Cascas residuais de pitaia de polpa vermelha (hylocereus polyrhizus) como biossorvente para remoção do hormônio 17α-metiltestosterona

Abstract

Emerging contaminants, such as endocrine disrupting hormones, are compounds detected in low concentrations (ng L-1

– μg L-1 ), which cause various environmental disturbances, especially to water resources. Due to their low water solubility, these pollutants tend to naturally accumulate in solids in solution, so adsorption is a promising treatment approach. In this sense, aiming at the development of sustainable technologies, which include the treatment of pollutants and also the reuse of agro-industrial residues, residual peels of red pulp pitaya (Hylocereus polyrhizus) in natura (IN) and after alkaline treatment (CT) were

investigated. regarding the efficiency of removing the endocrine disrupting hormone 17α- methyltestosterone in aqueous solution. Effects of the amount of biosorbent, the initial

concentration and the pH of the medium were evaluated and indicated the best conditions for carrying out the studies. The characterizations showed changes in the surface of the material after the alkaline treatment process, in which the formation of micropores was observed, in addition to changes in the composition and thermal stability of the biomass. Infrared analysis after adsorption revealed the influence of -OH functional groups of phenols and alcohols, C=O of carboxylic acids and esters and bonds associated with aromatic rings on hormone removal. The mass transfer process was shown to be governed by a pseudo-second order kinetics in which the slow step corresponded to the formation of chemical bonds. The isothermal study revealed high efficiency at low concentrations, reaching equilibrium quickly, in which the removal occurred in homogeneous sites with monolayer formation. According to the adjustment to the Dubinin-Radushkevich model for the treated material, the micropores formed by the chemical modification were relevant in the removal of methyltestosterone. These results, associated with the low concentrations at which emerging contaminants are found, point to pitaya biosorbent as a potentially advantageous and low-cost alternative for removing the hormone.