Removal of the heavy metal ions from aqueous solution using modified natural biomaterial membrane based on silk fibroin

Water-insoluble silk fibroin (WSF) membrane was prepared by co-blending and interaction of fibroin and silane coupling agent. A novel Schiff base with a chelating group, 3,5-bis-{2-hydroxyphenyl-5-[(2-sulphate-4-sulphatoethylsulphonyl-azobenzol) methylene amino]} benzoic acid (BHSABA), was applied to modify WSF membrane. The morphological structure and surface element analysis of WSF and its modified membrane (MWSF) were investigated by scanning electron microscopy (SEM) and energy dispersive spectrometer (SEM-EDS). The sorption behavior of MWSF membrane for six metal ions, Cu(II), Co(II), Ni(II), Cr(III), Pb(II) and Cd(II), were measured. MWSF membrane had the significantly selective sorption for Pb(II) and Cd(II) metal ions and the removal percentage being 82% and 56%, respectively. The adsorption kinetics of MWSF membrane for Cd(II) was analyzed by the pseudo-first-order and pseudo-second-order equations. The adsorption removal process for Cd(II) metal ion was in line with the pseudo-second-order model. MWSF membrane as bioabsorbent has potential application for removal heavy metal ions from the aqueous solution. (C) 2016 Elsevier B.V. All rights reserved.