Biosorption of rare earth elements by Escherichia coli

Biosorption, which takes place by passive metal-sequestering, has recently attracted attention as an alternative to conventional separation processes such as precipitation and solvent extraction. In this work, the adsorption behavior of rare earth elements (REEs) onto an Escherichia coli (E. coli) bacterial adsorbent was examined. The adsorption of REEs increased with increasing pH of the feed solution. Also, E. coli showed a higher selectivity for heavier REEs, especially for scandium. To elucidate the adsorption mechanism, the functional groups on the E. coli were chemically modified. By analyzing the adsorption behavior and FT-IR spectra of these E. coli samples before and after adsorption, it was confirmed that REEs are adsorbed at phosphate and carboxyl groups on the surface of E. coli. It is concluded that E. coli is a potential novel adsorbent for REEs.