AlLi-LDH中Al-O八面体环吸附锂的机制

Mechanism of lithium adsorption by AlLi-LDH with Al-O octahedral ring

采用共沉淀法合成铝锂层状双氢氧化物(AlLi-LDH)并进行提锂试验。AlLi-LDH的空间群为P32或C2/m,微观形貌呈直径为5~10μm的规则球形。AlLi-LDH吸附Li^(+)后,空间群转化为P32。当Li^(+)浓度为95.4 mg/L时,1 h后锂吸附量为8.98 mg/g;吸附48 h后,吸附量增加到16.50 mg/g;根据二级吸附模型预测Li^(+)吸附总量为17.57 mg/g。当Mg^(2+)/Li^(+)的质量比为1067时,Mg^(2+)/Li^(+)分离系数为29536。空间群为P32时,Li-O的相互作用强度变弱,且相互作用属于静电效应。具有P32空间基团的AlLi-LDH更容易吸附和解吸Li^(+)。

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 5-10μm.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 Mg^(2+)/Li^(+)separation coefficient was 29536 when the mass ratio of Mg^(2+)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.