Method for producing a modified aqueous chlorite solution, solution produced thereby and utilization thereof

0001Title: Process for the preparation of a modified aqueous chlorite solution, the solution prepared thereafter and the use thereof

0002Technical field

0003The invention relates to a process for the preparation of a stabilized, modified aqueous chlorite solution containing a peroxy compound, the chlorite solution obtained by this process and the various possible uses thereof as a biocide.

0004Underlying state of the art Modified aqueous chlorite solutions, in particular also aqueous sodium chlorite solutions stabilized by means of peroxy compounds, find diverse uses in technology as well as in other areas, for example for oxidative purposes. Solutions of this type are used, inter alia, for the treatment of water for drinking water purposes and for swimming pool water and also for process water for decontamination. Their stability is in need of improvement. There has therefore been no lack of attempts to remedy this deficiency. It is generally known to use alkaline stabilizers, such as sodium carbonate, and hydrogen peroxide and inorganic compounds derived therefrom, such as perborates.

0005Furthermore, it is known that aqueous chlorite solutions in which chlorine dioxide is in equilibrium with chloric acid in the acidic range can be stabilized by means of pyridine (cf. Holleman / Wiber "Textbook of inorganic chemistry", 47th-56th ed., 1960, p. 127). The stabilized chlorite solution produced in this way is also not sufficiently stable. In addition, pyridine-stabilized chlorite solutions cannot be used in systems in which an additional exposure to organic substance must be avoided, such as in the field of drinking water and swimming pool water treatment. Among other things, pyridine is a carcinogenic substance.

0006Stabilized or non-stabilized chlorite solutions play a special role in the treatment of swimming pool water. Conventional, also stabilized

0007Chlorite solutions have to go through an acidic reaction route at a pH value - 3 in such a "chlorine / chlorine dioxide process". For this purpose, separate apparatuses which are not directly integrated into the water cycle are mandatory. This applies both to the acid process and to the subchloric acid process, which are subordinate to the chlorine / chlorine dioxide process mentioned above. If sodium chlorite and hydrochloric acid are used here, then sodium chloride and chlorine dioxide are formed from sodium chlorite and hydrochloric acid by this so-called hydrochloric acid process at the pH mentioned above. For this reaction, reaction towers with Raschig rings of a size are recommended that guarantee an appropriate reaction time in order to achieve the highest possible conversion rate. This is also intended to ensure that the residual chlorite content in the swimming pool water is as low as possible when the reaction product is introduced, in particular not more than 0.1 mg / l. In order to prevent redisportionation to chlorite chlorate, the ratios of chlorine to chlorine dioxide are prescribed at 10: 1 in swimming pool water. In the hypochlorous acid processes mentioned, the reactions now proceed as follows: for example, a sodium chlorite solution and chlorine are metered into a water container upstream of the water disinfection. A reaction then takes place at a pH of ■ £ .3^'stage hypochlorous acid and ultimately chlorine dioxide is formed. The solution prepared in this way is then metered into the pool water as required.

0008In the two processes described above (acid process and hypochlorous acid process), a high additional outlay on equipment is required and, moreover, it must be constantly ensured that the hydrochloric acid supply and the hypochlorous acid process in the acid process Chlorine supply is absolutely guaranteed in order to avoid disadvantageous addition of unreacted chlorite into the pool water. However, since occasional defects cannot be ruled out with certainty, this is always a source of danger for the bathing guest. In addition, the accidental mixing of the commercially available chlorite solutions with acids can lead to explosion-like phenomena. Disclosure of the invention

0009The invention was therefore based on the object of improving the process described at the outset in such a way that a more stable process product can be produced which can be used safely and with greater efficiency for the treatment of water, in particular swimming pool water, and furthermore have other possible uses is accessible.

0010According to the invention, this object is achieved in that a weakly acidic aqueous solution of a largely stable peroxy compound is given and an aqueous solution of chlorite is metered in until the pH value of 7 forms a greenish solution is exceeded.

0011For the purposes of the invention, peroxy compounds are therefore used to stabilize the chlorite in the aqueous solution, which stabilize the oxidation system based on the chlorite for a long time while maintaining the desired oxidative activity. The term "peroxy compounds", which is to be understood as far as possible, includes hydrogen peroxide (HO ») and derivatives of hydrogen peroxide, in particular peroxy compounds (preferably in the form of inorganic compounds) which contain the ion 0 ~ 2- as

0012Contain ligand, or in which - O - is replaced by - O - 0—, peroxides and peracids and their salts. The peroxy compounds include, in particular, inorganic peroxyacids and their salts. Perborates, percarbonates and persulfates are preferably used here. The peracids that come into question according to the invention include not only the peroxy acids already mentioned, but also oxo acids of the perchloric acid type, including their salts. The salts described are preferably alkali and alkaline earth salts, with the corresponding sodium, potassium and calcium compounds being in the foreground. Stabilization by peroxides is preferably carried out by sodium or barium peroxide.

0013In the event that the stabilized modified chlorite solution is used in systems in which additionally introduced organic substances are harmless, the above peroxy compounds can also be organic in nature; Within the framework of the teaching given, however, the person skilled in the art will be able to determine further stabilizing peroxy compounds which are suitable for the purposes of the invention. In doing so, he will also be able to easily determine the appropriate concentration of the stabilizing peroxy compound. It must^' it is surprising that preferably relatively low concentrations of peroxy compound are sufficient for the purposes according to the invention and lead to particularly favorable effects when the stabilized product is used. This applies in particular to a 0.001 to 0.01 molar concentration of the peroxy compound in the greenish finished solution. Depending on the particular aqueous system, the selected starting materials and the area of ​​application, this range can of course be exceeded or undershot, for example by one decimal place. Higher concentrations regularly bring no advantages with regard to the objective of the invention and frequently exclude the desired effects or do not allow them to be achieved to the desired extent.

0014The small amount of stabilizing peroxy compound for the essence of the invention also means practically no additional cost.

0015A suitable stabilizing peroxy compound is converted into a weakly acidic solution in the process according to the invention. This solution preferably has a pH value of 3 3, a pH value of * s 1 1 being particularly advantageous. With the latter value, not only is optimal process control carried out, but a particularly stabilized product is obtained. Acidification can be carried out using mineral acids, such as hydrochloric acid, sulfuric acid etc., but also by adding hydrogen compounds, ie acidic organic salts, in particular alkali metal or alkaline earth metal salts, or in the form of a combination of the above compounds. Sodium, potassium and

0016Calcium salts are preferred, especially in the form of their hydrogen sulfates. When selecting the acidifying compounds, the later application of the product according to the invention should also be taken into account. In general, it is of particular advantage if the acidification is carried out using sulfuric acid. It has been shown in the fields of use of the agent according to the invention, which are described in detail later, that when sulfate ions are present, the

0017Effects are obviously very cheap. This can also be done, for example, by adding a sulfate and acidifying with another acid. In principle, hydrochloric acid can also be used. - Here-r

0018However, OMP1 at opposes the use of

0019Sulfuric acid has a certain disadvantage in that, in spite of the described interaction with chlorite, excessive amounts of chloride give rise to chlorine dioxide prematurely and not only when necessary, which then disrupts the desired equilibrium system with outgassing and thus through the removal of chlorine dioxide. This leads to an undesirable weakening of the system in the sense of the invention.

0020An aqueous chlorite solution is metered into the weakly acidic aqueous solution of the peroxy compound, the concentration of which does not play a decisive role. In particular, it can be a commercially available aqueous alkali and / or alkaline earth metal chlorite solution, in particular a sodium and / or calcium chlorite solution. The pH value of the commercially available alkali chlorite solution is generally above 12. Solutions of this type regularly contain about 300 g / l. It goes without saying that the .or value can also be fallen below. Since, according to the invention, a highly concentrated stabilized and modified chlorite solution is regularly sought, a strong, concentrated chlorite solution will of course also be used as the starting material. The starting chlorite solution is preferably metered in with stirring until the initially partially gassing dark brown solution has assumed a greenish-yellow or greenish color. This is usually the case when the pH is above 7. A pH of about 7 to 8, in particular 7.5 to 8, is preferred here.

0021Surprisingly, it has been found that the amount of peroxy compound can be drastically reduced in the process according to the invention if a small amount of a water-soluble phosphate, for example sodium metapolyphosphate, is incorporated into the finished solution.

0022An excessive reaction can occur in the process according to the invention in the form of explosive phenomena when the aqueous starting solutions used only have a low carbonate hardness or when it is demineralized water. In such a case, it is advisable to work under an inert gas atmosphere. It is preferred to add a generally sufficient small amount of a bicarbonate, for example sodium bicarbonate, to the acidic aqueous solution before metering in the chlorite solution. In the case of aqueous starting solutions of medium or high carbonate hardness, such a measure is generally not necessary, since a kind of protective gas layer made of carbon dioxide is formed between slightly emitting chlorine dioxide and the air. This means that no explosive air / chlorine dioxide mixture can arise. With a ratio of the components of air to chlorine dioxide of about 10: 1, such a mixture tends to explode the chlorine dioxide into chlorine and oxygen.

0023The stabilized modified chlorite solution according to the invention shows an extraordinarily favorable storage time of several months without the desired oxidative effect being significant. is reduced. After some time, a yellow-brown color appears due to the proportionally released chlorine dioxide, but this does not significantly impair the desired effectiveness. "If you remove the dissolved chlorine dioxide content from this aqueous solution, for example by shaking with carbon tetrachloride, then after a short time the greenish color of the clear aqueous solution mentioned reappears. This is to be interpreted as meaning that the chlorite solution always imitates chlorine dioxide when it is withdrawn in the sense of an equilibrium reaction. This replication occurs even in great dilution, for example even if the chlorine dioxide formed has consumed its oxidative effect due to the influence of reducing substances, * especially organic substances.

0024In contrast to the conventional chlorite solutions of the prior art, the stabilized modified chlorite solution according to the invention has a positive redox potential of between about 450 to 500 mV, depending on the exposure to light. For the later mode of action and for the areas of activity described in more detail below, it is essential that a stabilizing effect is achieved with the smallest possible and controllable Mengo r.-eroxy compound. Since the stabilizing effect of peroxy compounds against chlorine dioxide or chlorite solutions is strongly pH-dependent, a relatively large amount of peroxy compound must be added to an acidic chlorine dioxide solution to be stabilized according to the known procedure. The same applies to stabilization in the alkaline range. Here even large excess amounts of peroxy compound have to be added due to the fact that this decomposes strongly in the alkaline range. After the pH reduction, it is no longer possible to determine how much peroxy is still present in the finished solution. In principle, however, larger proportions of peroxy compounds interfere with the later use of the two chlorite solutions described last and to be attributed to the prior art to an unacceptable degree in the fields of application already described. On the other hand, a chlorite solution should be adjusted as pH-neutral as possible in certain fields of application, which is not the case for the solutions described above and manufactured according to the prior art, in contrast to the chlorite solution according to the invention, their technological

0025Background should be made even clearer by the following explanations with regard to the described prior art.

0026In the method according to the invention, for example, the procedure is as follows: a predetermined acidic (in particular sulfuric acid) solution, the pH of which is preferred<img file="WO8403274A1_D0001.tif" /> 1, a very small amount of peroxy compound is added so that a concentration of ^β-r-wa sets 0.0022 mol peroxy compound. This finished solution contains about 100 g of chlorine dioxide per 1. In order to stabilize such an amount of chlorine dioxide with the smallest possible amounts of peroxy compound in the pH range from 7 to 8, the procedure is as follows: about 200 l of tap water with a carbonate hardness of 18 about 6 kg of a pearlized sodium hydrogen sulfate are incorporated with stirring. About 100 ml of a 30% H_0_ solution are added to this solution. After stirring for about 10 minutes, this reading was fed with 200 liters of an approximately 30% sodium chlorite solution for about 10 minutes until the neutral point was reached. In the still highly acidic phase, the small amount of peroxy compound is sufficient to keep the still small amount of chlorine dioxide stable. Since the stabilizing character of the peroxy compound with respect to chlorine dioxide increases with increasing pK value, the processes run cleanly in accordance with a self-regulating equivalent in this procedure. In addition, a complex connection of the chlorine dioxide may arise, in which the peroxy compound does not intervene in the chemical reaction mechanism as in other known processes (such as, for example, according to the equation 2 CIO + 2 HO

0027+ H₂0₂ - ^ 2 CIO ~ + 2 H-0 + 0₂). When a pH of approximately 7 is reached, the previously dark brown solution changes its color to lime green. This solution has an oxidation potential of approximately 300 mV. If this solution is exposed to direct or indirect daylight for about 24 hours, a so-called kick reaction takes place after a certain time. The solution then takes on a golden yellow color. This is simultaneously connected to a potential jump to approximately + 450 to 550 mV.

0028If the solution prepared in the manner described above is treated with carbon tetrachloride, the proportion of free chlorine dioxide is then shaken out. This means that the free chlorine dioxide changes to the carbon tetrachloride phase with a yellow color. The aqueous phase is light. However, after a short time it can be observed that chlorine dioxide is again added in the remaining aqueous phase (yellow color). This process can be repeated until the aqueous phase is exhausted. If the stabilized chlorite solution according to the invention is poured into warm water, then in addition to the typical chlorine-like smell, there is also a slight smell of ozone. If the reading according to the invention is greatly diluted with water, the equilibrium present in it shifts in the direction of the chlorine dioxide, which also applies in the pH range from about 7 to 8.5.

0029If the modified chlorite aqueous solution stabilized according to the invention is used in practice, then the desired effect of the neutral or weakly alkaline solution occurs through acidification or under the action of any reaction partner, for example chlorine, which releases chlorine dioxide which is released under normal conditions represents a yellowish-reddish gas. Due to the presence of chlorine, especially in the case of an increased chloride content, or mineral acids in a treated aqueous system, the reaction of chlorine dioxide formation takes place primarily over the undesired chlorate. The desired course of the reaction is no longer disturbed, even when strong mineral acids are added in high concentration, unlike the known chlorite solutions. The latter, under the action of strong mineral acids, continue to exhibit the explosive phenomena already mentioned.

0030On the other hand, there are also cases in which the chlorite solution according to the invention is subject to de-stabilization in that there is a reaction partner in the system to be treated for the perox compound present in small amounts, which reduces this and thus abolishes the stabilization of the chlorite solution. Such a reaction partner can be, for example, the peroxidases and catalases present in various germ cells, ie to enzymes of the plant and animal metabolism, which are used for

0031^ .Z he ​​group of peroxidoreductases belong. By their

0032Exposure to chlorine dioxide is released. This fact gives the stabilized, modified chlorite solution in biocidal use

0033, low dosing quantities high selectivity.

0034The chlorite solution according to the invention, in particular in the form of a sodium chlorite solution, can be used with particular advantage in water treatment. The focus here is on the treatment of drinking water, process water and swimming pool water for disinfection purposes. This disinfestation is preferably carried out with simultaneous use of chlorine, so that the chlorine dioxide which is very effective for the de-icing purposes is produced. For the preparation of the chlorite solution according to the invention, for example, a sodium chlorite solution with about 300 g of sodium chlorite per liter is used. The finished solution generally contains the equivalent of 8 to 15% by weight of chlorine dioxide, the range from 10 to 12% by weight being regularly of particular advantage from the various points of view. Various other constituents can also be added to this solution, such as sodium chloride, sodium sulfate and sodium chlorate. The sodium chlorite solution according to the invention can be adjusted by dilution in such a way that it complies with the KOK (coordination group for pool construction and pool operation) guidelines, a residual chlorite content in the pool water being set at a maximum of 0.3 πng / 1 pool water. But then it also complies with DIN draft -19643 with a maximum of 0.1 mg / 1. The above statements also apply to other chlorite solutions, such as other alkali and alkaline earth chlorite solutions.

0035The chlorite solution according to the invention is of particular value in the treatment of whirlpool bath water, which will be discussed in detail below: _.^ ΛJOX 'r W ^OMIP^PO^I. . First of all, it should be emphasized that the explosion-like phenomena occurring in the known processes described at the outset are excluded if the chlorite solution according to the invention is used. Even when mixed with concentrated sulfuric acid, it cannot be caused to explode. Their special suitability for the treatment or conditioning of swimming pool water has been verified by an expert report from the Hyσieninstitut / Gelsenkirchen. A proof of equivalence showed that the solution according to the invention behaves completely differently from commercially available or otherwise stabilized chlorite solutions. In the experiment of the Hygiene Institute, the solution according to the invention was dosed directly into the pool water circuit (a pH value of 7.5) by means of a fine metering pump via an inoculation point between the flocculation vaccination point and the filter. Chlorine dioxide was detected in all water samples taken, but not the chlorite (CIO-) to be avoided. In this context, it is also important to note that even the smallest amounts of peroxy compounds in chlorinated pool water have a disruptive effect. Peroxides take on reductive character compared to the strong oxidizing agents, such as chlorine. They therefore significantly depress the oxidation potential, which plays an essential role in swimming pool water as a parameter for the speed of germ killing. Last but not least, the addition of disinfectant in many swimming pools is controlled automatically using these parameters. In the event of an artificial change (reduction) in the oxidation potential, multiple quantities, for example of chlorine, would get into the bathing water in an uncontrolled manner. This risk is largely eliminated by the use of the chlorite solution according to the invention. The micron phenomena of peroxy compounds introduced into the pelvic circulation are of a magnitude that can just be eliminated by peroxidase occurring, for example, from finely divided metal impurities on the filter or in some germs. The chlorine dioxide released spontaneously in this way selectively in contaminated and contaminated filter material causes additional phenomena which do not take place comparatively in conventional chlorine / chlorine dioxide processes.

0036Furthermore, it was shown in the aforementioned proof of equivalency that the period between the necessary filter backwashes resulting from differential pressure doubled or the amount of pool water required for backwashing could be reduced by half. Furthermore, it could be shown that the filters treated with the solution according to the invention discharge twice the amount of pollutants in half the time. This may be due to better coagulation of the organic / inorganic contaminants and to a prevention of the filter material from sticking together. This makes it easier and faster to remove the captured dirt particles. In addition, the chlorite solution according to the invention prevents the strong contamination of highly loaded filters. Accordingly, it also serves as a filter aid in the specially set manner. The use described outlines considerable savings in fresh water, waste water, heating and treatment costs. In the indoor swimming pool Bockum / Hövel in Hamm, chosen for the examination of the mentioned proof of equivalency

0037«&amp; SSd^" this is as follows: in the normal treatment of flocculation-filtering-chlorination, the amount of fresh water required per bather is 0.11 m³ , while in the corresponding procedure with the chlorite solution according to the invention an average of 0.03 per bath ³ Fresh water is required. The saving per swimmer was accordingly 0.08 m³.

0038As a result, the following can be summarized for the use of the chlorite solution according to the invention for the treatment of swimming pool water: this solution can be added directly to the chlorinated swimming pool water, chlorine dioxide being formed directly in the pH range from about 7 to 7.8. However, treatment with the solution according to the invention is preferably carried out between the flocculation and filter stages. Here 7._B. about 24 ml of an approximately 10% by weight chlorite solution over approximately 180 m³ Circulated swimming pool water is eliminated. The 100% conversion to chlorine dioxide proceeds so quickly that chlorite, but chlorine dioxide, could not be detected in any case when dosing on the raw water side. The water quality achieved is superior to that of known processes (acid process or hypochlorous acid process). As shown, the processing method using the agent according to the invention is extraordinarily inexpensive.

0039^D-i-^e Stabilized / modified chlorite solutions according to the invention can, however, also be used for further useful purposes. It has been shown that, in particular, dilute chlorite solutions according to the invention have excellent biocidal activity in the broadest sense. This applies in particular to a dilute sodium chlorite solution according to the invention, preferably in an approximately 0.1 to 0.5% by weight concentration. So she can be

0040Use IPO hygienic disinfectant body care, for example for foot care in swimming pools, saunas, etc., especially when treating sweaty feet. It is also particularly suitable for skin diseases and skin that can be treated externally

0041Irritation, in particular in the case of skin lichen, psoriasis, eczema and lupus, skin fungi or in general in the case of inflammatory skin diseases which are caused by bacteria and protozoa, by viruses or fungi (candidiasis, trichophytia, pityriasis and herpes, etc.). Skin diseases in the throat or mouth, such as tooth bleaching, can also be treated with the agent according to the invention, in particular the sodium chlorite solution. So these funds are a kind of pharmaceutical. In addition, the chlorite solution according to the invention can be quite generally regarded as a skin care product which can be added to the bath water in small concentrations when bathing. Some of the applications just mentioned above are all to be described in detail below.

0042First, it was found in the pharmaceutical sector that the solution according to the invention is highly compatible with the skin. In this way, it can even be given to healthy chewing in a concentrated manner without allergic reactions becoming apparent. The skin generally reacts strongly allergically to normal chlorite solutions of the same concentration. So in

0043On the contrary found that a dilute chlorite solution according to the invention surprisingly breaks down allergies. Even spectacular antifungal effects were confirmed in 1:10 dilutions of the concentrated solution to water. As well

0044OMPI 1, the chlorite solution according to the invention proves to be effective in the healing of some of the most severe neurodermatitis for many years. Here, however, the solution must be applied in a very dilute form, for example

00455 20 to 30 ml per bath with a slow increase to the limit of the patient's tolerance.

0046A very astonishing phenomenon occurs

0047- * 0 the treatment of psoriasis (psoriasis). With daily to bi-daily veins (approx. 100 ml per tub bath with the exclusion of other bace additives), about 80% of psoriasis have a peeling of the scales, even without mechanical action, after the first

004815 Baths. Itching generally subsides quickly. The raised areas of skin flatten out and the dark red color gives way to a pale pink. After a stagnation phase of around 2 to 3 months, which usually occurs, normalize the previously affected skin porter. The successive elimination of small amounts of ozone during bathing may play a role in this treatment (metabolism regulation via extensive skin contact). Bathing of the body and feet, etc.

004925th permanently eliminates the smell of sweat. Other useful areas of application are mouthwashes with a 3% solution, which eliminates bleeding gums.

0050A very amazing effect was also achieved with the _Q Treatment of diabetic gangrene (open legs) detected. In a single case, a wound of thumb width and a length of about 7 cm healed when treated with a dilute sodium chlorite solution according to the invention (dilution 3 with water in a ratio of 1: 100) after treatment of about 8 weeks.

0051OMPI Finally, the chlorite solutions according to the invention, preferably the sodium chlorite solution, can be used in the industrial sector, for example in the fight against slime in aqueous systems. This also applies to the preservation of drinking water in different containers or tanks, especially on ships. Such a solution can be used there very effectively and without problems in terms of application technology. The drinking water treated with the solution according to the invention remained germ-free in closed containers for months. Also, with the amounts used here in the ppm range, no taste impairment of the water was found. There are also no concerns from a toxicological point of view.

0052The oxidizing effect of the chlorite solutions according to the invention can, for example, also be used in other technical areas, for example in combination with mineral acids or chlorine. They can therefore be used for the production of cellulose, for the bleaching of oils, fats and waxes, leather and for the disinfection or deodorization of malodorous 7- ±> wastes and waste water. A special application is the step bleaching of cellulose.

0053In summary, it can be stated that the modified aqueous chlorite solution stabilized in accordance with the invention can advantageously be used wherever it is to have an oxidative effect, in particular on account of the formation of chlorine dioxide. This can be dead matter of organic, in particular reducing substances, as well as living organisms, such as microorganisms, fungi and the like. So you can

0054Describe chlorite solution in the broadest sense as a biocidally active agent with absolute skin compatibility, ie it can serve as an insecticide, fungicide, herbicide etc., where up to now commercially available sodium chlorite solutions have been used, but with little success were used or showed little suitability. A further advantage of the chlorite solution according to the invention is that it generally enables 100% conversion of chlorite into chlorine dioxide in a wide pH range, in particular also in an alkaline medium. It is described in the literature that chlorite solutions can only achieve the desired degree of conversion to chlorine dioxide of 100% in a pH range of -3. In addition, the solution according to the invention is very simple and easy to prepare, for example by the predetermined acidic solution (preferably a pH value 1 1) with a concentrated commercial chlorite solution in a volume ratio of approximately 1: 1 to to set a pH just above 7 is mixed without much technical effort.

0055The invention will be explained in more detail below using an example:

0056example

0057In 1 1 Kasser (carbonate hardness: 18 degrees) of a pH value of 0.5, 0.5 g of a 30 wt .-% hydrogen peroxide solution. 0.9 l of a commercially available sodium chlorite solution (about 300 g of sodium chlorite / l) are added to this solution with thorough stirring. The solution passes through a brown color which, when the pH value exceeds 7 after the stabilization reaction has ended, changes to a light lime green color. A pH of about 7.5 is established in the solution. This solution provides

0058SAN, IPO reitung in an indoor pool a 100 l conversion to chlorine dioxide. The reaction is so rapid that chlorite can never be detected on the pure water side, but chlorine dioxide can still be detected in small amounts. The water quality is significantly improved. The fresh water additive per bath guest can be reduced to 20%.

0059The aqueous solution prepared in the above manner finally shows a 0.1 to 0.5% by weight

0060Concentration also has an excellent effect in the treatment of psoriasis and skin fungi.