Synthesis of H 4 Mn 5 O 12 Nanotubes Lithium Ion Sieve and Its Adsorption Properties for Li + from Aqueous Solution

Li 4 Mn 5 O 12 with nanotubes morphology was successfully prepared by hydrothermal and solid phase reaction. The as‐obtained adsorbent was determined by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and N 2 ad/desorption technologies. The characterization results indicated that spinel H 4 Mn 5 O 12 took on two‐dimensional nanotubes morphology with the diameter of pore ∼200 nm, BET surface area is 92.997 m 2 ⋅g −1 , and the corresponding pore size centers at 3.4, 35.9 and 156.5 nm. The adsorption experimental results showed that the maximum Li + adsorption capacity of H 4 Mn 5 O 12 was as high as 37.0 mg⋅g −1 , and the adsorption process fit well with Langmuir model. In addition, adsorption kinetic experimental data were well fitted by the pseudo‐second‐order model, which indicated the adsorption process followed chemisorption involving in ion exchange. The effects of co‐existing cations on lithium recovery suggested that Na + , K + , Ca 2+ and Mg 2+ ions had very small effect on recovery of lithium. The regeneration of H 4 Mn 5 O 12 for the multicyclic Li + adsorption and desorption were also assessed. The result implied that most of Li + could be desorbed within 40 min, but the adsorption capacity decreased when the number of cycles was five, which indicated that the structure of H 4 Mn 5 O 12 was needed to be improved. Lithium adsorption onto H 4 Mn 5 O 12 could be attributed to electrostatic interaction and ion exchange between Li + and H + according to the results of adsorption isotherm and kinetics properties.