DE1087561B - Process to reduce the escape of chlorine dioxide from acidic chlorite baths or chlorine dioxide solutions - Google Patents

Description

GERMAN

When working with aqueous solutions of Chlo ~ rites or chlorine dioxide always escape certain amounts of chlorine dioxide from the acidic chlorite baths, which involve a high level of danger and nuisance for workers. Processes are already known which tend to reduce the escape of chlorine dioxide from acidic chlorite baths. For example, peroxides, predominantly hydrogen peroxide, have already been used for this purpose added to acidic chlorite baths. However, the method has the disadvantage that this creates an additional Consumption of the expensive bleach occurs.

It is also known to reduce corrosion when working with aqueous solutions of chlorites or To prevent chlorine dioxide in stainless steel equipment from adding nitrates to the baths. Among other things is called the ammonium nitrate.

It also prepares the escape of Cblofdiocxyd from acidic chlorite baths there are also considerable technical difficulties in practice, and attempts have been made to to remedy the inconvenience by suction and absorption devices, which, however, was considerable Causes costs, whereby a loss of valuable substance cannot be avoided.

It has now been found that the escape of chlorine dioxide from acidic chlorite baths or chlorine dioxide solutions can be reduced if ammonium salts of lower aliphatic carboxylic acids, especially ammonium acetate, and sulfonic acids and / or adds carboxylic acids or their salts which have a higher molecular weight aliphatic radical which is interrupted by a carbonamide or a carbon ester group.

The quantities of ammonium salts of lower aliphatic carboxylic acids to be used per liter of liquor can vary within wide limits. In general, it is sufficient to add about 0.5 to 2 g / l of liquor. the end For reasons of economy, amounts of about 0.6 to about 1 g will be used. Of course larger amounts than specified can also be used. The amounts of sulfonic acids and / or Carboxylic acids or their salts, which contain a higher molecular weight aliphatic radical, which is replaced by a Carbonamide or carbon ester group is interrupted can also vary within wide limits. It is often sufficient to use about a quarter of the amount of ammonium salt of lower aliphatic carboxylic acids used to be used, but the same and higher amounts can easily be used.

In addition to the invention to be used substances can be the Chloritbädern or the Chlordioxydlösungen further still the usual, necessary for adjusting the p _H -value additives such. B.

Procedure for reduction

the escape of chlorine dioxide

from acidic ciorite baths

or chlorine dioxide solutions

Applicant:

Farbwerke Hoechst Aktiengesellschaft

formerly Master Lucius & Brüning,

Frankfurt / M., Brüningstr. 45

Wilhelm Waibel, Frankfurt / M.-Sdiwanheim,
has been named as the inventor

Add hydrochloric acid, acetic acid, phosphoric acid, bisulfates, orthophosphates and the like.

To avoid corrosion damage when working in. Stainless steel equipment To avoid it, it is advisable to add acids of nitrogen oxides or their salts.

As higher molecular weight sulfonic and / or carboxylic acids are, for example, the reaction products of fatty acids with aminosulfonic or aminocarboxylic acids or with protein degradation products, also the Condensation products of fatty acid salts and halosulfonic or halocarboxylic acids called. The following may be mentioned in particular: oleyl taurine, oleylmethylaminoacetic acid, stearoxymethane and ethynesulphonic acids. Such compounds are known as surfactants.

It has also been found that there is a durable means of reducing the leakage of Chlorine dioxide is obtained from acidic chlorite baths or chlorine dioxide solutions if ammonium salts are lower aliphatic carboxylic acids, especially ammonium acetate, and sulfonic and / or carboxylic acids or their salts, which contain a higher molecular weight aliphatic radical, which is replaced by a carbonamide or carbon ester group is interrupted, mixes intimately. It is possible in this way to get one from the start to maintain a suitable mixing ratio, so that you can later use it by entering in Water receives working solutions that contain the aid in sufficient quantities.

If you want to produce a means that is used at the same time in chlorite baths in stainless steel equipment to provide corrosion protection, the above mixture can also contain salts of acids

009 588/400

add nitrogen oxides, preferably sodium nitrate. These mixtures are very stable.

It is not necessary in all cases to use solid mixtures of ammonium salts of lower aliphatic Carboxylic acids, in particular; Ammonium acetate and Sulphonic acids and / or carboxylic acids or their salts, optionally salts of the acids of nitrogen oxides to manufacture. The inventive concept of the present application is also realized when preparing concentrated solutions of the components mentioned. Concentrated like that too Solutions are durable. For use it is only necessary to provide this with the required amount Dilute water.

Solid salt mixtures according to the invention can be obtained by intimately mixing the solid salts It is advisable to ensure that salts of the same grain size are used. However The salt mixtures can also lower the ammonium salts by evaporating or spraying solutions aliphatic carboxylic acids in addition to the sulfonic and / or carboxylic acids mentioned or their salts and optionally containing salts of the acids of nitrogen oxides, are prepared.

Other additives usually used in combination are used with chlorites, the solid mixtures or the concentrated solutions, or depending on the type; the additives, the working solutions can be added.

Compared to that from the Austrian patent specification 173 427 known use of ammonium nitrate in conjunction with the above surface-active substances are shown when using ammonium salts of lower aliphatic carboxylic acids, in particular ammonium acetate, together with the sulfonic acids and / or carboxylic acids given above or their salts a much better prevention of chlorine dioxide development.

A solution of 2 g / 1 of sodium chlorite and 0.3 g / l of a condensation product of fatty acid and protein degradation products is at a _pH value of 3.3 and 60 ° C in the presence of 0.75 g / l ammonium nitrate in the course of 1 hour a Ciorit decrease of 0.18 g / l. In addition, the solution has a yellow-olive color. If, under otherwise identical conditions, 0.75 g / l ammonium acetate is used instead of the ammonium nitrate, the solution is almost colorless after 1 hour and the chlorite decrease is only 0.10 g / l. ■

In the German patent 821 483 ^- a process for bleaching fibers and structures made therefrom is described, wherein the bleaching baths are fluorine compounds, in particular hydrofluoric acid or its salts, e.g. B. ammonium bifluoride should be added. This process has the disadvantage that hydrofluoric acid, as well as its salts, attack stainless steels as well as ceramic materials which are used for the manufacture of the bleaching vessels or fittings in acidic chlorite bleaching solutions. In addition, however, a significantly better utilization of the chlorite and a better prevention of the escape of chlorine dioxide is achieved in the method according to the present invention than is the case with the known method; For example, a. Solution containing per liter 1 g of sodium chlorite and 0.5 g of ammonium bifluoride containing and a temperature of 60 ° C and a _pH value of 3.5 has, after! Hour, a decrease of 9% sodium chlorite, wherein determining further, that the solution is olive colored by free chlorine dioxide. In contrast, the chlorite decrease in a solution which, under the same conditions, contains 0.5 g / l ammonium bifluoride, 0.5 g ammonium acetate and 0.3 g pleylmethyltaurine, is only 3.8%. In addition, the solution remains light, as practically no free chlorine dioxide is split off.

example 1

A Viskosezellwollgewebe is at a liquor ratio of 1:20 with a solution of 1 g / l sodium chlorite, 0.35 g / l oleylsarcoside and 0.6 g / l Ämmoniumacetat at a _pH value of 3.4 and a temperature of 70 ° C treated. The fabric bleached in this way has a whiteness of 80.6Vo. 0.26% sodium chlorite is consumed.

If the process is carried out in exactly the same way using 0.6 g / l ammonium nitrate and instead of ammonium salts of lower aliphatic carboxylic acids, in particular ammonium acetate, is so the consumption of sodium chlorite 0.32%, i.e. it is around 27% higher than when it was used of ammonium acetate, without a higher whiteness being obtained.

The amounts of surfactants and ammonium acetate given in the example above can also be varied within wide limits with regard to the ratio. With higher "additives can you can reduce the bleaching speed largely depending on the requirements, and you can completely Achieve odorless working. In addition, this results in a significant saving in chlorite.

Example 2

A Viskosezellwollgewebe 40 minutes at a liquor ratio of 1:20 with a solution of 1 g / l sodium chlorite, 5 g / l ammonium acetate, and 0.2 g / l Oleylmethyltaurin at a _pH value of 3.5 and a temperature of 75 Treated at ° C and then rinsed. With a consumption of only 0.18% sodium chlorite, the fabric treated in this way has a whiteness of 79.8%. No release of chlorine dioxide occurs.

Example 3

A Viskosezellwollgewebe 40 .... minutes at a liquor ratio of 1:20 with a solution of 1 g / l sodium chlorite, 0.3 g / l ammonium acetate, and 3 g / l Oleylmethyltaurin at a _pH value of 3.5 and Treated at a temperature of 75 ° C and then rinsed. The fabric treated in this way has a whiteness of 80.2% with a consumption of only 0.21 sodium chlorite. There is no escape of chlorine dioxide during bleaching.

Claims (3)

Patent claims: 1. Process to reduce the escape of chlorine dioxide from acidic chlorite bleach baths or chlorine dioxide solutions, thus identified δο records that one adds ammonium salts to the baths or solutions lower aliphatic carboxylic acids, especially ammonium acetate, and sulfonic acids and / or carboxylic acids or. whose salts are added which contain a higher molecular weight aliphatic radical, which is interrupted by a carbonamide or carbon .. "ester group. . 2. The method according to claim 1, characterized in that acids of nitrogen oxides, preferably nitric acid, and / or salts thereof are added to the baths ..- ■ - .. _; . . -, __ / ... 5 6 3. Means for carrying out the method, if necessary, on salts of acids of the nitrogen claim 1 or 2, characterized by a geoxide, preferably nitrates, and optionally contains ammonium salts of lower aliphatic and other additives in solid or concentrated carboxylic acids, especially ammonium acetate, and trated aqueous form. Sulphonic acids and / or carboxylic acids or their 5 Salts that have a higher molecular weight aliphatic Documents considered: Contain the remainder of the carbonamide or German patent specification No. 821 483; Carbon ester group is interrupted, as well as against Austrian patent specification No. 173 427. © 009 588/400 8.60