Performance study of heavy metal ion adsorption onto microwave-activated banana peel

In this paper, the normally dried banana peel (BPD) was activated by microwave (BPM). A comparative study of Cr(VI) and Ni(II) removal from aqueous solution using BPD and BPM was performed. Effects of initial concentration, pH value, time, and dosage on the adsorption capacity were studied. The pore structure, specific surface area, and morphology of BPM and BPD were characterized by N-2 adsorption apparatus and scanning electron microscopy, respectively. Batch tests were carried out to investigate the adsorption performance. The results showed that the adsorption capacity of Cr(VI) and Ni(II) onto BPM is much higher than that onto BPD. The process of Cr(VI) and Ni(II) onto BPD could not fitted well with Lagergren first-order model or pseudo-second-order model. But the process of Cr(VI) and Ni(II) adsorption onto BPM-fitted pseudo-second-order model, with the rate constants (k(2)) of 9.36 and 6.01 g mg(-1) min(-1). The isothermal of Cr(VI) and Ni(II) adsorption onto BPD and BPM can be described by Freundlich model. The Freundlich exponent n was between 2.14 and 2.83, which was indicated favorable adsorption.