Wastewater treatment with heterogeneous Fenton-type catalysts based on porous materials

The Fenton reagent which was discovered by H. J. H. Fenton over 100 years ago is still of special interest for wastewater treatment in the present time. The main objective of heterogeneous Fenton catalysts is the combination of high activity, low iron leaching and the possibility of employing the system at pH environments near neutrality. This review discusses the use of iron-containing pillared clays as well as micro- and mesoporous (alumino-) silicate catalysts prepared by ion-exchange, impregnation or direct synthesis for the degradation of organic compounds like phenol and organic dyes including Orange II. Moreover, the treatment of more complex waste streams is reviewed. After a general introduction into the chemistry of the Fenton and the photo-Fenton reaction as well as the catalysts employed, specific examples are discussed with respect to the active species present, the stability of the catalyst and the influence of reaction conditions such as pH, temperature and the presence of impurities.