wherein said catalyst
ink does not ignite spontaneously when dried to completion in air
at a temperature of 140.degree. C. or greater.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a catalyst ink composition,
typically for use in the fabrication of membrane electrode
assemblies used in fuel cells.
BACKGROUND OF THE INVENTION
[0002] European Patent Application EP 0 955 687 A2 discloses a
method for preparing a slurry for forming a catalyst layer of a PEM
fuel cell electrode. In the disclosed method, MOH is added to a
water/alcohol solution of a perfluorosulfonate ionomer (PFSI)(such
as Nafion.TM.) to convert the PFSI to M.sup.+ form. An organic
polar solvent such as dimethyl sulfoxide, N,N-dimethyl formamide or
ethylene glycol is added ('687 at para. 24, para. 27, and claim 6).
The mixture is then heated to drive off alcohol and catalyst is
added to form the slurry. After the slurry has been applied to a
backing layer and dried to form a catalyst layer, the catalyst
layer is treated with acid to convert the PFSI from M.sup.+ form to
H.sup.+ form. ('687 at para. 44 and claim 5).
[0003] U.S. patent application Publication US2002/0045081 discloses
the use of sulfonated PEEK polymers dissolved in N-methyl
pyrrolidone (NMP), a polar aprotic solvent ('081 at Example 1).
[0004] U.S. Pat. No. 5,906,716 discloses a metalized cation
exchange membrane preferably made with a cation-exchange polymer
that is soluble in a polar aprotic solvent (such as NMP) and
comprises arylene units in the backbone of the polymer, e.g.,
sulfonated PEEK polymers ('716 at Example 1).
[0005] U.S. patent application Publication US2002/0019308 discloses
a composite catalyst.
[0006] Japanese Unexamined Patent Publication 2000-353528 discloses
a porous electrode catalyst layer and a method of making a porous
electrode catalyst layer. The Examples appear to disclose the use
of a solution of Nafion.TM. in NMP, obtained by solvent exchange of
a stock solution of Nafion.TM..
[0007] Japanese Unexamined Patent Publication 2001-273907A
discloses a porous electrode catalyst layer and a phase separation
method of making a porous electrode catalyst layer. The Examples
appear to disclose the application of suspension of catalyst in
Nafion.TM. solution followed by drying and then application of a
PVdF/NMP solution followed by solvent exchange with water to create
a porous layer of PVdF.
[0008] International Patent Application WO 01/71835 A2 discloses a
method of manufacturing a membrane/electrode composite.
[0009] UK Patent Application GB 2 316 802 A discloses gas diffusion
electrodes based on polyethersulfone carbon blends.
[0010] U.S. Pat. No. 5,716,437 discloses an aqueous ink for use in
electrode manufacture.
[0011] WO 99/21239 discloses a method for the production of metal
colloid solutions by reducing dissolved catalyst metals in the
presence of a cation exchange polymer.
SUMMARY OF THE INVENTION
[0012] Briefly, the present invention provides a catalyst ink
comprising: 25-95% by weight water; 1-50% by weight of at least one
solid catalyst, typically a highly dispersed platinum catalyst;
1-50% by weight of at least one polymer electrolyte in acid
(H.sup.+) form; and 1-50% by weight of at least one polar aprotic
organic solvent. The catalyst ink typically has a viscosity at 1
sec.sup.-1 of 10 Pa.multidot.sec or less. The catalyst ink
typically does not ignite spontaneously when dried to completion in
air at a temperature of 80.degree. C. or greater.
[0013] In this application:
[0014] "highly dispersed platinum catalyst" means a
platinum-containing catalyst having a specific surface area of
greater than 100 m.sup.2/g, more typically greater than 500
m.sup.2/g, and most typically greater than 900 m.sup.2/g, such as a
catalyst dispersed on a powdered carbon support;
[0015] "highly fluorinated" means containing fluorine in an amount
of 40 wt % or more, typically 50 wt % or more and more typically 60
wt % or more;
[0016] "dried to completion" means dried until water content is
essentially in equilibrium with ambient air, or lower; and
[0017] "standard boiling point" means the boiling point reported in
standard reference works.
[0018] It is an advantage of the present invention to provide a
catalyst ink, in particular a catalyst ink for use in fuel cell
fabrication, which exhibits favorable rheology during application
and does not spontaneously ignite when dried to completion in air
at an elevated temperature.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0019] The present invention provides a catalyst ink comprising:
25-95% by weight water; 1-50% by weight of at least one solid
catalyst, typically a highly dispersed platinum catalyst; 1-50% by
weight of at least one polymer electrolyte in acid (H.sup.+) form;
and 1-50% by weight of at least one polar aprotic organic solvent.
The catalyst ink typically has a viscosity at 1 sec.sup.-1 of 10
Pa.multidot.sec or less. The catalyst ink typically does not ignite
spontaneously when dried to completion in air at a temperature of
80.degree. C. or greater.
[0020] The catalyst ink according to the present invention may be
used in the fabrication of membrane electrode assemblies (MEA's)
for use in fuel cells. An MEA is the central element of proton
exchange membrane fuel cells such as hydrogen fuel cells. Fuel
cells are electrochemical cells which produce usable electricity by
the catalyzed combination of a fuel such as hydrogen and an oxidant
such as oxygen. Typical MEA's comprise a polymer electrolyte
membrane (PEM) (also known as an ion conductive membrane (ICM)),
which functions as a solid electrolyte. One face of the PEM is in
contact with an anode electrode layer and the opposite face is in
contact with a cathode electrode layer. Each electrode layer
includes electrochemical catalysts, typically including platinum
metal. The anode and cathode electrode layers may be applied to the
PEM in the form of a catalyst ink to form a catalyst coated
membrane (CCM). Fluid transport layers (FTL's) facilitate gas
transport to and from the anode and cathode electrode materials and
conduct electrical current. In a typical PEM fuel cell, protons are
formed at the anode via hydrogen oxidation and transported to the
cathode to react with oxygen, allowing electrical current to flow
in an external circuit connecting the electrodes. The FTL may also
be called a gas diffusion layer (GDL) or a diffuser/current
collector (DCC). In an alternate manufacturing method, the anode
and cathode electrode layers may be applied to the FTL in the form
of a catalyst ink, rather than to the PEM, and the coated FTL's
sandwiched with a PEM to form an MEA.
[0021] Any suitable catalyst may be used in the practice of the
present invention. The catalyst is typically a highly dispersed
platinum catalyst having a specific surface area of greater than
100 m.sup.2/g, more typically greater than 500 m.sup.2/g, and most
typically greater than 900 m.sup.2/g. Typically, carbon-supported
catalyst particles are used. Typical carbon-supported catalyst
particles are 50-90% carbon and 10-50% catalyst metal by weight,
the catalyst metal typically comprising Pt for the cathode and Pt
and Ru in a weight ratio of 2:1 for the anode.
[0022] Any suitable polymer electrolyte may be used in the practice
of the present invention. The polymer electrolyte is typically
highly fluorinated or perfluorinated. The polymer electrolyte is
typically an acid-functional fluoropolymer, such as Nafion.RTM.
(DuPont Chemicals, Wilmington Del.) and Flemion.TM. (Asahi Glass
Co. Ltd., Tokyo, Japan). The polymer electrolytes useful in inks
for use in the present invention are typically copolymers of
tetrafluoroethylene and one or more fluorinated, acid-functional
comonomers. Typically the polymer electrolyte bears sulfonate
functional groups. Typically the polymer electrolyte contains no
arylene units in the polymer backbone. Most typically the polymer
electrolyte is Nafion.RTM.. The polymer electrolyte typically has
an equivalent weight of 1200 or less, more typically 1100 or less,
more typically 1050 or less, and most typically about 1000. In the
ink according to the present invention, the polymer electrolyte is
substantially in protonated form or acid (H.sup.+) form, rather
than in salt form.
[0023] The polar aprotic organic solvent typically has a standard
boiling point of at least 80.degree. C., more typically at least
100.degree. C., more typically at least 160.degree. C., and most
typically at least 200.degree. C. The polar aprotic organic solvent
is typically selected from the group consisting of:
dimethylsulfoxide (DMSO), N,N-dimethyacetamide (DMA), ethylene
carbonate, propylene carbonate, dimethylcarbonate,
diethylcarbonate, N,N-dimethylformamide (DMF),
N-methylpyrrolidinone (NMP), dimethylimidazolidinone, acetonitrile,
butyrolactone, hexamethylphosphoric triamide, isobutyl methyl
ketone, and sulfolane; and more typically selected from the group
consisting of N-methyl pyrrolidinone (NMP), N,N-dimethylformamide,
N,N-dimethylacetamide, dimethylsufoxide (DMSO) and acetonitrile.
Most typically, the polar aprotic organic solvent is N-methyl
pyrrolidinone (NMP).
[0024] The catalyst ink typically contains 25-95% water, more
typically 50-80% water, and more typically 60-75% water. The
catalyst ink typically contains 1-50% solid catalyst, more
typically 5-25% solid catalyst, and more typically 10-20% solid
catalyst. The catalyst ink typically contains 1-50% polymer
electrolyte, more typically 1-20% polymer electrolyte, more
typically 1-10% polymer electrolyte, and more typically 3-8%
polymer electrolyte. The catalyst ink typically contains 1-50% of a
second solvent, typically a polar aprotic organic solvent, more
typically 3-25% polar aprotic organic solvent, more typically 5-15%
polar aprotic organic solvent, and more typically 8-14% polar
aprotic organic solvent. The catalyst ink typically contains 5-30%
solids (i.e. polymer and catalyst).
[0025] The ink may be mixed by any suitable method. The ink is
typically made by stirring with heat which may be followed by
dilution to a coatable consistency. The ink typically has a
viscosity at 1 sec.sup.-1 of 10 Pa.multidot.sec or less, more
typically 6 Pa.multidot.sec or less, more typically 2
Pa.multidot.sec or less, and most typically 1.0 Pa.multidot.sec or
less.
[0026] The ink may be used in the manufacture of a CCM or MEA for
use in a fuel cell. The ink may be applied to a PEM or FTL by any
suitable means, including both hand and machine methods, including
hand brushing, notch bar coating, fluid bearing die coating,
wire-wound rod coating, fluid bearing coating, slot-fed knife
coating, three-roll coating, or decal transfer. In the case of
decal transfer, the ink is first applied to a transfer substrate
and dried, and thereafter applied as a decal to a PEM. Coating may
be achieved in one application or in multiple applications. After
coating, the ink may be dried in an oven or the like, in air, at
temperatures in excess of 80.degree. C., more typically in excess
of 110.degree. C., and more typically in excess of 140.degree. C.
The ink according to the present invention preferably will not
self-ignite when dried to completion under these conditions.
Typically, an ink that will not self-ignite during drying will also
be more safe to manufacture, handle and use.
[0027] This invention is useful in the fabrication of membrane
electrode assemblies for use in fuel cells.
[0028] Objects and advantages of this invention are further
illustrated by the following examples, but the particular materials
and amounts thereof recited in these examples, as well as other
conditions and details, should not be construed to unduly limit
this invention.
EXAMPLES
[0029] Unless otherwise noted, all reagents were obtained or are
available from Aldrich Chemical Co., Milwaukee, Wis., or may be
synthesized by known methods.
[0030] Formulation of Inks
[0031] With reference to Table I, several catalyst inks were made,
including comparative catalyst inks and catalyst inks according to
the present invention. Anode inks (Examples 1C (comparative), 2C
(comparative), and 3-6) and cathode inks (Examples 7C
(comparative), 8C (comparative), 9 and 10) were made.
[0032] Anode inks were made as follows: 30 g of catalyst powder
(SA27-13RC, 27% Pt & 13% Ru on 60% carbon from N.E. Chemcat
Corp., Tokyo, Japan) were weighed into a (16 oz) glass jar (8.9 cm
diameter by 8.9 cm height). Then, 112.2 g of a Nafion.TM. solution
(SE-10172, 10% in Water, CAS#31175-20-9, DuPont Fluoroproducts,
Wilmington, Del., USA) were gradually added to the catalyst powder
in the glass jar while the contents were uniformly dispersed with a
spatula to ensure no dry clumps of catalyst powder remained in the
mixture. The glass jar was then placed in ice bath, to minimize
solvent evaporation, under a rotor-stator high-shear mixer
(Ultra-Turrax T25, IKA Works, Wilmington, N.C.) and deagglomerated
for 1 minute at 16,000 rpm. Then 20.4 g of the additional solvent
indicated in Table I was added and high-shear mixing at 16,000 rpm
was continued for an additional 10 min. Additional solvents were
selected from: Water (B.P. 100.degree. C.), Ethylene Glycol (B.P.
197.degree. C., CAS#107-21-1), N-methyl pyrrolidinone (NMP)(B.P.
202.degree. C., CAS#872-50-4), N,N-Dimethylformamide (DMF)(B.P.
153.degree. C. CAS#68-12-2), N,N-Dimethylacetamide (DMA)(B.P.
165.degree. C., CAS#127-19-5), and Dimethylsulfoxide (DMSO)(B.P.
189.degree. C., CAS#67-68-5). After high shear deagglomeration, a
rubber spatula was used to scrape the catalyst dispersion off the
rotor-stator mixing head and off the wall of the glass jar and the
jar was tightly sealed to prevent solvent loss from the catalyst
dispersion.
[0033] Cathode inks were made as follows: 30 g of catalyst powder
(SA50BK, 50% Pt on 50% carbon from N.E. Chemcat Corp., Tokyo,
Japan) were weighed into a (16 oz) glass jar (8.9 cm diameter by
8.9 cm height). Then, 84 g of a Nafion.TM. solution (SE-10172, 10%
in Water, CAS#31175-20-9, DuPont Fluoroproducts, Wilmington, Del.,
USA) were gradually added to the catalyst powder in the glass jar
while the contents were uniformly dispersed with a spatula to
ensure no dry clumps of catalyst powder remained in the mixture.
80.1 g of additional water were added. The glass jar was then
placed in ice bath, to minimize solvent evaporation, under a
rotor-stator high-shear mixer (Ultra-Turrax T25, IKA Works,
Wilmington, N.C.) and deagglomerated for 1 minute at 16,000 rpm.
Then 22.5 g of the additional solvent indicated in Table I was
added and high-shear mixing at 16,000 rpm was continued for an
additional 10 min. Additional solvents were selected from: Water
(B.P. 100.degree. C.), Ethylene Glycol (B.P. 197.degree. C.,
CAS#107-21-1), N-methyl pyrrolidinone (NMP)(B.P. 202.degree. C.,
CAS#872-50-4), and Acetonitrile (B.P. 81.6.degree. C.,
CAS#75-05-8). After high shear deagglomeration, a rubber spatula
was used to scrape the catalyst dispersion off the rotor-stator
mixing head and off the wall of the glass jar and the jar was
tightly sealed to prevent solvent loss from the catalyst
dispersion. For Example 10, the weights reported above were cut to
one third, i.e., 10 g of anode catalyst powder, 28 g of Nafion.TM.
solution, 26.7 g of additional water and 7.5 g of additional
solvent (acetonitrile) were used.
[0034] Properties of Inks
[0035] The ink from each Example was examined for flocculation,
measured for viscosity, and tested for incineration under drying
conditions.
[0036] The ink from each Example was examined for flocculation by
eye and classified as strongly flocculated or weakly flocculated.
The results are reported in Table I.
[0037] A Bohlin Constant Stress Rheometer (available from Bohlin
Instruments Inc., East Brunswick, N.J.) was used to continuously
measure the viscosity of a catalyst dispersion as a function of
shear rate. Flow properties under constant stress conditions were
measured using a C14 cup-and-bob geometry at shear rates of between
1 and 800 sec.sup.-1.
[0038] A plot was made of shear viscosity vs. shear rate. Shear
rate (S) and shear viscosity (V) are related by the following
equation, known as the "Power Law Fluid" equation:
V=k S.sup.(n-1)
[0039] where, "k" is a constant that indicates viscosity at 1
sec.sup.-1 and "n" is the Power Law Index (PLI), which indicates of
the effect of shear on viscosity. If the shear viscosity of a
material is insensitive to shear rate, i.e., the fluid is a
Newtonian fluid, the PLI is 1.0. Those dispersions whose viscosity
decreases with shear are non-Newtonian and known as thixotropic.
The PLI of these thixotropic fluids range from 0 to 1. The
principles of the power law index are further described in C. W.
Macosko, "Rheology: Principles, Measurements, and Applications",
ISBN #1-56081-579-5, at page 85, incorporated herein by
reference.
[0040] Incineration was tested by notch-bar application of a 3"
(7.6 cm) wide by 3-mil (76 micron) thick coating of the catalyst
ink on a release liner comprising a 1-mil thick silicone-coated
microstructured polypropylene having microfeatures with a depth of
about 50 micron. Immediately after coating, the coating along with
the liner were placed in aluminum pan and placed in a convective
air oven at 140.degree. C. The coating was allowed to dry for 10
min. Later, the coatings were examined for either complete drying
or incineration of the catalyst coating.
1TABLE I Ex. 1C Ex. 2C Ex.3 Ex. 4 Ex. 5 Ex. 6 Ex. 7C Ex. 8C Ex. 9
Ex. 10 Type of Ink Anode Anode Anode Anode Anode Anode Cathode
Cathode Cathode Cathode Additional Water Ethyene NMP NMF DMA DMSO
Water Ethylene NMP Acetonitrile Solvent Glycol Glycol Type of
Solvent Inorganic Protic- Aprotic- Aprotic- Aprotic- Aprotic-
Inorganic Protic- Aprotic- Aprotic- Organic Organic Organic Organic
Organic Organic Organic Organic Total Solids 25.4% 25.4% 25.4%
25.4% 25.4% 25.4% 17.7% 17.7% 17.7% 17.7% Flocculation strong weak
weak weak weak weak strong strong weak weak Viscosity at 1
sec.sup.-1 14.5 0.92 0.9 1.67 5.79 1.86 14.6 12.62 0.45 0.95 (Pa
.multidot. sec) Power Law Index 0.3956 0.6622 0.6604 .06155 0.5016
0.6014 0.2509 0.2414 0.6823 0.6361 Incineration No Yes No No No No
No Yes No No
[0041] Various modifications and alterations of this invention will
become apparent to those skilled in the art without departing from
the scope and principles of this invention, and it should be
understood that this invention is not to be unduly limited to the
illustrative embodiments set forth hereinabove. All publications
and patents are herein incorporated by reference to the same extent
as if each individual publication or patent was specifically and
individually indicated to be incorporated by reference.
* * * * *