Degussa Aktiengesellschaft

Nas Corp.

Edgar Bilger

Hubert Wolf

Wedigo Von Wedel

John Tarabocchia

Ernst-Robert Barenschee

Urban Gubisch

Christian HÖLSCHER

Klaus Seikel

A process for removing halogenated organic compounds from waste gases optionally containing NO.sub.x, in which the waste gas is optionally supplemented with SO.sub.2, optionally led through a fixed bed or fluidized bed of a solid and contacted with Caro's acid or one of its salts. The Caro's acid can be produced in situ by adding H.sub.2 O.sub.2 and optionally H.sub.2 SO.sub.4.

Process for removing halogenated organic compounds from waste gases

A method for removing sodium polysulfide from used sodium/sulfur batteries provides that the cells are granulated under protective measures, the scrap is treated in a solution of sodium cyanide and the solution obtained is treated with air. The solution then contains sodium thiocyanate and sodium hydroxide, which latter can be reacted by means of CO.sub.2 to Na.sub.2 CO.sub.3, precipitated and separated.

Method of removing sodium polysulfide from used sodium/sulfur batteries

According to the invention, cyanide concentrations of approximately 0.001 to 5 mg cyanide/1 are colorimetrically determined in a continuous manner by means of the known cyanidepicric acid color reaction. The solution containing free cyanide and/or cyanide releasable from cyanocomplexes is converted in a system enclosed in a gas-tight manner in the presence of chelate complexing agents, picric acid and alkaline buffer systems in 1-60 minutes at 50.degree.-120.degree. C. to the color complex and the absorbency is measured spectrophotometrically. The method avoids the extraction step which was previously necessary under 0.2 mg CN/1, avoids errors due to HCN gas evolution losses, is easy to manage, not prone to trouble and suitable for the continuous monitoring of waste-water streams or for controlling cyanide detoxification methods.

Method for the colorimetric determination of the cyanide concentration

A process for the production of solid or dissolved alkalithiocyanate by reaction of dissolved alkalicyanide with an alcoholic sulphur suspension at the boiling point of the alcohol. The alcohol is distilled off as an azeotrope and the unreacted sulphur is separated. For the isolation of the solid product, a pH of 5-9 is adjusted in the solution obtained and thus a crystallization or evaporation is carried out.

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Hasselroth, Germany

Edgar Bilger