Lithium-selective extraction utilizing lithium-trap LiAlFe-LDHs/MWCNTs/QCS composite membrane within the ship lock-type ion selective permeability system

A lithium aluminum iron layered double hydroxides/multiwalled carbon nanotubes/quaternized chitosan (LiAlFe-LDHs/MWCNTs/QCS) composite membrane with lithium-ion vacancies (Li + -trap) was fabricated through vacuum filtration method and pre-desorption process. The Li + -trap LiAlFe-LDHs/MWCNTs/QCS composite membrane had been developed for the selective extraction of Li + within the ship lock-type ion selective permeability (SL-ISP) system. In the Li + -trap LiAlFe-LDHs/MWCNTs/QCS composite membrane, the Li + -trap within LiAlFe-LDHs was pivotal for achieving selective Li + extraction. This selectivity was realized through the cyclic intercalation of Li + into the Li + -trap sites within the interlayer structure of LiAlFe-LDHs, a process that also facilitates the permeation of Cl - . The interference of impurity ions was further eliminated by the SL-ISP system, thus facilitating the selective extraction of Li + . Upon investigation, the Li + -trap LiAlFe-LDHs/MWCNTs/QCS composite membrane was found to achieve a Li + flux of 0.055 mol·m −2 ·h −1 and a separation factor of 8.3 at an equimolar concentration ( C Mg, Li  = 0.05 M) within the SL-ISP system. Additionally, the Li + -trap LiAlFe-LDHs/MWCNTs/QCS composite membrane demonstrated excellent separation performance in simulated brine, with a calculated Li + permeation flux of 0.053 mol·m −2 ·h −1 . The separation factors of Li + /Mg 2+ , Li + /K + , Li + /Na + and Li + /Ca 2+ reached values of 91.84, 69.75, 81.51 and 17.99, respectively. Therefore, the Li + -trap LiAlFe-LDHs/MWCNTs/QCS composite membrane could be effectively applied in the SL-ISP system for the selective extraction of Li + .