Removal of lead from water solution by reusable magnetic adsorbent incorporating selective lead-binding peptide

Abstract

As a reusable adsorbent to remove lead from water, a peptide-based magnetic adsorbent incorporating lead-binding peptide was constructed. First, a 7-mer lead-binding peptide (TNTLSNN) was covalently bonded onto the surface of a magnetic bead. Compared to the adsorption capacity of a bare magnetic bead (4.0 mg lead/g bead), the peptide-linked bead exhibited a capacity more than eight times higher than that of a bare bead (34.1 mg lead/g bead). The regenerated peptide bead, by desorbing the lead from the bead with EDTA, could be repeatedly used (tested over six cycles) for the following round of lead adsorption without any significant loss of adsorption capacity. The selective removal of lead in the presence of other interfering metals was demonstrated with the individual or the combinatory use of four metal ions, namely Pb(II), Ni(II), Co(II), and Cu(II), where the amount of adsorbed Pb(II) was remarkably higher than those of the other metal ions. The adsorption isotherm followed the Langmuir model well, with the maximum adsorption loading (qmax) of 70.4 mg lead/g bead.