The heterogeneous photo-Fenton reaction using goethite as catalyst

摘要

In the present work the degradation of 2-chlorophenol (2-CP) used as model compound, applyingnthe Heterogeneous photo-Fenton reaction, was studied. Small particles of goethite or ironnoxyhydroxide were used as a source of iron. The influence of catalyst loading, radiation intensitynand the molar ratio between hydrogen peroxide and contaminant were examined. Improvementnby illumination is highly significant. During the progress of 2-CP degradation, the reaction showsnan unusual acceleration. This autocatalytic comportment, with stronger tendencies at higherntemperatures, implies a completely different behaviour from the one typically expected. Thenautocatalytic performance is successfully explained by the joint action of two factors: (i) thenevolution of the available iron in the homogeneous phase during the course of the reactionnand (ii) the autocatalytic contribution of some of the reaction intermediates in the iron cycle.nThe small iron concentration leaching into the solution is produced by two typical liquid mediumn– solid goethite surface dissolution processes. A reaction mechanism has been proposed and, inna first stage, parameters have been obtained for the dark reaction. In a second step, thencomplete data for the irradiated operation were obtained.