Electrochemical approach to the recycling of nitration waste concentrated sulphuric acid

Electrolysis of nitration waste sulphuric acid, from the manufacture of trinitrotoluene, results in the formation of a dark solution in which the concentration of aromatics is reduced to much lower levels. The resulting acid can be decolourized by oxidation with H sub(2)O sub(2) or by anodic oxidation in the cell. The H sub(2)O sub(2)-treated electrolysed acid has a nitroaromatic content of 107 p.p.m. and a total carbon content of 278 p.p.m., corresponding to a reduction of 98.7% and 90.3%, respectively. The dark intermediate product appears to result from the anodic oxidation of amines which are initially produced at the cathode, and is destroyed by further anodic oxidation on prolonged electrolysis.