Salah Meddah - ۱Environment Engineering Laboratory, University Badji-Mokhtar of Annaba, Algeria. ۲Department of Process Engineering, Faculty of Engineering Sciences, University Badji-Mokhtar of Annaba, Algeria.
Imene Djeghader - ۲Department of Process Engineering, Faculty of Engineering Sciences, University Badji-Mokhtar of Annaba, Algeria. ۳Organic Synthesis Laboratory, Modeling and Optimization of Processes, University Badji-Mokhtar of Annaba, Algeria.
Mohamed El-Hadi Samar - ۱Environment Engineering Laboratory, University Badji-Mokhtar of Annaba, Algeria. ۲Department of Process Engineering, Faculty of Engineering Sciences, University Badji-Mokhtar of Annaba, Algeria.
Fadhel Ismail - ۲Department of Process Engineering, Faculty of Engineering Sciences, University Badji-Mokhtar of Annaba, Algeria. ۳Organic Synthesis Laboratory, Modeling and Optimization of Processes, University Badji-Mokhtar of Annaba, Algeria.

The objective of this work was to model and optimize the degradation of black azodye Naphthol Blue Black (NBB) by the Fenton process (advanced oxidation)using a minimum of experiments. A Plackett-Burman screening design was firstapplied to determine the main factors influencing the process. The dyediscoloration efficiency gave a yield approximately equal to ۹۷ % in the bestconditions of several operating parameters used. The variance analysis (ANOVA)showed the effects of all different factors and deduced the most important ones.Subsequently, a second quadratic design of experiments central composite type(CCD) was applied using the response surface methodology (RSM) to optimizethe most important parameters deduced by the first design cited above, in order toobtain the best performance of the discoloration of NBB with this process. So from the contour plots and the response surfaces, the discoloration yield enhanced to the maximum and the optimization plot given by the Mnitab software, showed the following optimized parameters [NBB]=۳۷.۵ mg/L, [H۲O۲]=۶۶.۵ mg/L, [Iron]=۳.۵ mg/L and pH=۳.۴ for a yield of ۱۰۰ % with a desirability of ۱.۰۰۰۰. At last, to confirm that the discoloration was due to the degradation of the dye, the chemical oxygen demand (COD) was studied and in the optimized conditions, the degradation reached ۹۴.۷۸ % after ۱۲۰ min of treatment. The kinetics of the dye degradation showed by the COD abatement was relatively slow compared to the kinetics of the dye discoloration.

Water treatment, Fenton Process, Degradation, Azo dye, Experimental designs