Hydrothermal oxidation of a nitrogen-containing compound: the fenuron

Fenuron [C6H5NHCONH(CH3)2] oxidation in hydrothermal conditions was examined in the temperature range between 200 and 540°C at 25 MPa with residence times of 20–410 s. Under these conditions, the chemical oxygen demand reduction ranged between 70% (at 200°C) and 99.92% (at 540°C). Nitrogen atoms of the fenuron molecule were first transformed into ammoniacal nitrogen, nitrate ions and nitro groups of nitrobenzene. Then, they were converted into molecular nitrogen by a redox process between ammoniacal nitrogen and oxidized forms of nitrogen (NO−3, NO2). At 540°C and 25 MPa for a residence time of 39 s, fenuron was totally degraded into water, carbon dioxide and gas nitrogen, which are acceptable end products for the environment.