Una nueva generación de carbones activados de altas prestaciones para aplicaciones medioambientales

Resumen

[EN] Activated carbon (AC) is a highly prized item on the world market for its numerous applications in the field of medicine, the biopharmaceutical industry and the environment. The search for environmentally sustainable and low cost processes has intensified research into the use of solid wastes from different sources as precursors of these carbon materials. In this thesis, anthracene oil was used as a precursor material of activated carbon. It was converted into pitch by polymerization using an oxygen-assisted heat treatment. The resultant pitch was partially pyrolyzed to generate a biphasic system consisting of mesophase and an isotropic phase (polymerized pitch). The two phases were separated and both were subjected to chemical activation. The resulting activated carbons showed surprising textural characteristics, such as a high surface area (up to 3200 m2·g-1) and a good micropore and mesopore development. The activated carbons were tested for adsorption processes in liquid phase and for the removal of organic compounds (benzene and toluene) and their adsorption capacity was found to be among the highest ever reported in the literature, reaching values of up to 860 mg·g-1 and 1200 mg·g-1, respectively, and 1200 mg·g-1 for the combined adsorption of benzene and toluene from an industrial wastewater. It was also observed that the adsorption kinetics in the batch experiments was extremely fast and was in accordance with the pseudo-second order kinetic model. This high kinetic performance was attributed to the combined presence of micropores and mesopores in the activated carbons. Finally, the potential of these activated carbons for the catalytic degradation of phenol in aqueous solution was analyzed when they were used as photocatalysts in physical mixtures of AC and TiO2. It was found that the apparent synergy between the AC and TiO2 particles resulted from an erroneous simplification of the Langmuir-Hinshelwood equation to a first order equation. When an extended form of the Langmuir-Hinshelwood equation which takes into account the inhibitory effect of the phenol concentration was applied, no synergistic effect of AC was observed. Thus, in physical mixtures, the AC merely reduces the inhibitory effect of the phenol concentration by decreasing its initial value but there is no synergistic effect.