Acidity control of the gliding arc treatments of aqueous solutions: application to pollutant abatement and biodecontamination

¹ Laboratoire d'Électrochimie (L.E.I.C.A.), UFR des Sciences de l'Université de Rouen, 76821 Mont Saint-Aignan, France
² Laboratoire des Sciences et Techniques de l'Environnement et de la Valorisation (S.T.E.V.A.), Faculté des Sciences de l'Ingénieur, BP 188, Mostaganem, Algeria
³ George Asashi Technical University, 51–53 Boulevardu Mangeron, 66000 Iasi, Romania

Corresponding author: Jean-Louis.Brisset@univ-rouen.fr

Received: 18 December 2003
Revised: 7 August 2004
Accepted: 7 September 2004
Published online: 21 December 2004

Abstract

A tight control of acidity is needed for performing oxidation–reduction reactions of organic compounds dissolved in liquid media, since the relevant reactions often involve the occurrence of protons; the matching kinetics are therefore acidity dependent. This feature holds for plasma treatments of aqueous wastes which are intended to abate the concentration in organic pollutants. Exposure of aqueous solutions to a gliding arc plasma in humid air induces acid and oxidising reactions in the condensed phase. Acid effect results from the occurrence of NO species formed in the plasma and leads to the formation in water of nitrous and nitric acids, which are responsible for a steep pH fall. Using selected buffers allows accurate controlling of the acidity, which is necessary for most of the plasma-chemical or plasma-biochemical reactions.