Polyethylenimine-cross-linked cellulose nanocrystals for highly efficient recovery of rare earth elements from water and a mechanism study

Feiping Zhao, Eveliina Repo, Yang Song, Dulin Yin, Samia Ben Hammouda, Li Chen, Simo Kalliola, Juntao Tang, Kam C. Tam, Mika Sillanpää

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205 Citations (Scopus)


The ever-increasing demand for Rare Earth Elements (REEs) due to their increased use in various high-tech and futuristic applications has stimulated the development of new sustainable approaches for efficient REE separation and recovery. Herein, we report on the development of polyethylenimine (PEI) cross-linked cellulose nanocrystal (CNC) materials for use as high performance sustainable adsorbents for REEs. This cross-linking reaction occurs in aqueous solution and traditional toxic cross-linkers are not involved. Importantly, PEI acts not only as an emerging cross-linker but also as coordination sites for REE binding. The adsorbents were qualitatively and quantitatively characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), elemental analysis, zeta-potential, thermogravimetric analysis (TGA), and conductometric-potentiometric titration. In a single-component system, the adsorption behavior showed heterogeneous adsorption capacities of 0.611, 0.670, and 0.719 mmol g-1 for La(III), Eu(III), and Er(III), respectively. The similarity of chemical properties makes REEs difficult to separate from each other, but the materials displayed preferential adsorption for Er(III) compared to La(III) and Eu(III) in a ternary REE solution. The FT-IR, XPS and EDS mapping results revealed the importance of the primary and secondary amino functional groups as the principal REE binding sites. Overall, this study demonstrates a facile route for separation, recovery, and enrichment of REEs from aqueous solution.

Original languageEnglish
Pages (from-to)4816-4828
Number of pages13
JournalGreen Chemistry
Issue number20
Publication statusPublished - 2017
Externally publishedYes

ASJC Scopus subject areas

  • Environmental Chemistry
  • Pollution


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