Carbon Paste Electrodes Obtained from Organic Waste After a Biodrying Process and Validation in an Electro-Fenton System Towards Alternative Valorization

• Published in: Journal of the Mexican Chemical Society 2023-12, Vol.67 (4), p.359-370
• Main Authors: Vela-Carrillo, A.Z., Godínez, Luis A., García-Espinoza, J. D., Martínez, R.J., Franco-Hernández, M.O., Piña-Guzman, A.B., Santos, M.C., Robles-Martínez, F., Robles, I.
• Format: Article
• Language: English
• Subjects: Chemistry, Multidisciplinary
• ISSN: 1870-249X; 2594-0317
• DOI: 10.29356/jmcs.v67i4.1962

The transformation of agricultural waste into activated carbon represents an attractive approach as new and alternative source, but also as a reduction of pollution associated to the degradation of precursors. The organic residues sugarcane (Saccharum officinarum) bagasse-shell, orange (Citrus sinensis) peel-bagasse, and eucalyptus (Eucalyptus globulus) leaves, obtained from a biodrying process were transformed into activated carbons using phosphoric acid as activating agent. The resulting materials were physicochemically characterized and after that, carbonaceous electrodes were prepared to test the feasibility of using them in a discoloration electro-Fenton wastewater treatment process. Orange peel-bagasse biodried precursor transformed into activated carbon showed the highest efficiency when used as the modifier in a carbon paste electrode due to its highest porosity, electroactive area (24.9x10-2 cm2), and roughness (1.21 a.u.), also to its chemical affinity for anionic molecules. These properties, in addition to the capability of electro-sorb iron ions on the surface during the Fenton reaction, allowed a 44 % methyl orange discoloration efficiency. Sugarcane bagasse-peel and eucalyptus leaves biodried residues were also evaluated with efficiencies under 30 %, mainly attributed to intrinsic composition of the precursor materials.     Resumen. La transformación de los residuos agrícolas en carbón activado representa un enfoque atractivo y novedoso, además de que representa una alternativa a la reducción de la contaminación asociada a la degradación de residuos orgánicos. Los residuos orgánicos de bagazo de caña de azúcar (Saccharum officinarum), bagazo y cáscara de naranja (Citrus sinensis), y hojas de eucalipto (Eucalyptus globulus), que fueron obtenidos de un proceso de biosecado, se transformaron en carbón activado utilizando ácido fosfórico como agente activante. Los materiales resultantes se caracterizaron fisicoquímicamente y después de eso, se prepararon electrodos de pasta de carbón modificados con estos materiales, para estudiar la viabilidad de utilizarlos en un proceso de tratamiento de aguas residuales mediante electro-Fenton. El precursor biosecado de bagazo y cáscara de naranja transformado en carbón activado mostró la mayor eficiencia cuando se usó como modificador en un electrodo de pasta de carbón, debido a su mayor porosidad, área electroactiva (24.9x10-2 cm2) y rugosidad (1.21), también debido a su mayor afinidad química por moléculas