Carvão ativo de farelo de girassol modificado com grupo sulfônico e amino para remoção de fenilalanina em soluções puras e multicomponentes contendo tirosina.

Abstract

This work aims to investigate the applicability of sunflower meal as a precursor material for the production of active charcoal used in the adsorption of phenylalanine, tryptophan, tyrosine, and in binary solutions of phenylalanine with tyrosine. Thermal conversions were carried out in a microwave oven and conventional oven (muffle). Chemical modification of the adsorbent surface with the introduction of sulfonic groups was carried out using an adapted methodology, which exhibited some advantages such as reduced time and less use of reagents. The MPS500 charcoal showed a higher performance index for the adsorption of the amino acid when compared to the unmodified charcoal. The predominance of micro and mesopores influenced the reduction of the equilibrium time of the adsorption process, when compared to other adsorbents. The FTRI analyzes confirmed the introduction of sulfonic groups, and the qualitative analysis of the elements presented in the samples by EDS corroborate these results. The adsorption equilibrium data of L - phenylalanine at temperatures of 25, 35 and 45 °C were analyzed and the best fit occurred for the Freundlich isotherm model. The adsorption kinetics that best described the experimental data was the pseudo-second order model, indicating a short equilibrium contact time, confirmed by laboratory results. The thermodynamic parameters indicated a spontaneous exothermic process, with greater randomness of the system. In binary systems, the activated carbon produced was more selective for the adsorption of phenylalanine and with less adsorption of tyrosine. The carbon modified with quaternary ammonium presented infeasibility of its use as an adsorbent for the adsorption of L-phenylalanine, since the modification resulted in a decrease of the adsorption capacity. The adsorption mechanism could be explained by the synergism of textural properties and chemical interactions such as dipole - dipole hydrogen bonding, Yoshida hydrogen bonds, n -  interactions, and nonpolar interactions with phenylalanine on surfaces functionalized with sulfonic groups. Thus, it is concluded that sunflower meal can be used as a precursor material in the production of low cost activated carbon for phenylalanine removal.