Hydrogen peroxide solution
Field of the invention The present invention relates to a hydrogen peroxide solution of hydrogen peroxide in water with at least one stabilizer suitable as disinfectant and sterilizer. The invention further relates to a method for disinfecting products or spaces and diverse other applications, and to a method for preparing such a hydrogen peroxide solution.
Background of the invention The use of a hydrogen peroxide solution to disinfect or sterilize spaces or products, such as for instance in the food industry and packaging industry and in the field of pharmaceutical and cosmetic products, is sufficiently well known and for instance described in European patent application EP 1 043 273. It is always necessary here to use a stabilizer since a hydrogen peroxide solution deteriorates relatively quickly. Use has traditionally been made of glycerine, glycerol, silver nitrate and lactic acid as stabilizers. In EP 1 043 273 the present inventor has described that a polyalcohol, and mannitol in particular, gives reasonably good results, with a deterioration of 0.4% in 14 days. In US 5 658 595 reference is made to the use of glycerol as stabilizer in a hydrogen peroxide solution. However, the described solutions are not suitable for adding supplements or additives. In addition, some of the compounds used as stabilizer such as glycerine and glycerol may induce the formation of undesired residues. A hydrogen peroxide solution, particularly in concentrated form with an even greater stability, does however remain very desirable. In addition, a hydrogen peroxide solution, particularly in concentrated form, with greater stability and to which supplements or additives can be added is also highly desirable. The present invention therefore aims to provide an improved hydrogen peroxide solution which has a greater stability compared to other known solutions.
Summary of the invention In a first aspect, the present invention provides for a hydrogen peroxide solution of hydrogen peroxide in water with at least one stabilizer, suitable as disinfectant and sterilizer, characterized in that the solution comprises sorbitol, preferably D-sorbitol, as stabilizer. In a preferred embodiment the invention relates to a hydrogen peroxide solution of hydrogen peroxide in water with at least one stabilizer, suitable as disinfectant and
sterilizer, characterized in that the solution comprises 0.5 - 10 % by weight of sorbitol as stabilizer, and 10 - 50% by weight of hydrogen peroxide. In a particularly preferred embodiment, the solution is characterized in that is at least 99% homogeneous, and preferably at least 99.5% homogenous. In a second aspect, the present invention provides for a composition comprising a hydrogen peroxide solution according to the present invention, and preferably also and one or more contaminating substances. The present hydrogen peroxide solution can be applied in various ways. The solution can be applied as such, or in compositions according to the present invention wherein it is combined with nutrient supplements.
Detailed description of the invention Surprisingly, it has been found that applying sorbitol as stabilizer makes the hydrogen peroxide solution extremely homogeneous, whereby the hydrogen peroxide solution according to the invention has particular properties. The present invention therefore provides in a first aspect for an improved hydrogen peroxide solution. More in particular, the present invention relates to a hydrogen peroxide solution of hydrogen peroxide in water with at least one stabilizer, suitable as disinfectant and sterilizer, characterized in that the solution comprises sorbitol 0.5 - 10 % by weight of sorbitol as stabilizer, and 10 - 50% by weight of hydrogen peroxide. The present invention thus provides a hydrogen peroxide solution particularly in concentrated form. In a particular embodiment the hydrogen peroxide solution according to the present invention comprises 10 - 50% by weight of hydrogen peroxide, more in particular 35 - 50% by weight. The great advantage of such concentrated solutions with sorbitol is that after 100 days a deterioration of only about 0.4% occurs, i.e. 99.6% of the initial concentration of hydrogen peroxide is still present in the solution. Such a hydrogen peroxide solution in sorbitol is also designated BIOPROX™ in the name of Verfimport NV. As stabilizer the hydrogen peroxide solution in particular comprises sorbitol, more in particular D-sorbitol, also known as D-glucitol. More preferably D-sorbitol is applied with a non-toxic value and a purity of at least 98%, preferably of at least 98.5%. In a particularly preferred embodiment, the invention relates to a solution wherein sorbitol, and preferably D-sorbitol, is present in an amount of 0.5 - 10 % by weight or in an amount of 1-7.5 % by weight, or in amount of 3-5 % by weight. By using sorbitol as a stabilizer a wide application in the food industry and pharmaceutical industry hereby becomes possible. More in particular, in contrast to other known stabilizers such as glycerine, glycerol, mannitol, and the like, sorbitol has the important characteristic and advantage of
preventing the formation of undesired residues in the solution. Such residues could greatly disturb and impede the application of the solution (e.g. by clogging pipes, nozzles or the like). It becomes therefore easier to use the present solution under various application conditions, and the area and conditions under which the solution may be applied can be greatly increased. In accordance with the present invention, the obtained solution shows a greatly improved stability and homogeneity, and thus reduced deterioration in function of the time. More in particular, the present solution is characterized in that the solution is at least 99% homogeneous, preferably at least 99.5% homogeneous. As used herein the term "% homogenous solution" refers to a solution wherein the indicated % of the initial concentration of hydrogen peroxide is still present in the solution after 100 days. As used herein the terms "homogeneity" and "stability" may be considered as equivalents. This high degree of homogeneity makes it possible that contaminating substances can be added to the solution, a condition that was previously not possible, since a reaction with the hydrogen peroxide would have taken place. The present solution may easily be supplemented with different kind of contaminating substances. In this application contaminating substances are understood to mean substances which react with hydrogen peroxide, and in many cases react even violently with the atomic oxygen present in hydrogen peroxide while forming radicals. Examples of such substances are salts and esters of alkali metal and alkaline-earth metal ions, of acid radical ions such as halogenides in the ion form such as for instance chlorine, and other trace elements. Surprisingly, addition of these substances does not have adverse effects on the solutions' properties, and in particular does not change the solutions' homogeneity and stability. More preferably the homogeneous hydrogen peroxide solution further comprises at least one organic acid, for instance hexanoic acid, pentanoic acid, citric acid, lactic acid or glycol acid. An organic acid is particularly important if the solution is used in an environment above room temperature, and particularly in the tropics, and in addition also acts as a fungicide. In a particularly preferred embodiment, the invention relates to a solution wherein organic acid(s) is (are) present in an amount of 1-5 % by weight, and preferably in an amount of 1.5 - 3 % by weight. The stabilizer, and then sorbitol in particular, is preferably present in deficiency in the hydrogen peroxide solution, wherein the weight ratio of hydrogen peroxide and the stabilizer, in particular sorbitol, lies between 5:1 and 100:1 and preferably between 5:1 and 50:1 , and more preferably between 7:1 and 10:1.
The organic acid(s) is (are) preferably present in deficiency in the hydrogen peroxide solution, wherein the weight ratio of hydrogen peroxide and the organic acid(s) lies between 2:1 and 50:1 , more preferably between 5:1 and 20:1. According to a preferred embodiment, the weight ratio of the stabilizer, and then sorbitol in particular, and the organic acid(s) lies between 10:1 and 1 :10, more preferably between 5:1 and 1 :5 or between 1 :2 and 2: 1. In a particularly preferred embodiment, the present hydrogen peroxide solution has a pH value comprised between 1.5 and 4.5, and preferably between 2.0 and 4.0. In a preferred example, the pH of the solution is 3. In a preferred embodiment the invention further provides a composition containing a hydrogen peroxide solution according to the present invention. In another preferred embodiment the invention further provides a composition containing a hydrogen peroxide solution according to the present invention together with contaminating substances. In this application contaminating substances are understood to mean substances which react with hydrogen peroxide, and in many cases react even violently with the atomic oxygen present in hydrogen peroxide while forming radicals. Examples of such substances are salts and esters of alkali metal and alkaline-earth metal ions, of acid radical ions such as halogenides in the ion form such as for instance chlorine, and other trace elements. Salts of alkali metal and alkaline-earth metal ions such as potassium and calcium, as well as other trace elements such as silicon and selenium can serve as nutrient supplements. Therefore, in another embodiment, the present invention provides for a composition wherein the contaminating substances are nutrient supplements, and preferably nutrient supplements selected from the group comprising salts and esters of sodium, potassium and phosphate. According to a further aspect of the invention, there is provided a method for administering biocide and fertilizer to agricultural or horticultural products in one operation, wherein such a composition containing a hydrogen peroxide solution is applied together with contaminating substances. The present composition can also be applied as root and leaf feed. This is a particularly advantageous application of the stable hydrogen peroxide solution, wherein both biocide in the form of hydrogen peroxide and nutrient supplements such as sodium, potassium and phosphate can be administered simultaneously to agricultural or horticultural products in one operation. The use of standard chemicals in which the nutrient supplements are normally dissolved can be reduced by 15 - 20%, which is a great advantage not only economically but also ecologically. In a preferred embodiment, the composition according to the present invention which comprises the present hydrogen peroxide solution in combination with one or more nutrient supplements
is also designated FERTIFORT™ in the name of Verfimport NV. In addition, the present hydrogen peroxide solution is not phyto-toxic and may thus by directly applied to plants. According to yet another aspect of the invention the hydrogen peroxide solution according to the invention can be advantageously applied in a climate control and air- conditioning system, whereby the atmosphere in a space can be controlled. The present invention also provide for a climate control and air-conditioning system comprising a hydrogen peroxide solution according to the present invention. The present invention also provides for an atomizing system comprising a hydrogen peroxide solution according to the present invention. The present invention further provides for a method for controlling the atmosphere in a space characterized in that a climate control and air-conditioning system according to the present invention is applied. According to yet another aspect of the invention there is provided a method for disinfecting products or spaces, wherein a hydrogen peroxide solution according to the invention is applied. The solution can be applied particularly advantageously in the removal of the so-called biofilm, a layer of fat in for instance pipes which remains after the transport of water or aqueous solutions through the pipes in question, or on the inside of a car window, where a biofilm layer builds up gradually due to the air circulation. The legionella infection, which is dangerous to humans, is also countered by removing the biofilm. Reduced biofilm formation is here also a significant extra advantage in the above mentioned feeding of crops by means of a homogeneous hydrogen peroxide solution together with nutrient supplements via capillary tubes. This is a great improvement relative to the traditionally applied stabilizer glycerine, which in the presence of lipids results in blockage of the capillary tubes. The solution according to the invention can also be advantageously applied in the disinfection of swimming water as a substitute for the much used chlorine, which is of particular significance for swimmers with bronchial disorders. The hydrogen peroxide solution can also be advantageously applied in the protection and storage of foodstuffs due to the strongly reduced effect on pathogen formation of harmful microorganisms. Reductions have been measured here from a pathogen count higher than 1000000 reduced to a pathogen count lower than 3000 to 4000. The hydrogen peroxide solution according to the invention can further be used as a disinfecting shower after work in for instance the cattle farming sector. The stable and non-toxic homogeneous hydrogen peroxide solution preferably having sorbitol as stabilizer can also be advantageously applied according to the invention in the field of personal hygiene, such as for instance in oral and skin care, in the treatment of wounds which do not close easily or warts, and in deodorants. The application of this
hydrogen peroxide solution in the total medical sector, such as in disinfecting of operating equipment and the like, can also be envisaged. The application of the hydrogen peroxide solution according to the invention in keeping clean equipment wherein foodstuffs are processed, cleaned, packaged and stored, such as processing machines, refrigerators, freezers, bread bins and the like, also falls within the scope of the invention. According to another aspect of the invention, there is provided a method for removing ammonia from animal manure, wherein a hydrogen peroxide solution according to the present invention is applied. In this manner ammonia can be completely removed. Also in this application, the above described problem of clogging of capillaries, atomizers and piping systems can be avoided. This problem occurs when traditionally glycerine is used as stabilizer, since in the presence of lipids which are found in the plant-like substances in manure glycerine can induce clogging. The most important fields of application are formed by the atomizing of a small quantity of the solution over chicken and pig manure, wherein the released ammonia gas is converted into ammonium salt. If the ventilation in a poultry farm fails, it will be possible to prevent the mass death of the chickens, which occurs within 5 minutes, by applying the hydrogen peroxide solution in atomized form. According to another important aspect of the invention, there is provided a method for removing water from aqueous sludge, wherein a hydrogen peroxide solution according to the present invention is applied. The removal of water from sewage sludge is important for the storage of sludge, wherein separation is arranged between the aqueous phase and the solids in this same sludge. The hydrogen peroxide solution according to the invention breaks the binding between the aqueous phase and the solids usually bound by polymers. The degree of water removal which can be achieved is related to the type of sludge. Finally, as special application, the use can be mentioned of the hydrogen peroxide solution according to the invention in separating techniques, for instance of animal manure, wherein particles floating in a liquid medium are expelled and chemically converted into other elements. For this purpose the solution is mixed with the animal manure, whereafter the mixture undergoes a further treatment and is carried along a set of electrodes, wherein in addition to the separations a large stream of gas bubbles is also produced at the electrodes by electrochemistry. The invention also provides a method for preparing a hydrogen peroxide solution according to the invention, wherein the stabilizer is mixed with the hydrogen peroxide solution in a mixer, wherein the height is greater than the diameter, with an extracting means in the top of the mixer and an outlet to the outside.
An example of safe manufacture of the hydrogen peroxide solution takes place in a round mixer which is provided with a propeller mixing gear with a maximum rotational speed of 900 rotations/min. The ratio of the mixer (height : diameter) must be 2:1. At said height there results a heat of reaction of a maximum of 1 DEG C. It is recommended to make a mixing tank no larger than 1250 litres. The outlets are preferably all provided with a static, stainless steel mixer of a minimum of 3 revolutions. The use of ball valves is recommended in respect of the low turbulence of these valves. In the top of the mixer an extracting means must preferably be placed with an outlet outside the mixing area. To prevent unintended and unexpected reactions, it is necessary to provide the mixer with a stainless steel annular conduit which is connected to a storage tank filled with an iron compound, for instance an iron chelate. Such a reaction can be weakened by adding iron chelate when the reaction occurs. It will be apparent that the solution has a very wide field of application, which is in fact only possible due to the prolonged action of the solution according to the invention. If the action were less sustained, treatment would have to be carried out repeatedly with short intervals, or new solutions would have to be introduced repeatedly into a system. Preferably taken as starting point for the solution according to the invention is a stabilized 50% solution of hydrogen peroxide, at least almost pure sorbitol and one or more organic acids. As already stated above, the action of the hydrogen peroxide solution can be further improved by adding an organic acid to the solution, which will preferably be in a quantity of 1-5% by weight of organic acid. When the hydrogen peroxide solution is atomized or sprayed, the organic acid can for instance be pentanoic acid, hexanoic acid or glycol acid, wherein a solution according to the invention with glycol acid will be used mainly to preserve diverse foodstuffs. Such a solution destroys all possible contaminants, germs, fungi, bacteria by combustion without adding its own odour or taste to the product and also without discoloring the product. In the application as nutriment for plants in a combination with nutrient supplements, atomizing is the appropriate method because of the danger of undesired reactions when droplets of hydrogen peroxide solution are exposed to sunlight. The present invention also relates to the use of a hydrogen peroxide solution according to the present invention for disinfecting products or spaces; for removing ammonia from animal manure; for removing water from aqueous sludge; and/or for controlling the atmosphere in a space. In another embodiment, the invention further relates to the use of a hydrogen peroxide solution and/or a composition according to the present invention for administering biocide and fertilizer to agricultural or horticultural products.
In yet another embodiment the invention further relates to the use of a hydrogen peroxide solution and/or a composition according to the present invention for treating and killing algae or the like (e.g. cyanobacteria), which may be free-living, or attached to a surface (e.g. boats or the like). In such context a hydrogen peroxide solution and/or a composition according to the present invention may be used in a method for cleaning surfaces which are contaminated with algae or the like.
Examples
Example 1: Comparison of different stabilizers in hydrogen peroxide solutions The wide utility of the hydrogen peroxide solution according to the invention is clearly shown when the application of the stabilizer sorbitol, with which hydrogen peroxide forms a homogeneous solution, is compared to the application of other stabilizers, see the table 1 appended below.
Table 1
Example 2: Application of a hydrogen peroxide solution according to the present invention in swimming pools The applicant has demonstrated that a solution according to the present invention can advantageously applied be for the disinfection of swimming water. When applying a hydrogen peroxide solution according to the present invention in the swimming water, it was possible to reduce the number of (potentially harmful) microorganisms, such as for instance Pseudomonas aeruginosa, in the water.
Example 3: Examples of suitable in hydrogen peroxide solutions according to the present invention are provided in Table 2
Table 2
It will be apparent to the skilled person that the inventive concept allows a wide application of the homogeneous hydrogen peroxide solution as described here, and is certainly not limited to the examples given in this description.