Wastewater treatment is an important subfield of environmental chemistry. Fenton-like reactions are very promising for the removal of organic compounds from wastewater. In the classical Fenton reaction, a mixture of Fe2+/Fe3+ ions is used to catalyze the production of strongly oxidizing hydroxyl radicals from H2O2. These radicals attack and degrade the organic molecules, e.g. azo, henothiazine or xanthene dyes which results in the decolorization of wastewater. SECM can be used to study the catalytic activity for generation of hydroxyl radicals.
Novel catalysts, such as nanostructured Fe3O4 were studied in the redox competition mode where H2O2 is consumed at the catalyst and at the microelectrode simultaneously. A decrease in current at the microelectrode is attributed to lower concentration of H2O2 in the vicinity of the catalyst and therefore higher catalytic activity for the generation of hydroxyl radicals.

Gao, Y., Hu, C., Zheng, W. J., Yang, S., Li, F., Sun, S. D., & Chen, Y. M. (2016). Fe3O4 anisotropic nanostructures in Hydrogels: efficient catalysts for the rapid removal of organic dyes from wastewater. ChemPhysChem, 17(13), 1999-2007.