Adsorção do corante azul de metileno em adsorvente da casca de pequi pura e modificada como alternativa para tratamento de efluentes.

Abstract

Pequi peels account for approximately 84% of the weight of the fruit, and most of them are discarded inappropriately, causing environmental impact. Therefore, this research aimed to characterize the pure pequi peel and the peel modified with sulfuric acid as an adsorbent, aiming at their use in the adsorption of methylene blue dye in aqueous solution. The moisture content and ash content were determined; the modified pequi peel presented a lower moisture content compared to the pure pequi peel. The adsorption kinetics were applied with variations in contact time from 0 to 240 minutes between adsorbent and adsorbate. With the results obtained, the Freundlich and Langmuir adsorption isotherms were used to perform the adjustments of the results obtained. The pH of the solutions was determined, and a greater adsorption was observed in solutions with pH > 7. The kinetic study of the adsorption of methylene blue by the pure and modified pequi peel adsorbent concluded that the modified pequi peel was more effective in this adsorption, due to an electrostatic interaction between the active surface of the modified pequi peel and the dye molecules, which is cationic, favoring the adsorption in this solution. The results obtained were the adsorption capacity of 3.85 mg g-1 in the contact time of 5 min for the pure pequi peel and 3.97 mg g-1 for the modified pequi peel.