Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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RECYCLABLE CLEANING COMPOSITIONS
RELATED APPLICATION DATA
This application claims priority under 35 U.S.G. ~119 from provisional
application serial no. 60/209,765, filed June 6, 2000.
FIELD OF THE TNVENTION
The present invention relates to recyclable cleaning compositions. More
particularly, the invention relates to cleaning compositions including an
alkaline solution of
at least one surfactant and having improved surfactant recovery upon membrane
filtration of
the solution.
BACKGROUND OF THE INVENTION
An aqueous cleaning process for cleaning soiled hard surface articles, in its
basic form includes a cleaning stage, a rinsing stage, and a drying stage.
Hard surface articles
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cleaned by such a process include metal, glass, plastic and ceramic articles.
Soils typically
present on hard surface articles include contaminants such as oils, mineral
salts and suspended
particulates. During the cleaning stage of the cleaning process, contaminants
are removed
from the articles by contact between a cleaning solution and the articles. As
these
contaminants are removed from the articles and introduced into the aqueous
cleaning solution,
the aqueous cleaning solution may become too concentrated with contaminants to
perform
adequately. Contaminants that reduce the effectiveness of the cleaning
solution include
organic components, such as free floating and emulsified oils, and inorganic
materials
including mineral salts or suspended particulates. Other materials, which are
inherent to the
cleaning chemistry, may also concentrate over time and decrease the
effectiveness of the
cleaning solution.
Aqueous based cleaning solutions that have been used to clean soiled articles
may contain from 1 to 5% emulsified oils and up to 50% free floating oils,
depending upon
the articles being cleaned and the effectiveness of the solutions. A greater
amount of the oils
may also be present in the solutions. These "used" solutions are hereafter
referred to as soiled
cleaning solutions. The prior art discloses methods of treating the soiled
cleaning solutions
to remove the contaminants contained therein. Treatment of such soiled
cleaning solutions,
however, can be impractical for small waste generators and costly for large
waste generators.
Classical treatment methods for soiled aqueous based cleaning solutions
include decanting,
skimming, and coalescing. These treatment methods are useful for removing
large amounts
of free floating oil contaminants, but axe not effective for removing
emulsified oil
contaminants.
Emulsified oil as well as free floating oil may be removed from soiled
cleaning
solutions via membrane filtration. The act of removing contaminants from the
aqueous
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cleaning solution via membrane filtration is known as cleaner recycling. An
aqueous cleaning
solution is considered recyclable if the contaminants contained therein can be
removed in a
sufficient proportion such that the cleaning solution may be effectively
reused in the cleaning
process. Typically, a recycling process using membranes will trap solids, free
floating oils,
and emulsified oils while passing some surfactant, alkalinity builders, other
adjuvants and
water back into the aqueous cleaning solution.
Recycling by membrane filtration, therefore, not only reduces or eliminates
the
discharge of contaminated water into the environment, but it also allows the
aqueous cleaning
solution to be used for an extended time frame. An effective recycling
process, therefore,
results in economic and enviromnental advantages fox the user.
Membrane filtration typically involves a pressure driven process that will
remove particles and oil from the soiled cleaning solutions. Several types of
membrane
processes are used in the industry, including ultrafiltration and
microfiltration. The major
problems with membrane filtration involve cost, chemical fouling, scaling and
membrane
compatibility. In addition, active cleaning components are often removed via
membrane
filtration resulting in a less effective permeate. Furthermore, prior art
membrane filtration
processes are limited to lower temperatures since higher temperatures
detrimentally affect
cleaning, foaming and anti-corrosion properties of the cleaning solutions. The
effectiveness
of the prior art recycled compositions as well as their length of use,
therefore, are substantially
reduced. The invention that is described below overcomes these prior art
limitations.
As indicated above, high surfactant permeability is required for the effective
recycling of soiled cleaning solutions. High surfactant permeability is
defined as the ability
of the surfactant to maintain 50% by weight (or greater) of its starting value
upon recycling
in unsoiled conditions and to maintain 30% by weight (or greater) of its
starting value upon
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recycling in soiled conditions. The identification of surfactants with high
surfactant
permeability may be attained by known methods. However, the known methods of
measuring surfactant permeability are very time consuming and considerable
analytical effort
is required to support these permeability measurements. Given the large number
of available
surfactants, an alternative approach is needed to identify surfactant
candidates likely to have
high surfactant permeability. The invention that is described herein provides
this
identification
Much has been disclosed in the literature concerning the filtration of aqueous
cleaning solutions. U.S. Patent No. 5,205,937 to Bhave et al. discloses
aqueous cleaning
systems wherein a high percentage of the cleaner is said to pass through to
the permeate for
recycling. The amount of cleaner in the permeate, however, is measured by
alkalinity
titration. In fact, most of the nonionic surfactants disclosed therein do not
pass through the
membrane.
U.S. Patent 5,654,480, U.S. Patent 5,843,317 and U.S: Patent 5,919,980 all to
Dahanayake, et al., U.S. Patent 6,004,466 to Derian et al., and U.S. Patent
6,013,185 to
Ventura, et al. claim improved surfactant recovery upon ultrafiltration of
surfactant containing
aqueous solutions. The degree of recycling and recovery in these patents was
determined by
comparing the surface tension of permeate and feed streams. This method of
measurement,
however, is qualitative and raises technical issues on the validity of the
results.
For example, any soil introduced into the system could effect the nature of
the
surface tension curve in the area between critical micelle concentration (CMC)
and infinite
dilution. In addition, it is well known that surfactant systems are comprised
of a variety of
oligomers and selective partitioning of some oligomers will effect the CMC
resulting in
possible significant error. In this case, CMC measurements to determine
surfactant
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concentration would be invalid. In addition, this prior art is silent on
determining recyclability
in the presence of soil.
To determine the actual recyclability of surfactant systems, the surfactant
system must be tested in the presence of soil. It is well lcnown in the art
that surfactant are
5 composed of several oligomers (polydisperse, hydrophobe, and lipophobe)
which behave
differently in their partitioning between oil and water phases. For instance,
a typical nonionic
surfactant having a reported HLB (hydrophobic/lipophobic balance) of 12 will,
in fact, contain
a range of components having HLB from about 4 to 14. The
hydrophobic/lipophobic balance
(HLB) values measure hydrophobicity and are used to characterize surfactants
for their
water/oil solubility. Therefore, in the application of recycling in the
presence of soil, the low
HLB surfactant components will naturally be eliminated due to the higher
partitioning of these
materials into the rejected oil phase. Thus, the presence of soil must be
considered in the
identification of optimum and unique systems for recycle use.
Woodrow, et al., Metal Finishing, November 1998, discusses a case study in
the regeneration of a soiled aqueous cleaner using ultrafiltration. In this
study, the recycled
cleaners were measured and compared in connection with refractive indexes,
solution pH and
conductivity of permeate of feed solutions as well as gravimetric
determination of surfactants.
It was determined that filtration reduced oils below 0.01 % but also
significantly reduced the
amount of active cleaning ingredient in the permeate.
The literature references referred to in this disclosure are incorporated
herein
in their entirety.
An obj ect of the invention is to provide a recyclable cleaning composition
and
process for removing contaminants from hard surface articles where a membrane
system is
employed to treat the soiled cleaning solution whereby the membrane will rej
ect hydrophobic
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oily contaminants contained in the soiled cleaning solution while allowing the
active
ingredients of the cleaning solution to permeate the membrane for reuse.
A second object of the invention is to provide an aqueous waste cleaning
system for removing contaminants from hard surface articles where a membrane
system is
used to treat the soiled cleaning solution, the permeate retains a high degree
of active cleaning
constituents and where the membrane used therein has a pore size range from
about 0.05 to
about 5 microns.
A third object of this invention is to provide a method for rapidly screening
surfactants for penneablilty.
These and other objects of the invention will become readily apparent upon
consideration of the following detailed description of the invention, taken in
connection with
the accompanying drawings.
SUMMARY OF THE INVENTION
It has been surprisingly found that increased surfactant recovery can be
obtained via a filtration process using aqueous compositions containing
certain surfactant
systems which, when filtered, result in a permeate having increased surfactant
concentrations
as compared to the prior art. The recyclable cleaning compositions of the
present invention
comprise an aqueous alkaline solution containing from 1 % to 20% by weight of
a synthetic
detergent comprising at least one surfactant, and a high degree of
permeability through a
membrane having a pore size of about 0.05 to about 5.0 microns after the
composition has
been used in the cleaning process.
The cleaning composition may optionally contain builders, corrosion
inhibitors, anti-scaling materials, alkalinity electrolytes, hydrotropes,
antifoam materials,
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wetting agents, solvents and~other adjuvants and these adjuvants are also
permeable through
the membrane for recycling and reuse. The cleaning composition also can be
used at low
concentrations while imparting good cleaning and low foaming profiles.
The present invention also provides a process for the filtration of
contaminants
from an aqueous surfactant containing composition by passing the soiled
cleaning solution
through a membrane having a pore size of about 0.05 to about 5.0 microns where
the
contaminants are filtered off and the permeate contains a high level of
cleaning agents and is
recycled for reuse.
The present invention also provides a method for rapidly screening surfactants
for permeability.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic representation of the recycle system of the present
invention.
Fig. 2 is a graph showing membrane pore size versus percent recyclability for
Formula A versus Formula B in unsoiled condition at 80°F.
Fig. 3 is a graph showing membrane pore size versus percent recycliability for
Formula A versus Formula B in unsoiled condition at 140°F.
Fig. 4 is a graph showing membrane pore size versus percent recycliability for
Formula A versus Formula B in soiled conditions at 80°F.
Fig. 5 is a graph showing membrane pore size versus percent recyclability for
Formula A versus Formula B in soiled condition at 140°F.
Fig. 6 is a graph showing the HPLC Log P Calibration Curve (alkyl benzene
standards).
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Fig. 7 is a graph showing HPLC Profiles of Neodol~ 91-6 and of Poly-
Tergent° SL-92.
Fig. 8 is a graph showing Calculated vs. Estimated Surfactant Log P Results.
Fig. 9 is a graph showing Permeability Results in unsoiled conditions.
Fig. 10 is a graph showing Neodol~ 91-6 Hydrophobe Permeability Results in
unsoiled conditions.
Fig. 11 is a graph showing Poly-Tergent~ SL-92 Hydrophobe Permeability
Results in unsoiled conditions.
Fig. 12 is a graph showing Surfactant Permeability vs. Log P in unsoiled
' conditions.
Fig. 13 is a graph showing Surfactant Permeability vs. Cloud Point in unsoiled
conditions.
Fig. 14 is a graph showing Permeability vs. Log P for all hydrophobes in
unsoiled conditions.
Fig. 15 is a graph showing Permeability vs. Log P for unsoiled conditions at
140°F for all hydrophobes.
Fig. 16 is a graph showing permeability results of surfactants in the presence
of Cosmoline~ 1102.
Fig.17 is a graph showing permeability results of Neodol~ 91-6 in the presence
of Cosmoline 1102.
Fig. 18 is a graph showing permeability results of Polytergent~ SL-92 the
presence of Cosmoline 1102.
Fig. 19 is a graph showing Permeability vs. Cloud Point for Cosmoline~ 1102
Soil at 140°F.
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Fig. 20 is a graph showing Permeability vs. Log P for Cosmoline°
1102 soil
at 140°F for all hydrophobes.
Fig. 21 is a graph showing Permeability vs. Cloud Point for Pennzoil
° 4096
Gear Lubericant SAE 80W90 GLS soil at 140°F.
Fig. 22 is a graph showing Permeability vs. Log P for Pennzoil °
4096 Geax
Lubericant SAE 80W90 GLS soil at 140°F for all hydrophobes.
Fig. 23 is a graph showing Permeability vs. Log P for Pennzoil °
4096 Geax
Lubericant SAE 80W90 GLS soil at 140°F for all hydrophobes.
Fig. 24 is a graph showing Permeability Results - Unsoiled vs. Pennzoil
° 4096
Gear Lubericant SAE 80W90 GLS soil.
Fig. 25 is a graph showing permeability result of Barlox ° 12i
Multiple Oil
Addition Study
Fig. 26 is a graph showing Temperature Effect on Permeability Results -
Cosmoline° 1102 Soil.
DETAILED DESCRIPTION OF THE INVENTION
The objects and advantages mentioned above as well as other objects and
advantages may be achieved by the compositions and methods hereinafter
described.
The recyclable cleaning compositions of the present invention are useful in
the
cleaning of hard surface articles such as metal, glass, plastic, ceramic or
other haxd surface
articles. The recyclable cleaning compositions of the present invention axe
designed to clean
hard surface articles by lifting soil and contaminants from the articles and
preventing
redeposition of said soils and contaminants.
The cleaning compositions of the present invention axe designed to be used in
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a variety of cleaning machines including, but not limited to, hand parts
washers, immersion
dip baths, power spray systems, ultrasonic baths, and spray wands.
The recyclable cleaning compositions of the present invention comprise an
aqueous alkaline solution containing a detergent comprising certain classes of
individual
surfactants and their mixtures, that when combined with other formulation
ingredients, such
as builders, corrosion inhibitors, antiscaling materials, alkalinity
electrolytes, hydrotropes,
antifoam materials, wetting agents and other adjuvants, provide unique
cleaning compositions
that demonstrate improved recycling capabilities as well as high utility in
terms of cleaning,
foaming and surface protection.
10 Important to the present invention is the choice of surfactants which allow
the
present invention to provide a high degree of cleaning and also provide a high
degree of
permeability when tested with various membranes ranging in pore size from 0.05-
5.0 microns.
A high degree of permeability means that at least 50% by weight of the
surfactant in the
solution permeates a membrane having a pore size of about 0.05 to 5.0 microns
in unsoiled
conditions, and at least 30% by weight of the surfactant in the detergent
permeates the same
sized membrane, after the solution is contaminated or soiled under at least
one set of soiled
conditions. A preferred set of soiled conditions would include the use of
Cosmoline~ 1102
from Houghton International, Inc. of Valley Forge, PA, as the soil with the
operating
temperature of 140 degrees F. The recyclable cleaning compositions of the
present invention
comprise a detergent that includes one or more surfactants that have an
estimated Log P, as
defined below, of less than 4.5. The compositions of the present invention are
designed for
use at temperatures below about 90°C.
Membranes of all types can be used with this invention including but not
limited to those made of ceramic, polysulfone, polyacrylnitrile (PAN), and
cellulose.
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The formulations of the present invention employ certain classes of individual
surfactants and their mixtures, which when combined with other formulation
ingredients such
as builders, corrosion inhibitors, alkalinity electrolytes, antiscaling
materials, hydrotropes,
antifoam materials, wetting agents, solvents, other adjuvants and mixtures
therof, provide
unique cleaning compositions with useful properties of recyclability and waste
water clean-up
as well as providing high utility in terms of cleaning, foaming and surface
protection.
The formulations of the present invention may also contain water which dilutes
the aqueous alkaline solution of the present invention.
The recyclable industrial cleaning compositions of the present invention are
~ an improvement over the prior art at least because the compositions of the
present invention
may be freed of contaminants via filtration over a wide range of temperatures
while retaining
a significant amount of their cleaning components under soiled conditions.
Moreover, the
cleaning compositions may be used at low concentrations and also provide
excellent cleaning,
low foaming and corrosion protection upon recycle and reuse.
A practical family of formulations which are based on a combination of
surfactants and builders and other adjuvants which meet a technical criteria
for permeabilities
to specific membrane pore sizes are disclosed herein.
Recycle System Process Description
Fig. 1 depicts a schematic view of one type of recycle system process. As can
be seen from Fig. 1, the original cleaning composition is contained in an
initial tank, called
a customer tank, and is pumped to a holding tank where soiled articles are
present. After
cleaning of the articles, the soiled cleaning solution is then pumped from the
holding tank and
through a membrane. The soiled cleaning solution then flows across the
membrane and the
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components that are too large to permeate the pores of the membrane are
separated from the
solution. The separated material is called the retentate. The retentate is
returned to the
holding tank as depicted, although the retentate may also be discarded. The
solution that
passes through the membrane is called the permeate. The permeate is returned
to the
customer tank for reuse.
The permeability of surfactant containing compositions may be measured by
preparing a two liter sample of a test solution containing at least one
surfactant and heating
it to the temperature for the study. The test solution is placed in a test
solution container. The
test solution is fed into a standard cross flow membrane of pore size and
material of
construction of choice for the study. The permeate solution is collected and
the retentate
stream is recycled back into the test solution container. The test continues
until 90% of the
original two liter test solution volume in the container has been consumed.
Analyses for
active components (e. g., surfactants) are then compared between the original
test solution, the
retentate and the permeate. The % permeability of surfactant containing
compositions is
calculated using the equation below.
The % permeability is defined as
permeability = concentration ~pea,,eate~ * 100
concentration ~lnitial)
Results can easily be obtained by measuring the total organic carbon content
(TOC), among
other tests.
The Temperature of Operation and HLB
The range in temperature for cleaning hard surface articles, called the
operating
temperature, generally is from about 111 °F to about 181.4°F
(about 44°C to about 83°C). The
choice of surfactant system for the aqueous cleaning composition depends upon
the behavior
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of the surfactant system in water as a function of temperature. As the
temperature increases,
surfactants generally tend to become insoluble and ineffective for recycling.
The point at
which a surfactant becomes insoluble and precipitates or "clouds out" is
called its cloud point.
Without being held to any theory, it is believed that when nonionic
surfactants
are mixed in aqueous systems, the surfactant becomes solubilized by forming
hydrogen bonds
with the surrounding water molecules thereby becoming hydrated. As the
temperature of the
system is increased, the surfactant/water hydrogen bonds are broken and the
surfactant
becomes dehydrated. When the surfactant becomes dehydrated, it has reached its
cloud point.
At its cloud point, a surfactant becomes insoluble in water but highly soluble
in oil.
Surprisingly, it has been found that it is difficult to judge permeability
based
solely on cloud points. For example, Table A shows that Poly-Tergent° E-
17A, an ethylene
oxide-propylene oxide-ethylene oxide (EO-PO-EO) block copolymer made by BASF
Corp.
of Mt. Olive, N.J., has roughly the same permeability (based on total organic
carbon) of Poly-
Tergent ° SL92, a linear alcohol alkoxylate, at room temperature
(68°F) despite the wide
difference in cloud point.
Similarly, surfactant hydrophobicity would be expected to determine the degree
to which soil partitioning occurs. The hydrophobic/lipophobic balance (HLB)
values
measure hydrophobicity and are used to characterize surfactants for their
water/oil solubility.
HBL values, however, do not lend themselves well to estimating permeability in
connection
with small pore membranes, as can be seen in Table A which shows that Poly-
tergent ° E-
17A, has roughly the same permeability (based on total organic carbon) of Poly-
tergent °
SL92, despite the wide difference in HLB.
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Table A
Permeability and Cloud Point
Surfactant Permeability (% cloud pointHLB MW
TOC) Fo
Poly-tergent 55 32 2.4 2500
E-17A
Poly-tergent 53 92 12.9 850
SL-92
The Composition
Important to this invention is the choice of surfactant or surfactants for the
cleaning compositions. The surfactants of this invention allow the disclosed
formulations to
provide a high degree of cleaning as well as a high degree of recyclability.
The cleaning
compositions contain from 1% to 20% by weight of a synthetic detergent. The
detergent
comprises a surfactant or surfactants selected from amine oxide surfactants,
nonionic
ethoxylated surfactants, anionic surfactants, alkyl polyglucoside surfactants,
amphoteric
surfactants and mixtures thereof, wherein at least one of the surfactant or
surfactants have a
Log P of less than 4.5 as determined by the method set forth herein.
The octanol/water partition coefficient is a common measure of hydrophobicity
used for environmental and pharmaceutical applications. Because of the large
range in values,
octanol/water partition coefficients are typically reported as Log KoW, also
known as Log P.
This measurement is calculated by the following equation:
Log P= Log COllCoctanol)
(concaa)
The prefeiTed amine oxide surfactants are those with an alkyl chain length of
from about C8 to CIZ. Amine oxide surfactants of this type are available
commercially under
the name Mackamine ~ (alkyldimethyl amine oxide) manufactured by McIntyre
Chemical of
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Chicago, IL and Barlox° 12i (proprietary dimethyl amine oxide)
manufactured by Lonza Inc.
of Fairlawn, N.J.
The preferred nonionic ethoxylated surfactants include capped alkyl
ethoxylates, alcohol ether carboxylates and alkoxylated amine surfactants.
Commercially
5 available alkyl ethoxylates ofthis type includeNeodol° 91-6
manufactured by Shell Chemical
Co. of Houston, TX, Poly-Tergent SL-92 manufactured by BASF Corp. of Mt.
Olive, NJ,
Triton ° RW100, Triton ° SP-190 by Union Carbide of
Charleston, SC.
The preferred anionic surfactants include sodium dodecylbenzene sulfonate,
sodium alkyl sulfate, sodium alkyl phosphate esters, sodium alkyl ether
sulfates, and others.
10 A commercially available surfactant of this type is Avanel °S74 from
BASF Core. of Mt.
Olive, NJ.
The alkylpolyglucoside surfactants are commercially available such as
Glucopon° 425 manufactured by Henkel Corp. in Ambler, PA and
Triton°CG110 by Union
Carbide of Charleston, SC.
15 The preferred amphoteric surfactants include sultaines, betaines, imidazole
derivatives, alkylaminoproprionate and diproprionates. Commercially available
examples of
amphoteric surfactants are Mirataine ° JC-HA manufactured by Rhodia,
Inc., Foamtaine
°CAB-A by Alzo, Inc. of Sayerville, NJ and Amphoteric ° 400 from
Tomah Products of
Milton, WL.
The present invention may also contain adjuvants as described below.
The present invention may contain builders such as alkali earth metal and/or
ammonium salts of carbonate, bicarbonate, hydroxides, phosphates, and
silicates or mixtures
thereof for the purpose of providing a builder system, and to provide
buffering and/or pH
adjustability. Other optional ingredients that provide buffering and pH
adjustability include
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potassium hydroxide, sodium hydroxide and simple amines such as
triethanolamine and 2-(2-
aminoethyl)-ethanol.
A preferred embodiment of the present invention contains a blend of potassium
carbonate and potassium bicarbonate. A preferred range of this blend is a
ratio of 1/20 to 20/1
and the preferred weight percent of this blend is about 2 to 15 weight percent
of the
composition. A more preferred blend ratio is 1/2 to 2/1 and a more preferred
weight percent
is about 7 to 12 weight percent.
LTse of corrosion inhibitors such as borax, benzotriazole or carboxylic acid
amine mixtures may be included to protect the soiled hard surface articles
from flash rusting.
The preferred weight % of corrosion inhibitors is 0.1 to 8 weight percent of
the composition.
Cobratec° TT-100, a benzotriazole, by PMC Specialties in Rocky River,
OH, is an example
of a corrosion inhibitor. Hostocor ° 2732 and DeCore ° IMT-
100LF, carboxylic acid amine
mixtures, manufactured and Clairiant Corp. in Charlotte, N.C. and Deforest of
Boca Raton,
FL, respectively, are also examples of corrosion inhibitors.
Anti-scaling materials such as acrylic acid, gluconates and phosphonates, in
both acid and salt form, may be included to help prevent hard water
interference. Hard water
interference is manifested in scale formation. These materials also act as
sequestering agents.
The preferred weight percent of the gluconates and phosphonates is 0.5-5
weight percent of
the composition. Commercially available phosphonates include Belcore°
577 and Dequest°
from the FMC Corp., Princeton, NJ and Solutia Inc. of St. Louis, MO,
respectively.
Anti-foam materials such as block copolymers having an HLB of 6 or below,
capped alcohol alkoxylates and specialty high molecular weight polymers, such
as
polysiloxane polymers, can be used to minimize foaming. Preferred weight % of
such
components range from 0.01 to 5 weight percent of the composition.
Commercially available
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components of this type are Antarox ~ L-61 of Rhodia, Inc. and T Zaps MC-2 by
Trico
Technologies of Mundelein, IL.
Hydrotropes, such as neodecanoic acid and isononanoic acid , may also be
added to keep the composition from separating. The preferred weight percent of
this
ingredient is from about 5 to 25 weight percent of the composition. A
preferred hydrotrope
is Detrope~ SA-45 manufactured by DeForest Chemicals of Boca Raton, FL.
Wetting agents may also be used in the compositions. The preferred weight
percent of this ingredient is from about 1 to 10 weight percent. A preferred
wetting agent is
Surfadone~LP100 from ISP in Wayne, NJ.
Solvents such as methyl, butyl, and propyl glycol ethers and diethers in their
ethylene, diethylene, propylene and dipropylene form, as well as alcohols,
such as isopropyl,
methyl and ethyl alcohol, may also be used to improve the cleaning
performance. The
preferred weight percent of this component is 1-15 weight percent. Dowanol ~
DPnB from
Dow Chemical is a commercially available product of this type.
The present invention may also contain additional surfactants such as Nonidet
~ SF-3, an anionic surfactant from Tomah Products of Milton, WI , Plurafac ~LF
1200 of
BASF Core. of Mt. Olive, NJ., Triton ~ SP-190 and Triton ~ DF20 by Union
Carbide of
Charleston, SC, and Antarox ~ BL-225 by Rhodia, Inc. of Cranbury, NJ, all of
which have a
Log P of greater than about 4.5.
The present invention also includes a diluted cleaning composition comprising
the cleaning composition and additional water where the additional water is
present up to
99.5% by weight of the diluted composition
Tables B-D set forth preferred formulations of the present invention.
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Table B
Formula 1
Component Wt.
KZCO3 8.0
Belcore~ 577 1.0
Cobratec~ TT-100 0.50
Borax 0.50
Sodium Silicate 6.00
KOH 2.83
Detrope~ SA-45 12.00
Triton ~' RW 100 1.25
Water QS
Table C
Formula 2
Component Wt.
Triethanolamine 3.0
Belcore~ 577 1.0
Cobratec~ TT-100 0.3
Detrope~' SA-45 10
Foamtaine~ CAB-A 3.0
Triton~ RW-100 . 2.0
Water 80.75
Table D
Formula 3
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19
Component Wt.
Triethanolamine 3.0
Belcore~ 577 0.58
Cobratec~ TT-100 0.58
Ammonium bicarbonate 0.5
T Zap~ MC-2 0.075
Triton~ RW 100 2.0
Triton~ CG 110 3.0
Tritons SP-190 1.0
Detrope~ SA-45 10
Water QS
The compositions of the present invention provide excellent cleaning, very
little foaming and excellent compatibility with varying degrees of water
hardness. Studies
showing these properties are described below. Cleaning results, foaming
results and
compatibility with water hardness for Formula 2 (Table C) are set forth below
in Tables E,
F, and G.
For the cleaning study, aluminum substrates were soiled with three soils -
Cosmoline~ 1102 from Houghton International, Inc. of Valley Forge, PA,
Pennzoil~ 4096
Gear Lubricant SAE 80W90 GL-5 grade from Pennzoil Corporation of Houston, TX,
and
Pennzoil~ Multi-purpose White Grease 705 from Pennzoil Corporation of Houston,
TX.
The soiled substrates were placed in a cleaning tank containing Formula 2. The
substrates
were agitated for ten minutes at 140 °F. The cleaning test was run ten
times. The results
are shown on Table E and reflect the gravamateric loss of weight of the soil
applied to the
substrates.
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Table E
Loss of Soil Weight
Cosmoline~ 1102 Pennzoil~ 80W90 White Grease 705
95.4 80 98.2
5 100 97.9 100
100 82.7 100
99.3 80.3 100
112 74.1 100
100 55.8 100
10 96.6 91.6 100
99.3 100 98
100 82.4 50.7
98.9 82.7 94.1
Formula 2 was also tested for its foaming characteristics. The results of
15 this study are set forth below in Table F. A quantity of Formula 2 was
placed in a
INTERCONT~ Top Loading Parts Washer and heated to 140 ° F. It was run
for ten
minutes at a spray pressure of 40 psi. This test was run on three different
fresh solutions
with the average result set forth below in Table F.
Table F
20 Amt of Foam 0 min 5 min 10 min 15 min
(mL) 60+ 43 5 3
60+ 1 0 0
The compositions of the present invention provide excellent compatibility
with varying degrees of water hardness, as can be seen from the results of the
following
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21
study. Water samples of varying water hardness were prepared. Formula 2 was
diluted to
10% and combined with the water samples and the resulting mixture was allowed
to stand
for 24 hours. The formation of a precipitate indicates an unstable product.
The results are
set forth on Table G.
Table G
Hardness of Water (ppm) Amount of Precipitate
0 none
100 none
150 none
300 none
500 none
1000 none
Membranes
The ability of a surfactant or surfactants to be recycled is assumed to be
affected by the ability of the surfactant to depart the micelle of soil and
migrate across the
membrane. Without being bound to any theory, the factors that influence
migration include
stability of the micelle and the ability of the surfactant to permeate through
the membrane.
The stability of the micelle may to depend both on the surfactant system and
the type of soil
being dispersed.
Membranes of all types can be used with this invention including but not
limited to those made of ceramic, polysulfone, polyacrylonitrile (PAN), and
cellulose.
Membranes that are slightly hydrophobic are preferred. The PAN membrane with a
0.05
micron pore size is most preferred, such as Part #0567 manufactured by
Osmonics Corp.,
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22
Minnetonka, MN.
The compositions of the present invention have a high degree of permeability
after use and are able to permeate a membrane having a pore size of from about
0.05 to about
microns after being utilized in cleaning. Smaller pore sizes will not yield
sufficient recovery
5 of surfactant ingredients and larger pore sizes will not reject oily
components effectively.
Surfactant OctanoUWater Partition Coefficient
The octanol/water partition coefficient is a common measure of hydrophobicity
used for environmental and pharmaceutical applications. Because of the laxge
range in values,
octanol/water partition coefficients are typically reported as LogI~oW, also
known as Log P.
This measurement is calculated by the following equation:
Log P=Log COnCo~tanol)
( COnCa9)
The permeability of a surfactant may be measured by its Log P or its
octanol/water partition coefficient. As discussed above, the % permeability is
defined as
permeability = concentration pen"eate * 100.
concentration Initial
Log P values can be determined by a variety of techniques, such as the
standard shaker flask technique, chromatography measurements, and calculation
based on
chemical structure. Log P values may be estimated from reverse phase HPLC
retention data
or measured directly.
Log P measurement based on High Performance Liquid Chromatography
(HPLC) is automatable. For the most accurate results, the HPLC system is
calibrated with
structural analogues of the compounds of interest that have known Log P
values. This is
necessary due to the nature of reversed phase HPLC, a separation technique
that is based
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23
primarily on the size and structure of the hydrophobe. Because of the
proprietary nature of
many commercial surfactants, another approach was used to estimate Log P
values by
referencing the HPLC data tb alkyl benzene standards and is described below.
The present invention shows that surfactant Log P values indicate the tendency
of a surfactant to distribute from the micelle to the aqueous phase and
permeate the
membrane. A low octanol/water partition coefficient indicates a higher
permeability whereas
a higher octanol/water partition coefficient indicates lower degree of
permeability.
Surfactants having a Log P of greater than 4.5 have a low permeability and
will be retained
in the retentate and will not be recycled back into the cleaning solution.
Prior art cleaning compositions typically contain surfactants the have a Log P
of greater than 4.5. The recyclability of those compositions, therefore, is
not adequate. The
composition of the present invention, on the other hand, contains at least one
surfactant
having a Log P value of less than 4.5. Therefore, they have greater
permeability than the prior
art compositions as well as significantly improved recyclability over the
prior art.
In addition to the utility Log P as an indication of recyclable, other
physical
properties such as critical micelle concentration (CMC) may also indicate
recyclability.
Recyclability
In general, inorganic materials are permeable regardless of the temperature of
operation. The temperature of operation, however, significantly limits the
surfactants that
may be used in the cleaning process since temperature affects the cleaning
ability and
recyclability of surfactants. In addition, the presence of soil will have a
significant impact on
the recyclability of a given surfactant system.
An aqueous cleaning formulation is defined as being useful for recycling if
its
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24
surfactant component does not fall below about 50% by weight of its starting
value, upon
recycling in unsoiled conditions. An aqueous cleaning formulation is defined
as being useful
for recycling if its surfactant component does not fall below 30 % by weight
of it starting
value upon recycling in at least one set of soiled conditions. As discussed
above, the product
of this invention, due to its unique formulation, allows the surfactant
component to permeate
a membrane filter by at least 50% of its starting value in unsoiled condition
and at least 30%
of its starting value in soiled conditions.
Analysis for active components are compared between the original test solution
and remaining retentate and the permeate solutions. Results may be obtained by
the following
equation which shows the results as a percent of actives found in permeate
versus the starting
solution.
Recyclability = Permeate/Feed x 100
Studies were run to determine how specific formulas perform in a range of
membrane systems and operating temperatures, in soiled and unsoiled
conditions. A study
was also run to determine the relationship between surfactant permeability
behavior, cloud
points and Log P. The materials, methods of these studies are discussed below.
The results
of these studies are set forth in the examples.
Materials and Methods For Examples
The materials and method used for Example 1 are set forth in that section.
The materials and methods for Examples 2-7 follow.
Surfactants For Examples 2-7.
Nonionic surfactants and ionic surfactants were chosen for their range of
structures, cloud points, and expected Log P values. For Examples 2-7, the
following
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surfactants were were chosen: Neodol° 91-6, a mixture of primary C9,
C1o and C11 alcohol
ethoxylates with an average ethylene oxide (E0) content of 6.0 moles, was
obtained from
Shell Chemical Co. (Houston, TX). Surfonic° L-108/85-5, a mixture of
C6, C$ and Clo (C$
major) alcohol ethoxylates with an average EO content of 5.0 was obtained from
Huntsman
5 Corporation (Houston, TX). Poly-Tergent° SL-92 and Poly-
Tergent° 5505-LF, both
proprietary primary alcohol alkoxylates, were obtained from Olin Corporation
(Stamford,
CT). Naxel °AAS-985, a linear alkyl benzene sulfonic acid (LAS), was
obtained from
Ruetgers-Nease Corporation (State College, PA). Foamtaine° CAB-A,
cocamidopropyl
betaine ammonium salt (45% aqueous solution), was obtained from Akzo Inc.
(Sayreville,
10 NJ). Mackamine° C8 (41% solution) and Mackamine° C10 (30%
solution), linear octyl
dimethyl amine oxide and linear decyl dimethyl amine oxide, respectively, were
obtained
from McIntyre Group Ltd. (University Park, IL). Pluronic° L-61, an
ethylene
oxide-propylene oxide-ethylene oxide block co-polymer (EO-PO-EO) with a
molecular
weight of 2000 daltons and containing approximately 10% EO, was obtained from
BASF
15 Corporation (Mount Olive, NJ). Barlox° 12 (30% solution), dodecyl
dimethyl amine oxide,
and Barlox° 12i (30% solution), a proprietary branched alkyl dimethyl
amine oxide, were
obtained from Lonza, Inc. (Fairlawn, NJ). Glucopon° 425N (50%
solution), a mixture of C8,
C1°, C12, and C14 alkyl mono- and di-glucosides, was obtained from
Henkel Corporation
(Ambler, PA). Tomah AO-405, a proprietary alkyl etheramine alkoxylate, was
obtained from
20 Tomah Products (Milton, WI). Triton ° RW100, an ethoxylated alkyl
amine, was obtained
from Union Carbide of Charleston, SC.
Soils
Cosmoline° 1102 was obtained from Houghton International, Inc.
(Valley
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26
Forge, PA). Cosmoline~ 1102 was developed for use by the United States
military, and is in
common commercial use for surface protection of metal parts. It consists
primarily of low to
moderate molecular weight mineral spirits (boiling point of 157 °C) and
contains protective
agents for metals.
Pennzoil~ 4096 Gear Lubricant SAE 80W90 GL-5 grade (Pennzoil
Corporation, Houston, TX) was obtained from an automotive supply store. It
consists
primarily of base oils with additives to achieve the American Petroleum
Institute's (API) GL-
5 service grade and the Society for Automotive Engineers (SAE) rheological
specifications.
An SAE 80W-90, API GL-5 oil is one of the most popular gear oils in use, and
is considered
to be a universal gear oil for car and light truck rear axles.
Pennzoil~ Multi-purpose White Grease 705 (Pennzoil Corporation, Houston,
TX) was obtained from an automotive supply store. It is a lithium type
petroleum grease with
a National Lubricating Grease Institute (NLGI) #2 grade viscosity. It has a
stated operating
temperature of up to 260 °F. Typical applications include lubrication
of conventional brakes,
wheel bearings and chassis for passenger cars, truclcs, etc.
Rea-dents
House de-ionized water was generated with a Milli-Q Water System (Millipore
Corporation, Milford, MA). HPLC grade methanol and HPLC grade ammonium acetate
were
obtained from Fisher Scientific (Pittsburgh, PA). Toluene, ethylbenzene, butyl
benzene, hexyl
benzene, and octyl benzene were obtained from Sigma-Aldrich Corp. (Milwaukee,
WI).
Potassium carbonate was manufactured by Church & Dwight Co., Inc. (Princeton,
NJ). All
materials were used without further purification.
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Total Organic Carbon (TOC)
A Sievers 800 Portable Total Organic Carbon analyzer was used for the TOC
measurement of aqueous samples (Sievers Instruments, Denver, CO). Analysis is
based on
oxidation with ammonium persulfate and UV light. Reported results are the
average of
triplicate measurements.
High Performance Liquid Chromatography:
A Hewlett-Packard 1050 series HPLC (Palo Alto, CA) consisting of a quaternary
pump and autosampler was used for analysis of surfactants. Reversed phase HPLC
was
performed on all samples. Samples were filtered through Gelman 0.45 um PVDF
filters and
analyzed. Almost all separations were utilized the following conditions:
Column: Supelcosil LC-18 column, 15 cm x 4.6 mm, 5 um particle size (Supelco,
Bellefonte, PA).
Flow: lml/min. Temperature: ambient Injection Volume: SOuI
Mobile Phase A: 70:30 methanol: water (v + v) with lOmM ammonium acetate.
Mobile Phase B: 100% methanol.
Gradient Program
Time-min.0 20 27 28 33
B 17 83 83 17 27
Detection was achieved with either a Hewlett-Packard series UV detector set at
275mn, or a
Sedere Sedex 55 (Richard Scientific, Novato, CA) evaporative light scattering
detector
(ELSD). The ELSD was operated at 40°C, with a nitrogen flow rate of 1.8
1/min. A
Chromeleon Chromatography Data system (Dionex Corp. Sunnyvale, CA) was used to
collect
and process the HPLC data.
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Determination of Log P
The determination of the Log P value, which includes both calculated and
estimated, for surfactants is set forth below. The Log P values of the present
invention are
calculated according to the estimated Log P determination.
Determination of Surfactant HPLC Loa P Estimates
A reversed phase HPLC method was used to estimate surfactant Log P values. The
HPLC capacity factor, k', for each material was determined according to the
equation:
lc' _ (tR - to)~ to
where,
tR = component retention time, and
to = column void time.
Alkylbenzenes were used as Log P retention time standards: toluene (Log P
= 2.65), ethyl benzene (Log P = 3.13), butyl benzene (Log P = 4.18), hexyl
benzene (Log P
= 5.24) and octyl benzene (Log P = 6.30). The column void time was determined
from the
elution time of unretained salt. Under isocratic HPLC conditions, a plot of
Log k' vs. Log P
yields a straight line; the plot exhibits curvature under the gradient mobile
phase program that
was used. (Fig. 6). A quadratic curve results in an acceptable fit of the
calibration data,
permitting estimates of the surfactant Log P values from the retention data.
It is well known that many commercial surfactants do not constitute single
chemical species, but instead complex mixtures with varying hydrophobes (i.e.,
alkyl size) and
hydrophiles (e.g., level of ethoxylation). The reversed phase HPLC separation
used herein
separates primarily based on the size of the hydrophobe. The surfactants
studied had one of
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29
three possible HPLC separation profiles: 1 ) a single, narrow peak; 2) a
single, broad peak; and
3) multiple peaks. The peak maximum retention time was used to determine the
Log P
estimate for surfactants with either the narrow or the broad single peak
profiles. Examples
of multiple peak cases are those of Neodol~ 91-6 and of Polytergent ~ SL-92.
(Fig. 7).
Multiple hydrophobe peaks also occur for the LAS due to decyl benzene
sulfonate, undecyl
benzene sulfonate and dodecyl benzene sulfonate species; for Surfonic~ L108/85-
5 for C6, C8
and clohydrophobes; and for Glucopon~ 425 which has C8, Clo, C12 and C14 mono-
glucosides
as major oligomers. The median retention time was used for those surfactants
that exhibited
multiple peaks under the'separation conditions. In addition, the retention
time of the
individual hydrophobe peaks was used to calculate Log P values for these
oligomers. The
surfactant Log P estimates are listed in Table H.
Calculated Log P Values
The Log P value of a surfactant can be calculated with reasonable accuracy
if the structure is known, as described in the following publications by A.
Leo and C. Hansch
in "Substituent Constants for Correlation Analysis In Chemistry and Biology,"
John Wily,
New York (1979) and "Partition Coefficients and their Uses," Chem. Rev., 71,
525 (1971).
This method is based on the concept that the,various fragments of a molecule
contribute
additively to its Log P value. First, the molecule is conceptually divided
into fragments. The
fragment Log P contributions can be found in published tables. Factors are
used to adjust the
fragment results, based on the manner in which the fragments are put together
to make the
molecule.
Some assumptions were used to calculate the Log P values. For each alkyl
chain size in the LAS mixture, there exists a distribution of compounds with
phenyl
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substitution at positions along the alkyl chain (i.e., 2-phenyl, 3-phenyl,
etc.); the 3-phenyl
compound was used to calculate the Log P value for a given alkyl chain size
(C10, C1 l, and
C12). Likewise, the alcohol ethoxylates are mixtures of oligomers with an
average
ethoxylation level reported by the manufacturer; the average EO level was used
calculating
5 the Log P value. It was not possible to calculate a Log P value for the
amine oxides due to
lack of published amine oxide fragment value.
Calculated Log P values are included in Table H for alkyl monoglucosides,
linear alkyl benzene sulfonates, and for alcohol ethoxylates. It may be seen
that there is a bias
between the calculated Log P values and the corresponding HPLC estimated Log P
values.
10 The relationship between calculated and estimated Log P values is shown
graphically in Fig.
8. Clearly, there is a linear relationship between the two independent
approaches to
determining Log P. The bias may be due to the choice of alkyl benzenes as HPLC
Log P
calibration standards. The estimated Log P values could be adjusted using the
calculated
values as "standards." However, given the linear relationship between
approaches, there is no
15 inherent need to do this. The correlation between the alternative
approaches does serve to
provide some confidence in the use of HPLC for estimating Log P values for
surfactants with
unknown structures.
Membrane Filtration Unit Operation
A Membrex Benchmark GX (Fairfield, NJ), lab-scale rotating membrane
20 filtration unit was used for all permeability studies. Membrane cartridges
were made of
polyacrylonitrile with a O.OSum pore size (Part #0567, Osmonics Corp.,
Minnetonka, MIA.
Cloud Points
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Surfactant cloud point values were obtained from manufacturer literature as
reported for 1 % aqueous solutions and are reported on Table H.
Table H. Surfactants For Permeabilit~Studies
Surfactant Cloud Point Loge, HPLC Loge, Comment
(C)
estimate calculated
Mackamine~ None 2.5 C8 dimethyl
C8 amine
oxide
Mackamine~ None 3.4 C 10 dimethyl
C 10 amine
oxide
Barlox~ 12i None 4.0 Proprietary
branched
dimeth 1 amine
oxide
Barlox~ 12 None 4.5 C12 dimethyl
amine
oxide
Glucopon~ None 2.5 0.96 C8 mono-glucoside
425N
3.2 (3.8 2.0 C10 mono-glucoside
median)
4.3 3.1 C 12 mono-glucoside
5.2 4.2 C 14 mono-glucoside
Naxel~AAS-98SNone 3.2 2.1 C10LAS
3.7 (median)2.6 C11 LAS
4.1 3.2 C12 LAS
Tomah AO-405 70 4.4 Proprietary
branched
allcoxylated
ether
amine
Foamtaine None 3.6 Cocamidopropyl
CAB-A
betaine
Surfonic~ 43 2.6 1.5 C6 hydrophobe
L108/85-5
3.4 (median)2.6 C8 hydrophobe
4.5 3.7 C 10 hydrophobe
Neodol~ 91-6 52 4.1 3.1 C9 hydrophobe
4.6 (median)3.6 C 10 hydrophobe
5.1 4.1 C 11 hydrophobe
Poly-Tergent~92 4.1 Proprietary
SL-92 C6, C8,
C10 alcohol
alleoxylate
(P1)
4.4 Proprietary
C6, C8,
C 10 alcohol
alkoxylate
(P2)
4.9 Proprietary
C6, C8,
(5.2 median) C 10 alcohol
alkoxylate
(P3)
5.4 Proprietary
C6, C8,
C10 alcohol
allcoxylate
(P4)
5.7 Proprietary
C6, C8,
C10 alcohol
alkoxylate
(P5)
5.9 Proprietary
C6, C8,
C 10 alcohol
alkoxylate
P6
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Poly-Tergent~47 6.2 Proprietary
S505- C6, C8,
LF C 10 alcohol
alkoxylate
Triton~ RW 85 4.0 ethoxylated
100 allcyl amine
Pluronic~ 24 6.7 EO-PO-EO block
L-61 co-
ol er
The following examples set forth the evaluation of the permeability of various
surfactant systems.
As seen through the following examples, a high degree of recyclability
resulted
from fully formulated compositions of the present invention comprising at
least one surfactant
having a Log P of less than about 4.5.
It will be understood by those skilled in the art that various modifications
may
be made in the methods and compositions described above without departing from
the spirit
and scope of the present invention. Accordingly, it is intended that the
specific embodiments
described herein are intended as illustrative only, and that the invention is
limited only by the
claims appended hereto.
Example 1
This Example demonstrates how specific formulas would perform in a range
of membrane systems. The study was designed to test specific recyclability
factors including
formula components (surfactant systems), temperature, membrane pore size,
membrane
material compatibility and soiled systems versus unsoiled systems.
The original cleaning composition solution was contained in an initial tank
(customer tank) and pumped to a holding tank where soiled articles were
present. The
contaminated cleaning solution was then pumped from the holding tank through a
membrane.
The contaminated cleaning solution then flowed across the membrane. The
retentate was
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33
returned to the holding tank. The permeate was returned to the (initial)
customer tank for
reuse.
The two formulas tested included Formula A which has a surfactant system
that is phase stable up to 180°F and Formula B which has a surfactant
system that is phase
stable up to 105°-110°F. The formulations for Formula A and B
are set forth below on Tables
I and J. The formulations were prepare by combining the ingredients listed and
mixing at
room temperature.
Table I
Formula A
Ineredients Wt.%
Deionized Water 81.85
45% potassium hydroxide 2.65
Potassium bicarbonate 0.50
Belcor~ 575 0.58
Neodecanoic acid 2.62
Decore IMT-100LF 5.00
Cobratec~ TT-100 0.30
triethanolamine 3.00
Triton~ DF-20 0.50
Avanel~ S-74 1.50
Amphoteric 400 1.50
Totals 100.00
Table J
Formula B
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Ingredient Wt.
Deionized Water 75.51%
Acrylic acid copolymer 1.00%
Belcor~ 575 0.58%
Sodium Hydroxide (50 wt.%) Solution 3.00%
Potassium Hydroxide (45 wt.%) Solution 0.81%
Sodium Carbonate 2.50%
Sodium Bicarbonate 0.25%
Sodium Silicate 2.00%
Cobratec~ TT-100 0.30%
Isononanoic acid 3.95%
Nonidet~ SF-3 0.50%
Neodol~ 1-73B 2.00%
Poly Tergent~ S SOSLF 1.50%
Surfadone~ LP-100 2.00%
BASF Plurafac~ LF-1200 1.60%
Poly Tergent~ S 205LF 1.50%
Pluronic~ L61 1.00%
Two temperatures were tested including 80°F and 140°F.
Seven membrane
pore sizes were tested including 50,000 molecular weight cut off, 100,000
molecular weight
cut off, 0.05 microns 0.10 microns, 0.20 microns, 0.45 microns and 0.50
microns. Three types
of membrane materials were tested including PAN, polysulfone and ceramic.
Soiled and
unsoiled samples were tested. Soiled systems were tested with 0.5% by volume
of ThredKut
Light Cutting Oil. The formulations were analyzed by total organic carbon. The
total organic
carbon values for three samples per experiment were compared. The percent
recyclability was
determined by the equation
recyclability = permeate TOC value
feed TOC value
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Figures 2-5 illustrate the percent recyclability versus membrane pore size for
Formula A versus Formula B the in unsoiled and soiled conditions at
80°F and 140°F.
These experiments indicate that as temperature decreases, recyclability
increases, (although if the pore size is too large, soils will permeate the
membrane). As soil
is introduced, these experiments show that recyclability decreases. Formula A
is recycled best
at low temperatures and greater than 0.2 micron pore size.
Overall, the two formulas did not exhibit any material compatibility issues.
Both formulas seemed to work with all membranes without fouling or
degradation. The PAN
and polysulfone membranes performed better than the ceramic membrane for the
soiled
system at 80°F.
Example 2
The surfactants of Table H were evaluated for permeability, both in the
absence
and in the presence of soil. The surfactants studied were chosen based on
their range of cloud
points and Log P values. The objective of this work was to determine the
relationship
between surfactant permeability behavior, cloud points, and octanol/water
partition
coefficients and Log P.
Example 2 was run in the absence of soil. Results for all samples of Example
2 are included in Table I~.
A diagram for the experimental setup is given in Fig 1. One to two liters of
the aqueous alkaline solution of the present invention in its diluted form,
usually including
0.15% surfactant and 0.05% potassium carbonate, was placed in both the
customer (or initial)
and holding tanks (appropriately sized glass beakers). For experiments with
soil, oil was
added at a 1 % level to both tanks. The tanks were heated with magnetic
stirring on hotplates
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36
to either 140 °F or 100 °F. The temperature was maintained
throughout each experiment with
RTD temperature probes interfaced to the hotplates. The rotation rate of the
membrane
filtration unit was 3 000 RPM. Material from the holding tank was pumped into
the membrane
filtration unit at a flow of 600 ml/min. The outlet pressure was adjusted to
achieve a 5 psi
pressure drop across the membrane, resulting in permeate flows of
approximately 100-300
ml/min depending on the soil and the operating temperature. The transfer line
from the
customer tank to the holding tank was adjusted to equal the permeate flow rate
in order to
maintain a constant level in both customer and holding tank. One cycle or
turnover is defined
to be the time at which the cumulative volume of permeate equals the initial
volume of the
customer tank. Permeate samples were collected at 1, 5 and/or 10 cycles.
A 0.05 um PAN membrane was used in the filtration.
Surfactant levels in permeate samples were determined by TOC (unsoiled
studies only) and by HPLC/ELSD.
A sample of the initial cleaning solution was collected before addition of oil
(if added) and before starting membrane operation. This initial cleaning
soultion sample is
def ned to be the 100% permeable concentration. Serial dilutions of the 100%
permeable
sample were made to obtain calibration samples for the HPLC analysis. Point-to-
point
calibration curves were used for HPLC quantitation due to the non-linear
nature of the ELSD
response. For TOC analysis the initial cleaning solution sample was used for
the single point
calibration. For surfactants with multiple surfactant oligomers, individual
oligomer
permeability and overall surfactant permeability were determined. The overall
surfactant
permeability was calculated from the average of the oligomer results, except
for Surfonic~
L108/85-5 where the result for major C8 hydrophobe was used.
Overall system reproducibility was evaluated by determining the permeability
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of Neodol~ 91-6 with Cosmoline 1102 oil present on two days approximately one
week apart.
Between measurements, additional surfactants were evaluated, the membrane was
replaced
and routine system maintenance was performed. Permeability results for the two
Neodol~ 91-
6 runs agreed to <10% relative standard deviation (RSD). System accuracy is
estimated to
be <20%. The accuracy is affected by the non-linear nature of the ELSD and by
potential
changes in the ELSD response due to changes in surfactant oligomer
distributions (e.g., level
of ethoxylation).
The TOC results and the HPLC results are listed in Table K for permeability
studies conducted in the absence of soil. In general, there is good agreement
between TOC
results and HPLC results. The one exception are the results for the Pluronic~
EO-PO-EO
bloclc co-polymer for which the TOC result is about twice that of the HPLC
result. The HPLC
results are believed to more reliable as any contamination sources would not
be included.
Table K. Surfactant PermeabilityResults in Unsoiled S std ems.
Surfactant Cycle # % Permeability % Permeability
TOC HPLC
Mackamine~ C8 1 101 104
5 108 105
10 117 102
Barlox~ 12i 1 47 95
5 89 90
10 88 96
Neodol~ 91-6 1 45 58
5 47 54
10 54 54
Poly-Tergent~ 1 66 62
SL-
92
5 67 65
10 57 61
Pol -Ter ent~ 1 56 51
5505-
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LF
5 54 50
10 57 51
Pluronic~ L-61 1 46 20
5 50 21
10 43 23
A plot of the HPLC determined permeability results vs. cycle number is shown
in Fig. 9. All surfactants evaluated had no significant change in permeability
after Cycle 5.
Plots of individual hydrophobe results vs. cycle number are given in Figs. 10-
11 and listed in
Table L for Neodol~ 91-6 and for Poly-Tergent~ SL-92 (see Fig. 7 for
hydrophobe
identifications). The results for the individual hydrophobes are consistent
with the lower alkyl
size/lower Log P estimate hydrophobes exhibiting greater permeability
behavior. For
example, the C9 hydrophobe of the Neodol~' 91-6 had a much larger permeability
than the Cl i
hydrophobe.
Table L.
Unsoiled System Permeability Results for Surfactant Hydrophobes (HPLCI.
Surfactant/HydrophobeCycle #1- Cycle #5 - Cycle #10 -
% Permeabili % Permeabili % Permeabili
Neodol~ 91-6/C971 71 70
Neodol~ 91-6/C1056 50 53
Neodol~ 91-61C1147 40 39
Pol -Ter ent~ 89 96 92
SL-92/P1
Pol -Ter ent~ 79 86 81
SL-92/P2
Pol -Ter ent~ 72 78 73
SL-92/P3
Pol -Ter ent~ 48 50 46
SL-92/P4
Pol -Ter ent~ 43 43 41
SL-92/PS
Pol -Ter ent~ 40 38 35
SL-92/P6
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Unsoiled system data were obtained for additional surfactants for Cycle 5
permeates only. All Cycle 5 results are listed in Table M. Results for
individual hydrophobes
are included where analysis was possible (Surfonic~ L108/85-5, Naxel~ AAS-98S
and
Glucopon~ 425N). The individual hydrophobe results are consistent with larger
hydrophobe
size (and correspondingly larger Log P estimate) exhibiting poorer
permeability behavior.
Table M. Permeability Results in Unsoiled S stem Cycle 5, 140 °F1.
Surfactant %
Permeabili
Mackamine~ C8 105
Barlox~ 12i 90
Barlox~ 12 80
Naxel~AAS-98S/C10 69 Ave = 62
Naxel~AAS-98S /C1163
Naxel~ AAS-98S 55
/C12
Gluco on~ 425/C8 104 Ave = 68
Gluco one 425/C 87
Gluco on~ 425/C 44
12
Gluco on~ 425/C14 35
Surfonic~ L108/85-5/C6120 Ave = 106
Surfonic~ L108/85-5/C8106
Surfonic~' L108/85-5/C1086
Neodol~ 91-6/C9 71 Ave = 54
Neodol~ 91-6/C10 50
Neodol~ 91-6/C11 40
Pol -Ter ent~ SL-92/P196 Ave = 65
Pol -Ter ent~ SL-92/P286
Pol -Ter ent~ SL-92/P378
Pol -Ter ent~ SL-92/P450
Pol -Ter ent~ SL-92/PS43
Pol -Ter ent~ SL-92/P638 .
Pol -Ter ent~ 5505-LF50
Pluronic~ L-61 21
*Cave = overall surfactant permeability based on average oligomer results,
except for
Surfonic~ L108 for which the C8 oligomer result is used.
A plot of the HPLC surfactant permeability results for the unsoiled systems
vs.
Log P estimate is given in Fig. 12. Similarly, a plot of permeability vs.
cloud point is given
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in Fig. 13 (a cloud point value of 100 °C was used for surfactants that
do not exhibit a cloud
point). A reasonable relationship between permeability and Log P estimate
appears to exist
based on this data. The relationship between surfactant cloud point and
permeability behavior
is less clear (Fig. 13). A considerable range of permeability performance was
observed for
those surfactants that do not exhibit cloud point values (i.e., those plotted
at a cloud point of
100 °C).
A plot of permeability vs. Log P estimates for all surfactants including the
individual hydrophobes is given in Fig. 14. Fig. 15 shows the same plot, but
with labels to
identify the different classes of surfactant. There appears to be a reasonable
correlation
between Log P estimate (or hydrophobe size) and % Permeability.
Example 3
Example 3 was performed in the same way as Example 2 but in the presence
of soil. The method described in Example 2 was followed in Example 3. The
permeability
performance of surfactants in soiled systems is of interest given the desire
to separate the
aqueous cleaning materials from soil. Two oils were evaluated in this study:
Cosmoline~
1102 and Pennzoil~ 80W90 oil. Observationally, the Cosmoline~ oil formed
stronger
emulsions with the surfactants and exhibited poorer oil/water splitting than
the Pennzoil~ oil.
Depending on the surfactant, samples in the Cosmoline~ oil studies tended to
have some
visible oil observed in the permeates, while no significant oil was observed
in the permeates
for the Pennzoil~ system.
The permeability results determined at 140 °F for the soiled systems
are listed
in Table N. The Cosmoline~ 1102 system initially was evaluated for a small set
of
surfactants, with permeate samples obtained from Cycles 1, 5, and 10. Of the
surfactants
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studied there was essentially no difference in Cycle 5 vs. Cycle 10 results;
the exception is
Neodol~ 91-6. Based on these results, only Cycle 5 samples were collected and
analyzed for
the remaining studies reported in Table N.
Table N. Soiled System Permeability Results.*
Surfactant/hydrophobeCosmoline Cosmoline Cosmoline Pennzoi180W90
1102- 1102 1102 - C cle
C cle 1 - C cle 5 - C cle 5
10
Mackamine'~ C8 94 95 99 95
Mackamine'~ C10 53
Barlox~' 12i 41 40 43 98
Barlox~' 12 63
Tomah AO-405 30
Foamtaine~ CAB-A 9
Gluco on~ 425/C8 74 Ave = 97 Ave =
29 66
Gluco on~'425/C10 22 77
Gluco one' 425/C12 <20 49
Gluco on*' 425/C14 <20 39
Naxel~AAS-98S/C10 60 Ave = 72 Ave =
41 52
Naxel~'AAS-98S 38 52
/C11
Naxel~' AAS-98S 26 31
/C12
Surfonic~' L108/85-5/C6 91 Ave = 94 Ave =
52 82
Surfonic*' L108/85-5/C8 52 82
Surfonic*' L108/85-S/C10 41 56
Neodol 91-6/C9 39 Ave = 33 Ave = 23 Ave = 61 Ave =
39 32 16 38
Neodol~ 91-6/C1030 24 12 32
Neodol~' 91-6/C1147 38 13 20
Pol -Ter ent~' 48 Ave = 48 Ave = 48 Ave = 85 Ave =
SL-92/P 1 38 38 38 70
Pol -Ter ent~' 39 38 38 86
SL-92/P2
Pol -Ter ent~' 32 32 32 76
SL-92/P3
Pol -Ter ent~ 31 31 31 61
SL-92/P4
Pol -Ter ent~' 37 37 37 56
SL-92/P5
Pol -Ter ent~' 41 42 41 54
SL-92/P6
Poly-Tergent~' 17 26 28
S505-LF
Pluronic'~ L-61 19 12 24
*Ave = overall surfactant permeability based on average ohgomer results,
except for ~urtomc° Ltuu for wmcn the ~u ougomer resun
is used.
As may be seen in Table N, there is a hydrophobe size effect on the
permeability results of the C8, Clo, C12, and C14 alkyl mono-glucosides
(Glucopon~), the C8,
Clo and C12 alkyl dimethyl amine oxides (Mackamine~ and Barlox~), the Clo,
C11, and C12
alkyl benzene sulfonates (Naxel~), and the C6, C8, and Clo alcohol ethoxylates
(Surfonic~)
The smaller hydrophobes exhibit greater permeability than the laxger
hydrophobes for a given
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hydrophile. The prior art regarding alkyl polyglucosides and amine oxides
conducted in the
absence of soil do not note an effect of hydrophobe size.
In the Cosmoline~ system, there does not appear to be a difference in the
permeability results for the various hydrophobes ofNeodol~ 91-6 and of Poly-
Tergent~ SL-92 ,
(Figs. 16-18). These results are unusual considering the large difference in
hydrophobe
permeabilities observed in the unsoiled system and in the Pennzoil~ system.
The cause of
this alkoxylate hydrophobe "normalization" in the presence of the Cosmoline~
soil is not
known. However, the permeabilities of both these surfactants axe low in the
Cosmoline~
system when compared to the surfactants that do exhibit the hydrophobe effect.
Plots of Permeability vs. Cloud Point and of Permeabilty vs. Log P for the
two soils are given in Figs. 19-22 and 16 and Figs. 20 and 21 (a cloud point
value of 100 °C
was used for surfactants that do not exhibit a cloud point). There does not
appear to be a
correlation between permeability and cloud point for either soil system (Figs.
19 and 21). In
the Cosmoline~ 1102 system, the surfactant permeability results decrease
rapidly with
increasing Log P and then level off at a Log P value of about 4 (Fig. 20). In
the Pennzoilm
80W90 soil system, the surfactant permeability results decrease steadily with
increasing Log
P estimates (Fig. 22 and 23). Thus, the type of soil present has a significant
effect on the
permeability results. The differences observed may be due to the
emulsification propensity
of the Cosmoline~ 1102.
The Pennzoil~ system results appear to be similar to those obtained for the
unsoiled system (Fig. 14). A plot of surfactant permeability results in the
unsoiled system vs.
those obtained in the Pennzoil~ 80W90 system is shown in Fig. 24.
Example 4
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The Barlox~ 12i surfactant was evaluated further to study the effect of
surfactant
concentration and multiple oil additions on permeability results. The initial
bath surfactant
concentration was increased to two and one half (2.5) times that of the
standard diluted
conditions (i.e., 0.375%, not corrected for solids level). Cosmoline°
1102 oil was added at
1 %, temperature was equilibrated to 140 °F and the membrane operation
was started. A
permeate sample was collected at Cycle 5. Then, l % additional Cosmoline~ 1102
was added
to the customer bath (based on total customer and feed bath volumes). A second
permeate
sample was collected after 5 additional cycles (i.e., Cycle 10). Again, 1%
more Cosmoline~
oil was added and the process repeated for Cycles 15 and 20. The permeability
results axe
given in Table O and plotted in Fig. 25.
Table O. Barlox~ 12i Multiple Oil Addition Study Permeability Results.*
C cle %Permeabili
0 100
59
50
32
31
*Barlox~ 12i concentration: 0.375%; 1% Cosmoline~ 1102 added every S cycles.
The Baxlox~ 12i level in the permeate decreases after each addition of
Cosmoline~' 1102 until Cycle 15, at which point the permeate concentration
does not
significantly change. The Cycle 5 permeate result of 59% is significantly
higher than the
40% permeability result for the Barlox~ 12i base case (Table N), while the
cycle 15 and 20
result of 31-32% axe lower but probably not significantly different than the
base case. The
simplest explanation for these results is that the Cosmoline~ 1102
exhaustively extracts about
65% of the Baxlox~ 12i. Assuming the extraction endpoint falls somewhere
between the
Cycle 10 and the Cycle 15 result, a ratio of about 5.3:1 to 8:1 of Cosmoline~
1102: Barlox~
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12i is needed for complete extraction (i.e., 2-3% oi1:0.375% surfactant). For
the base case
study the ratio of oilaurfactant is 6.7:1, also resulting in complete
extraction. The existence
of an extraction endpoint implies that there is a specific surfactant
structures) that is being
selectively removed by the Cosmoline~ while the remaining surfactant
structures) are not
affected.
Example 6
The permeability of four surfactants was evaluated at 100 °F in the
presence
of 1% Cosmoline~ 1102 oil. Two of the surfactants have cloud points (Neodol~
91-6 and
Poly-Tergent~ SL-92) while the other two surfactants do not have cloud points
(Barlox~ 12i
and Naxel~ AAS-9~S). The results are listed in Table N and are plotted in Fig.
26 with a
comparison to the 140 °F results.
Table P. Effect of Temperature on Surfactant Permeability.
Surfactant % Permeability% Permeability
140 F 100 F
Barlox~ 12i 40 32
Pol er ent~ 48 (Aye 63 (Aye = 56)
SL-92 (P1) = 38)
Polyter ent~ 38 61
SL-92 (P2)
Polytergent~ 32 55
SL-92 (P3)
Polyter ent~ 31 50
SL-92 (P4)
Polyter ent~ 37 53
SL-92 (PS)
Polytergent~ 42 54
SL-92 (P6)
eodol~ 91-6 33 (Aye 55 (Aye = 56)
(C9) = 32)
eodol~ 91-6 24 52
(C10)
eodol~ 91-6 38 62
(C11)
axel~AAS-98S/C1060 (Aye 68 (Aye = 50)
= 41)
axel~AAS-98S 38 46
/C11
axel~ AAS-98S 26 37
/C12
The largest temperature related effect was seen in the two surfactants that
have
cloud points. The permeability results of the Neodol~ 91-6 and of the Poly-
Tergent~ SL-92
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increased the most upon lowering the system temperature from 140 °F to
100 °F. These
results are consistent with greater aqueous solubility of alkoxylated
surfactants at lower
temperatures. The Barlox~ 12i and Naxel~ AAS-98S exhibit good water solubility
at both
temperatures and thus, the permeability results are less temperature
sensitive.
Example 7
Example 7 involves a fully formulated composition, Formula 3, as described
in Table B and was tested in a soil system comprising a 1:1:1 ratio of
Cosmoline~ 1102,
Pennzoil ~ 4096 SAE 80W90 GL-5 Multipurpose Gear Lube and Pennzoil~
Multipurpose
White Grease 705 (Pennzoil Corp., Houston, TX) and was run according to
Example 1. The
purpose of this test was to determine the recyclability of Barlox 12i.
The cycle 5 results showed that the permeability of Formula 3 is 72%. This
result lies between the result of 40% permeability determined with the
Cosmoline ~ 1102 only
system and the result of 98% permeability measured for the Pennzoil~ 84W90
only system.
Though permeability in the White Grease only system was not investigated, it
appears from
the mixed soil results that the White Grease does not have a large detrimental
effect on the
Barlox~ 12i permeability. The calculated Log P for the Barlox~ 12i surfactant
included
therein is 4.
