Air corona removal of phenols

Exposure to the neutral activated species of an a.c. point-to-plane type corona discharge in air of aqueous alkaline solutions of phenol and substituted phenols (pentachlorophenol, triiodo 2,4,6 phenol and picric acid) leads to the oxidative destruction of the solutes up to the CO2 state in the case of phenol. The influence of the discharge parameters, such as the current intensity, is considered. The destruction of phenates follows overall pseudo first-order kinetics, and the kinetic constants are linearly dependent on the current. A scheme for the degradation kinetics is proposed involving a multistep mechanism, and the occurrence of dihydroxybenzenes as reaction intermediates is suggested. Applications of corona treatment to waste waters may be considered as a versatile method for the elimination of toxic chemicals and the purification of industrial waters.