Optimization of the heterogeneous Fenton-oxidation of the model pollutant 2,4-xylidine using the optimal experimental design methodology

Among advanced oxidation processes (AOP), the photochemically enhanced Fenton reaction (photo-Fenton) may be particularly effective for the treatment of industrial waste water, and the possibility to use solar light is an additional advantage of this process. In the present work, a Fe3þ-exchanged zeolite Y was tested as a heterogeneous photo-Fenton catalyst for the degradation of the model organic pollutant, 2,4-xylidine. The performance of the catalyst was investigated using a bench photochemical reactor as well as solar reactors. The incident solar radiant powers (determined by ferrioxalate actinometry) showed linear correlations with the outputs of a Si-photodiode and a bolometer mounted on the solar unit, and could therefore be easily estimated from the on-line observation of the sensor outputs. The experimental design methodology was used for planning the experiments under normalized conditions and for modeling the rates of 2,4-xylidine oxidation as a function of the concentrations of the additives (Fe3þ-exchanged zeolite catalyst and hydrogen peroxide). Although a direct quantitative comparison between both reactors is difficult (different geometries and volumes, different spectral distribution of the radiation sources), the performance of the solar reactor appears to compare favorably with that of the bench photochemical reactor. 2004 Published by Elsevier Ltd.