Preparation of lithium aluminum layered double hydroxides and their lithium deintercalation performance
lithium/aluminum layered double hydroxides(Li/Al-LDHs)is an adsorbent suitable for lithium extraction from high magnesium to lithium ratio brine.However,there are issues such as low adsorption capacity,unclear adsorption mechanism and insufficient understanding of applicable conditions.In this work,Li/Al-LDHs were prepared using aluminum powder and lithium hydroxide as raw materials.The applicable conditions and the influence of anions and cations in the solution on the adsorption process were investigated.The lithium extraction performance under different solution compositions was tested and the lithium desorption mechanism was characterized by FTIR and XPS.The results showed that the maximum adsorption capacity of Li/Al-LDHs in brine was 8.350mg/g,and the cation selectivity order was Li+>Na+>Mg2+>Ca2+>K+.The adsorption of Li+by Li/Al-LDHs followed the Langmuir isotherm adsorption model and the pseudo-second-order adsorption kinetics model.The adsorption process was mainly based on the sieving effect of size.When Li+entered the interlayer space of the adsorbent,an equal amount of anions(Cl-,SO42-,etc.)was needed to maintain charge balance.The lithium adsorption capacity increased with the increase of the total ion concentration in the solution,making it more suitable for lithium extraction from high salt content brines.This research findings can serve as valuable technical references for the subsequent utilization of Li/Al-LDHs derived from discarded aluminum metal in lithium extraction from salt lake brines.
lithium/aluminum layered double hydroxides(Li/Al-LDHs)adsorbenthigh magnesium to lithium ratioadsorptionlithium extraction
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