Adsorption and degradation of rhodamine B and bromocresol green by FeOCl under advanced oxidation process
Claudia Revilla Pacheco, Melani Ruth Riveros Cruz, Jaime Cárdenas García, Ruly Terán Hilares, Gilberto de Jesús Colina Andrade, David A. Pacheco Tanaka, Alejandra Mogrovejo-Valdivia
Abstract
FeOCl has gained popularity as a heterogeneous catalyst for pollutant removal in the Fenton process. However, humidification and adsorption of FeOCl are usually not considered in the process. In this way, the adsorption and Fenton activity using rhodamine B (RhB, cationic compound) and bromocresol green (BCG, anionic compound) as pollutants models, at various pH were studied (2, 3.6, 7, and 10). These studies show a very low adsorption level for RhB only at pH 10; therefore, the removal was due to the Fenton reaction. For BCG, at pH 10 the adsorption is almost zero, and at pH 7 after 240 min the adsorption was almost complete, at pH 7, the dye removal by adsorption is akin to Fenton, therefore, at this pH, the remotion was entirely attributed to adsorption. The solution’s removal is the result of the adsorption and Fenton reaction. Additionally, the photocatalytic and photo-Fenton activity of FeOCl was studied by the removal of RhB from a solution at pH 3.6, removing about 84 and 95% of the dye respectively. Under these circumstances, FeOCl is a potential catalyst that could be used for Fenton, photo-Fenton, and photocatalysis. However, the present paper’s experimental data shows that its activity depends largely on the percentage of humidity in the catalyst and the ionic charge of the contaminant that will be treated by the catalyst once it has been activated by water vapor. Characterization essays, such as XRD, show a match for the synthesized FeOCl and FT-IR shows a peak change in the -OH groups range. This could be a possible explanation for the apparition of free radicals.