Preparation Of TiO₂ Loaded PVDF-based Lithium Ion Imprinted Membrane And Study Of Its Lithium Adsorption Behavio

Under the promotion of the"double carbon"policy,the realization of energy structure adjustment is an irreversible direction.With the widespread use of lithium batteries and the approaching of the waste date,recycling lithium from waste lithium batteries is full of new opportunities and challenges.Under the background of fire and wet recovery processes,the development of clean,green,convenient and efficient liquid phase lithium separation and extraction technology is the priority among priorities.In this study,a novel LIIMs（lithium ion imprinted membrane）was prepared by coupling membrane separation technology and ion imprinting technology.The surface morphology and structure composition of synthetic LIIMs were systematically characterized by a variety of methods.The adsorption performance of Li⁺by LIIMs was investigated based on isothermal adsorption,kinetic adsorption and cyclic adsorption systems.The selective adsorption capacity of LIIMs for lithium in simulated leach solution and actual solution was studied,and the selective separation mechanism of LIIMs was also discussed.The results show that:（1）The LIIMs with high adsorption capacity and excellent selectivity were prepared.The absorption behavior can be well described by Langmuir model and quasi-second-order kinetic model（PSO）,which indicates that the adsorption is mainly a chemical monolayer adsorption.The selective separation factors（α）of Mg²⁺,K⁺,Ca²⁺and Na⁺were 6.80,17.00,21.30 and 24.60,respectively.（2）LIIMs simulates the leaching solution containing lithium with rapid adsorption kinetics,and the adsorption equilibrium is achieved within 40 min.The kinetic adsorption conforms to the PSO model and is controlled by chemisorption.The fitting curve of W-M model has no origin,and internal diffusion is not the only limiting step of controlling the adsorption process.The E_a of LIIMs was 54.93 k J/mol,which further confirmed that the adsorption method was chemical adsorption.ΔG is negative at different temperatures,and the adsorption of Li⁺by LIIMs may be spontaneous.The FT-IR and XPS results showed that the selective adsorption mechanism was Li-O coordination chelation.（3）LIIMs showed good selectivity to Li⁺in simulated Li-containing leaching solution.The priority order of adsorption of ions by LIIMs is Li⁺>Fe²⁺>Cu²⁺>Ca²⁺>Zn²⁺>Mn²⁺>K⁺>Na⁺,and the separation factor（α）values for Fe²⁺,Cu²⁺,Ca²⁺,Zn²⁺,Mn²⁺,K⁺and Na⁺were 10.93,19.30,22.66,23.49,26.14,27.57and 39.00,respectively.In the actual solution,the adsorption priority sequence of all ions by LIIMs did not change,and the separation factor（α）values of Fe²⁺,Cu²⁺,Ca²⁺,Zn²⁺,Mn²⁺,K⁺and Na⁺were 6.56,14.08,15.81,18.40,18.68,20.39 and 25.08,respectively.（4）In the simulated Li-containing leaching solution,the adsorption capacity of Li⁺by LIIMs decreased to 61.8%after 8 cycles of experiments.In the actual solution,the adsorption capacity of Li⁺by LIIMs has been reduced to 50%of the initial capacity.This indicates that in the process of adsorption-desorption cycle,and the complexity of the actual solution will affect the adsorption capacity of LIIMs.