Polpa e casca do jatobá: biossorventes aplicados no processo de remoção de cromo aquoso

Abstract

Effluents containing toxic metals pose risks to both living beings and the environment, therefore, these effluents need to be properly treated. New materials, such as biosorbents, have been extensively tested in the treatment of these effluents due to their effectiveness and low cost. The aim of this study was to synthesize biosorbents from the pulp (BP) and peel (BC) of jatobá fruit for the removal of aqueous Cr (VI). Both biosorbents were characterized by Fourier- transform infrared spectroscopy (FTIR), atomic absorption spectrometry (AAS), thermogravimetric analysis (TG) and differential thermal analysis (DTA), zero point of charge (pH PCZ), and through physical characterization and fruit yield in relation to the whole fruit. The results show that both biosorbents have slightly acidic pH PCZ and are composed mainly of elements such as calcium, magnesium, copper, manganese, zinc, and iron, at relatively low concentrations. FTIR analyses revealed the presence of functional groups such as hydroxyls and carboxyls on the surfaces of the biosorbents. Additionally, TG and DTA thermograms indicated that the biosorbents are predominantly composed of organic materials that decompose in several thermal events. Removal tests were conducted by altering the pH of Cr (VI) solutions, based on experimental results it was found that the optimal removal of Cr (VI) ions occurred at pH 3 for both biosorbents, with maximum removal of 91.2% for BP and 95.5% for BC. The adsorption process followed a pseudo-second-order kinetics for both biosorbents, and equilibrium adsorption was best represented by the Freundlich isotherm for both biosorbents. The results suggest that biosorbents produced from jatobá fruit pulp and peel have the potential to remove chromium (VI) from effluents.