Desorption behavior of U(VI) from kaolinite and hematite by Shewanella putrefaciens cells and extracellular polymeric substances.

The desorption of U(VI) from minerals by microorganisms and their extracellular polymeric substances (EPS) was characterized with Shewanella putrefaciens (S. putrefaciens) as a typical bacterial strain, while kaolinite and α-Fe₂O₃ as typical minerals. Based on the results, EPS contributed significantly to U(VI) desorption from minerals. Two kinds of mechanisms should be mainly involved in U(VI) desorption, including the competition for the adsorption sites of minerals between U(VI) and bacterial cells or EPS, and the formation of stable U(VI)–bacterial cells or U(VI)–EPS complexes. Desorption kinetics indicated that the desorption process of U(VI) on minerals was a complex heterogeneous diffusion and chemical desorption process. [ABSTRACT FROM AUTHOR]