WO2013068599A2

WO2013068599A2 - Process for producing an anolyte composition

Info

Publication number: WO2013068599A2
Application number: PCT/EP2012/072426
Authority: WO
Inventors: Heinrich Eckhoff
Original assignee: Lohas Products GmbH
Current assignee: Lohas Products GmbH
Priority date: 2011-11-11
Filing date: 2012-11-12
Publication date: 2013-05-16
Anticipated expiration: 2014-05-11
Also published as: WO2013068599A3

Abstract

The present invention provides processes for producing an anolyte composition comprising the following steps: (a) providing an aqueous solution comprising one or more alkaline earth or alkali metal chloride salts in a concentration of 0.2 to 25 g/l; (b) passing the solution through an anode chamber of an electrolysis cell to obtain an anolyte; (c) reducing the concentration of oxidizing agents in the anolyte. The present invention further provides processes for producing an anolyte composition comprising the following steps: (a) providing an aqueous solution comprising one or more alkaline earth or alkali metal chloride salts in a concentration of 0.2 to 25 g/l; (b) passing the solution through a first cathode chamber to obtain a catholyte; (c) passing at least part of the catholyte through a first anode chamber to obtain an anolyte having a pH between 6 and 8; (d) reducing the concentration of oxidizing agents in the anolyte.

Description

Process for Producing an Anolyte Composition

The present invention relates to a process for producing an anolyte composition, i.e. an electrochemically activated water-based solution comprising alkaline earth or alkali metal chloride salts, which process comprises a step reducing the concentration of oxidizing agents in the anolyte.

Electrolysis of aqueous liquids comprising one or more alkaline earth or alkali metal chloride salts, usually sodium chloride, carried out in electrolysis cells comprising a separation between anode and cathode, such a diaphragm, to produce an anolyte and a catholyte liquid have been described in numerous publications, like US 5,635,040 and WO 98/13304, and respective electrolysis cells are commercially available.

Anolyte liquids have been used for numerous applications, including the use as an oxidizing agent, a purification agent, disinfectant, etc.

The prior art uses of anolyte compositions have been limited by a number of problems. First of all, the anolyte contains strong oxidizing agents, including chlorate, chlorine, chlorite and/or hypochlorite. While these oxidizing agents contribute to the antimicrobial activity of the anolyte, they also cause problems, as some of these agents, in particular chlorate, are toxic for humans. Due to the presence of strong oxidizing agents a respective anolyte can further not be mixed with organic oxidizing agents or surfactants, as these agents would be oxidized for example by chlorate.

Further, the anolyte is metastable or unstable, as the oxidizing activity of the anolyte is usually lost in a period between a few minutes and a few days.

There is thus a need to improve the stability of the electrolyte and at the same time to reduce the oxidizing agents harmful for humans. This problem is now solved by a process according to one of claims 1 to 10. The invention also relates to an anolyte solution according to claim 11 and 12, to the use of the anolyte according to claims 13 and 14, processes for the production of compositions comprising the anolyte according to claim 15 and respective compositions according to claim 16.

Accordingly, in a first aspect the present invention provides a process for producing an anolyte composition comprising the following steps:

(a) providing an aqueous solution comprising one or more alkaline earth or alkali metal chloride salts in a concentration of 0.2 to 25 g/1;

(b) passing the solution through an anode chamber of an electrolysis cell to obtain an anolyte;

(c) reducing the concentration of oxidizing agents in the anolyte .

In a second aspect a process for producing an anolyte composition is provided that comprises the following steps:

(b) passing the solution through a first cathode chamber to obtain a catholyte;

(c) passing at least part of the catholyte through a first anode chamber to obtain an anolyte having a pH between 6 and 8;

(d) reducing the concentration of oxidizing agents in the anolyte .

As used herein, the term "anolyte" refers to an aqueous liquid generated by electrolysis in the anode chamber of an electrolysis cell comprising separated anode and cathode chambers . In more general, the term "electrolysis" refers to a method using an electric current to initiate an otherwise non- spontaneous reaction. The term "electrolyte" refers to an aqueous solution obtained by electrolysis. An electrolyte may comprise free ions and/or free radicals generated by electrolysis. In the context of the present invention, the term electrolyte is also used to refer to an electrochemically activated water-based solution, such as a catholyte and more preferably anolyte solution obtained by an electrochemical treatment of water.

In step (a) of the process an aqueous solution comprising one or more alkaline earth or alkali metal chloride salts is provided. Preferably, the solution provided in step (a) comprises sodium chloride. The concentration of the one or more alkaline earth or alkali metal chloride salt(s), preferably the concentration of sodium chloride, in the solution provided in step (a) may range from about 2 to about 25 g/1, preferably from about 2.5 to about 18 g/1, more preferably from about 2.5 to about 6 g/1. It has surprisingly been found that even such low amounts of chloride salts are sufficient to yield effective electrolytes such as effective anolyte solutions having high activity. Due to the rather low amount of chlorides in the starting solution, even the obtained electrolytes such as anolytes are characterized by a low amount of chlorides such as less than 6 g/1, preferably less than 3 g/1, which in turn reduces the undesired corrosive properties of the obtained solutions.

Any one of the known methods for providing an aqueous solution comprising one or more alkaline earth or alkali metal chloride salts can be used in step (a) . According to a preferred embodiment water is simply mixed with the salt. It is particularly preferred to use demineralised or at least softened water, as calcium is known to block the pores of the membrane of an electrolysis cell.

According to the first aspect, the solution is passed through an anode chamber of an electrolysis cell to obtain an anolyte. Any electrolysis cell known in the art may be used for this purpose. For example, the solution of step (a) can be fed into the an anode chamber by a supply means such as a peristaltic pump. An electrical current is applied while the solution passes through the anode chamber. The solution leaving the anode chamber is referred to the anolyte.

The method of the first aspect of the present invention is further characterized in that the process comprises a step, wherein the concentration of the oxidizing agents in the anolyte is reduced. Any known method to reduce the concentration of oxidizing agents may be used for this purpose. For example, the concentration of oxidizing agents may be reduced by passing the anolyte through a filter for oxidizing agents, such as a charcoal filter.

In accordance with the second aspect, step (b) is characterized in that the solution is passed into at least one cathode chamber to obtain a catholyte solution. For example, the solution of step (a) is fed into the at least one cathode chamber by a supply means such as a peristaltic pump. An electrical current is applied while the solution passes through the cathode chamber. The solution leaving the at least one cathode chamber is referred to the catholyte.

Step (c) of the second aspect of the present invention comprises passing at least a part of the catholyte solution obtained in (b) into a first anode chamber to obtain an anolyte having a pH between 6 and 8. It is generally known that the pH of the anolyte can be controlled by the amount and pH of the catholyte solution fed into the anode chamber. In a preferred embodiment, the amount of catholyte and/or the pH of the catholyte fed into the anolyte chamber is controlled in such a manner pH of the anolyte is between 6.5 and 7.5.

In step (d) of the process of the second aspect of the present invention, the concentration of the oxidizing agents in the anolyte is reduced. Any known method to reduce the concentration of oxidizing agents may be used for this purpose. For example, the concentration of oxidizing agents may be reduced by passing the anolyte through a filter for oxidizing agents, such as a charcoal filter.

In a particularly preferred embodiment of the second aspect of the present invention, the process for producing an anolyte composition comprises a number of cathode and anode chambers connected hydraulically in series. The number of cathode chambers through which the solution is passed is preferably identical with the number of anode chambers used in step (c) . Accordingly the solution provided in step (a) may be passed through at least two cathode chambers connected in series and subsequently through at least two anode chambers also connected in series.

According to this embodiment, the solution provided in step (a) is serially is passed through 2 to 6 cathode chambers and subsequently serially through 2 to 6 anode chambers. The use of a series of 3, 4 or 5 cathode and anode chambers is particularly preferred.

Hence, an electrolyser comprising one or more electrochemical cells is provided, wherein each cell comprises a cathode chamber and an anode chamber. The cathode chamber and anode chamber are separated by at least one separator, such as diaphragm or membrane like a semi-permeable or ion-selective membrane, preferably a zirconium-aluminum ceramic membrane. Moreover, an electric current source for the electrodes of the anode and cathode chambers is provided.

Electrolytic cells for producing an electrolyte, and in particular for producing electrochemically activated water such as anolyte or catholyte, are known from e.g. US 5,635,040. Preferably, the at least one cathode chamber and at least one of the anode chambers cells used in the process according to the invention form an electrolytic cell comprising co-axial cylindrical and rod electrodes separated by the separator, such as a semi-permeable or ion-selective membrane like a zirconium-aluminum ceramic membrane. Preferably, the internal electrode is used as anode, while the external electrode is used as cathode.

In all embodiments of the present invention it is particularly preferred that the anode is in the form of a rod. While the rod may have borings or holes it should preferably not have a tubular form.

In one embodiment, the electrodes used in the present process, and in particular the electrodes of the first and at least second anode chambers, are made from a material which is selected from the group consisting of coated titanium, platinum, doped diamond, metal coated with doped-diamond and mixtures thereof. If the electrode is made from titanium, it is coated with an electrocatalytic active coating. In particular, the electrocatalytic coating can comprise ruthenium oxide, iridium oxide, platinum, platinum oxide or mixtures thereof. Suitable examples of doped diamond that can be used as a solid electrode or a coating material on other materials such as metals include boron-doped diamond. In another preferred embodiment, the material used as anode or anode coating depends on the position of the anode in the anode series. It is particularly preferred that an anode at the end of the anode series, such as the ultimate anode in the anode cascade, is substantially free of ruthenium and/or iridium oxide, but rather is made from platinum or titanium coated with platinum or platinum oxide.

In a further preferred embodiment of the processes of the second aspect of the invention, the catholyte solution obtained in step (b) is degassed prior to passing it into the first anode chamber in step (c) . Thus, gases such as hydrogen formed in the at least one cathode chamber are removed by common degassing means such as a commonly used gas separator.

According to step (d) of the processes of the second aspect of the present invention the concentration of the oxidizing agents is reduced. In particular, this process step is suitable to reduce the concentration of chlorate, chlorine, chlorite and/or hypochlorite.

It is preferred that this process step reduces the concentration of chlorate in the anolyte by at least 80%, preferably at least 90%, most preferably by at least 95%.

In a further aspect, the processes of all aspects of the present invention may comprise the addition of a carbonate, preferably calcium carbonate, to the anolyte obtained in step (c) or (d), i.e. after reducing the oxidizing agents. Respective processes for producing an anolyte are preferably characterized in that the anolyte obtained has an oxidizing power of between 100 ppm and 1800 ppm, preferably 500 ppm to 1500 ppm, more preferably 500 ppm to 900 ppm, free chlorine equivalents and that the carbonate, in particular the calcium carbonate, is added in a concentration in the range provided by the equation: C = F * 0, wherein C is the concentration of carbonate in mg/1, F is a coefficient ranging between 0.55 and 0.8, preferably between 0.6 and 0.75, and 0 is the oxidizing power in ppm free chlorine equivalents.

Determination of free chlorine equivalents is a method well known in the art and is generally used to characterize a solution containing different types of chlorine species by reference to the oxidizing power of chlorine.

Further, metal salts may be added to the anolyte compositions of all aspects of the present invention in liquid or solid form. The metal salt is preferably a metal sulfate. More preferably, the metal salt is selected from the group consisting of sodium sulfate, magnesium sulfate, aluminum sulfate, sodium carbonate, calcium carbonate and mixtures thereof .

Preferably, the metal salt is added to the anolyte solution in amounts suitable for stabilization of the anolyte. The amount of the metal salt in the anolyte solution obtained in step (d) generally ranges from 1 to 50 g/liter, preferably from 5 to 20 g/liter or from 7 to 15 g/liter.

Due to the step reducing the concentration oxidizing agents in the anolyte (step (c) of the first and (d) of the second aspect) of the processes for producing an anolyte according to the present invention, one can also add further oxidizing agents to the anolyte. Consequently, the present invention also relates to methods, wherein one or more organic oxidizing agents, such as chitosan, akacid, or the addition of organic surfactants, or of metal organic oxidizing agents are added to the anolyte obtained after the step of reducing the concentration of the oxidizing agents.

The most preferred additional oxidizing agent included in the processes and products of all aspects of the present invention is chitosan. Chitosan is a well known natural cationic polymer with anti-microbial activity. Chitosan and water soluble chitosan derivatives are known and can be used as oxidizing agents in the compositions, methods and uses of the present invention. In accordance with the present invention, the term "chitosan" is used to refer to chitosan as such as well as water soluble derivatives thereof. Water soluble chitosan derivatives are commercially available and include chitosan HC1, carboxymethylchitosan, chitosan lactate and/or chitosan acetate. Certain water soluble citosan derivatives are also listed in the European Pharmacopoeia as suitable for medical use. The use of water soluble chitosan derivatives in the processes and products of the present invention is particularly preferred.

However, not all of the compositions, methods and uses of the present invention require a water soluble cationic polymer as part of the oxidizing agent and consequently chitosan and water insoluble chitosan derivatives, such as chitosan glutamate may be used in these embodiments.

Moreover, the anolyte solution obtained by the process according to the invention is preferably characterized in that it has an oxidation-reduction potential (ORP) of about 250 mV to about 1500 mV, preferably 650 mV to about 1500 mV such as 650 mV to 1000 mV. The oxidation-reduction (or redox) potential can be determined using commercially available devices and standard conditions.

Without any limitation to a particular theory, it was surprisingly found that the anolyte obtained in the process of the present invention has an improved stability and activity and can therefore be stored for prolonged periods without suffering a substantial loss of activity such as biocidal activity. Further, the filtered anolyte can be mixed with further oxidizing agents.

In a further aspect the invention is also directed to a filtered anolyte composition, preferably having a pH between 6 and 8. The filtered anolyte composition is preferably obtainable by the processes according to the invention as described above. According to the most preferred aspect, the anolyte compositions of the present invention are characterized by a very low concentration of oxidizing agents harmful for humans, in particular by a low concentration of chlorate. The chlorate concentration in these anolyte compositions is preferably very low, such as below 2ppm, for example below lppm or below 0.5ppm or below 0.2ppm.

The anolyte compositions of the present invention are characterized by an antibacterial activity that is equal to or higher than a solution of chlorine in water in a concentration of at least 6ppm, preferably equal to or higher than a solution of chlorine in water in a concentration of at least lOppm, 20ppm or 50ppm. Depending on the intended use, the anolyte compositions of the present invention can be characterized by a high antibacterial activity equal to or higher than a solution of chlorine in water in a concentration of at least 300ppm.

In another aspect, the upper limit of the antibacterial activity of the anolyte compositions of the present invention is about equal to a solution of chlorine in water in a concentration of up to 500ppm or 600ppm, preferably

In a further aspect the invention also provides a filtered anolyte composition further comprising one or more of organic oxidizing agents, such as chitosan and/or akacid, organic surfactants, and/or metal organic oxidizing agents.

In a further aspect, the present invention provides electrolytes, such as anolyte, comprising further stabilizing compounds, including silicates. The silicates are preferably alkaline earth or alkali metal silicates and can be added in a concentration of 0.01 to 120 g/1 (dry weight of the alkaline earth or alkali metal silicates) . Respective silicates act as pH stabilizer and thus stabilize the above oxidizing agents.

According to another embodiment, the electrolyte like the anolyte solution of the invention may comprise zinc in the form of a salt, including zinc sulphate or zinc oxide.

The electrolyte solutions of the present invention can be used as a cleaning agent, a detergent, an oxidizing agent, a disinfection agent or a plant protecting agent. Consequently, the present invention also provides a cleaning agent, a detergent, an oxidizing agent, a disinfection agent or a plant protecting agent that comprises an electrolyte as described above .

In a related embodiment, the present invention provides the use of the anolytes, as described above as a cleaning agent, detergent, oxidizing agent, disinfection agent or plant protecting agent.

In particular, the anolytes can be used for the cleaning of surfaces in restaurants, hospitals, chemical production plants, production lines for the preparation of foods, beverages, animal feed and/or pharmaceutical or cosmetic production plants, etc. For example, the anolyte solutions of the present invention may be sprayed onto surfaces using techniques for spraying liquid compositions on surfaces that are generally available in the art. Accordingly, the present invention is also directed to a nebulizer containing the anolyte compositions of the present invention. The nebulizer can be used to generate a fine spray of the anolyte composition for the disinfection of surfaces or entire rooms.

In a related embodiment, the method of the present invention is carried out in such a manner that an anolyte is produced using process steps (a) to (c) outlined above and fed into the water lines of a house, for example a hospital, a restaurant, a slaughterhouse, a farm etc. Only those water lines that are subsequently used for human or animal consumption are fed by an anolyte composition that has additionally passed through process step (d) as described above.

According to a different embodiment, the anolyte compositions of the present invention are applied to plants as a plant protecting agent. Respective agents exert positive effects on plant growth due to their antimicrobial activity. The electrolytes like the anolyte solutions of the present invention further induce secondary plant metabolites due to a stress reaction of the plant. The metal salt can surprisingly support these effects and the agents of the present invention therefore causes improved plant protection. In this embodiment, the use of magnesium sulfate or zinc sulfate is preferred; the use of magnesium sulfate is particularly preferred .

In one aspect, the plant protection agent further comprises plant nutrients, including trace mineral salts, including salts of boron (B) , chlorine (CI), iron (Fe), zinc (Zn), copper (Cu) , molybdenum (Mo) , nickel (Ni) , selenium (Se) , and/or sodium (Na) .

Alternatively, the electrolytes, like the anolyte solutions of the present invention can directly be used for human or animal consumption or the preparation of pharmaceutical or cosmetic products and can be incorporated into respective products to be used for this purpose. The invention therefore also provides food, beverages, animal feed and pharmaceutical or cosmetic compositions comprising an electrolyte such as an anolyte solution as described above, as well as the use of the electrolytes for the preparation of these products. As used in the present application, the term pharmaceutical or cosmetic composition comprises orally applied forms (such as tablets, liquids), intramuscularly or intravenously applied forms (for example liquids) as well as topically applied forms (such as creams, gels, liquids, plaster) . According to a preferred aspect of the pharmaceutical use the electrolytes such as anolytes of the present invention are used for the treatment of wounds, including treatment of wounds by disinfection.

Accordingly, the present invention further provides processes for the production of a pharmaceutical or cosmetic composition, food, beverage, animal feed, mouthwash, nasal spray, inhalation aerosol, bath water, bath water additive, crushed ice, ice-cream, cleaning agent, detergent, oxidizing agent, disinfection agent or plant protecting agent comprising the production of an anolyte composition using the methods of the present invention described above.

Finally, the invention is also directed to apparatuses suitable for carrying out the process according to the invention .

In a preferred embodiment, the apparatus comprises a plurality of electrolytic cells as described above. Each electrolytic cell comprises a cathode chamber and an anode chamber. The cathode chamber and anode chamber are separated by a separator, such as a diaphragm or a membrane. Moreover, the apparatus comprises an electric current source for the electrodes of the anode and cathode chambers. The solution obtained in step (a) is passed through at least one cathode chamber. Then, the catholyte obtained passes at least partly from the at least one cathode chamber into an inlet of the first anode chamber. A further flow path can allow the remainder catholyte (if present) to flow to an outlet. In addition, it is preferred that the apparatus comprises a gas separator to remove the gas from the catholyte prior to passing it into the first anode chamber .

Claims

1. Process for producing an anolyte composition comprising the following steps:

(c) reducing the concentration of oxidizing agents in the anolyte .

2. Process for producing an anolyte composition comprising the following steps:

(b) passing the solution through a first cathode chamber to obtain a catholyte;

(d) reducing the concentration of oxidizing agents in the anolyte .

3. Process for producing an anolyte according to claim 1 or 2, wherein the aqueous solution comprises alkaline earth or alkali metal chloride salts in a concentration of 0.2 to 12 g/1 and serially is passed through 2 to 6 cathode chambers and subsequently serially through 2 to 6 anode chambers, and wherein the anode in at least one of the anode chambers is shaped in the form of a rod.

4. Process for producing an anolyte according to one of claims 1 to 3, wherein gas is removed from the part of the catholyte that is subsequently passed through the one or more anode chambers . Process for producing an anolyte according to one of claims 1 to 4, wherein the concentration of oxidizing agents in the anolyte is reduced by passing the anolyte through a filter, preferably an active charcoal filter.

Process for producing an anolyte according to one of claims 1 to 5, wherein the concentration of the oxidizing agent chlorate, chlorine, chlorite and/or hypochlorite is reduced in step (c) of claim 1 or step (d) of claim 2.

Process for producing an anolyte according to one of claims 1 to 6, wherein the concentration of chlorate in the anolyte is reduced in step (c) of claim 1 or step (d) of claim 2 by at least 80%, preferably at least 90%, most preferably by at least 95%.

Process for producing an anolyte according to one of claims 1 to 5, further comprising the addition of a carbonate, preferably calcium carbonate, to the anolyte obtained in step (c) of claim 1 or step (d) of claim 2.

Process for producing an anolyte according to any one of claims 1 to 8, wherein the anolyte obtained has an oxidizing power of between 500 ppm and 1500 ppm free chlorine equivalents and wherein the carbonate, in particular the calcium carbonate, is added in a concentration in the range provided by the equation: C = F * 0, wherein

C is the concentration of carbonate in mg/1,

F is a coefficient ranging between 0.55 and 0.8, preferably between 0.6 and 0.75, and

0 is the oxidizing power in ppm free chlorine equivalents.

Process for producing an anolyte according to any one of claims 1 to 9, further comprising the addition of one or more organic oxidizing agents, such as chitosan, akacid, or the addition of organic surfactants, or of metal organic oxidizing agents to the anolyte obtained in step (c) of claim 1 or (d) of claim 2.

11. An anolyte composition obtainable by a process according to any one of claims 1 to 10, wherein the anolyte preferably has a pH between 6 and 8.

12. An anolyte composition according to claim 11 further comprising one or more of organic oxidizing agents, such as chitosan and/or akacid, organic surfactants, and/or metal organic oxidizing agents.

13. Use of an anolyte composition according to claim 11 or 12 as a cleaning agent, detergent, oxidizing agent, disinfection agent or plant protecting agent.

14. Use of an anolyte composition according to claim 13 as a cleaning and disinfection agent for the cleaning of surfaces in restaurants, hospitals, chemical production plants, production plants for foods and beverages and pharmaceutical or cosmetic production plants.

15. Process for the production of a pharmaceutical or cosmetic composition, food, beverage, animal feed, mouthwash, nasal spray, inhalation aerosol, bath water, bath water additive, crushed ice, ice-cream, cleaning agent, detergent, oxidizing agent, disinfection agent or plant protecting agent comprising the production of an anolyte composition according to any one of claims claim 1 to 10.

16. Food, beverage, animal feed, pharmaceutical or cosmetic composition, mouthwash, nasal spray, inhalation aerosol, bath water, bath water additive, crushed ice, ice-cream, cleaning agent, detergent, oxidizing agent, disinfection agent or plant protecting agent comprising an anolyte composition according to claim 11 or 12.