The performance and mechanism of recovering lithium on H4Ti5O12 adsorbents influenced by (1 1 0) and (1 1 1) facets exposed

The improved adsorption capacities by increasing specific surface area methods are merely reached about 50% of H 4 Ti 5 O 12 ’s theoretical adsorption capacity, and the adsorption behavior and mechanism of lithium on special facets of H 4 Ti 5 O 12 remain unclear. In this study, a flower-shaped Li 4 Ti 5 O 12 and an octahedral Li 4 Ti 5 O 12 were prepared with the specific surface areas of 176.23 and 83.02 m 2 /g, and the corresponding adsorption behaviors of the obtained adsorbents exposed with (1   1   0) and (1   1   1) facets were investigated by using experimental and computational methods. The maximum Li + uptake values on H 4 Ti 5 O 12 (1   1   0) and H 4 Ti 5 O 12 (1   1   1) are 26.85 mg/g and 33.56 mg/g at 45 °C in 24 mM LiCl solutions, respectively. The fifth reuse ability of H 4 Ti 5 O 12 (1   1   1) still remains 88.9% of the original’s, which is higher than H 4 Ti 5 O 12 (1   1   0) (76.3%). Although with lower specific surface area, the octahedral H 4 Ti 5 O 12 have higher ions selectivity , greater adsorption capacity, and better reuse ability than flower-shaped H 4 Ti 5 O 12 , which may due to the special (1   1   1) facet exposed. Firstly, H 4 Ti 5 O 12 (1   1   1) owned small hole sizes can inhibit other ions diffusing into H 4 Ti 5 O 12 and improve the ion selectivity. Secondly, the immigration paths by the First-principles calculations revealed that the Li + migrate onto the Li 4 Ti 5 O 12 (1   1   1) is easier to than Li 4 Ti 5 O 12 (1   1   0) through 8a-16c-8a-16c sites. At last, [Li(H 2 O) 4 ] + can form the stable complexes and its adsorption energies on (1   1   1) are higher than on (1   1   0) facets, which may lead to larger adsorption capacity and better reuse ability. This work will help to understand the [Li(H 2 O) 4 ] + adsorption behavior and mechanism on different crystal facets by experiments and computations.