Evaluation of degradation and kinetics parameters of acid orange 7 through wet air oxidation process

Abstract

AbstractAmong the industrial effluents presenting constraints to traditional biological treatments, those from textile industries are of particular concern. Wet air oxidation is an effective process that significantly increases biodegradability of the treated effluent. In this study, the advantage of this process was tested for the treatment of acid orange 7, a dye molecule used as a model textile effluent. Different experimental conditions of temperature (200 to 300 °C) and duration of treatment were used to determine its degradation yield during the wet air oxidation process, at a total pressure of 30 MPa. All these conditions led to complete degradation of acid orange 7, but residual Total Organic Carbon always remained. Oxidation byproducts were identified by the means of GC and HPLC analyses. Acetic acid remains the major compound not oxidized. These experiments resulted in the proposal of a reaction scheme associated with kinetic constants. Finally, the optimal conditions for the improvement of the biodegradability of the effluent were determined. This wet air oxidation process could then be coupled with a biological treatment to obtain an overall degradation meeting the criteria for release into the environment.