(467a) Lanthanide Binding Tag Peptides for the Foam Fractionation of Rare Earth Elements | AIChE

(467a) Lanthanide Binding Tag Peptides for the Foam Fractionation of Rare Earth Elements


Ortuno, L. - Presenter, City college of New York
Crane, S., University of Pennsylavania
Stebe, D. K. J., University of Pennsylvania
Bu, W., NSF's ChemMatCARS, University of Chicago
Lin, B., NSF's ChemMatCARS, University of Chicago
Tu, R. S., City College of New York
Maldarelli, C., Levich Institute, City College of New York
Solvent extraction is widely used for separation of rare earth elements trivalent cations (REEs or Ln3+) from an aqueous phase into an organic solvent. This process is energy intensive and environmentally unfriendly, requiring large volume of organic solvent and organo-phosphate surfactants. Here, we exploit the high affinity of a surface-active Lanthanide Binding Tag (LBT) peptide (LBT1, YIDTNNDGWYEGDELLA), that coordinates selectively with Ln3+ ions for its use in a bioinspired/eco-friendly extraction processes in which the complexed LBT1-Ln3+ peptide adsorbs to the air/aqueous interfaces of bubbles for foam recovery. To understand the surface activity and identify the bound cationic species at the air-water interface, we characterized the surface molecular adsorption and arrangement of LBT1 and the more surface active LBT1-LLA, which has three additional hydrophobic residues (-LLA) attached to the C-terminus of LBT1. For this, we measured the relaxation dynamic tension of the each LBT in the absence and presence of Tb3+ cations. X-ray reflectivity (XRR) and X-ray fluorescence near total reflection (XFNTR) measurements on the adsorbed layer were used to compute the surface concentration of the peptide and the Ln+3 cation, and the thickness of the interfacial layer. The addition of three hydrophobic residues to LBT1 increased the surface density of the peptide by three-fold. Additionally, the LBT1-LLA improved the adsorption of Tb3+ ions to the air-water interface up to approximately 30% over LBT1 peptides. The interfacial density of Tb-bound LBT1-LLA increased between 50% and 100% compared with the Tb-free, unbound LBT1-LLA. We also observed a four-fold increase in the surface coverage of LBT1 in the Tb-bound state over the Tb-free state. The enhancement in the surface activity of LBTs peptides is improved by the addition of hydrophobic residues appended to the C-terminus of the peptide. This improvement in the hydrophobicity of these biomolecules could be advantageous for a green, eco-friendly separation method of REEs.