Selecting and improving activated homogeneous catalytic processes for pollutant removal. Kinetics, mineralization and optimization.

The degradation of a model pollutant, tartrazine, very used in food industry and usually present in WWTPs effluents and surface waters, was investigated by nine activated homogeneous catalytic processes, namely, Fe/HO, Fe/HO, UV/HO, UV/SO, UV/Fe/HO, UV/Fe/HO, UV, VIS/Fe/HO, and VIS/Fe/HO/CO. In order to compare the mineralization and oxidation ability of each process, the removal of dye, chemical oxygen demand (COD) and total organic carbon (TOC) were analyzed, as well as the overall kinetic rate constant. Also, the different oxidation path-ways (direct photolysis and/or oxidation by free radicals) were estimated for each system. After the comparison, the Fenton process, which had the highest mineralization values, was tested in luminous and dark phases using designed experiments, and the influences of all operating variables were studied by RSM.