Abstract: Disclosed is a process for the degradation of highly toxic halogenated organic compounds, in particular polychlorinated dibenzodioxins (PCDD) and dibenzofurans (PCDF), contained in gases containing no SO.sub.2 by oxidation using preferably hydrogen peroxide. The SO.sub.2 -free gas is passed, in the presence of hydrogen peroxide, over a substantially inorganic solid contact catalyst, in particular pyrogenic or precipitated silica or aluminum silicate. A residual PCDD/PCDF content of below 0.1 ng TE/Nm.sup.3 may be achieved in the thus treated gas; the highly toxic compounds are oxidized on the solid contact catalyst.

Abstract: 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.

Abstract: A method for the removal of nitrogen oxides from waste gases and for obtaining nitric acid is described. The waste gas is charged with the required amount of hydrogen peroxide, converted into the gas phase, and the gas mixture is reacted on a solid catalyst to hydrogen nitrate, which is either withdrawn for further use or is converted into nitric acid either by condensation or by scrubbing with water. The method permits the removal of NO.sub.x at low concentrations below 2000 ppm with efficiencies above 90%.