Cu(II) adsorption from aqueous solutions using the inner and outer portions of sugarcane bagasse

In the present work, the adsorption capacity of internal and external portions of treated sugarcane bagasse (SCB) to remove Cu(II) from aqueous solution was evaluated. In order to reuse this solid waste as an effective adsorption material, both portions were treated with three different solutions (hot water, ethanol and NaOH) to remove sugar, external gummy tissue and impurities. Adsorption experiments were carried out in a batch system at room temperature. The kinetic data were fitted to pseudo-second order and Elovich models for the internal portion, and to the Elovich model for the external portion reaching equilibrium times from 8 to 24 h. Freundlich and Langmuir–Freundlich models described well the adsorption behavior of all systems. The compositional differences of the two portions of SCB and the surface chemistry were analyzed. Material characterization by scanning electron microscopy, Fourier transformed infrared spectroscopy, and X-ray photoelectron spectroscopy demonstrated morphologic and chemical modifications of the material after each treatment. Results showed that external SCB treated with a sodium hydroxide solution and internal SCB treated with ethanol solution were the best adsorbent materials, and provided a surface with more affinity to remove Cu(II).