Sequestering of Cu(II) from aqueous solution using cassava peel (Manihot esculenta)

Cassava peel is a prospective cheap biosorbent for metal ions sequestration. In this research, the ability of cassava peel to remove Cu(II) from aqueous solution was evaluated. Its physical characteristics were probed by nitrogen adsorption measurements and scanning electron microscopy while its biosorption mechanism was studied by Fourier Transform Infrared (FTIR), Scanning Electron Microscopy/Energy Dispersive using X-ray analysis-(SEM/EDX), X-ray mapping and X-ray Photoelectron Spectroscopy (XPS). Biosorption experiments were carried out isothermally at three different temperatures (30 °C, 45 °C and 60 °C) in a static mode. The maximum adsorption capacity (41.77 mg g−1) was attained at the highest temperature. The pH and particle size effects in relation to biosorption capacity were also discussed. In addition, Langmuir, Freundlich, Sips and Toth equations were tested for data correlation. Langmuir and Freundlich models were the best choices since they contained less parameter with equally good fitting performance in comparison to the other three parameters equations. For kinetic studies, sorption rates were better represented using a pseudo second-order expression in comparison to a more commonly used pseudo first-order equation. Also, thermodynamic variables showed that the process was spontaneous (ΔG < 0), endothermic (ΔH > 0) and irreversible (ΔS > 0).