Modification of crosslinked chitosan beads with histidine and Saccharomyces cerevisiae for enhanced Ni(II) biosorption

Glutaraldehyde-crosslinked chitosan beads modified with histidine and Saccharomyces cerevisiae (SC-HIS-CCBs) were applied as new biosorbents for enhanced adsorption of Ni(II) from aqueous solutions. The SC-HIS-CCBs were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis. The effects of various parameters, such as pH, contact time, and amount of biosorbent, on Ni(II) biosorption were investigated. The optimal pH was found to be 6.0. Isotherm data fit the Freundlich equation well, although they could be described by the Langmuir equation. The pseudo-second-order kinetic model could better follow the biosorption process in contrast to the pseudo-first-order kinetic model. The thermodynamic parameters of Ni(II) biosorption, including Gibbs free energy change (Delta G), enthalpy change (Delta H), and entropy change (Delta S), were calculated. The negative Delta G value indicated the spontaneous nature of Ni(II) biosorption on the SC-HIS-CCBs. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.