Electrode-Induced UO22+ immobilization by Leifsonia sp. within an iron-Sulfur complex system

In-situ bacterial remediation has shown substantial potential for decommissioned uranium mining areas. Our previous research indicated that the similar redox potentials of Fe(III)/Fe(II) and U(VI)/U(IV), along with iron's significance in bacterial growth and metabolism, provide a basis for synergistic uranium remediation. This study investigated the impacts of diverse electrode voltages on U(VI) immobilisation by Leifsonia sp. in an iron-sulfur co-existing system. Bacteria immobilise U(VI) by adsorption. SEM-EDS and XPS analyses confirmed that electro-stimulated bacteria (under applied voltage) reduced U(VI) to U(IV), forming Fe-U complexes. For comparison, under open-cell conditions (i.e. the electrochemical cell was in an open-circuit state without applying any external constant voltage), U(VI) removal was negligible. The optimal voltage (3.0 V) enhanced U(VI) removal via bacterial adsorption and incorporation into Fe-S compounds. However, too high a voltage hindered U(VI) removal.