Synthesis of Zn-Al layered double oxides using eucalyptus leaf extract as template for efficient and ultrafast thorium(IV) removal

Efficient capture of Th(IV) from aqueous solution is of importance to both solve the radioactive pollution for environmental safety and provide clean energy for sustainable development. However, it still faces huge challenge. In this study, eucalyptus leaf extract was applied as template agent to fabricate Zn/Al-bimetallic layered double oxides (ZnAlLDO), providing more active sites for Th(IV) removal. The removal process of Th(IV) onto ZnAlLDO could reach equilibrium within 5 min and the maximum removal capacity calculated from the Langmuir model was 1153.71 mg g −1 at pH = 4.0 and 298 K. Over 97 % Th(IV) could be removed by ZnAlLDO during the dynamic adsorption process and the removal efficiency still remained at a high level (85 %) after 5 cycles. The Th(IV) removal process on ZnAlLDO was ascribed to electrostatic attraction, complexation and ion exchange. It could be believed that the ZnAlLDO with large removal capacity (1155.5 mg g −1 ), fast equilibrium time (5 min) and easy desorption (91.76 %) with high recovery (85 %) might be a promising adsorbent for the separation of Th(IV).