Highly Efficient Lithium Recovery from Pre-Synthesized Chlorine-Ion-Intercalated LiAl-Layered Double Hydroxides via a Mild Solution Chemistry Process
Highly Efficient Lithium Recovery from Pre-Synthesized Chlorine-Ion-Intercalated LiAl-Layered Double Hydroxides via a Mild Solution Chemistry Process
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通过温和溶液化学工艺从预合成的氯离子插层 LiAl 层状双氢氧化物中高效回收锂
作者：
Sun Ying;Yun Rongping;Zang Yufeng;Pu Min;Xiang Xu
盐湖卤水提锂是满足日益增长的各种锂产品需求的关键。我们报道了通过温和的溶液反应从预合成的锂层状双氢氧化物（LDHs）中回收锂。锂离子从固态LiAl-LDHs中释放出来，得到含锂溶液。LiAl-LDHs相逐渐转变为以Al(OH)3为主的相，锂回收到水溶液中。锂的回收率和含锂溶液的浓度取决于LiAl-LDHs的结晶度、LiAl-LDHs-1浆料的初始浓度、反应温度和反应时间。在优化条件下，滤液中锂离子浓度为141.6 mg/L，锂回收率达86.2%。有趣的是，高结晶度LiAl-LDHs固液分离后的滤液中未检测到铝离子，说明锂和铝分别在液相和固相完全分离。固体产物的27Al核磁共振谱表明，锂从LiAl-LDHs晶格空位中回收影响有序Al(OH)3相八面体构型的AlO6配位。XPS O 1s光谱显示，随着锂回收率的增加，Oad峰强度增大，OL峰强度减小，表明Al-OH键逐渐形成，金属-氧-金属键断裂。
Lithium extraction from salt lake brine is critical for satisfying the increasing demand of a variety of lithium products. We report lithium recovery from pre-synthesized LiAl-layered double hydroxides (LDHs) via a mild solution reaction. Lithium ions were released from solid LiAl-LDHs to obtain a lithium-bearing solution. The LiAl-LDHs phase was gradually transformed into a predominantly Al(OH)3 phase with lithium recovery to the aqueous solution. The lithium recovery percentage and the concentration of the lithium-bearing solution were dependent on the crystallinity of LiAl-LDHs, the initial concentration of the LiAl-LDHs-1 slurry, the reaction temperature, and the reaction time. Under optimized conditions, the lithium recovery reached 86.2% and the Li+ concentration in the filtrate is 141.6 mg/L. Interestingly, no aluminum ions were detected in the filtrate after solid–liquid separation with high crystallinity LiAl-LDHs, which indicated the complete separation of lithium and aluminum in the liquid and solid phases, respectively. The 27Al NMR spectra of the solid products indicate that lithium recovery from the lattice vacancies of LiAl-LDHs affects the AlO6 coordination in an octahedral configuration of the ordered Al(OH)3 phase. The XPS O 1s spectra show that the Oad peak intensity increased and the OL peak intensity decreased with the increasing lithium recovery, which indicated that the Al-OH bond was gradually formed and the metal–oxygen–metal bond was broken.