Synthesis of La-doped Mg-Al layered double oxide for selective tellurite adsorption

Polonium was a highly toxic and radioactive nuclide commonly detected in wastewater from spent fuel reprocessing and lead‑bismuth-cooled reactor systems, making its removal essential for nuclear safety. In this work, lanthanum-modified magnesium‑aluminum layered double oxide (La-MgAl-LDO) was prepared by doping La(III) in Mg-Al layered double oxide (Mg-Al-LDO). Additionally, tellurium, which has similar chemical properties, was used as a substitute for polonium to investigate the adsorption performance. Under the optimized conditions (pH = 6, m/V = 0.2 g/L, and C 0  = 20 mg/L), La-MgAl-LDO achieved a maximum removal efficiency of 99% for tellurite. The adsorption of Te(IV) onto La-MgAl-LDO followed the pseudo-second-order and Freundlich models, indicating that the adsorption process was characterized by multilayer chemical adsorption. The Te(IV) adsorption mechanisms mainly include co-precipitation and surface complexation. In addition, the study confirmed that La 3+ reacted with Te(IV) to form a stable solid precipitate (La 2 Te 6 O 15 ), which played a crucial role in the removal of Te(IV) from aqueous solution.