U.S. patent application number 09/553876 was filed with the patent office on 2001-12-20 for method of clarifying water using low molecular weight cationic dispersion polymers.
Invention is credited to Cardile, Richard P., Sparapany, John W..
Application Number | 20010052501 09/553876 |
Document ID | / |
Family ID | 24211126 |
Filed Date | 2001-12-20 |
United States Patent
Application |
20010052501 |
Kind Code |
A1 |
Sparapany, John W. ; et
al. |
December 20, 2001 |
Method of clarifying water using low molecular weight cationic
dispersion polymers
Abstract
This invention is directed to a method of clarifying water
comprising adding to the water an effective clarifying amount of a
low molecular weight water-soluble cationic dispersion polymer
prepared by polymerizing one or more cationic monomers and one or
more nonionic monomers and one or more chain transfer agents under
free radical forming conditions in an aqueous solution of an
anionic salt in the presence of a stabilizer polymer, wherein the
cationic dispersion has a cationic charge of from about 1.0 mole
percent to about 75 mole percent and an RSV of from about 0.2 dl/g
to about 6 dl/g.
Inventors: |
Sparapany, John W.;
(Bolingbrook, IL) ; Cardile, Richard P.; (Geneva,
IL) |
Correspondence
Address: |
Michael B Martin
Nalco Chemical Center
One Nalco Center
Naperville
IL
60563-1198
US
|
Family ID: |
24211126 |
Appl. No.: |
09/553876 |
Filed: |
April 20, 2000 |
Current U.S.
Class: |
210/732 |
Current CPC
Class: |
C02F 1/56 20130101; C02F
11/147 20190101; C02F 1/682 20130101; C02F 2103/001 20130101; C08F
220/56 20130101; C02F 11/148 20190101; C08F 220/56 20130101; C08F
220/34 20130101; C08F 220/56 20130101; C08F 220/34 20130101; C08F
220/34 20130101 |
Class at
Publication: |
210/732 |
International
Class: |
C02F 001/52 |
Claims
What is claimed is:
1. A method of clarifying water comprising adding to the water an
effective clarifying amount of a low molecular weight water-soluble
cationic dispersion polymer prepared by polymerizing one or more
cationic monomers and one or more nonionic monomers and one or more
chain transfer agents under free radical forming conditions in an
aqueous solution of an anionic salt in the presence of a stabilizer
polymer, wherein the cationic dispersion has a cationic charge of
from about 1.0 mole percent to about 75 mole percent and an RSV of
from about 0.2 dl/g to about 6 dl/g.
2. The method of claim 1 wherein the low molecular weight
water-soluble cationic dispersion polymer of claim 1 wherein the
nonionic monomers are selected from acrylamide and methacrylamide
and the cationic monomers are selected from
dimethylaminoethylacrylate methyl chloride salt and
dimethylaminoethylmethacrylate benzyl chloride salt.
3. The method of claim 2 wherein the low molecular weight
water-soluble cationic dispersion polymer has a cationic charge of
from about 10 mole percent to about 35 mole percent and a RSV of
from about 0.3 dl/g to about 6.0 dl/g.
4. The method of claim 2 wherein the low molecular weight
water-soluble cationic dispersion polymer has a cationic charge of
from about 10 mole percent to about 35 mole percent and a RSV of
from about 0.4 dl/g to about 5.0 dl/g.
5. The method of claim 2 wherein the low molecular weight
water-soluble cationic dispersion polymer is a copolymer of
acrylamide and dimethylaminoethylacrylate methyl chloride salt and
has a cationic charge of from about 10 mole percent and a RSV of
from about 0.5 dl/g to about 6 dl/g.
6. The method of claim 2 wherein the low molecular weight
water-soluble cationic dispersion polymer is a terpolymer of
acrylamide, dimethylaminoethylacrylate methyl chloride salt and
dimethylaminoethylacrylate benzyl chloride salt and has a cationic
charge of about 35 mole percent and a RSV of from about 0.5 dl/g to
about 6 dl/g.
7. The method of claim 6 wherein the low molecular weight
water-soluble cationic dispersion polymer has a RSV of about 2.5
dl/g.
8. The method of claim 1 wherein the water is selected from raw
water, waste water and process water.
9. A method of dewatering sludge comprising adding to the sludge an
effective amount of a low molecular weight water-soluble cationic
dispersion polymer prepared by polymerizing one or more cationic
monomers and one or more nonionic monomers and one or more chain
transfer agents under free radical forming conditions in an aqueous
solution of an anionic salt in the presence of a stabilizer
polymer, wherein the cationic dispersion has a cationic charge of
from about 1.0 mole percent to about 75 mole percent and an RSV of
from about 0.2 dl/g to about 6 dl/g.
10. A method for improving retention and drainage performance in a
papermaking process comprising adding to a papermaking slurry an
effective amount of a low molecular weight water-soluble cationic
dispersion polymer prepared by polymerizing one or more cationic
monomers and one or more nonionic monomers and one or more chain
transfer agents under free radical forming conditions in an aqueous
solution of an anionic salt in the presence of a stabilizer
polymer, wherein the cationic dispersion has a cationic charge of
from about 1.0 mole percent to about 75 mole percent and an RSV of
from about 0.2 dl/g to about 6 dl/g.
Description
TECHNICAL FIELD
[0001] This invention is directed to a method of clarifying water
using low molecular weight, low charge cationic dispersion
polymers.
BACKGROUND OF THE INVENTION
[0002] In the water treatment field of solids/liquid separation,
suspended solids are removed from water by a variety of processes,
including sedimentation, straining, flotation, filtration,
coagulation, flocculation, and emulsion breaking among others.
Additionally, after suspended solids are removed from the water
they must often be dewatered so that they may be further treated or
properly disposed of. Liquids treated for solids removal often have
as little as several parts per billion of suspended solids or
dispersed oils, or may contain large amounts of suspended solids or
oils. Solids being dewatered may contain anywhere from 0.25 weight
percent solids, to 40 or 50 weight percent solids material.
Solids/liquid or liquid/liquid separation processes are designed to
remove solids from liquids, or liquids from liquids.
[0003] While strictly mechanical means have been used to effect
solids/liquid separation, modern methods often rely on mechanical
separation techniques that are augmented by synthetic and natural
polymeric materials to accelerate the rate at which solids can be
removed from water. These processes include the treatment of raw
water with cationic coagulant polymers that settle suspended
particulates and make the water usable for industrial or municipal
purposes. Other examples of these processes include the removal of
colored soluble species from paper mill effluent wastes, the use of
organic flocculant polymers to flocculate industrial and municipal
waste materials, sludge recovery, emulsion breaking, drainage aids
in the manufacture of pulp and paper and flotation aids in mining
processing.
[0004] Clarification generally refers to the removal of
nonsettleable material by coagulation, flocculation and
sedimentation. Coagulation is the process of destabilization of the
colloid by neutralization of the surface charge of the colloid.
Once neutralized, particles no longer repel each other and can come
together to form larger settleable solids. Coagulation is necessary
for removal of colloidal sized suspended matter. Flocculation is
the process of bringing together the destabilized, "coagulated"
particles to form a larger agglomeration or floc for the purpose of
increasing the solid-liquid separation process.
[0005] Clarification chemicals are typically utilized in
conjunction with mechanical clarifiers for the removal of solids
from the treated water. The clarification chemicals coagulate
and/or flocculate the suspended solids into larger particles, which
can then be removed from the water by gravitational settling or
flotation.
[0006] Depending upon the characteristics of the water being
treated, differing chemical types and programs may be utilized. It
is conventional to utilize a dual polymer program for clarification
of raw water in which an aluminum chemistry is commonly used with
an organic coagulant to remove soluble color and other
contaminants. Clarification of waste waters can depend on the
nature of the solids being removed and the mechanical process.
Chemical treatment for waste water clarification is typically
employed when colloidal solids need to be removed so that the
biochemical oxygen demand, chemical oxygen demand and total
suspended solids being discharged to a receiving stream need to be
minimized. Typically, this comprises using a low molecular weight
cationic coagulant followed by a higher molecular weight
flocculant.
[0007] Processes for the preparation of high molecular weight
cationic dispersion polymer flocculants are described in U.S. Pat.
Nos. 5,006,590 and 4,929,655. Use of a cationic dispersion polymer
flocculant and a cationic coagulant for clarifying ink-laden water
obtained from the recycling of paper stocks is disclosed in
commonly assigned U.S. Pat. No. 5,750,034. High molecular weight,
high polymer actives cationic dispersion polymers for water
clarification, dewatering and retention and drainage are disclosed
in commonly assigned U.S. Ser. No. 09/054,980. The use of high
molecular weight cationic dispersion polymers as retention and
drainage aids in papermaking is disclosed in commonly assigned EPA
97116538.6 and U.S. Ser. No. 09/010,156.
SUMMARY OF THE INVENTION
[0008] In its principal embodiment, this invention is directed to a
method of clarifying water comprising adding to the water an
effective clarifying amount of a low molecular weight water-soluble
cationic dispersion polymer prepared by polymerizing one or more
cationic monomers and one or more nonionic monomers and one or more
chain transfer agents under free radical forming conditions in an
aqueous solution of an anionic salt in the presence of a stabilizer
polymer, wherein the cationic dispersion has a cationic charge of
from about 1.0 mole percent to about 75 mole percent and an RSV of
from about 0.2 dl/g to about 6 dl/g.
[0009] The cationic dispersion polymers of this invention have
superior performance than conventional coagulants for clarifying
raw, process and waste waters. The polymers of this invention also
show equivalent or improved performance when the polymers are used
as a coagulation aid for conditioning sludge for dewatering. The
use of these polymers affords removal of particulate materials
without the unwanted addition of oils and surfactants contained in
conventional latex polymers. Additionally, these polymers require
no inverter system and can be introduced to the process stream
using simple feeding equipment.
[0010] The superior performance of very low molecular weight
cationic dispersion polymers having significantly lower cationic
charge than conventional coagulants, which typically have a
cationic charge of 100 mole percent is unexpected. It is theorized
that the mode of action is not solely charge neutralization, but
may employ a mechanism of shielding where the anionic charge on the
colloidal particle is effectively shielded from the anionic charge
of another colloidal particle and the particles can
agglomerate.
[0011] A further advantage of the cationic dispersion polymer of
this invention is that it can be used as the sole treatment agent
and the performance is often much greater than the conventional
coagulants. Though other treatment agents may be added as adjuncts,
they are not required for activity.
[0012] In another embodiment, this invention is directed to a
method of dewatering sludge comprising adding to the sludge of an
effective amount of a low molecular weight water-soluble cationic
dispersion polymer prepared by polymerizing one or more cationic
monomers and one or more nonionic monomers and one or more chain
transfer agents under free radical forming conditions in an aqueous
solution of an anionic salt in the presence of a stabilizer
polymer, wherein the cationic dispersion has a cationic charge of
from about 1.0 mole percent to about 75 mole percent and an RSV of
from about 0.2 dl/g to about 6 dl/g.
[0013] In another embodiment, this invention is directed to a
method for improving retention and drainage performance in a
papermaking process comprising adding to a papermaking slurry an
effective amount of a low molecular weight water-soluble cationic
dispersion polymer prepared by polymerizing one or more cationic
monomers and one or more nonionic monomers and one or more chain
transfer agents under free radical forming conditions in an aqueous
solution of an anionic salt in the presence of a stabilizer
polymer, wherein the cationic dispersion has a cationic charge of
from about 1.0 mole percent to about 75 mole percent and an RSV of
from about 0.2 dl/g to about 6 dl/g.
[0014] Further, the aqueous dispersion of this invention, if
required in the form of an aqueous solution resulting from dilution
with water, can be advantageously used in a number of technological
fields as flocculating agents, thickeners, soil conditioners,
adhesives, food additives, dispersants, detergents and additives
for medicines or cosmetics, among others.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Definitions of Terms
[0016] As used herein, the following abbreviations and terms shall
have the following meanings:
[0017] AcAm for acrylamide;
[0018] DMAEA.BCQ for dimethylaminoethylacrylate benzyl chloride
quaternary salt;
[0019] DMAEA.MCQ for dimethylaminoethylacrylate methyl chloride
quaternary salt;
[0020] EPI-DMA for epichlorohydrin-dimethlyamine;
[0021] AIVN for 2,2'-azobis(2,4-dimethylvaleronitrile); and
[0022] AIBN for 2,2'-azobis(2-methylpropionitrile).
[0023] "Raw water" means water from natural geographical sources
including rivers, lakes, well water, rain water, and the like.
[0024] "Process water" means water used in a process such as a
manufacturing process (paper machine), steel production, chemical
production processes, refinery processes, food production processes
(i.e., sugar process), and the like.
[0025] "Waste water" means water from a manufacturing process,
municipal waste or other waters which are required to be treated
prior to discharge to a receiving stream, lake or other water
way.
[0026] "Papermaking process" means a method of making paper
products from pulp comprising forming an aqueous cellulosic
papermaking slurry, draining the slurry to form a sheet and drying
the sheet. The steps of forming the papermaking slurry, draining
and drying may be carried out in any conventional manner generally
known to those skilled in the art. Conventional coagulants,
conventional flocculants, alum, cationic starch or a combination
thereof may be utilized as adjuncts with the low molecular weight
cationic dispersion polymers of this invention, though it must be
emphasized that no adjunct is required for effective retention and
drainage activity.
[0027] "Monomer" means a polymerizable allylic, vinylic or acrylic
compound. The monomer may be anionic, cationic or nonionic. Vinyl
monomers are preferred, acrylic monomers are more preferred.
[0028] "Nonionic monomer" means a monomer as defined herein which
is electrically neutral. Representative nonionic monomers include
acrylamide, methacrylamide, N-methylacrylamide,
N,N-dimethyl(meth)acrylam- ide, N-isopropyl(meth)acrylamide,
N-(2-hydroxypropyl)methacrylamide, N-methylolacrylamide,
N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide,
poly(ethylene glycol)(meth)acrylate, poly(ethylene glycol)
monomethyl ether mono(meth)acryate, N-vinyl-2-pyrrolidone, glycerol
mono((meth)acrylate), 2-hydroxyethyl(meth)acrylate, vinyl
methylsulfone, vinyl acetate, and the like. Preferred nonionic
monomers include acrylamide and methacrylamide. Acrylamide is more
preferred.
[0029] "Cationic monomer" means a monomer as defined herein which
possesses a net positive charge. Cationic monomers have formula
1
[0030] wherein A.sub.1 is O or NH; B.sub.1 is C.sub.2-C.sub.4
alkylene or hydroxypropylene; R.sub.1 is H or CH.sub.3, R.sub.2 and
R.sub.4 are independently C.sub.1-C.sub.2 alkyl; R.sub.3 is H,
C.sub.1-C.sub.2 alkyl or arylalkyl; and X.sub.1 is an anionic
counterion. Representative cationic monomers include
dimethylaminoethylmethacrylate benzyl chloride salt (DMAEM.BCQ),
dimethylaminoethylacrylate benzyl chloride salt (DMAEA.BCQ),
dimethylaminoethylacrylate methyl chloride salt (DMAEA.MCQ),
dimethylaminoethylmethacrylate methyl chloride salt (DMAEM.MCQ),
dimethylaminoethylmethacrylate methyl sulfate salt (DMAEM.MSQ),
dimethylaminoethylacrylate methyl sulfate salt (DMAEA.MSQ),
methacrylamidopropyltrimethylammonium chloride (MAPTAC),
acrylamidopropyltrimethylammonium chloride (APTAC), and the like.
Dimethylaminoethylacrylate methyl chloride salt and
dimethylaminoethylmethacrylate benzyl chloride salt are
preferred.
[0031] "Alkyl" means a monovalent group derived from a straight or
branched chain saturated hydrocarbon by the removal of a single
hydrogen atom. Representative alkyl groups include methyl, ethyl,
n- and iso-propyl, cetyl, and the like.
[0032] "Alkoxy" and "alkoxyl" mean an alkyl-O-group wherein alkyl
is defined herein. Representative alkoxy groups include methoxyl,
ethoxyl, propoxyl, butoxyl, and the like.
[0033] "Alkylene" means a divalent group derived from a straight or
branched chain saturated hydrocarbon by the removal of two hydrogen
atoms. Representative alkylene groups include methylene, ethylene,
propylene, and the like.
[0034] "Hydroxypropylene" means a propylene group substituted with
hydroxy.
[0035] "Aryl" means an aromatic monocyclic or multicyclic ring
system of about 6 to about 20 carbon atoms, preferably of about 6
to about 10 carbon atoms. The aryl is optionally substituted with
one or more alkyl, alkoxy, halogen or haloalkyl groups.
Representative aryl groups include phenyl or naphthyl, or
substituted phenyl or substituted naphthyl. A preferred substituent
is alkyl.
[0036] "Arylalkyl" means an aryl-alkylene- group wherein aryl and
alkylene are defined herein. Representative arylalkyl include
benzyl, phenylethyl, phenylpropyl, 1-naphthylmethyl, and the like.
A preferred arylalkyl is benzyl.
[0037] "Halogen" means fluorine, chlorine, bromine or iodine.
[0038] "Haloalkyl" means an alkyl group, as defined herein, having
one, two, or three halogen atoms attached thereto. Representative
haloalkyl groups include chloromethyl, bromoethyl, trifluoromethyl,
and the like.
[0039] "Anionic counterion" means any organic or inorganic anion
which neutralizes the positive charge on the quaternary nitrogen
atom of a cationic monomer as defined herein. Representative
anionic counterions include halogen, sulfate, phosphate,
monohydrogen phosphate, nitrate, and the like. A preferred anionic
counterion is halogen.
[0040] "Chain transfer agent" means any molecule, used in
free-radical polymerization, which will react with a polymer
radical forming a dead polymer and a new radical. Chain transfer
agents are used herein to control the molecular weight of the
cationic dispersion polymers of this invention. Representative
Chain Transfer Agents are listed by K. C. Berger and G. Brandrup,
"Transfer Constants to Monomer, Polymer, Catalyst, Solvent, and
Additive in Free Radical Polymerization," Section II, pp. 81-151,
in "Polymer Handbook, " edited by J. Brandrup and E. H. Immergut,
3d edition, 1989, John Wiley & Sons, New York. Preferred chain
transfer agents include salts such as sodium formate, sodium
hypophosphite, and the like, alcohols such as methanol, ethanol,
propanol, benzyl alcohol, glycerol, and the like and combinations
thereof. Sodium formate, sodium hypophosphite and benzyl alcohol
and combinations of these chain transfer agents are more
preferred.
[0041] "Reduced Specific Viscosity" (RSV) is an indication of
polymer chain length and average 5 molecular weight. The RSV is
measured at a given polymer concentration and temperature and
calculated as follows: 1 RSV = [ ( o ) - 1 ] c
[0042] wherein .eta.=viscosity of polymer solution;
[0043] .eta..sub.o=viscosity of solvent at the same temperature;
and
[0044] c=concentration of polymer in solution.
[0045] As used herein, the units of concentration "c" are
(grams/100 ml or g/deciliter). Therefore, the units of RSV are
dl/g. The RSV is measured at 30.degree. C. The viscosities .eta.
and .eta..sub.o are measured using a Cannon-Ubbelohde Semi-Micro
dilution viscometer, size 75. The viscometer is mounted in a
perfectly vertical position in a constant temperature bath adjusted
to 30.+-.0.02.degree. C. The error inherent in the calculation of
RSV is about 0.5 dl/g. For the RSV measurements reported herein,
the polymer concentration used is 0.045% polymer actives dissolved
in either a 1.0N or a 0.125N sodium nitrate solution.
[0046] Similar RSVs measured for two linear polymers of identical
or very similar composition is one indication that the polymers
have similar molecular weights, provided that the polymer samples
are treated identically and that the RSVs are measured under
identical conditions.
[0047] "Dispersion polymer" means a water-soluble polymer dispersed
in an aqueous continuous phase containing one or more inorganic
salts. Representative examples of dispersion polymerization of
water-soluble polymers in an aqueous continuous phase are found in
U.S. Pat. Nos. 4,929,655, 5,006,590, 5,597,859 and 5,597,858 and
European patent nos. 630 909 and 657 478.
[0048] The cationic dispersion polymer of this invention is
prepared by preparing a mixture of water, one or more polyvalent
anionic salts, nonionic monomers, cationic monomers and chain
transfer agents, a particle stabilizing polymer, any polymerization
additives such as chelants, pH buffers and charging the mixture to
a reactor equipped with a mixer, a temperature regulating
thermocouple, a nitrogen purging tube, and a water condenser.
[0049] A batch or semi-batch polymerization method can be employed
to prepare the dispersion polymer of this invention. In a batch
polymerization, the polymeric stabilizing polymers, chain transfer
agents, monomers, chelant, and water are initially added to the
reactor. All or a portion of the formulation salt/salts are also
added to the reactor at this time. Mechanical agitation is started
and the reactor contents are heated to the desired polymerization
temperature. When the set-point temperature is reached, the
initiator is added and a nitrogen purge is started. The reaction is
allowed to proceed at the desired temperature until completion and
then the contents of the reactor are cooled. Additional inorganic
salts may be added during the polymerization to maintain
processability or influence final product quality. Moreover,
additional initiator may be added during the reaction to achieve
desired conversion rates and facilitate reaction completeness. Post
polymerization additives such as additional salt, water,
stabilizers for molecular weight and pH and anti-foaming and
biocidal agents may also be added to the reaction mixture.
[0050] Use of a semi-batch polymerization method will vary from a
batch polymerization method only in that one or more of the
monomers used in the synthesis of the polymer are held out in part
or whole at the beginning of the reaction. The withheld monomer is
then added over the course of the polymerization. If acrylamide
monomer is used as a semi-batch monomer, a chelant is often also
added during the semi-batch period.
[0051] Polyvalent anionic salts suitable for preparing the
dispersion polymer include inorganic or organic sulfates,
phosphates, chlorides or a mixture thereof. Preferred salts anionic
salts include ammonium sulfate, sodium sulfate, magnesium sulfate,
aluminum sulfate, ammonium hydrogen phosphate, sodium hydrogen
phosphate, potassium hydrogen phosphate and ammonium chloride. The
salts are used in aqueous solution typically having a combined
total concentration of 15 weight percent or above in the product
mixture.
[0052] Suitable polymeric stabilizing agents include water-soluble
cationic polymers that are preferably soluble in the aqueous salt
solution. The dispersant is used in an amount of from about 1 to
about 10% by weight based on the total weight of the hydrophilic
dispersion polymer.
[0053] The polymeric stabilizing agents, also referred to as
stabilizers, keep the formed polymer particles from becoming
agglomerated and forming a gel rather than a fine dispersion of
particles. Suitable stabilizers include homopolymers of cationic
diallyl-N,N-disubstituted ammonium monomers or
N,N-disubstituted-aminoethyl(meth)acrylate monomers and their
quaternary salts, copolymers of diallyl-N,N-disubstituted ammonium
monomers and N,N-disubstituted-aminoethyl(meth)acrylate monomers
and their quaternary salts and cationic polymers comprising 20 mole
percent or more of cationic diallyl-N,N-disubstituted ammonium
monomers or N,N-disubstituted-aminoethyl(meth)acrylate monomers and
their quaternary salts and one or more nonionic monomers,
preferably acrylamide, methacrylamide or styrene. The molecular
weight of the stabilizer is preferably in the range of about 10,000
to 10,000,000. Preferred dispersants include homopolymers of
diallyldimethyl ammonium chloride, dimethylaminoethylacrylate
methyl chloride quaternary salt and dimethylaminoethylmethacrylate
methyl chloride quaternary salt.
[0054] A multifunctional alcohol such as glycerin or polyethylene
glycol may also be included in the polymerization system. The
deposition of the fine particles is smoothly carried out in the
presence of these alcohols.
[0055] The polymerization reaction is initiated by any means that
results in generation of a suitable free-radical. Thermally derived
radicals, in which the radical species results from thermal,
homolytic dissociation of a water-soluble azo, peroxide,
hydroperoxide and perester compound are preferred. Especially
preferred initiators are azo compounds including
2,2'-azobis(2-amidinopropane) dihydrochloride and
2,2'-azobis(N,N'-dimeth- yleneisobutylamine) hydrochloride, and the
like.
[0056] A seed polymer may be added to the reaction mixture before
the initiating polymerization of the monomers for the purpose of
obtaining a fine dispersion. The seed polymer is a water-soluble
cationic polymer insoluble in the aqueous solution of the
polyvalent anion salt. The monomer composition of the seed polymer
need not be identical to that of the water-soluble cationic polymer
formed during polymerization. The seed polymer is preferably a
polymer prepared from the above monomer mixture by the process
described herein.
[0057] Since the dispersion polymers do not contain surfactants or
oil, the dispersion polymers are environmentally friendly.
Moreover, the absence of oil in the dispersion polymers equates to
such polymers having virtually zero volatile organic content (VOC),
which is another environmental advantage of such polymers.
[0058] Preferred Embodiments
[0059] In a preferred aspect of this invention, the nonionic
monomers are selected from acrylamide and methacrylamide and the
cationic monomers are selected from dimethylaminoethylacrylate
methyl chloride salt and dimethylaminoethylmethacrylate benzyl
chloride salt.
[0060] In another preferred aspect, the low molecular weight
water-soluble cationic dispersion polymer has a cationic charge of
from about 10 mole percent to about 35 mole percent and a RSV of
from about 0.3 dl/g to about 6 dl/g.
[0061] In another preferred aspect, the low molecular weight
water-soluble cationic dispersion polymer has a cationic charge of
from about 10 mole percent to about 35 mole percent and a RSV of
from about 0.4 dl/g to about 5 dl/g.
[0062] In another preferred aspect, the low molecular weight
water-soluble cationic dispersion polymer is a copolymer of
acrylamide and dimethylaminoethylacrylate methyl chloride salt and
has a cationic charge of from about 10 mole percent and a RSV of
from about 0.5 dl/g to about 6 dl/g.
[0063] In another preferred aspect, the low molecular weight
water-soluble cationic dispersion polymer is a terpolymer of
acrylamide, dimethylaminoethylacrylate methyl chloride salt and
dimethylaminoethylacrylate benzyl chloride salt and has a cationic
charge of about 35 mole percent and a RSV of from about 0.5 dl/g to
about 6 dl/g.
[0064] In a more preferred aspect, the low molecular weight
water-soluble cationic dispersion polymer is a terpolymer of
acrylamide, dimethylaminoethylacrylate methyl chloride salt and
dimethylaminoethylacrylate benzyl chloride salt and has a cationic
charge of about 35 mole percent and a RSV of from about 0.5 to
about 3.0 dl/g.
[0065] The effective clarifying dosage of the cationic dispersion
polymer depends on the characteristics of the water being treated
and can be readily determined by one of ordinary skill in the art.
Polymer should be dosed at a sufficient level to cause coagulation
of the dispersed material and cause improved settling. Typical
dosages are from about 0.1 to 500 ppm based on polymer actives.
However, dosages can be much higher and are dependent on the type
and concentration of solids in the stream. Dosages as high as 5000
ppm may be required.
[0066] In a preferred aspect, the water is selected from raw water,
waste water and process water.
[0067] The foregoing may be better understood by reference to the
following Examples, which are presented for illustration and are
not intended to limit the scope of the invention.
EXAMPLE 1
[0068] A low RSV 90/10 mole percent
acrylamide/dimethylaminoethylacrylate methyl chloride quaternary
salt dispersion polymer is prepared as follows:
[0069] To a 1.5 liter resin reactor equipped with a stirrer,
temperature controller and water condenser are added 338.92 g of
deionized water, 226.57 g of a 49.5% solution of acrylamide (Nalco
Chemical Company, Naperville, Ill.), 43.6 g of a 80% solution of
dimethylaminoethylacrylate methyl chloride quaternary salt (CPS
Chemical Co.), 13.5 g of glycerol, 5 g of adipic acid, 50 g of a
15% solution of a dimethylaminoethylacrylate methyl chloride
quaternary salt homopolymer (IV=2.0,Nalco Chemical Co.), 0.4 g of
EDTA, a chain transfer agent (see Table 1, sodium formate or sodium
hypophosphite) and 302 g of ammonium sulfate. The mixture is heated
to 48.degree. C. and 1.0 g of a 1% solution of
2,2'-azobis(2-amidinopropane) dihydrochloride (Wako Chemicals USA,
Inc., Richmond Va.) is added. The resulting solution is sparged
with nitrogen at the rate of 1000 cc/min. After 15 minutes, the
polymerization begins and the solution becomes viscous. Over the
next four hours, the temperature is maintained at 48.degree. C. At
three hours after initiation, 3 g of a 1% solution of
2,2-azobis(2-amidinopropane) dihydrochloride is added. At fours
after initiation, another 4 g of a 10% solution of
2,2'-azobis(2-amidinopropane) dihydrochloride is added to the
dispersion and the mixture is further reacted for 4 hours at
48.degree. C. Then 10 g of sodium thiosulfate and 5 g of acetic
acid are added to the dispersion mixture. The RSVs of the resultant
dispersion polymers are a function of the concentration of chain
transfer agent, and ranged from 15.6 dl/g to 1.0 dl/g.
1TABLE 1 Effect of Chain Transfer Agent (CTA) concentration on
polymer RSV. CTA concentration (ppm) RSV (1M NaNO.sub.3) none
(control) -- 18.5 dl/g sodium formate 100 15.6 dl/g sodium formate
500 11.4 dl/g sodium formate 2000 6.0 dl/g sodium hypophosphite 500
2.0 dl/g sodium hypophosphite 1000 1.0 dl/g
EXAMPLE 2
[0070] A 20.4% polymer solids, 65/15/20 mole percent
acrylamide/dimethylaminoethylacrylate benzyl chloride quaternary
salt/dimethylaminoethylacrylate methyl chloride quaternary salt
dispersion terpolymer is prepared as follows.
[0071] A 1.5 liter reaction flask is fitted with a mechanical
stirrer, thermocouple, condenser, nitrogen purge tube, an addition
port and heating tape. To this reaction flask are added 153.0 g of
acrylamide (48.6% aqueous solution (Nalco Chemical Co. of
Naperville, Ill.), 81.8 g of dimethylaminoethylacrylate benzyl
chloride quaternary salt (71.5% aqueous solution, Nalco Chemical
Co. of Naperville, Ill.), 70.4 g dimethylaminoethylacrylate methyl
chloride quaternary salt (79.5% aqueous solution, CPS Chemical
Company of Old Bridge, N.Y.), 36.4 g of a homopolymer of
dimethylaminoethylacrylate methyl chloride quaternary (15% aqueous
solution, Nalco Chemical Co., Naperville, Ill.), 55.4 g of a
homopolymer of diallyldimethylammonium chloride (12% aqueous
solution, Nalco Chemical Co., Naperville, Ill.), 1.0 g of sodium
formate, 0.2 g of ethylenediaminetetraacetic acid, tetra sodium
salt (Dow Chemical Co., Midland, Mich.), 160.0 g of ammonium
sulfate, 15.0 g sodium sulfate and 352.0 g of deionized water. The
mixture is heated to 47.degree. C. while stirring at 900 rpm. After
reaching 47.degree. C, 1.5 g of a 1.0% aqueous solution of
2,2-azobis(2-amidinopropane) dihydrochloride (Wako VA-50, Wako
Chemicals, Dallas, Tex.) is added to the reaction mixture and a
constant purge of nitrogen is started. After two hours, 9.1 g of
dimethylaminoethylacrylate benzyl chloride quaternary salt (71.5%
aqueous solution), 7.8 g dimethylaminoethylacrylate methyl chloride
quaternary salt (79.5% aqueous solution) and 3.0 g of a 1% aqueous
solution of 2,2'-azobis(2-amidinopropane) dihydrochloride are added
in sequence, in one shot portions. After an additional three hours,
4.0 g of a 10% aqueous solution of 2,2'-azobis(2-amidinopropane)
dihydrochloride is added and the reaction temperature is raised to
55.degree. C. After two hours at 55.degree. C. the reaction is
cooled, and 10.0 g acetic acid and 20.0 g ammonium chloride are
added.
[0072] The final product is a smooth milky white dispersion with a
bulk viscosity of 130 cp and a reduced specific viscosity of 9.8
dl/g, measured for a 0.045% solution of the polymer in 0.125N
aqueous sodium nitrate at 30.degree. C.
EXAMPLE 3
[0073] A 20.6% polymer solids, 65/15/20 mole percent
acrylamide/dimethylaminoethylacrylate benzyl chloride quaternary
salt/dimethylaminoethylacrylate methyl chloride quaternary salt
dispersion terpolymer is prepared as follows:
[0074] To the reactor described in Example 1 are added 150.5 g of
acrylamide (49.4% aqueous solution), 81.9 g of
dimethylaminoethylacrylate benzyl chloride quaternary salt (71.5%
aqueous solution), 70.4 g dimethylaminoethylacrylate methyl
chloride quaternary salt (79.5% aqueous solution), 32.0 g of a
homopolymer of dimethylaminoethylacrylate methyl chloride
quaternary (15% aqueous solution), 48.0 g of a homopolymer of
diallyldimethylammonium chloride (15% aqueous solution, Nalco
Chemical Co., Naperville, Ill.), 0.1 g of sodium formate, 2.0 g of
benzyl alcohol, 0.2 g of ethylenediaminetetraacetic acid, tetra
sodium salt, 155.0 g of ammonium sulfate, 15.0 g sodium sulfate and
368.0 g of deionized water. The mixture is heated to 47.degree. C.
while stirring at 900 rpm. After reaching 47.degree. C, 1.5 g of a
1.0% aqueous solution of 2,2'-azobis(2-amidinopropane)
dihydrochloride is added to the reaction mixture and a constant
purge of nitrogen is started. After two hours, 4.6 g of
dimethylaminoethylacrylate benzyl chloride quaternary salt (71.5%
aqueous solution) and 4.0 g dimethylaminoethylacrylate methyl
chloride quaternary salt (79.5% aqueous solution) are added in
sequence, in one shot portions. After an additional hour, a second,
equal monomer addition is made as before (4.6 g of
dimethylaminoethylacrylate benzyl chloride quaternary salt (71.5%
aqueous solution) and 4.0 g dimethylaminoethylacrylate methyl
chloride quaternary salt (79.5% aqueous solution)), followed by
addition of 3.0 g of a 1% aqueous solution of
2,2'-azobis(2-amidinopropane) dihydrochioride. After an additional
three hours, 4.0 g of a 10% aqueous solution of
2,2'-azobis(2-amidinopropane) dihydrochloride is added and the
reaction temperature is raised to 55.degree. C. After 1.5 hours at
55.degree. C. the reaction is cooled, and 10.0 g acetic acid and
10.0 g ammonium chloride are added.
[0075] The final product is a foamy, milky white dispersion with a
bulk viscosity of 360 cp and a reduced specific viscosity of 5.2
dl/g, measured for a 0.045% solution of the polymer in 0.125N
aqueous sodium nitrate at 30.degree. C.
[0076] Various levels and/or combinations of sodium formate and
benzyl alcohol are used to modify polymer molecular weight.
Examples of some of the tested combinations and their effect on
molecular weight are listed Table 1.
2TABLE 2 Effect of Chain Transfer Agent on Molecular Weight Grams
of sodium formate Grams of benzyl alcohol in approximately in
approximately RSV (dl/g) 1 kg reaction 1 kg reaction (0.125N
NaNO.sub.3) 0.5 0 13.2 1.0 0 9.8 5.0 0 2.5 0.1 2.0 5.2 6.0 2.0 1.5
5.0 2.0 1.6
[0077] The experimental polymer products tested in Examples 4-8 are
listed in Table 3. Polymer A is a representative high molecular
weight AcAm/DMAEA.MCQ dispersion polymer available from Nalco
Chemical Company. Polymers B-E are low molecular weight
AcAm/DMAEA.MCQ dispersion polymers prepared according to Example 1.
Polymer F is a representative high molecular weight
AcAmn/DMAEA.MCQ/DMAEA.BCQ dispersion polymer available from Nalco
Chemical Company. Polymers G-K are low molecular weight
AcAm/DMAEA.MCQ/DMAEA.BCQ dispersion polymers prepared according to
Examples 2-3. Polymers L-O are representative commercially
available solution or emulsion coagulants.
3TABLE 3 Product Polymer Cationic Charge RSV Type Cationic* Number
(Mole %) (dl/g) (Form) Chemistry Type A 10 13.0 Dispersion
DMAEA.MCQ B 10 6.0 Dispersion DMAEA.MCQ C 10 11.0 Dispersion
DMAEA.MCQ D 10 2.0 Dispersion DMAEA.MCQ E 10 1.0 Dispersion
DMAEA.MCQ F 35 20 Dispersion DMAEA.MCQ/BCQ G 35 15.3 Dispersion
DMAEA.MCQ/BCQ H 35 9.8 Dispersion DMAEA.MCQ/BCQ I 35 5.2 Dispersion
DMAEA.MCQ/BCQ J 35 2.5 Dispersion DMAEA.MCQ/BCQ K 35 1.5 Dispersion
DMAEA.MCQ/BCQ L 100 0.2 Solution DADMAC M 50 18.6 Emulsion
DMAEA.MCQ N 30 22.5 Emulsion DMAEA.MCQ O 100 0.1 Solution
EPI-DMA
[0078] The effectiveness of the low molecular weight water-soluble
cationic dispersion polymers of this invention for clarifying
wastewater is demonstrated using the procedures summarized
below.
[0079] Polymer Solution Preparation for Testing
[0080] A one g sample of the dispersion polymer product is added to
199 g of deionized water and mixed at 800 rpm for 30 minutes using
a cone drive mix motor fitted with a 1.5 inch diameter cage paddle.
The 0.5 percent solution produced by this method is then used
without further dilution.
[0081] Jar Test
[0082] The clarification of solids from water is tested using a
Gang Stirrer and employing standard jar testing practices. For
example, a 250 ml sample of the test water is placed into a 500 ml
beaker and stirred at 200 rpm on the Gang Stirrer. To the stirred
water sample, an aliquot of the polymer solution is added. The
mixture is stirred for one minute at 200 rpm followed by slow
mixing for five minutes at 50 rpm. The solids are then allowed to
settle without stirring for five minutes. Solids settled volume and
supernatant water clarity (turbidity) are measured. The turbidity
is measured using a Hach 2100 P turbidimeter.
[0083] Drainage Test
[0084] Drainage testing involves treating a sample of a solids
slurry or sludge with polymer and mixing the sludge and polymer
together until effective flocculation occurs. Then the
sludge-polymer mixture is poured onto a belt filter cloth and the
water drained at 5, 10 and 15 seconds is measured. The water
drainage and filtrate turbidity can be used as a relative
performance measurement between polymers and polymer dosages.
[0085] The drainage testing performed to evaluate the polymers of
this invention requires placing 200 ml of the water/solids slurry,
in a 500 ml graduated cylinder. Then an aliquot of the polymer
solution and enough additional water is added to the sludge in the
500 ml cylinder to bring the total volume to 225 ml in the 500 ml
graduate cylinder. The individual amounts of polymer solution and
water added to the sludge can vary to allow for different dosages
of polymer. However, the total volume of polymer solution and
dilution water remained at 225 ml. The cylinder is then capped and
inverted 5 times to thoroughly mix the polymer and the sludge. The
flocculated solids are then poured onto a belt filter fabric and
the water drainage is recorded at 10 seconds. The amount of water
drained and the clarity (turbidity) of the filtrate are recorded.
The turbidity is measured using a Hach 2100 P turbidimeter.
EXAMPLE 4
[0086] Secondary biosolids settling is evaluated in this example. A
500 ml water sample is treated using the Jar Test Procedure. The
results are presented in Table 4. In Example 4, the water turbidity
is measured to show performance of the low molecular weight
dispersion polymers. The data show that the lowest molecular weight
DMAEA.MCQ/BCQ polymers tested produced the cleanest (lowest
turbidity) water. These polymers are H and J. The higher molecular
weight experimental polymers tended to require high polymer dosages
to achieve the lower turbidity. Compared to the standard solution
polymer L, the low molecular weight dispersion polymers are much
more active in coagulating the dispersed solids.
4TABLE 4 Chemical Plant No. 1: Aeration Basin Biosolids
Clarification Supernatant Water Turbidity (NTU) Polymer Polymer
Product (RSV, dl/g) Dose (ppm) O A(17) B(6.0) C(11.0) G(20) H(9.8)
J(2.5) 8 35.7 44.3 31.9 21.5 31.9 10 37.6 51.1 32 18 25.5 11 26.3
12 29.6 37 28.1 13.8 20.4 13 25.2 15 27 40 23.6 12.2 18.3 16 16 18
24.6 36.1 21.2 11.4 16.4 20 18.4 24 17 27 26.5 33 24.4 40 24 50
19.8 60 16.9
EXAMPLE 5
[0087] In Example 5, a storm water treatment application is
evaluated. Here raw water is treated with polymer using the Jar
Test Procedure and supernatant turbidity is measured to determine
performance of the polymers. The results presented in Table 5 show
the lowest molecular weight polymer (J) is the best performing
experimental polymer compared to the current commercial coagulant
(L), for this application.
5TABLE 5 Chemical Plant No. 2: Storm Water Clarification
Supernatant Water Turbidity (NTU) Polymer Polymer Product and (RSV,
dl/g) Dose (ppm) L A(17) B(6.0) C(11.0) G(20) H(9.8) J(2.5) 0 127
127 127 127 127 127 127 5 92.2 77.9 52 7.5 113 80.7 91.9 104 97.9
57.7 53.4 10 105 76.7 77.5 94.1 75.7 46.3 18.5 13 84 43.2 76.1 92
70 12.7 11.2 24 124 62.5 67 55.7
EXAMPLE 6
[0088] In Example 6 the treatment of the oily waste water is
performed using the Jar Test Procedure and supernatant turbidity is
measured to determine performance of the polymers. The results are
shown in Table 6. The testing shows that these polymers could break
the emulsion and produce settable solids and cleaner supernatant
water.
6TABLE 6 Chemical Plant No. 3: Oil in Water Emulsion Breaking
Clarification Supernatant Water Turbidity (NTU) Polymer Polymer
Number and (RSV, dl/g) Dose (ppm) A(17) B(6.0) C(11.0) G(20) H(9.8)
J(2.5) 0 516 516 516 516 516 516 4 108 134 78.1 5 99.5 150 196 6
96.5 95.5 73.9 8 88 96.4 82.1 91.5 100 148 10 84.1 86.5 77.5 11 88
69.2 109 12 13 78.9 65.2 104 16
EXAMPLE 7
[0089] In Example 7, biosolids settling testing is performed using
the Jar Test Procedure and supernatant turbidity and settled solids
volume are recorded. The best performing dispersion polymers are I,
J, K, with RSVs of 5.2, 2.5 and 1.5, respectively. The performance
trend found in this application is that the 35 mole percent
dispersion polymers with RSVs between 6 and 1.5 dl/g produced the
lowest turbidity supernatant water and lowest settled solids
volume. Thus, these polymers outperformed the higher molecular
weight dispersion polymers.
7TABLE 7 Chemical Plant No. 4: Secondary Biosolids Clarification
Supernatant Water Turbidity (NTU)/Settled Solids Volume (ml)
Polymer RSV Polymer Dosage (ppm) Number (dl/g) 0 2.5 5 10 15 A 17
242/200 177/170 37.1/160 34.5/140 31.2/150 B 6.0 242/200 42.2/180
40.2/180 41.6/170 39.2/160 C 11.0 242/200 58.6/180 45.6/180
37.8/200 42.8/200 D 2.0 242/200 42.4/150 37.6/150 31.6/150 38.6/150
E 1.0 242/200 82.7/160 35.4/150 31.6/140 28.3/140 F 25 242/200
234/170 204/150 99.2/150 315/150 G 20 242/200 45.2/150 37.5/140
37.6/110 33.2/120 H 9.8 242/200 83.7/150 33.5/150 21.8/140 20.0/140
I 5.2 242/200 38.9/150 21.3/150 18.3/140 12.0/140 J 2.5 242/200
39.8/150 20.5/140 14.4/130 10.6/110 K 1.5 242/200 196/170 150/160
26.0/150 12.8/140
EXAMPLE 8
[0090] In this example, sludge from a municipal plant is used to
evaluate the coagulant effects of the experimental polymers.
Drainage testing is performed where the experimental polymer is
added to the sludge and mixed with the solids. Then, the cationic
commercial flocculant is added at the same dosage for all the
tests. The sludge is mixed and poured onto a filter screen. The
water drainage and turbidity of the filtrate water are recorded.
Changes in drainage volume and turbidity are solely due to changes
in the experimental polymer molecular weight (RSV) and composition.
Greater water drainage with lower turbidity is generally desired at
low polymer dosages. The results are presented in Table 8. Polymer
N is the standard flocculant used for the drainage test. The
results show the greatest reduction in turbidity and greatest water
drainage volume occurred with the experimental dispersion polymers
with RSVs less than about 6 dl/g. The best performing 10 mole
percent cationic dispersion polymer is B (RSV=6 dl/g) and the best
performing 35 mole percent cationic dispersion polymer is K
(RSV=1.5 dl/g).
8TABLE 8 Municipal Plant No. 1: Sludge Dewatering Filtrate Water
Turbidity (NTU)/Water Drainage Volume (ml) Polymer RSV 0.5%
Dispersion Polymer N Dosage (ml of a 0.5% Solution) Number (dl/g)
Dose (ml) 1 1.5 2 2.5 3 N 22 0 456/82 114/115 36/140 53/150 B 6.0
1.5 33/115 57/110 62/120 D 2.0 1.5 41/110 44.8/105 53.4/115 E 1.0
1.5 55.1/115 66.2/110 74.4/108 H 9.8 1.5 80/115 45/125 32.4/150 I
5.2 1.5 52.5/115 27/135 21.5/152 J 2.5 1.5 82/138 27/142 35.5/145 K
1.5 1.5 31.7/120 35/135 20.4/145
EXAMPLE 9
[0091] The effectiveness of the low molecular weight water-soluble
cationic dispersion of this invention as a retention and drainage
aid is shown in Example 9. Testing is performed by adding 0 2.5 ppm
of the low molecular weight polymer into 500 ml of paper furnish
and mixing by pouring the mixture from beaker to beaker. Five
beaker to beaker pours are used and then the cationic flocculent at
10 ppm is added and the mixture is mixed for an additional 7 beaker
to beaker pours. The mixture is then poured onto a retention wire
and the turbidity of the filtrate is measured. The results
presented in Table 9 clearly show the lower RSV (molecular weight)
polymers have more activity in reducing filtrate turbidity than the
high molecular weight polymers and the L standard coagulant
chemistry.
9TABLE 9 Paper Mill 1: Retention and Drainage Testing Measured
Water Turbidity (NTU) at 2.5 ppm Dosage Polymer RSV Number (dl/g)
Turbidity (NTU) No Polymer 750 L 0.2 273 F 25 151 G 20 138 H 9.8
101 I 5.2 131 J 2.5 80 K 1.5 76
* * * * *