HK1068863B - Method for producing an essentially chlorite-free, stable, aqueous chlorine-oxygen solution, the chlorine-oxygen solution obtained by means of said method, and the use of the same - Google Patents

Description

Method for producing stable aqueous chlorine-oxygen solution substantially free of chlorite, chlorine-oxygen solution obtained by said method and use thereof

The invention relates to a method for producing a stable, aqueous chlorine-oxygen solution which is substantially free of chlorite, to the chlorine-oxygen solution obtained according to said method and to the use thereof.

In particular in the field of water treatment, for example in the purification of swimming pool water, corresponding standards, guidelines and regulations must be strictly adhered to. The general condition here is that as simple, energy-saving and environmentally friendly as possible must be ensured, so that there is always a need for corresponding modified oxygen carriers in the form of chlorine systems which are suitable for the purposes mentioned above, but which do not generate free chlorine. Free chlorine has a number of disadvantages because it is very corrosive and side reactions occur which lead to the formation of chlorine-nitrogen compounds, hydrogen halide chlorides and similar substances. In addition to the toxicological aspect of the side reaction products formed, chlorine is lost by side reactions, which leads to the loss of the desired bactericidal or disinfectant effect.

The oxidizing properties of the compounds should make possible their productive use in swimming pool areas, for example as scavengers. The products are halogen-containing oxo complexes, some of which constitute complex charge-transfer structures, and the detailed structural details of which have not been analyzed to date, since the isolation of such complexes is rather difficult. One such known anionic complex is "tetrachlorodecaoxide," which contains stabilized active oxygen in a chlorite ion matrix along with chlorine dioxide.

There have been some proposals in the prior art for such systems. EP 0200155B 1, EP 0200156B 1 and EP 0200157B 1 relate to chemically stabilized aqueous chlorite base solutions in defined concentrations for intravenous and peripheral surgical administration or to the use of aqueous solutions for the preparation of a medicament for intravenous administration in an infected state caused by parasites, fungi, bacteria or mycoplasma or for the treatment of swelling. Here, only the drug and various treatment methods are centered.

According to the teaching of DE 3438966 a1, a preparation is described which consists of a stabilized chlorite matrix, in particular Tetrachlorodecaoxide (TCDO), in combination with preferably equimolar amounts of an iron porphyrin compound, wherein the two components are added only slightly before the time of use. The formulations are useful as disinfectants for topical or intravenous administration, wound treatment, for storage or surface disinfection applications.

DE 3403631C 2 and EP 0136309B 1 disclose a process for preparing chlorite solutions, in which an aqueous solution containing sulfate ions and having a pH of 3 or less is mixed with a peroxide having a relatively low concentration, the peroxide having a molar concentration of about 0.001 to 0.01 in the end product, after which an alkaline aqueous chlorite solution is added in such an amount that the pH is adjusted to a value above 7.0, in particular 7.5 to 8.0. This aqueous chlorite is useful as a biocide for dermatological and dermatitis treatments as well as water purification applications.

From US-A-2358866 of 1944, A stabilized chlorite solution is furthermore known which is adjusted to be acidic and which is stabilized by adding, for example, A stoichiometric amount of hydrogen peroxide at A pH of 2 to 7 at approximately 80 ℃. The generation of chlorine dioxide is suppressed by the addition of hydrogen peroxide, which has corrosive properties and a number of disadvantages. Particularly good results are obtained in the pH range of 5 to 7.

US 4296103 relates to perborate-stabilized oxychloride solutions containing 4-15 parts by weight of sodium or potassium perborate per liter of water, which are used for therapeutic purposes by oral administration with the addition of peroxides or percarbonates. The solution consists of sodium or potassium chlorite, sodium hypochlorite, hydrochloric acid, sulfuric acid, sodium or potassium perborate, and sodium peroxide. In particular, the addition of perborate here is important.

The literature "preparation of pure chlorine dioxide in the laboratory", world and Degussa, products, processes, methods, page number COMPLETE, XP-000847684 (10/7/1999) gives an indication of the reaction scheme when pure chlorine dioxide is prepared. Sodium chlorite and sodium peroxodisulfate are therefore used. Sodium peroxodisulfate is used here in excess of the stoichiometric amount when reacting with sodium chlorite. The prepared chlorine dioxide solution did not contain chlorite even after being left for a period of 77 days, and the solution was stored in a brown glass bottle due to photosensitivity. This known chlorine dioxide solution is stable for several weeks at room temperature, but preferably in a refrigerator at about 4 ℃, without significant changes in the composition of the solution. Therefore, precautions are taken to maintain the desired stability.

The object of the present invention is therefore to provide a stable chlorine-oxygen solution which meets the requirements for water treatment, in particular swimming pool water treatment, i.e. which can be used without toxicity, in an environmentally friendly manner and economically and is suitable for large-scale use in terms of application technology.

The above-mentioned object is achieved according to the invention by a process for the production of a substantially chlorite-free, stable aqueous chlorine-oxygen solution having the following steps:

dissolving a bisulfate compound in water; (2) adding acid to the aqueous hydrogen sulfate-containing solution in such an amount that the pH of the final product obtained in the form of a stable aqueous chlorine-oxygen solution substantially free of chlorite is maintained between about 3 and 5; (3) adding peroxide; (4) an aqueous chlorite solution of approximately 60 to 90, in particular 70 to 80, mol% chlorite, based on the peroxide concentration, is added dropwise.

The bisulfate compound used in step (1) is first dissolved in water. Preference is given to using alkali metal or alkaline earth metal hydrogen sulfates. In a preferred embodiment, about 5 to 20, especially 5 to 10 mole percent of the bisulfate compound is used, based on the concentration of the peroxide. The pH is adjusted accordingly in step (2) by acidifying the aqueous solution with a mineral acid. According to a preferred embodiment, dilute sulfuric acid, in particular 1.0-10N H, is used₂SO₄. The peroxide, either in solid form or as an aqueous solution, is added to the acidic aqueous solution in step (3). Preference is given to using hydrogen peroxide or peroxides of alkali metals or alkaline earth metals as peroxide, it being possible here for the person skilled in the art within the scope of the invention to use other suitable peroxides in common. Mixtures of peroxides are of course also possible. The peroxide used in the process according to the invention is mainly used to stabilize the resulting system.

Sodium chlorite is preferably used as the chlorite in step (4). According to a particularly suitable variant of the process of the invention, step (4) is carried out over a period of about 1/4 to 1/2h, i.e. the dropwise addition of the aqueous chlorite solution is carried out within a predetermined period of time. The aim is to allow the reaction to proceed at a controlled slow rate.

The color of the solution changed from brown to yellow-green during the preparation process. It is believed that the brown color formed is due to the formation of the charge-transfer-complex Cl₄O₁₀ ^2-After which a yellow-green color is generated and maintained. There is a complex containing an active oxygen species,the yellowish green color of the solution, which is characteristic of tetrachlorodecaoxide, is similar in color to the yellowish green color of the chlorine-oxygen solution according to the invention.

The chlorine-oxygen solutions produced according to the invention can be stored for several months without losing their oxidizing effect and in particular exhibit the following advantages: it can be simply metered in and used and can be used in an environmentally friendly and economical manner completely without toxicity, since large-scale and cost-effective production is possible and suitable for large-scale use in water treatment from the point of view of application technology. Other advantages are for example the application to site disinfection, the application as a basic substance for medicaments for skin treatment, but also all other applications.

The invention also relates to a stable aqueous chlorine-oxygen solution which is essentially free of chlorite and is obtainable by the above-described process.

The chlorine-oxygen solution according to the invention can be used particularly advantageously for water treatment, in particular for the treatment of drinking water, process water or for disinfecting or sterilizing swimming pool or bathing pool water. It is entirely possible to provide the desired dosage by corresponding dilution of the prepared solution.

The chlorine-oxygen solution is used according to the invention in such an amount that from about 0.1 to 0.3, in particular from 0.1 to 0.15, mol of chlorite is used as starting material in one liter of water to be treated.

The present invention is described in detail below according to one embodiment, but it should not be construed as being limited thereto. Other embodiments within the scope of the disclosure will be apparent to those skilled in the art from consideration of the specification.

Examples

0.2g of sodium hydrogensulphate is dissolved in 18ml of water, then 1.2ml of 10N sulphuric acid are added and 3.8ml of a 30% hydrogen peroxide solution are carefully added with stirring. To this solution 15.7ml of sodium chlorite solution (25% strength) was added dropwise over 15 minutes. The solution changed from brown to yellow-green and then remained stable.

Claims (12)

1. A process for preparing a stable aqueous chlorine-oxygen solution, wherein a peroxide and an aqueous chlorite solution are used in an acidic, hydrogen sulfate-containing aqueous solution during the reaction, characterized in that it comprises the following steps:

(1) dissolving a bisulfate compound in water;

(2) adding acid to the aqueous solution containing hydrogen sulphate in such an amount that the pH value in the final product obtained in the form of a stable aqueous chlorine-oxygen solution is maintained between 3 and 5;

(3) adding peroxide; and

(4) an aqueous chlorite solution of 60-90 mole% chlorite, based on the amount of peroxide, is added dropwise.

2. The process according to claim 1, characterized in that an alkali metal or alkaline earth metal hydrogen sulfate is used as the hydrogen sulfate compound in step (1).

3. A method according to claim 1 or 2, characterized in that the amount of the bisulfate compound used in step (1) is in the range of 5 to 20 mole%, based on the amount of the peroxide used.

4. The process according to claim 1 or 2, characterized in that the acid used in step (2) is dilute sulfuric acid.

5. A process according to claim 4, characterized in that the acid used is 1.0-10N sulfuric acid.

6. The process according to claim 1 or 2, characterized in that the peroxide in step (3) is selected from the group consisting of hydrogen peroxide or peroxides of alkali or alkaline earth metals.

7. A process according to claim 1 or 2, characterized in that sodium chlorite is used as chlorite in step (4).

8. The process according to claim 1 or 2, characterized in that step (4) is carried out for a period of time from 1/4 to 1/2 h.

9. An aqueous chlorine-oxygen solution obtained by the process according to one of the preceding claims and containing a complex containing active oxygen.

10. Use of the aqueous chlorine-oxygen solution according to claim 9 for water treatment or for disinfection of swimming pool or bathing pool water.

11. Use of the chlorine-oxygen solution according to claim 10 in an amount of from 0.1 to 0.3 mol of chlorite as starting material per liter of water to be treated.

12. Use of the chlorine-oxygen solution according to claim 10 for the treatment of drinking water.