CS256866B1 - A method of protecting silver oxide from carbon dioxide - Google Patents

Abstract

The method solves the problem of protecting silver oxide from the action of carbon dioxide from the air. Silver oxide is used to prepare the cathode mixture of silver-zinc galvanic cells. For this purpose, silver oxide without silver carbonate must be used. Protection against the action of carbon dioxide from the air is achieved by adsorption of an aromatic organic substance containing an -OH group in the meta position in an amount of 0.01 to 5% by weight. For example, eosin or tropeolin can be used with advantage.

Description

(54) A method of protecting silver oxide from the action of carbon dioxide

The method solves the protection of silver oxide from the action of carbon dioxide from the air. Silver oxide is used to prepare a cathode mixture of silver-zinc galvanic cells.

For this purpose, a striation oxide must be used. without silver carbonate. Protection against exposure to airborne carbon dioxide is achieved by adsorption of the aromatic organic substance containing the -OH group in the meta position in an amount of 0.01 to 5% by weight. For example, eosin or tropeoline can be advantageously used.

56866

BACKGROUND OF THE INVENTION The present invention relates to a method of protecting silver oxide from the action of carbon dioxide by an organic material sorbed onto the surface of crystals.

Silver oxide is used to prepare a cathode mixture of silver-zinc galvanic cells, with the aid of carbon dioxide from air to silver oxide to form silver carbonate which impairs the cathode being prepared. For this purpose, silver oxide without silver carbonate must be used and must not be produced during the preparation of the cathode or during its treatment. For this reason, it is necessary to work either in the protective atmosphere of nitrogen or under vacuum, or to shorten the time when the silver oxide or the silver oxide mixture containing it is in contact with air during the synthesis of silver oxide and its treatment. The sorption of carbon dioxide proceeds rapidly, so that these measures are inefficient and complicate the work with silver oxide.

This deficiency removes the method of protecting silver oxide from the action of air carbon dioxide according to the invention, which comprises adsorbing aromatic organic compounds having an -OH group in the meta position in the amount of 0.01 to 5% by weight.

Organic compounds will prevent carbon dioxide from reaching the surface and silver carbonate will no longer form. The silver oxide prepared in this way can be operated freely in the air and there is no longer any need to introduce measures to eliminate the presence of carbon dioxide, and the quality of the silver-zinc cell is thus greatly improved. The reaction of silver oxide with carbon dioxide and the method of protecting it is based on the fact that the silver oxide is slightly alkaline and can react with acidic substances.

If an acidic organic substance is adsorbed onto the surface of the silver oxide, even a very thin layer prevents further reaction with carbon dioxide. The organic substance is first sorbed by chemisorption at the alkaline centers of silver oxide and a further amount is physically sorbed. The choice of silver oxide protection agents is not simple, since the silver oxide has an oxidizing capability and readily reacts with compounds that have slightly reducing properties or are easily oxidized. Furthermore, compounds containing only -COOH and -CO2H groups have been found to be ineffective.

These substances do not prevent further reaction with carbon dioxide. Aromatic organic substances containing the -OH groups in the meta position are active. Aromatic organic compounds containing the -OH groups in the ortho or para position readily reduce silver oxide to metallic silver.

Thus, aromatic organic compounds with a -OH group in the meta position can be used to protect the silver oxide. These compounds have an acidic reaction and are often used as acidic organic dyes for wool or polyamide fabrics.

Fig. 1 shows the curve of the increment of the content of silver carbonate in freshly precipitated silver oxide which has been freely stored in air at 20 ° C. The reaction of the silver oxide with the carbon dioxide can be monitored simply by increasing the weight of the loosely stored silver oxide in the air.

Figure 2 shows the weight variations of silver oxide which has been prepared in varying amounts by eosin. The effective amount was verified experimentally mainly in the preparation of cathode mixture for silver-zinc cells. The sorption of carbon dioxide is rapidly decreasing with a content of 0.1% by weight of eosin and no longer appears at higher additions.

The invention will be further explained and described in the following example:

Freshly precipitated silver oxide (100 g) was mixed with an aqueous solution of tropeolin. The tropeolin solution is prepared to contain 1 g tropeoline in 60 g distilled water. Mixing with silver oxide yields a thick suspension which is dried at 70 ° C. After cooling, the prepared silver oxide does not change for at least 250 hours under the influence of carbon dioxide from the air.

The invention can be used in all areas where it is necessary to protect silver oxide over the effects of airborne carbon dioxide, in particular in the preparation of a cathode composition for silver-zinc cells.

Claims (1)

OBJECT OF YOU FIND Method for protecting silver oxide from the action of air carbon dioxide, characterized in that aromatic organic substances with an -OH group in the meta position in the amount of 0.01 to 5% by weight are adsorbed to the silver oxide surface.