Characterization of PEI-modified biomass and biosorption of Cu(II), Pb(II) and Ni(II).

The objective of this work is to develop a surface-modified biosorbent with enhanced sorption capacity for heavy metal ions. The biomass of Penicillium chrysogenum was modified with polyethylenimine (PEI) and then crosslinked with glutaraldehyde. The crosslinked PEI was chemically bonded on the biomass surface through the amine and carboxylate groups on the pristine biomass. The presence of the amine group was confirmed by X-ray photon spectroscopy (XPS) and Fourier transform infrared (FTIR) analysis, and the concentration of the amine groups on the biomass surface was found to be 2 mmol/g through potentiometric titration. The rugged morphology of the biomass surface after the modification was observed by scanning electron microscope (SEM). Compared with the pristine biomass, the modified biomass with amine groups showed a significant increase in sorption capacity for three metal ions, namely, copper, lead and nickel. The sorption isotherms of the biomass for three metals were well described by Langmuir equation, with a maximum sorption at 92 mg copper, 204 mg lead and 55 mg nickel per g biomass. The binding sites for the three metals attributed to the amine groups on the biomass surface were verified by FTIR analysis.