Note: Descriptions are shown in the official language in which they were submitted.
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
COMPOSITIONS, DEVICES AND METHODS FOR STABILIZING AND INCREASING THE EFFICACY
OF HALOGEN DIOXIDE SOLUTIONS
FIELD OF THE INVENTION
The present invention relates to compositions and methods for increasing the
stability
and/or efficacy of halogen dioxide, and particularly chlorine dioxide,
generated via electrolysis of
salts of halogen (and particularly chlorine) dioxide. The present invention
further relates to
electrolysis devices for producing halogen dioxide, comprising the stabilizing
and efficacy-
increasing compositions of the present invention, as well as methods of using
the halogen
dioxide-stabilizing and efficacy-increasing compositions and devices disclosed
herein.
BACKGROUND OF THE INVENTION
Chlorine dioxide, C102, is one of the most effective bleaching agents for use
in industrial
and .domestic process and services, and for commercial and consumer products.
The strong
oxidative potential of the molecule makes it ideal for a wide variety of uses
that include
disinfecting, sterilizing, and bleaching. Concentrations of chlorine dioxide
in an aqueous solution
as low as 1 part per million (ppm) or less, are known to kill a wide variety
of microorganisms,
including bacteria, viruses, molds, fungi, and spores. Higher concentrations
of chlorine dioxide,
up to several hundred ppms, provide even higher disinfection, bleaching and
oxidation of
numerous compounds for a variety of applications, including the paper and pulp
industry, waste
water treatment, industrial water treatment (e.g. cooling water), fruit-
vegetable disinfection, oil
industry treatment of sulfites, textile industry, and medical waste treatment.
Chlorine dioxide offers advantages over other commonly used bleaching
materials, such
as hypochlorite and chlorine. Chlorine dioxide can react with and break down
phenolic
compounds, and thereby removing phenolic-based tastes and odors from water.
Chlorine dioxide
is also used in treating drinking water and wastewater to eliminate cyanides,
sulfides, aldehydes
and mercaptans. The oxidation capacity of C102, in terms of available
chlorine, is 2.5 times that
of chlorine. Also, unlike chlorinelhypochlorite, for which bactericidal
efficacy is believed to
diminish at a pH greater than 7, the bactericidal efficacy of chlorine dioxide
is believed to remain
effective at pH levels of 7 to 10. Additionally, chlorine dioxide can
inactivate C. par~~um oocysts
in water at appropriate concentration ranges (i.e. about 100 to 200 ppm) while
chlorine/hypochlorite cannot due to its resistance thereof. Hypochlorite and
chlorine both react
with the bleached target by inserting the chlorine molecule into the structure
of the target.
Though this mode of reaction can be effective, it can result in the formation
of one or more
chlorinated products, or by-products, which can be undesirable both from a
economic sense (to
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
2
eliminate hydrocarbons from the reaction media) and a safety and environmental
standpoint. In
addition, the step of bleaching by hypochlorite and chlorine results in the
destruction of the bleach
species itself, such that subsequent bleaching requires a fresh supply of the
chlorine bleach.
Another disadvantage is that certain microorganisms that are intended to be
killed by these two
commonly-used bleach materials can develop a resistance over time,
specifically at lower
concentrations of the chlorine or hypochlorite.
Chlorine dioxide is generally used in an aqueous solution at levels up to
about 1 %. It is a
troublesome material to transport and handle at high aqueous concentrations,
due to its low
stability and high corrosiveness. This has required end users to generate
chlorine dioxide on
demand, usually employing a precursor such as sodium chlorite (NaC102) or
sodium chlorate
(NaCl03). A typical process for generating chlorine dioxide from sodium
chlorate salt is the acid-
catalyzed reaction:
NaC103 + 2HCl -~ NaCI + 1/2C12 + C102 + H20
Sodium chlorite is easier to convert to chlorine dioxide. A typical process
for generating chlorine
dioxide from sodium chlorite salt is the acid-catalyzed reaction:
5NaC10z + 4HCl -~ 4C102 + 5 NaCI + 2H20
In addition to further identifying novel, on-demand generation devices for
halogen (and
particularly chlorine) dioxide, there remains an equally substantial need to
identify compositions
that are adapted to stabilize and increase the efficacy of halogen (and
particularly) chlorine
dioxide solutions upon generation. In some contexts, the use of such
compositions would
alleviate the need for on-demand chlorine dioxide generation by maximizing the
"shelf life" of
pre-generated, active chlorine dioxide solutions. In other contexts, the
identification of stabilizing
and eff cacy-increasing compositions would maximize the stability and
performance of halogen
dioxide solutions following their on-demand generation, whether via
electrolysis or otherwise. In
any instance, the halogen dioxide stabilizing and efficacy-increasing
compositions of the present
invention address and resolve the quandaries associated with the contemporary
employment of
chlorine dioxide, particularly with respect to the low stability of halogen
dioxide solutions.
SUMMARY OF THE INVENTION
The present invention relates to compositions, devices and methods for
stabilizing and
increasing the efficacy of halogen (and particularly chlorine) dioxide
solutions, whether pre-
generated or generated on-demand. The stabilizing and efficacy-increasing
compositions of the
present invention incorporate a hydroxide ion scavenging solution and/or an
Interfacial Tension
(TFT) lowering agent into a halogen dioxide solution, whether pre-generated or
generated on-
demand. The incorporation of a hydroxide ion scavenging solution into a
halogen (and
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
3
particularly chlorine) dioxide solution plays a key role in controlling the pH
of ~ the resultant
solution - thereby stabilizing the resultant solution for. a longer period of
time than experienced
without the use of a hydroxide ion scavenging system. Further, it is believed
that the
incorporation of an Interfacial Tension (IFT) lowering agent, in conjunction
with or independent
of a hydroxide ion scavenging system, into a halogen dioxide solution
maximizes the
performance, antimicrobial and otherwise, of the resultant mixture.
Thus, in accordance with a first aspect of the present invention, compositions
for
increasing the stability and/or efficacy of halogen dioxide, and particularly
chlorine dioxide, are
disclosed and claimed. In one aspect, a composition for stabilizing a chlorine
dioxide solution,
whether pre-generated or generated on-demand, employing a hydroxide ion
scavenging system is
disclosed. In another aspect, a composition for increasing the efficacy,
antimicrobial and
otherwise, of a chlorine dioxide solution, incorporating an Interfacial
Tension (IFT) lowering
agent is disclosed. In yet another aspect of the present invention, halogen
dioxide (and
particularly chlorine dioxide) solutions incorporating both a hydroxide ion
scavenging system and
an Interfacial Tension (IFT) lowering agent are disclosed and claimed. In yet
still other aspects of
the present invention, the stabilizing and/or efficacy-increasing compositions
of the present
invention further comprise one or more adjunct ingredients for the provision
of certain aesthetic
and/or performance benefits to the resultant, halogen dioxide solution.
In another aspect of the present invention, electrolysis devices for the on-
demand
generation of stable and efficacious halogen dioxide, and particularly
chlorine dioxide, are
disclosed and claimed. In one aspect of the present invention, said devices
incorporate a
hydroxide ion scavenging system for the stabilization of halogen dioxide
generated therein. In
another aspect of the present invention, the electrolysis devices disclosed
herein incorporate an
Interfacial Tension (IFT) lowering agent to maximize the efficacy of the
halogen dioxide upon
generation. In yet another aspect of the present invention, the electrolysis
devices disclosed
herein incorporate both a hydroxide ion scavenging solution and an Interfacial
Tension (IFT)
lowering agent. The precise configuration of the device and/or nature of the
composition will
depend upon the needs and/abilities of the formulator, as well as the purpose
for which use of the
device is intended.
In another aspect of the present invention, methods for stabilizing and/or
increasing the
efficacy of halogen dioxide (and particularly chlorine dioxide) solutions,
whether pre-generated or
generated on-demand, are disclosed. In one aspect of the present invention, a
method for
stabilizing halogen dioxide, and particularly chlorine dioxide, is provided.
In another aspect of
the present invention, a method of increasing the efficacy of halogen dioxide,
and particularly
chlorine dioxide, is provided. In other aspects, methods of sanitizing and/or
cleaning surfaces
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
4
using the present compositions are provided. Said methods generally involve
the application of
one or more of the aforementioned, halogen dioxide stabilizing and/or efficacy-
increasing
compositions to a halogen dioxide solution for which increased stability
and/or efficacy is desired.
In another aspect of the present invention, the methods disclosed herein
relate to the use of an
electrolysis device employing the present compositions to stabilize and/or
increase the efficacy of
halogen dioxide generated on-demand. Other methods disclosed herein relate to
the use of the
claimed devices and compositions for application onto a substrate for which
sanitation and/or
cleaning is desired. The precise steps of each method disclosed herein (and
discussed further
infra) will depend upon the stabilizing and/or efficacy-increasing composition
for which
incorporation into a halogen dioxide solution is sought, the specific needs
and/or abilities of the
formulator and the application for which the use of the methods claimed herein
is desired.
In yet still other aspects of the present invention, various product and/or
physical forms of
the solutions and/or systems described herein are disclosed. In one aspect of
the present
invention, a wipe comprising the solutions and/or systems described herein is
disclosed. In
another aspect of the present invention, the solutions and/or systems
described herein are provided
in a gaseous form. In yet another aspect of the present invention, the
solutions and/or systems
described herein are provided in a solid form. In yet still another aspect of
the present invention,
the solutions and/or systems described herein are provided in a gel
formulation.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, "stabilizing" is intended to refer to the use of a hydroxide
ion scavenging
system in a halogen dioxide, preferably chlorine dioxide, solution to control
the hydroxide ion
concentration of said solution such that the stability of the resultant
solution is greater than that of
a halogen dioxide solution that does not employ such a system. In this
respect, the term
"increased stability" is intended to refer to a hydroxide ion scavenging
system-comprising
halogen dioxide solution having at least about 5%, preferably at least about
10%, higher halogen
dioxide concentration at 25 C, three hours following formulation thereof
versus the concentration
of a corresponding halogen dioxide that does not comprise the stabilizing
system, measured at 25
C and three hours following formulation thereof.
As used herein, "efficacy-increasing" is intended to refer to the
incorporation of a
hydroxide ion scavenger and/or IFT lowering agents into a halogen dioxide, and
particularly
chlorine dioxide, solution to convey one or more antimicrobial performance
and/or aesthetic
benefits to said solution. Said benefits include, but certainly are not
limited to, increased
antimicrobial kill and/or log reduction in antimicrobial solutions, improved
odor elimination,
selective bleaching or color modification and combinations thereof. In this
respect, the term
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
"increased antimicrobial performance" is intended to refer to a hydroxide ion
scavenger and/or
IFT lowering agent-comprising halogen dioxide solution having at least about
5%, preferably at
least about 10% greater reduction in the number of microbes than a
corresponding halogen
dioxide solution that does not comprise the hydroxide ion scavengers or IFT
lowering agents.
As used herein, "hydroxide ion scavenging system" is intended to refer to any
agent that
can be employed into a halogen (or chlorine) dioxide solution and, upon such
employment,
increase the stability of said solution, particularly when compared to the
stability of such a
solution that does not incorporate a hydroxide ion scavenging agent. Indeed,
the hydroxide ion
scavenging agents and/or system of the present invention is adapted to
increase the concentration
of halogen dioxide by at least about 5%, preferably at least about 10%, at 25
C, three hours
following formulation in comparison to the concentration of a corresponding
halogen dioxide that
does not comprise the stabilizing system (also measured at 25 C and three
hours following
formulation thereof).
As used herein, the phrases "IFT lowering agents" and/or "IFT system" are
intended to
refer to one or more agents suitable for incorporation into a halogen, and
particularly chlorine,
dioxide solution to increase the efficacy, antimicrobial and otherwise, of
said solution. Agents
suitable for use in the halogen-dioxide efficacy-increasing compositions of
the present invention
are discussed in more detail, infra.
As used herein, the terms "pre-generated" or "pre-generation" are intended to
refer to the
generation of halogen dioxide, more particularly chlorine dioxide, greater
than about ~ hours,
preferably greater than about 2 hours, more preferably greater than about 1
hour, prior to its
intended deployment. Such generation may occur at a location other than that
in which
deployment of chlorine dioxide is desired, but may occur at the same location
of the intended
deployment.
As used herein, the term "on-demand" is intended to refer to the generation of
halogen (or
chlorine) dioxide less than about 3 hours, preferably less than about 2 hours,
more preferably less
than about 1 hour, prior to the time of intended deployment. In one aspect of
the present
invention, "on demand" is intended to refer to the generation of halogen
dioxide in less than about
1 second. "On-demand" generation of chlorine dioxide may typically be
effectuated via the use
of an electrolytic device, as disclosed and described infra.
As used herein, the terms "cleaning and/or disinfecting" are intended to refer
to the process
of applying (optionally followed by removing) a composition to a surface or
environment with the
intent of removing and/or inactivating unwanted contaminants.
Cofnnositio~zs for Stabili i~t~ of:dlor Iszcreasist~ tlae Efficacy ofHalo~efa
Dioxide
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
6
Hydroxide Iorz Scaverzgirzg Systerrz
In a first aspect of the present invention, compositions for stabilizing
and/or increasing the
efficacy of halogen, and particularly chlorine, dioxide are disclosed. In one
aspect of the present
invention, such compositions comprise a hydroxide ion scavenging system. The
hydroxide ion
scavenging system of the present ~ invention comprises a hydroxyl ion-reacting
agent that is
adapted to control the pH of the chlorine dioxide solution to which it is
added. By controlling the
pH of a chlorine dioxide solution via the addition of a hydroxyl ion-reacting
agent, the solution
experiences prolonged stability. Without wishing to be bound by theory, it is
believed that this
prolonged stability is attributable to reducing the hydroxyl ion concentration
in solution to lower
its interaction with dissolved chlorine dioxide. This prolonged stability may
also be related to the
potential for acidic reaction at a low pH. Reducing the hydroxyl ion
concentration to stabilize the
chlorine dioxide is useful in static solutions as well as solutions that
undergo high shear, as in the
case of turbulent spraying or atomization of halogen dioxide solutions.
Generally, the hydroxide ion scavenging system of the present invention is
employed into a
chlorine dioxide solution at a level of from about 0.001 to about 10%,
preferably 0.01 to about
7.5%, more preferably 0.05 to about 5%, most preferably 0.1 to about 2.5%, by
weight of the total
hydroxide ion scavenging system-comprising chlorine dioxide solution. A person
of ordinary
skill in the art will readily appreciate that the exact amount of hydroxide
ion scavenging agent
needed to stabilize a chlorine dioxide solution will depend upon many factors
including, but not
limited to, the nature of the hydroxide ion scavenging agent, the
concentration of the halogen
dioxide solution for which the conveyance of increased stability is desired
and the generation
method of the halogen dioxide solution under consideration. Suitable hydroxide
ion scavenging
agents for use in the present invention are selected from the group consisting
of: organic acids,
salts of organic acids, inorganic acids, salts of inorganic acids, and the
like. It should be noted
that the hydroxide ion scavenging agents of the present invention are adapted
to stabilize any
halogen dioxide solution.
Irzterfacial Terzsiorz (IFT) Lowering Systenz
In another aspect of the present invention, an Interfacial Tension (IFT)
lowering system for
stabilizing and/or increasing the efficacy of a halogen dioxide solution is
disclosed. Without
wishing to be bound by theory, it is believed that the addition of one or more
IFT-lowering agents
to a halogen dioxide (and particularly chlorine dioxide) solution provides the
overall effect of
increasing the efficacy of said solution by lowering the Interfacial Tension
of the resultant system.
Without wishing to be bound by theory, it is believed that the IFT-lowering
agents of the present
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
7
invention are adapted to reduce the tension at the interface between two
physical phases - thereby
decreasing the level of work and/or energy required to expand the interfaces.
The ability of the
present IFT-lowering agents to encourage expansion of the interfaces with
decreased energy is
believed to facilitate penetration and increased interfacial exposure of
halogen dioxide (and
particularly chlorine dioxide). Moreover, the IFT-lowering agents of the
present invention can
exhibit synergy in concert with halogen dioxides - thereby facilitating
microbe structure and
protein denaturing. It is further believed that surfactants forming a
monolayer of surfactant at air
interfaces can be used to regulate halogen dioxide partitioning into the
surrounding air. This may
be of special interest for situations in which halogen dioxide solutions
comprising the present
IFT-lowering agents are used in the context of decontamination, whether via
chamber, spray or
other means.
Depending on the spray device and IFT-lowering agent employed, the sprayed
particle size
of the aqueous, halogen dioxide solution can be controlled and optimized for
the particular
application. In some cases, very small particle sizes may increase the surface
area enough to
overcome surfactant barrier effects thus helping to facilitate the
partitioning of the halogen
(chlorine) dioxide into the gas/air phase. In such an instance, a transition
from aqueous chlorine '
dioxide exposure to gas phase chlorine dioxide exposure occurs, which may be
beneficial in
delivering the subject compositions to areas that are difficult to reach using
aqueous dispersions.
Use of small particle sizes may also be desirable for situations in which
substrate contact with the
aqueous solution is not desired. Copious levels of foam on a surface likewise
may serve as an
additional physical barrier to halogen dioxide loss from solution to the
surrounding atmosphere.
Of course, the precise composition of the present efficacy-increasing IFT-
lowering systems
will depend on the purpose for which employment of the resultant chlorine
dioxide solution is
desired and the needs and/or abilities of the formulator. Nevertheless, the
IFT-lowering system
and/or agents of the present invention are preferably incorporated into a
halogen dioxide solution
at a level of from about 0.00001 to about 10%, preferably from about 0.0001 to
about 5%, more
preferably from about 0.0005 to about 2%, most preferably 0.001 to about 1%,
by weight of the
total, IFT-lowering system-containing halogen dioxide solution. Of course, in
a particularly
preferred embodiment of the present invention, the IFT-lowering agents
disclosed herein are
incorporated, in the above-listed amounts, into a chlorine dioxide solution
for which increased
stability and/or efficacy is desired.
A wide variety of IFT-lowering agents can be used to stabilize and/or increase
the
efficacy of a halogen dioxide solution in accordance with the present
invention. Although a few
such agents have been included herein, it should be appreciated that other
agents can provide
similar benefits in increasing the efficacy of the halogen dioxide solutions
to which they are
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
added. Indeed, there exist several classes of agents that can be used as IFT-
lowering agents for
purposes of the present invention. These classes include, but certainly are
not limited to: IFT-
lowering polymers, IFT-lowering solvents, IFT-lowering surfactants and
combinations thereof.
In a particularly preferred aspect of the present invention, IFT-lowering
surfactants are employed
into halogen dioxide solutions to convey the aforementioned benefits afforded
by the present IFT-
lowering agents disclosed herein. IFT-lowering surfactants for use in
increasing the efficacy
and/or performance of the halogen dioxide solutions disclosed herein can be
nonionic, anionic,
amphoteric, amphophilic, zwitterionic, cationic, semi-polar nonionic, and
mixtures thereof.
Nonlimiting examples of such surfactants are disclosed in US Patent Numbers
5,707,950 and
5,576,282, incorporated herein by reference. A typical listing of anionic,
nonionic, amphoteric
and zwitterionic classes, and species of these surfactants, is provided in US
Patent Number
3,664,961 issued to Norris on May 23, 1972, and incorporated herein by
reference.
Nonlimiting examples of IFT-lowering surfactants useful herein include the
conventional
Cg-Clg alkyl ethoxylates and/or alcohol ethoxylates (AE), with EO about 1-22,
including the so-
called narrow peaked alkyl ethoxylates and C6-C 12 alkyl phenol alkoxylates
(especially
ethoxylates and mixed ethoxy/propoxy), alkyl dialkyl amine oxide, alkanoyl
glucose amide, C11-
Clg (linear) alkyl benzene sulfonates (LAS) and primary, secondary and random
alkyl sulfates
(AS and/or SAS), the C l 0-C 1 g alkyl alkoxy sulfates (AES), the C l 0-C 1 g
alkyl polyglycosides
and their corresponding sulfated polyglycosides (APG), C12-Clg alpha-
sulfonated fatty acid
esters, C12-Clg alkyl and alkyl phenol alkoxylates (especially ethoxylates and
mixed
ethoxy/propoxy), C12-Clg betaines and sulfobetaines ("sultaines"), Cl0-Clg
amine oxides, alpha
olefin sulfonates (AOS), alcohol ethoxy sulfates, sodium paraffin sulfonates,
amido propyl
amines, alkyl N-methyl glucamides, nitrilotriacetic acid (NTA), alkali metal
salts of natural fatty
acids and the like. Other conventional useful surfactants are listed in
standard texts.
In another aspect of the present invention, IFT-lowering polymers and/or IFT-
lowering
solvents are incorporated into halogen dioxide (and particularly chlorine
dioxide) solutions for
which the conveyance of increased stability and/or efficacy are desired.
Suitable IFT-lowering
polymers for use in the context of the present invention include, but
certainly are not limited to:
polyoxyalkylene block copolymers. Indeed, suitable IFT-lowering solvents for
use as IFT-
lowering agents, in the context of the present invention include, but
certainly are not limited to:
glycol ethers such as propylene glycol n-propyl ether. Of course, the
selection of the appropriate
IFT-lowering agent for use in the context of the present invention will depend
upon several
factors, some of which include: (1) Sufficient chemical compatibility between
the halogen dioxide
and IFT lowering agent; (2) the nature of the halogen dioxide solution for
which the conveyance
of increased stability and/or efficacy is desired; (3) the purpose for which
deployment of the
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
9
resultant, IFT-lowering agent-containing halogen dioxide solution is desired;
and (4) the needs
and/or abilities of the formulator of the present compositions.
Hydroxide Ion-Scavenging and IFT Lowering Systems
In another aspect of the present invention, the halogen dioxide compositions
disclosed
herein comprise both a hydroxide ion-scavenging system and an IFT-lowering
system. Such
compositions are adapted to stabilize halogen dioxide, and particularly
chlorine dioxide, for a
prolonged period and convey certain aesthetic and/or performance benefits to
said solution.
Indeed, it has been surprisingly discovered, and documented via the present
disclosure, that
synergy is exhibited via the employment of both a hydroxide ion scavenging and
IFT-lowering
system in a halogen dioxide solution. Without wishing to be bound by theory,
it is believed that
the dual employment of an hydroxide ion scavenger and IFT lowering agent like
a surfactant
serves the integral purpose of maximizing the amount of halogen dioxide
delivered to the desired
interface by facilitating maximum surface area coverage from lowered
interfacial tension while
maintaining higher intrinsic halogen dioxide concentrations via inhibited
degradation. Indeed, the
hydroxide ion scavenging system and IFT-lowering systems of the present
invention, when
employed in combination, are present in an amount of from about 0.00001 to
about 15, preferably
from about 0.0001 to about 10%, more preferably from about 0.0005 to about 5%,
most
preferably from about 0.001 to about 2.5%, by weight of the total, hydroxide
ion scavenging
system and surfactant system-containing chlorine dioxide solution.
Adjunct Lagredierrts
In yet another aspect of the present invention, the halogen dioxide
stabilizing and efficacy-
increasing compositions disclosed herein will comprise one or more adjunct
ingredients for
providing aesthetic and/or performance benefits to the resultant composition.
In one aspect of the
present invention, the hydroxide ion scavenging containing compositions will
comprise one or
more adjunct ingredients (as discussed further infra). In another aspect of
the present invention,
the IFT-lowering system- containing compositions will comprise one or more
adjunct ingredients.
In yet another aspect of the present invention, the adjunct ingredients
disclosed herein are
incorporated into a halogen dioxide solution comprising both a hydroxide ion
scavenging system
and an IFT-lowering system.
While not essential for the purposes of the present invention, several
conventional
cleaning adjunct materials illustrated hereinafter are suitable for use in the
present compositions
and may be desirably incorporated in preferred embodiments of the present
invention, for
example to assist or enhance cleaning performance, for treatment of the
substrate to be cleaned, or
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
to modify the aesthetics of the present composition as is the case with
perfumes, colorants, dyes
or the like. The precise nature of these additional components, and levels of
incorporation
thereof, will depend on the physical form of the composition and the nature of
the cleaning
operation for which its use is intended.
Adjuncts suitable for incorporation into the halogen (and particularly
chlorine) dioxide
stabilizing and efficacy-increasing compositions of the present invention
include, but certainly are
not limited to: bleaching systems, enzymes and enzyme stabilizers, builders,
dispersants, soil
release agents, chelating agents, suds suppressors, softening agents, dye
transfer inhibition agents,
non-phosphate builders, color speckles, silvercare, anti-tarnish and/or anti-
corrosion agents, dyes,
fillers, germicides, alkalinity sources, hydrotropes, anti-oxidants perfumes,
solubilizing agents,
carriers, processing aids, pigments, and pH control agents as described in US
Patent Numbers
5,705,464, 5,710,115, 5,698,504, 5,695,679, 5,686,014 and 5,646,101, all of
which are
incorporated herein by reference.
Devices Comnrisift~ tlae Stabilizing ayad Efficacy-Increasing Compositions
In another aspect of the present invention, devices comprising the stabilizing
and/or
efficacy-increasing compositions of the previous aspect are disclosed and
claimed. Said devices
are generally limited to those that are adapted to generate halogen dioxide
from halogen dioxide
salt precursors, on-demand (as defined supra). Nevertheless, the stabilizing
and efficacy-
increasing compositions of the present invention may further be employed to
stabilize and/or
increase the efficacy of halogen dioxide that is pre-generated. A complete
description of suitable
electrolysis devices for use in conjunction with the stabilizing and efficacy-
increasing
compositions of the present invention is included in US Patent Application
Serial Number
091947,846 filed in the United States Patent and Trademark Office on 20
September 2001, and
published on 09 January 2003. This application is incorporated, in its
entirety, herein by
reference.
In one aspect of the present invention, suitable on-demand generation devices
for use with
the stabilizing and/or efficacy-increasing systems disclosed herein employ an
electrical current
passing through an aqueous feed solution between an anode and a cathode to
convert a halogen
dioxide salt precurs~r dissolved within the solution into a halogen dioxide.
When an aqueous
solution flows through the chamber of the electrolysis cell, and electrical
current is passed
between the anode and the cathode, several chemical reactions occur that
involve the water, as
well as one or more of the other salts or ions contained in the aqueous
solution. These chemical
reactions, and other features of the generation device that can be used in
accordance with this
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
11
aspect of the present invention, are described in co-pending US Patent
Application Serial Number
09/947,846 filed in the United States Patent and Trademark Office on 20
September 2001. The
Applicants hereby incorporate the subject matter of this patent application,
and particularly its
disclosure with respect to the precise characteristics of on-demand generation
devices for use in
the context of the present invention, herein.
Multiple Chamber-Conaprisitag Electrolysis Device
In yet another aspect of the present invention, the on-demand generation
device described
in US Patent Application Number 09/947,846 (and incorporated herein by
reference) may
comprise additional chambers that facilitate the mixing of greater than one
solution to form the
stabilizing and efficacy-increasing compositions of the present invention.
Indeed, separation of
the subject compositions to delay mixing until use of the resultant halogen
dioxide solution is
desired, is particularly useful when using chlorite salts and the total
mixture comprises a pH that
of less than about 7 and preferably less than about 5. In one aspect of the
present invention, this is
achieved by separating a chlorite salt solution and a low pH surfactant
solution. In yet another
aspect of the present invention, this is achieved by separating a chlorite
salt solution containing
the surfactant and a second, low pH solution having other ingredients.
In the case of this "on-demand" generation, electrolysis in accordance with
the present
invention could occur in a number of ways. Nevertheless, in any instance,
electrolysis should
occur down stream of the chlorite-based solution or resultant mixture. In one
aspect of the present
invention, this would be accomplished by mixing two streams, following
electrolysis of the
chlorite (halite) stream. In yet another aspect of the present invention, on-
demand electrolysis
could be accomplished by mixing two streams, said mixing being prior to
electrolysis of the
chlorite-containing total mixture.
The practitioner of the present invention will appreciate that there exist
several
mechanisms adapted to achieve the above-described, requisite mixing. In one
aspect of the
present invention, one common pump, which is adapted to create suction
sufficient to draw both
streams is employed to achieve requisite mixing. In yet another aspect of the
present invention, a
pump is employed to draw one stream and a venturi is employed after discharge
thereof to draw
and mix in a second stream. In yet another aspect of the present invention,
two pumps pulling
separate streams that are mixed after the pumps are employed. In another
aspect of the present
invention, electrolysis can occur before or after a pump or venturi.
Nevertheless, it is generally
more practical to use a device that is adapted to engage in electrolysis after
any streams are
pumped so as to prevent any negative impact on the performance of the pump
caused by gas
formed during the electrolysis.
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
12
In another aspect of the present invention, devices producing the stabilizing
and efficacy-
increasing compositions are not restricted to formation of halogen (chlorine)
dioxide by
electrolysis. In particular, the aforementioned aspect relating to the mixture
of more than one
solution can be constructed and/or configured such that the halogen dioxide is
produced from
chemical reactions upon mixing. Non-limiting examples of such a configuration
include mixing a
low pH solution with a halite solution to facilitate halogen dioxide
production by halite
acidification. In such an instance, a pH of less than about 2 is preferred for
rapid halogen dioxide
formation. Another example relates to the mixing of a liquid hypochlorite
solution with a solution
containing excess chlorite salt at low pH to form chlorine dioxide. In such an
instance, a pH of
less than about 4 is preferred. In the case of forming halogen dioxide via
chemical means when
mixing two (or more) streams, the mixing could be accomplished via a number of
mechanisms
including, but not limited to, one common pump creating suction to draw both
streams, a pump on
one stream and a venturi after its discharge which is used as intake to mix in
a second stream, and
two pumps pulling separate streams that are mixed after the pumps (as
hereinbefore described).
In yet another aspect of the present invention, when additional chloride salt
is used to
facilitate electrolysis of chlorine into chlorine dioxide, the side reaction
of electrolysis of Cl- to
hypochlorite, OCl-, may be controlled via use of a hydroxyl ion scavenger in
the form of specific
acidic buffers. In one aspect, it may be desirable to have some OCl- present
with the chlorine
dioxide, in, for example, situations in which increased antimicrobial efficacy
is desired. In such
an instance, by utilizing a hydroxyl ion scavenger and controlling the final
pH to between about 2
and about 7, one can facilitate the conversion of OCl- ion to HOCI. For
anitmicrobial efficacy,
HOCI is generally a preferred species to use. Above a pH of about 7, OCl- is
the predominant
species, and at a pH of below about 2, C12 predominates. For situations in
which the presence of
the hypochlorite species it is not desirable, the solution may be formulated
to produce excess
chlorite that has not reacted from the electrolysis. This excess chlorite can
subsequently react
with the HOCI generated from the electrolysis to form additional chlorine
dioxide. The preferred
pH for this type of a reaction is less than about 4.
Virtual Membrane
In yet another aspect of the present invention, electrolysis devices in
accordance with the
present invention further comprise parallel plate electrodes configured such
that a virtual (e.g.
quasi, pseudo) membrane is formed. The virtual membrane of the present
invention is not a
permanent physical membrane, but rather, is a fluid-like membrane that is
formed by the flow
characteristics of the fluid solution undergoing electrolysis. Specifically,
the flow within the
parallel plates of the electrolysis devices disclosed herein is controlled
such that the Reynolds
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
13
number associated with the fluid is less than about 2000. Without wishing to
be bound by theory,
maintaining a Reynolds number below about 2000 establishes a fluid flow regime
within the
electrolytic cell that is configured in a planar form, parallel to the plates.
This configuration is
believed to facilitate transverse ion transport in solution as a result of the
applied electrical
potential, while minimizing and/or eliminating bulk fluid mixing normal to the
electrolysis plates
to prevent undesired juxtaposition and/or reaction of the byproducts of the
electrolytic reaction. A
description of the application of the present virtual membrane in the context
of the electrolysis
devices herein disclosed in provided in the "Examples" section of the present
disclosure.
Metlzods of Using StabiliTin~ andlor Efficacy-Increasinir Comyositions and
Electrolysis
Devices
In yet another aspect of the present invention, methods of stabilizing and
increasing the
efficacy of halogen (and particularly chlorine) dioxide are disclosed. In one
aspect, a method of
stabilizing a halogen dioxide solution is disclosed. Said method comprises the
steps of
incorporating a hydroxide ion-scavenging solution in accordance with the first
aspect of the
present invention into a halogen, preferably chlorine, dioxide solution for
which increased
stability is desired. In another aspect of the present invention, a method for
increasing the
efficacy of a halogen dioxide solution is disclosed. Said method generally
comprises the step of
incorporating an IFT-lowering agent and/or system in accordance with the first
aspect of the
present invention into a halogen, preferably chlorine, dioxide solution for
which increased
efficacy and/or performance is desired. In yet another aspect of the present
invention, a method
of both stabilizing and increasing the efficacy of a halogen dioxide solution
is disclosed. Said
method generally comprises the steps of adding both a hydroxide ion-scavenging
solution and an
IFT-lowering system and/or agent to a halogen dioxide, preferably chlorine
dioxide, solution for
which increased stability and/or efficacy is desired
In another aspect of the present invention, a method of stabilizing and/or
increasing the
efficacy of halogen (and particularly chlorine) dioxide solutions generated
via electrolysis is
disclosed. Said methods comprise the steps of introducing the stabilizing
and/or efficacy-
increasing compositions of the present invention into a device adapted to
electrolyze halite salt (as
hereinbefore described), and facilitating the mixture of said stabilizing
and/or efficacy-increasing
compositions with the resultant halogen dioxide mixture.
Product and/or -Plzysical Forms Conzprisin Q Halogen Dioxide Solutions:
Hydroxide Ioaz
Scaven -srins~ Systenz Comprising Halogen Dioxide Solutions: and/or IFT
Lowerifz~ Systenz-
Cof~nrisin ~ Halo~ezz Dioxide Solutions
CA 02522576 2005-10-17
WO 2004/103898 ;",~S PCT/US2004/015730
14
In yet another aspect of the present invention, various product forms of the
solutions
and/or systems described herein are provided. Indeed, in one aspect of the
present invention the
solutions and/or systems described herein are formulated into gel. In
accordance with this aspect
of the invention, the gel may be formulated by adding any suitable thickener
to a halogen dioxide
solution, a hydroxide ion scavenging system-comprising halogen dioxide
solution and/or an IFT-
lowering system-comprising halogen dioxide solution. Without wishing to be
bound by theory, it
is believed that incorporation of the present solutions and/or systems into
such a gel facilitates
adherence of the gel to the target surface and/or substrate for which the
conveyance of the subject
solution and/or system is desired. Further, and without wishing to be bound by
theory, it is
believed that formulation of the present systems into a gel will result in
lower degradation by
limiting mass transfer and/or loss of halogen dioxide to the atmosphere. Those
skilled in the art to
which the subject invention pertains, will readily appreciate the multitude of
thickeners and
methods suitable for use in formulation of the present gels.
In yet another aspect of the present invention, the solutions and/or systems
described
herein are incorporated into a wipe product. In this aspect of the invention,
halogen dioxide is
generated via encapsulation of reactive species into or onto a wipe. The wipe
may then be
"activated," thereby generating halogen dioxide, via shearing the wipe and/or
by electrolyzing a
wipe comprising one or more halogen dioxide salt precursors. In another aspect
of the present
invention, the wipe comprising one or more halogen dioxide salt precursors is
electrolyzed via
passage through and/or between the electrolysis plates between which
electrolysis of the halogen
dioxide salt precursors occurs. In yet another aspect of the present
invention, a wipe comprising
one more of the solutions and/or systems disclosed herein may be treated in a
chamber, in which
the halogen dioxide salt precursors included in said wipe are electrolyzed to
generate halogen
dioxide. In yet still another aspect of the present invention, the wipe
disclosed herein is sprayed
with a halogen dioxide solution prior to an intended use. In yet another
aspect of the present
invention a wipe comprising a hydroxide ion scavenging system and/or an IFT-
lowering system is
sprayed with a halogen dioxide solution prior to an intended use.
In yet still other aspects of the present invention, the systems and/or
solutions disclosed
herein are formulated into an aerosol and/or gaseous phase, adapted to
fumigate a surface and/or
area for which the conveyance of stabilized and/or efficacious halogen dioxide
is desired. In one
aspect of the present invention, a halogen dioxide solution is presented in an
aerosol and/or
gaseous phase. In yet another aspect of the present invention, a hydroxide ion
scavenging system-
comprising halogen dioxide solution and/or an IFT-lowering system-comprising
halogen dioxide
solution is presented in an aerosol and/or gaseous phase. In yet still another
aspect of the present
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
"''~ if,.,~ !f .:' ~L.,ir -..It ti...ta ....EE...~' ",tE.. :~:li .y,'-
..":Ir.'sL..tt
Case 9247L/CA
invention, the halogen dioxide solution, hydroxide ion scavenging system-
comprising halogen
dioxide solution and/or an IFT-lowering system-comprising halogen dioxide
solution disclosed
herein are presented in a solid phase for conveyance to a target surface.
Preyaratiye Examples
i
Example 1: Chlorine Dioxide Solution Comprising a Hydroxide Ion Scavenging
Systettt. The
following is an example of a chlorine dioxide solution containing a hydroxide
ion scavenger in
the form of citric acid. This solution contains about 120 ppm chlorine
dioxide.
Ingredient Wt%
Sodium chloride 0.057
Sodium chlorite ~ 0.024
Chlorine dioxide 0.012
Sodium hydroxide 0.009
Sodium carbonate 0.001
Citric acid 0.093
Water 99.804
Example 2: Chlorine Dioxide Solution Comprising a Su1"factant System
The following is an example of a chlorine di~xide solution containing the
anionic surfactant
Sodium Lauryl Sulfate (SLS). This solution contains about 120 ppm chlorine
dioxide.
Ingredient Wt%
Sodium chloride 0.057
Sodium chlorite 0.024
Chlorine dioxide 0.012
Sodium hydroxide 0.009
Sodium carbonate 0.001
Sodium Lauryl Sulfate 0.012
Water 99.885
Example 3: Chlorine Dioxide Solution Cotttprisittg a Surfactant System
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
16
The following is an example of a chlorine dioxide solution containing the
nonionic surfactant
APG or AlkylPolyGlucoside (trade name Glucopon). This solution contains about
120 ppm
chlorine dioxide.
Ingredient Wt%
Sodium chloride 0.057
Sodium chlorite 0.024
Chlorine dioxide 0.012
Sodium hydroxide 0.009
Sodium carbonate 0.001
Glucopon 425 0.012
Water 99.885
Example 4: Chlorine Dioxide Solution Cornp~ising a Hydf~oxide Ion Scavenging
System and
Surfactant System
The following is an example of a chlorine dioxide solution containing
hydroxide ion scavenger
citric acid and anionic surfactant SLS. A hydroxyl ion source is added to
interact with the citric
acid and adjust the mix pH to about 4. This solution contains about 100 ppm
chlorine dioxide.
Ingredient Wt%
Citric acid (anhydrous) 0.078
Sodium hydroxide 0.007
Sodium Lauryl Sulfate 0.010
Sodium carbonate 0.006
Magnesium carbonate hydroxide 0.002
PPG 2000 0.004
Antifoam 2-4293 0.001
Grapefruit oil 0.0001
Sodium chloride 0.048
Sodium chlorite 0.020
Chlorine dioxide 0.010
Water 99.8139
Example 5: Device Comps°isirag hydroxide ion scavenging arad Surfactant
Systems
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
17
An electrolysis cell of the general design depicted in Figure 1 of copending
US Patent Application
Serial Number 09/947,846 (published 20 September 2001 and incorporated herein
by reference)
was used to convert an aqueous solution comprising sodium chlorite into an
effluent solution
comprising chlorine dioxide. The electrolysis cell had a pair of confronting
electrodes having a
passage gap of about 0.19 mm. The anode was made of ES300 - titanium, coated
with ruthenium
oxide and iridium oxide. The cathode was made of 201 stainless steel. The
dimensions of the
planar electrodes were 75.2 mm long by 25.4 mm wide.
The aqueous feed solution was prepared by mixing 10 liters of de-ionized water
with 62.6
gms technical grade sodium chlorite stock (80% active, Aldrich Chemical
Company, Inc,
Milwaukee, WI 53233; Cat. No. 24415-5) with a stirnng bar until dissolved,
forming a 5000 ppm
sodium chlorite salt solution. The aqueous feed solution was retained in a 15-
liter glass container
placed within a light-proof box and cooled to 5 degrees Celsius. A peristaltic
pump metered the
aqueous feed solution from the glass container through the electrolysis cell
at a flow rate of 300
ml/minute. A direct current of 5.72 amps was applied across the electrodes by
a DC power
supply to provide a voltage potential of 4.5 volts across the electrolysis
cell. The effluent solution
was withdrawn from the electrolysis cell and analyzed. The effluent contained
109 ppm chlorine
dioxide and 4891 ppm of un-reacted sodium chlorite, for a chlorite conversion
of 2.9%.
The following examples were prepared to document use of a single solution
containing hydroxide
ion scavengers and a surfactant system capable of running through a sprayer
device equipped
with an electrolysis cell to generate chlorine dioxide from sodium chlorite in
the solution. A
phosphate based version and carbonate based version are presented.
Ingredient Wt% Wt%
Citric acid (anhydrous)0.2 0.23
NaOH (50% soln.) 0.24 0.17
Sodium Lauryl Sulfate0.05 0.05
NaZHP04 0.03 -
NaH2P04 H20 0.03 -
NaHC03 -
0.10
NaClO2 0.5 0.50
Water 98.95 98.95
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
18
The solutions comprise a pH between about 6 and 7 before the electrolysis, and
maintained a pH
between 6 and 9 after electrolysis is conducted. The discharge from the
electrolysis cell and
pump was estimated to have a chlorine dioxide level of 85 ppm. This solution
can also be
recycled through the cell/pump to further increase the chlorine dioxide
concentration. The
effluent from the cell/pump was subsequently discharged through a atomizing
spray nozzle to
create a fme mist of chlorine dioxide containing particles. The mist can be
used to cover surfaces
for treatment, or confined in a enclosed area to have a "fumigation" effect.
For the examples that follow, reference these component compositions:
I II
Ingredient Wt% Ingredient Wt%
Deionized Deionized
Water Water
99.9 97
Sodium Chlorite
stock (technical
grade) 0.05 NaHC03 1.77
Sodium Chloride Sodium Lauryl
0.05 Sulfate 1.23
III IV
Ingredient Wt% Ingredient Wt%
Deionized Deionized
Water Water
99.59 99.42
Citric acid Acid - Anionic
(anhydrous) 0.41 powder mix 0.58
(V)
V
Ingredient Wt%
Citric acid
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
19
(anhydrous) 77.61
Sodium Lauryl
Sulfate 10.31
Na2CO3 5.28
MgC03 2.00
PPG 2000 ' 3.7
Antifoam 2-4293
1.00
Grapefruit 0.10
oil
The following examples utilize the compositions above.
Examples A ~ E: Composition I was electrolyzed while being pumped through an
electrolytic
plate using 6.6 volts. A final mixture was then created comprising 83% of
electrolyzed
composition I and 17% deionized water.
Examples B & F: Composition I was electrolyzed while being pumped through an
electrolytic
plate using 6.6 volts. A final mixture was then created comprising 83% of
electrolyzed
composition I and 17% composition II.
Examples C & G: Composition I was electrolyzed while being pumped through an
electrolytic
plate using 6.6 volts. A final mixture was then created comprising 83% of
electrolyzed
composition I and 17% composition III.
Examples D & H: Composition I was electrolyzed while .being pumped through an
electrolytic
plate using 6.6 volts. A final mixture was then created comprising 83% of
electrolyzed
composition I and 17% composition IV.
Microbiological efficacy testing was conducted utilizing the example
compositions A-H described
above. The lower the Log Recovery number the better the performance.
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
Gram Positive Bacteria in Surface Spray test
Organism: S. aureus
Target CIOz solution concentration: 50 ppm
5 minute treatment time
A B C D
ClOz only C102 + C102+ Citric acid C102+ Acid/Surfactant
(pH~10.5) Alkaline/Surfactant (pH~3.5) (pH~4)
(pH~9)
Log Recovery I 6.02 I 2.52 I 1.57 I 0.62
Gram Negative Bacteria in Surface Spray test
Organism: P. aeruginosa
Target ClOz solution concentration: 50 ppm
5 minute treatment time
E F G H
C102 only 0102 + ClO2 + Citric acid ClOz + Acid/Surfactant
(pH~10.5) Alkaline/Surfactant (pH~3.5) (pH~4)
(pH~9)
Log Recovery I 6.32 I 4.79 I 3.16 I 0*
* represents complete kill (i.e., below limits of detection)
The next examples utilize the following component compositions:
VI VII
Ingredient Wt% Ingredient Wt%
Deionized Deionized
Water 99.75 Water 99.00
Sodium Chlorite Acid - Anionic
~
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
21
stock (technical 0.25 powder mix (V) 1.00
grade)
VIII
Ingredient Wt%
Deionized
Water
99.29
Citric acid
(anhydrous) 0.71
The following examples utilize the compositions above.
Example J: Composition VI was electrolyzed while being pumped through an
electrolytic plate
using 6 volts. A final mixture was then created comprising 50% of electrolyzed
composition VI
and 50% deionized water.
Example K: Composition VI was electrolyzed while being pumped through an
electrolytic plate
using 6 volts. A final mixture was then created comprising 50% of electrolyzed
composition VI
and 50% composition VIII.
Example L: Composition VI was electrolyzed while being pumped through an
electrolytic plate
using 6 volts. A final mixture was then created comprising 50% 4f electrolyzed
composition VI
and 50% composition VII.
Microbiological efficacy testing was conducted utilizing the example
compositions J-L described
above. The lower the Log Recovery number the better the performance.
Gram Positive Spores in Suspension test
Organism: Bacillus cereus spores
C102 solution concentration: ~~5 ppm
minute treatment time
J K L
ClOz only ~ ClOz + Citric acid ~ C102 + Acid/Surtactant
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
;"..
~1.",. !t ~ ~t t t~ n.~tt ,...tt.. ~~ "Sf., :::::.. .V~ .,~:;:~ .V",:!
Case 9247L/CA
22
(pH~10.5) ~ (pH~3.5) ~ (pH~3.5)
Log Recovery I 0.67 I 0.56 I <0.30*
* represents complete kill (i.e., below limits of detection)
Example 6: ,Stable and efficacious chlorine dioxide mixes produced f
°om a spray bottle having
two compartments
Solutions M and N are in the separate compartments and are mixed together by a
small centrifugal
pump pulling equal amounts from each compartment and mixing together at the
suction, and
further in the pump. The product is discharged from the pump through a spray
nozzle. The
discharge mixture has formed chlorine dioxide as a result of mixing the two
components M+N,
and the mix has the characteristic yellow appearance of a chlorine dioxide
solution which stays
stable and with the surfactant represents an effective antibacterial product.
M N
Ingredient Wt% Ingredient Wt%.
DI Water 99.12 DI Water 99.45
Citric Acid 0.78 Na C102 stock0.08
Sodium Lauryl NaOCI stock
Sulfate 0.10 (5.25% NaOCI0.47
active in
stock)
Example 7: Determination of Reynolds number (Re) in Parallel plate electrodes
for formation of
virtual rnembrane:
For a full channel, the hydraulic radius is the cross section area divided by
the wetted perimeter
Rh=A/P. For a non-circular pipe, the hydraulic diameter is four times the
Hydraulic radius.
Dh=4Rh
For a parallel plate channel of width w, and spacing s, the hydraulic radius
would be
w*s/(2*(w+s)). The hydraulic diameter is 4Rh or Dh= 2w*s/(w+s). For a channel
where w»s, D,,
becomes about 2s.
Re = D,,Vp/u ( ~2sVp/u when w»s)
total volumetric flow Q 144 cm~3/min
CA 02522576 2005-10-17
WO 2004/103898 PCT/US2004/015730
23
cell width w 2.5 Cm
cell spacing s 0.02 Cm
flow cross sectionA 0.05 cm~2
number of cells n 1
fluid density p 1 gm/cm~3
fluid dynamic a 1 CP
viscosity
cell flow velocityV 48 cm/sec
Characteristic Dh 0.039683 Cm
diameter
cell length 1 7.2 Cm
Reynolds number Re 190.4762
Residence Time RT 0.0025 Min
Cell Volume Vol 0.36 cm~3
All documents cited in the Detailed Description of the Invention are, in
relevant part,
incorporated herein by reference; the citation of any document is not to be
construed as an
admission that it is prior art with respect to the present invention.
While particular embodiments of the present invention have been illustrated
and
described, it would be obvious to those skilled in the art that various other
changes and
modifications can be made without departing from the spirit and scope of the
invention. It is
therefore intended to cover in the appended claims all such changes and
modifications that are
within the scope of this invention.
