Mechanism of lithium adsorption by AlLi-LDH with Al-O octahedral ring
(School of Metallurgical Engineering, Anhui University of Technology, Ma’anshan 243032, China)
Abstract: Aluminum-lithium layered double hydroxide (AlLi-LDH) was synthesized using a co-precipitation method for Li+ adsorption. AlLi-LDH crystallized in space group of P32 or C2/m, where the microstructure had regular spherical shapes with diameters of 5-10 μm. The space group of AlLi-LDH only belonged to P32 after Li+ adsorption. The Li+ adsorption from a solution with a Li+ concentration of 95.4 mg/L reached 8.98 mg/g after 1 h. The adsorption amount increased to 16.50 mg/g after 48 h, where the Li+ adsorption capacity determined by applying the second-order adsorption model was 17.57 mg/g. The Mg2+/Li+ separation coefficient was 29536 when the mass ratio of Mg2+ to Li+ was 1067. The interaction strength of Li-O was weaker for AlLi-LDH in the P32, where the interaction occurs via the electrostatic effect. The Li+ adsorption and desorption occurred more readily in AlLi-LDH belonging to P32 space group.
Key words: co-precipitation; aluminum-lithium layered double hydroxide; space group; adsorption; lithium