US20040231977A1

US20040231977A1 - Compositions, devices and methods for stabilizing and increasing the efficacy of halogen dioxide

Info

Publication number: US20040231977A1
Application number: US10/848,958
Authority: US
Inventors: Brian Roselle; Gregory Huntington; Mario Tremblay; Charles Pettigrew; Freddy Barnabas
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 2003-05-19
Filing date: 2004-05-19
Publication date: 2004-11-25
Also published as: BRPI0410758A; KR100803016B1; KR20060009355A; WO2004103898A1; CN1787963A; MXPA05012437A; EP1626928A1; JP2006526076A; CA2522576A1; CN100377991C

Abstract

Compositions and methods for increasing the stability and/or efficacy of chlorine dioxide, and particularly chlorine dioxide generated via electrolysis of chlorite. The present invention further relates to electrolysis devices for producing chlorine dioxide, comprising the stabilizing and efficacy-increasing compositions of the present invention, as well as methods of using both the chlorine dioxide-stabilizing and efficacy-increasing compositions and devices disclosed herein.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/471,670, filed May 19, 2003.[0001]

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, ClO ₂, 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 ClO ₂, in terms of available chlorine, is 2.5 times that of chlorine. Also, unlike chlorine/hypochlorite, 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. parvum 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 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 (NaClO ₂) or sodium chlorate (NaClO₃). A typical process for generating chlorine dioxide from sodium chlorate salt is the acid-catalyzed reaction:

NaClO₃+2HCl→NaCl+1/2Cl₂+ClO₂+H₂O

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:

5NaClO₂+4HCl→4ClO₂+5NaCl+2H₂O

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 efficacy-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 (IFT) 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 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 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. [0013]
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 “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. [0014]
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). [0015]
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. [0016]
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 3 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. [0017]
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. [0018]
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. [0019]

Compositions for Stabilizing and/or Increasing the Efficacy of Halogen Dioxide

Hydroxide Ion Scavenging System [0020]
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. [0021]
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. [0022]
Interfacial Tension (IFT) Lowering System [0023]
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 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. [0024]
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. [0025]
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. [0026]
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 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 U.S. Pat. Nos. 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 U.S. Pat. No. 3,664,961 issued to Norris on May 23, 1972, and incorporated herein by reference. [0027]
Nonlimiting examples of IFT-lowering surfactants useful herein include the conventional C[0028] ₈-C₁₈alkyl ethoxylates and/or alcohol ethoxylates (AE), with EO about 1-22, including the so-called narrow peaked alkyl ethoxylates and C₆-C₁₂alkyl phenol alkoxylates (especially ethoxylates and mixed ethoxy/propoxy), alkyl dialkyl amine oxide, alkanoyl glucose amide, C₁₁-C₁₈(linear) alkyl benzene sulfonates (LAS) and primary, secondary and random alkyl sulfates (AS and/or SAS), the C₁₀-C₁₈alkyl alkoxy sulfates (AES), the C₁₀-C₁₈alkyl polyglycosides and their corresponding sulfated polyglycosides (APG), C₁₂-C₁₈alpha-sulfonated fatty acid esters, C₁₂-C₁₈alkyl and alkyl phenol alkoxylates (especially ethoxylates and mixed ethoxy/propoxy), C₁₂-C₁₈betaines and sulfobetaines (“sultaines”), C₁₀-C₁₈amine 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 resultant, IFT-lowering agent-containing halogen dioxide solution is desired; and (4) the needs and/or abilities of the formulator of the present compositions. [0029]
Hydroxide Ion-Scavenging and IFT-Lowering Systems [0030]
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. [0031]
Adjunct Ingredients [0032]
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. [0033]
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 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. [0034]
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 U.S. Pat. Nos. 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. [0035]

Devices Comprising the Stabilizing and 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 U.S. patent application Ser. No. 09/947,846 filed in the United States Patent and Trademark Office on 20 Sep. 2001, and published on 09 Jan. 2003. This application is incorporated, in its entirety, herein by reference. [0036]
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 precursor 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 aspect of the present invention, are described in co-pending U.S. patent application Ser. No. 09/947,846 filed in the United States Patent and Trademark Office on 20 Sep. 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. [0037]
Multiple Chamber-Comprising Electrolysis Device [0038]
In yet another aspect of the present invention, the on-demand generation device described in U.S. patent application Ser. No. 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. [0039]
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. [0040]
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. [0041]
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). [0042]
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[0043] ⁻ 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 HOCl. For anitmicrobial efficacy, HOCl 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, Cl₂predominates. 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 HOCl 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 [0044]
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 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. [0045]

Methods of Using Stabilizing and/or Efficacy-Increasing Compositions 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 [0046]
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. [0047]

Product and/or Physical Forms Comprising Halogen Dioxide Solutions: Hydroxide Ion Scavenging System-Comprising Halogen Dioxide Solutions; and/or IFT-Lowering System-Comprising Halogen Dioxide Solutions

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. [0048]
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. [0049]
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 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. [0050]

PREPARATIVE EXAMPLES

Example 1

Chlorine Dioxide Solution Comprising a Hydroxide Ion Scavenging System. [0051]
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. [0052]

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 Surfactant System [0053]
The following is an example of a chlorine dioxide solution containing the anionic surfactant Sodium Lauryl Sulfate (SLS). This solution contains about 120 ppm chlorine dioxide. [0054]

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 Comprising a Surfactant System [0055]
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. [0056]

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 Comprising a Hydroxide Ion Scavenging System and Surfactant System [0057]

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 Comprising Hydroxide Ion Scavenging and Surfactant Systems [0059]
An electrolysis cell of the general design depicted in FIG. 1 of copending U.S. patent application Ser. No. 09/947,846 (published 20 Sep. 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. [0060]
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, Wis. 53233; Cat. No. 24415-5) with a stirring 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%. [0061]

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 Sulfate	0.05	0.05
Na₂HPO₄	0.03	—
NaH₂PO₄.H₂O	0.03	—
NaHCO₃	—	0.10
NaClO₂	0.5	0.50
Water	98.95	98.95

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 fine 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. [0063]
For the examples that follow, reference these component compositions: [0064]

Ingredient Wt %

I

Deionized Water 99.9

Sodium Chlorite 0.05

stock (technical

grade)

Sodium Chloride 0.05

II

Deionized Water 97

NaHCO₃ 1.77

Sodium Lauryl 1.23

Sulfate

III

Deionized Water 99.59

Citric acid 0.41

(anhydrous)

IV

Deionized Water 99.42

Acid - Anionic 0.58

powder mix (V)

V

Citric acid 77.61

(anhydrous)

Sodium Lauryl 10.31

Sulfate

Na2CO3 5.28

MgCO3 2.00

PPG 2000 3.7

Antifoam 2-4293 1.00

Grapefruit oil 0.10
The following examples utilize the compositions above. [0065]
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. [0066]
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. [0067]
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. [0068]
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. [0069]
Microbiological efficacy testing was conducted utilizing the example compositions A-H described above. The lower the Log Recovery number the better the performance. [0070]

Gram Positive Bacteria in Surface Spray Test

Organism: [0071] S. aureus
Target ClO[0072] ₂solution concentration: 50 ppm

5 minute treatment time



		B	C	D
	A	ClO₂+	ClO₂+	ClO₂+ Acid/
	ClO₂only	Alkaline/Surfactant	Citric acid	Surfactant
	(pH˜10.5)	(pH˜9)	(pH˜3.5)	(pH˜4)

Log	6.02	2.52	1.57	0.62
Recovery

Gram Negative Bacteria in Surface Spray Test

Organism: [0074] P. aeruginosa
Target ClO[0075] ₂solution concentration: 50 ppm

5 minute treatment time



		F	G	H
	E	ClO₂+	ClO₂+	ClO₂+ Acid/
	ClO₂only	Alkaline/Surfactant	Citric acid	Surfactant
	(pH˜10.5)	(pH˜9)	(pH˜3.5)	(pH˜4)

Log	6.32	4.79	3.16	0*
Recovery

The next examples utilize the following component compositions: [0077]

Ingredient Wt %

VI

Deionized Water 99.75

Sodium Chlorite 0.25

stock (technical

grade)

VII

Deionized Water 99.00

Acid - Anionic 1.00

powder mix (V)

VIII

Deionized Water 99.29

Citric acid 0.71

(anhydrous)
The following examples utilize the compositions above. [0078]
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. [0079]
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. [0080]
Example L: 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 VII. [0081]
Microbiological efficacy testing was conducted utilizing the example compositions J-L described above. The lower the Log Recovery number the better the performance. [0082]

Gram Positive Spores in Suspension Test

Organism: [0083] Bacillus cereus spores
ClO[0084] ₂solution concentration: ˜85 ppm
5 minute treatment time [0085]

J K L

ClO₂only ClO₂+ Citric acid ClO₂+ Acid/Surfactant

(pH˜10.5) (pH˜3.5) (pH˜3.5)

Log Recovery 0.67 0.56 <0.30*

Example 6

Stable and Efficacious Chlorine Dioxide Mixes Produced from a Spray Bottle Having Two Compartments [0086]
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. [0087]

Ingredient Wt %

M

DI Water 99.12

Citric Acid 0.78

Sodium Lauryl 0.10

Sulfate

N

DI Water 99.45

Na ClO₂stock 0.08

NaOCl stock 0.47

(5.25% NaOCl

active in stock)

Example 7

Determination of Reynolds Number (Re) in Parallel Plate Electrodes for Formation of Virtual Membrane: [0088]
For a full channel, the hydraulic radius is the cross section area divided by the wetted perimeter R[0089] _h=A/P. For a non-circular pipe, the hydraulic diameter is four times the Hydraulic radius. D_h=4R_h
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 4R[0090] _hor D_h=2w*s/(w+s). For a channel where w>>s, D_hbecomes about 2s.
Re=D _h Vp/u(˜2sVp/u when w>>s)



total volumetric flow	Q	144	cm{circumflex over ( )}3/min
cell width	w	2.5	Cm
cell spacing	s	0.02	Cm
flow cross section	A	0.05	cm{circumflex over ( )}2
number of cells	n	1
fluid density	p	1	gm/cm{circumflex over ( )}3
fluid dynamic viscosity	u	1	CP
cell flow velocity	V	48	cm/sec
Characteristic diameter	Dh	0.039683	Cm
cell length	l	7.2	Cm
Reynolds number	Re	190.4762
Residence Time	RT	0.0025	Min
Cell Volume	Vol	0.36	cm{circumflex over ( )}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. [0092]
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. [0093]

Claims

What is claimed is:

1. A hydroxide ion scavenging system for stabilizing a halogen dioxide solution, said system comprising

(a) from about 0.001% to about 10% by weight of the total of a hydroxide ion scavenger-comprising halogen dioxide precursor solution, a hydroxide ion scavenging system; and

(b) from about 0.000001% to about 50% by weight of the total of a hydroxide ion scavenging-comprising halogen dioxide precursor solution, one or more halogen salt precursors;

wherein agents for use in said hydroxide ion scavenging system are selected from the group consisting of: organic acids, salts of organic acids, inorganic acids, salts of inorganic acids, and mixtures thereof;

further wherein said hydroxide ion scavenging system is adapted to increase the concentration of a halogen dioxide solution by at least about 5% in comparison to the concentration of a corresponding halogen dioxide solution that does not comprise said hydroxide ion-scavenging system, when both solutions are measured at 25° C., three hours following halogen dioxide generation.

2. The hydroxide ion scavenging system of claim 1, wherein halogen dioxide is pre-generated.

3. The hydroxide ion scavenging system of claim 1, wherein halogen dioxide is generated on demand.

4. A hydroxide ion scavenging system for stabilizing a halogen dioxide solution, said system comprising

(a) from about 0.001% to about 10% by weight of the total of a hydroxide ion scavenging-comprising halogen dioxide solution, a hydroxide ion scavenging system; and

(b) from about 0.000001% to about 1% by weight of the total of a hydroxide ion scavenging-comprising halogen dioxide solution, halogen dioxide;

wherein said hydroxide ion scavenging agents are selected from the group consisting of: organic acids, salts of organic acids, inorganic acids, salts of inorganic acids, and mixtures thereof;

further wherein said hydroxide ion scavenging system is adapted to increase the concentration of a halogen dioxide solution by at least about 5% in comparison to the concentration of a corresponding halogen dioxide solution that does not comprise said hydroxide ion-scavenging system, when both solutions are measured at 25° C., three hours following generation.

5. The hydroxide ion scavenging system of claim 4, wherein said hydroxide ion scavenging system is used to stabilize a chlorine dioxide solution.

6. An Interfacial Tension (IFT)-Lowering system for increasing the stability and/or efficacy of a halogen dioxide solution, said system comprising:

(a) from about 0.00001% to about 10%, by weight of the total of an IFT-lowering system-comprising halogen dioxide precursor solution, an IFT-lowering system

(b) from about 0.000001% to about 50%, by weight of the total of an IFT-lowering system-comprising halogen dioxide precursor solution, one or more halogen salt precursors;

wherein agents for use in said IFT-lowering system are selected from the group consisting of: IFT-lowering polymers, IFT-lowering solvents, IFT-lowering surfactants and mixtures thereof; further wherein said IFT-lowering system is adapted to convey at least about 5% greater reduction in the number of microbes to the IFT-lowering system-comprising halogen dioxide solution, in comparison to a corresponding halogen dioxide solution that does not comprise the said IFT-lowering system.

7. An Interfacial Tension (IFT)-Lowering system for increasing the stability and/or efficacy of a halogen dioxide solution, said system comprising:

(c) from about 0.00001% to about 10%, by weight of the total of an IFT-lowering system-comprising halogen dioxide solution, an IFT-lowering system

(d) from about 0.000001% to about 1%, by weight of the total of an IFT-lowering system-comprising halogen dioxide solution, halogen dioxide;

8. The IFT-lowering system of claim 7, wherein said IFT-lowering system is used to increase the efficacy of a chlorine dioxide solution.

9. A halogen dioxide stabilizing and efficacy-increasing system, said system comprising the hydroxide ion-scavenging system in accordance with claim 1 and the IFT-lowering system in accordance with claim 6;

wherein said halogen dioxide stabilizing and efficacy-increasing system is characterized by a concentration of halogen dioxide of at least about 5% greater the concentration of a corresponding halogen dioxide that does not comprise said halogen dioxide stabilizing and efficacy-increasing system at 25° C., three hours following generation;

further wherein said halogen dioxide stabilizing and efficacy-increasing system is adapted to convey at least about 5% greater reduction in the number of microbes than a corresponding halogen dioxide solution that does not comprise said halogen dioxide stabilizing and efficacy-increasing system.

10. A halogen dioxide stabilizing and efficacy-increasing system, said system comprising the hydroxide ion-scavenging system in accordance with claim 4 and the IFT-lowering system in accordance with claim 7;

11. A halogen dioxide generating system, comprising:

a) a source of an aqueous feed solution comprising a halogen dioxide salt;

b) a non-membrane electrolysis cell comprising an anode and a cathode, and having a cell chamber with an inlet and an outlet;

c) a means for passing the aqueous feed solution into the chamber and along a passage adjacent to the anode, and out of the outlet;

d) an electric current supply to flow a current through the aqueous feed solution in the passage, to convert a portion of the halogen dioxide salt to halogen dioxide, and thereby form an aqueous effluent comprising halogen dioxide; and

e) a chamber comprising a system selected from the group consisting of: a hydroxide ion scavenging system for stabilizing said halogen dioxide solution; an IFT-lowering system for increasing the stability and/or efficacy of said halogen dioxide solution and combinations thereof.

12. The halogen dioxide generating system of claim 11 wherein the anode and the cathode are confronting and co-extensive, with a chamber gap of 1.0 mm or less.

13. The halogen dioxide generating system of claim 11 wherein the anode and the cathode are confronting and co-extensive, with a chamber gap of 0.5 mm or less.

14. The halogen dioxide generating system of claim 11 wherein the anode and the cathode are confronting and co-extensive, with a chamber gap of 0.2 mm or less.

15. The halogen dioxide generating system of claim 11 wherein the anode is a conductive porous anode.

16. A halogen dioxide generating system, comprising:

a) a source of an aqueous feed solution comprising a halogen dioxide salt;

e) a chamber comprising both a hydroxide ion scavenging system and an IFT-lowering system for increasing the stability and efficacy of the halogen dioxide solution.

17. The halogen dioxide generating system of claim 16 wherein the anode and the cathode are confronting and co-extensive, with a chamber gap of 1.0 mm or less.

18. The halogen dioxide generating system of claim 16 wherein the anode and the cathode are confronting and co-extensive, with a chamber gap of 0.5 mm or less.

19. The halogen dioxide generating system of claim 16 wherein the anode and the cathode are confronting and co-extensive, with a chamber gap of 0.2 mm or less.

20. The halogen dioxide generating system of claim 16 wherein the anode is a conductive porous anode.

21. A halogen dioxide generating and re-circulating system, comprising:

a) a source of an aqueous feed solution comprising a halogen dioxide salt;

c) a means for passing the aqueous feed solution into the chamber, and along a passage adjacent to the anode, and out of the outlet;

d) an electric current supply to flow a current through the aqueous solution between the anode and the cathode, to convert at least a portion of the halogen dioxide salt in the passage to halogen dioxide, and thereby form an aqueous effluent comprising halogen dioxide;

e) a means for delivering the aqueous effluent into contact with a halogen dioxide depletion target, whereby a portion of the halogen dioxide in the aqueous effluent oxidizes the depletion target and reverts back to a halogen dioxide salt;

f) a means for returning the depleted effluent comprising the reverted halogen dioxide salt back to the source; and

g) a means for delivering a hydroxide ion scavenging system for stabilizing said halogen dioxide solution.

22. A halogen dioxide generating and re-circulating system, comprising:

a) a source of an aqueous feed solution comprising a halogen dioxide salt;

g) a means for delivering an IFT-lowering system for increasing the stability and/or efficacy of said halogen dioxide solution.

23. A battery-powered electrolysis device for use to make on demand an aqueous solution comprising chlorine dioxide, comprising:

a) an electrolysis cell comprising an anode and a cathode, and having a cell chamber;

b) a means for pumping an aqueous feed solution comprising a halogen dioxide salt into the cell chamber and along a passage adjacent to the anode;

c) a battery for flowing electrical current between the anode and the cathode when the aqueous feed solution flows within the chamber and along the passage, whereby a portion of the halogen dioxide salt is converted to halogen dioxide; and

d) a means for delivering a hydroxide ion scavenging system for stabilizing said halogen dioxide solution.

24. The battery-powered electrolysis device according to claim 23, wherein the device is a solution spray bottle, wherein the pumping means comprises a electrically-driven pump that pumps solution from the bottle to the electrolysis cell, and wherein the electrolysis cell comprises an anode and a confronting, co-extensive cathode, having a cell chamber gap of 1.0 mm or less.

25. The battery-powered electrolysis device according to claim 23, wherein the device is a solution spray bottle, wherein the pumping means comprises a electrically-driven pump that pumps solution from the bottle to the electrolysis cell, and wherein the electrolysis cell comprises an anode and a confronting, co-extensive cathode, having a cell chamber gap of 0.5 mm or less.

26. The battery-powered electrolysis device according to claim 23, wherein the device is a solution spray bottle, wherein the pumping means comprises a electrically-driven pump that pumps solution from the bottle to the electrolysis cell, and wherein the electrolysis cell comprises an anode and a confronting, co-extensive cathode, having a cell chamber gap of 0.2 mm or less.

27. A battery-powered electrolysis device for use to make on demand an aqueous solution comprising chlorine dioxide, comprising:

d) a means for delivering an IFF-lowering system for increasing the stability and/or efficacy of said halogen dioxide solution.

28. The battery-powered electrolysis device according to claim 27, wherein the device is a solution spray bottle, wherein the pumping means comprises a electrically-driven pump that pumps solution from the bottle to the electrolysis cell, and wherein the electrolysis cell comprises an anode and a confronting, co-extensive cathode, having a cell chamber gap of 1.0 mm or less.

29. The battery-powered electrolysis device according to claim 27, wherein the device is a solution spray bottle, wherein the pumping means comprises a electrically-driven pump that pumps solution from the bottle to the electrolysis cell, and wherein the electrolysis cell comprises an anode and a confronting, co-extensive cathode, having a cell chamber gap of 0.5 mm or less.

30. The battery-powered electrolysis device according to claim 27, wherein the device is a solution spray bottle, wherein the pumping means comprises a electrically-driven pump that pumps solution from the bottle to the electrolysis cell, and wherein the electrolysis cell comprises an anode and a confronting, co-extensive cathode, having a cell chamber gap of 0.2 mm or less.

31. A method of stabilizing halogen dioxide, said method comprising the step of delivering a hydroxide ion scavenging system to a halogen dioxide solution for which increased stability is desired;

wherein said method is adapted to increase the concentration of a halogen dioxide solution by at least about 5% in comparison to the concentration of a corresponding halogen dioxide solution that does not contain said hydroxide ion scavenging system, when both solutions are measured at 25° C., three hours following generation; and

wherein said method is adapted to increase the efficacy of a chlorine dioxide solution.

32. A method of increasing the efficacy of halogen dioxide, said method comprising the step of delivering an Interfacial Tension (IFT)-lowering system to a halogen dioxide solution for which increased efficacy is desired;

33. A method of increasing the stability and efficacy of a halogen dioxide solution, said method comprising the step of delivering a hydroxide ion scavenging system and an Interfacial Tension (IFT)-lowering system to a halogen dioxide solution for which increased stability and efficacy is desired.