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Degradation of Recalcitrant Safranin T Through an Electrochemical Process and Three Photochemical Advanced Oxidation Technologies

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This work studies the degradation of safranin T (SF, a recalcitrant pollutant) by an electrochemical process and three photochemical advanced oxidation technologies (TiO2 photocatalysis, UV/H2O2, and photo-Fenton). The degradation routes of each process were elucidated initially. Based on the mineralization extent, improvement of the treated solutions’ biodegradability, and energy consumption, the most suitable process was identified. Interestingly, in the electrochemical system, safranin T was efficiently eliminated through electrogenerated HOCl. In contrast, the popular photo-Fenton process was unable to degrade SF. Moreover, the pollutant was refractory to highly energetic UV254 irradiation. Meanwhile, the UV/H2O2 and TiO2 photocatalysis processes removed SF slowly. Interestingly, the electrochemical system produced biodegradable solutions. Furthermore, the electrical energy consumption (EC) for the 100% removal of SF showed that the electrochemical process only spent 0.04 and 0.06% of the EC needed by TiO2 photocatalysis and UV/H2O2, respectively. Therefore, the fast SF degradation, the high biodegradability intensification, and the very low energy consumption evidenced the relative advantages of the electrochemical process for the remediation of water containing safranin T. Finally, to obtain a deeper understanding of SF degradation by the electrochemical system, an analysis of structural transformations was made. It was found that the electrogenerated HOCl initially attacked the central azine and the aromatic amines on SF. Subsequently, aliphatic compounds were formed, which due to their biodegradable character could be completely eliminated by a conventional biological system or discharged into natural media.

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The authors thank Stephanía Lopera, Estefanía Salazar, and Margee Perea for their research assistance. E. Serna-Galvis thanks Colciencias for his Ph.D. scholarship (Convocatoria 647 de 2014).


The authors thank IUCMA and Colciencias for the financial support through the projects: “Tratamiento de residuos orgánicos vía Procesos Avanzados de Oxidación (PAOs) del Laboratorio de Ambiental de la Institución Universitaria Colegio Mayor de Antioquia (IUCMA)” and “Desarrollo y evaluación de un sistema electroquímico asistido con luz solar para la eliminación de contaminantes emergentes en agua (No. 111565842980), respectively.

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Correspondence to Efraím A. Serna-Galvis or Ricardo A. Torres-Palma.

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Granda-Ramírez, C.F., Hincapié-Mejía, G.M., Serna-Galvis, E.A. et al. Degradation of Recalcitrant Safranin T Through an Electrochemical Process and Three Photochemical Advanced Oxidation Technologies. Water Air Soil Pollut 228, 425 (2017). https://doi.org/10.1007/s11270-017-3611-2

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  • Pollutant degradation
  • Water treatment
  • Processes comparison
  • Biodegradability intensification