The present invention relates to compositions comprising an anolyte and a carbonate, methods of making the same and the use of respective compositions as an oxidizing agent, a purification agent, disinfectant, etc.

Electrolysis of aqueous liquids comprising one or more alkaline earth or alkali metal chloride salts, usually sodium chloride, carried out in electrolysis cells containing a separation between anode and cathode, such as a diaphragma, to produce an anolyte and a catholyte liquid have been described in numerous publications 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 have been limited by the fact that the anolyte is not stable in aqueous liquids. There is thus a need to improve the stability of the anolyte.

This problem is now solved by the present invention, which provides compositions comprising anolyte and a carbonate.

In accordance with the present invention the term "anolyte" is used to refer to an aqueous liquid generated by electrolysis in the anode chamber of an electrolysis cell comprising separated anode and cathode chambers, wherein at least the anode chamber is fed with an aqueous liquid comprising one or more alkaline earth or alkali metal chloride salt, preferably sodium chloride or potassium chloride. The compositions of the present invention comprising an anolyte are generally further characterized by a redox potential of more than 400mV, more preferably more than 500mV, 600mV or more than 500mV. In a particularly preferred embodiment the redox potential of the composition ranges between 500 and 1500 mV.

The oxidation-reduction (or redox) potential can be determined using commercially available devices and standard conditions, in particular by measuring the potential difference of the composition relative to a reference electrode like the standard calomel electrode (SCE) .

When sodium chloride or potassium chloride is introduced into the anolyte chamber, the electrolysis will generate hypochlorous acid as an oxidizing agent. Depending on the electrolysis cell, further oxidizing agents may be generated, including ozone and other chlorine species. However, all of these oxidizing agents are metastable in the anolyte and will decay upon storage.

The oxidizing power of the oxidizing agents in the compositions of the present invention is preferably determined as free chlorine equivalents in ppm. The free chlorine equivalents may for example be determined by iodometry, also known as iodometric titration, wherein free iodine is titrated against a standard reducing agent such as sodium thiosulfate solution. The compositions of the present invention preferably have an oxidizing power between 500 and 1500 ppm of free chlorine equivalents.

Depending on the electrolysis cell, the anolyte may further have a pH that ranges between strongly acidic and neutral. The use of electrolysis cells capable of producing neutral anolyte, i.e. anolyte with a pH of 5.5 to 7.5, is preferred. As a consequence, the compositions of the present invention also preferably have a pH of 5.5 to 7.5.

The anolyte can be produced according to any one of the different methods available in the prior art for generating anolytes .

In accordance with the present invention the term "carbonate" is used to refer to a salt of carbonic acid, characterized by the presence of the carbonate ion, C03 ^~2 . The term carbonate in particular includes bicarbonates . In the compositions and methods of the present invention any carbonate may be used that will produce carbonate ions in aqueous liquids. However, the use of metal carbonates is preferred and the use of alkaline earth or alkali metal carbonates. The use of calcium carbonate is most preferred in the compositions and methods of the present invention.

The carbonate concentration of the compositions of the invention may for example range from 300 to 1200 mg/1, preferably from 400 to 1200 mg/1 and most preferably from 450 to 1000 mg/1. The concentration is provided as a final concentration in the composition and in relation to the carbonate compound added, for example the compositions of the present invention contain 300 to 1200 mg/1 of anhydrous calcium carbonate.

Without any limitation to a particular theory it was surprisingly found that the carbonates present in the compositions of the invention stabilize the oxidizing agents of the anolyte. The compositions are stabilized in the sense that the presence of the carbonate significantly reduces the decay of oxidizing agents in the anolyte. However, the compositions of the present invention are not stable in the sense that there is no decay of oxidizing agents at all in the anolyte .

In a preferred embodiment of the present invention the carbonate concentration in the composition is optimized in relation to the oxidizing power of the anolyte. The present inventors have surprisingly found that the stabilizing effect of carbonate, in particular of the calcium carbonate, can be optimized for anolytes that differ in their oxidizing power. The optimum concentration of the carbonate can be calculated on the basis of the equation:

C = F * 0, wherein

C is the concentration of carbonate in mg/1 as defined above (in particular the concentration of anhydrous calcium carbonate) ,

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.

For example, the present inventors have determined that optimal stability of oxidizing agents in the anolyte can be achieved with compositions comprising:

• 300 mg/1 calcium carbonate, if the oxidizing power is 500 ppm free chlorine equivalents;

• 500 mg/1 calcium carbonate, if the oxidizing power is 800 ppm free chlorine equivalents;

• 700 mg/1 calcium carbonate, if the oxidizing power is 1000 ppm free chlorine equivalents.

The carbonate is added to the anolyte after the electrolysis. In a preferred embodiment the present invention provides a method for preparing compositions of the present invention as described above, wherein calcium carbonate and/or sodium carbonate is added to the anolyte to reach a final concentration of 300 to 1200 mg/1 of calcium carbonate and/or sodium carbonate in the composition. The methods of the present invention are also characterized by the features used to characterize the compositions above.

In a related embodiment the aqueous liquid comprising one or more alkaline earth or alkali metal chloride salt (preferably sodium chloride or potassium chloride) used to produce the anolyte in the electrolysis cell is produced by dissolving respective alkaline earth or alkali metal chloride salts in softened water before electrolysis. In particular electrolysis is carried out with aqueous liquids comprising less than 50 mg/1 calcium carbonate, preferably less than 10 mg/1 or less than 0.1 mg/1 calcium carbonate. In the most preferred embodiment the liquid used to generate the anolyte does not contain any calcium carbonate and the calcium carbonate is added after the anolyte has been produced in the electrolysis cell .

The carbonate may be added in liquid or solid form.

The compositions of the present invention may further comprise other compounds, including further oxidizing agents, stabilizers, detergents etc.

In a preferred embodiment the compositions of the present invention further comprises other oxidizing agents, in particular chlorine dioxide or hydrogen peroxide.

In a further aspect, the present invention provides compositions 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 compositions of the invention may comprise zinc.

The compositions 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 a composition as described above .

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

In particular, the compositions 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 production plants, etc. For example, the compositions of the present invention may be sprayed onto surfaces using techniques for spraying liquid compositions on surfaces that are generally available in the art.

According to a different embodiment, the compositions of the present invention are applied to plants as a plant protecting agent. Respective agents exert positive effects on plant growth due to antimicrobial activity of the anolyte. If used as a plant protecting agent, the anolyte is preferably optimized, as a very high redox potentials or strongly acidic anolytes could be detrimental for the plant. The plant protection agent therefore preferably has a pH of more than 5.

Alternatively, the compositions of the present invention can directly be used for human or animal consumption or the preparation of pharmaceutical products and can be incorporated into respective products to be used for this purpose. In this embodiment, the compositions comprising an anolyte and a carbonate are used for the preparation of food, beverages, animal feed or pharmaceutical compositions. The invention therefore also provides food, beverages, animal feed and pharmaceutical compositions comprising a composition as described above, as well as the use of the compositions for the preparation of these products. As used in the present application, the term pharmaceutical 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 compositions of the present invention are used for the treatment of wounds, including treatment of wounds by disinfection.

If used for human or animal consumption, the compositions of the invention will not contain any compounds that are unsuitable for this purpose, such as chlorine dioxide or other strong oxidizing agents.