Efficient recovery of lithium from shale gas wastewater: Fe, Ni, and Al doping of H1.33Mn1.67O4 for improved adsorption capacity and manganese loss reduction

To minimize manganese loss during acid leaching and to enhance the lithium adsorption capacity from shale gas wastewater of H 1.33 Mn 1.67 O 4 , this adsorbent material was doped with metallic elements in this study. Doping was achieved using solid-phase synthesis, resulting first in a Li 1.33 R X Mn 1.67−X O 4 (R = Fe, Ni, Al) precursor powder through high-temperature calcination. Then, lithium was leached out under acidic environment to obtain the desired H 1.33 R X Mn 1.67−X O 4 (HMO-R) adsorbents. The equilibrium adsorption capacities of HMO-R powders were measured as 20.7 mg/g, 20.7 mg/g, and 29.0 mg/g, for Fe, Ni, and Al dopants, respectively, surpassing that of the former H 1.33 Mn 1.67 O 4 (13.7 mg/L). Moreover, an average reduction of manganese loss by 30% for HMO-R was observed during lithium recovery/extraction cycles by acid leaching compared to undoped Li 1.33 Mn 1.67 O 4 . Overall, the doped adsorbent exhibited a stable crystal structure and high adsorption capacity, enhanced stability, performance, and efficiency in cycling experiments with respect to the undoped material.