Hoechst Aktiengesellschaft

Alwin Topp

Georg Schaeffer

Klaus Schmiedel

The waste water being formed upon the preparation of hydroxy aromatics, preferably of resorcinol and .beta.-naphthol, by caustic alkaline melt of the corresponding aryl-sulfonic acids or aryl sulfonates is purified by wet oxidation with oxygen or oxygen-containing gases at temperatures of from about 100.degree. to 370.degree. C. and under a pressure of from about 1 to 300 bars. The COD-decomposition rates amount to about 90% and more. When a hydroxy aromatic is prepared by means of a caustic soda melt, this process provides a sulfate, especially sodium sulfate, which is of sufficient purity for further use without complementary purification stages. The obtention of the pure salt is important for the economy of the process.

Growing community of inventors

Hofheim am Taunus, Germany

Alwin Topp