Cross-linked HMO/PVA nanofiber mats for efficient lithium extraction from Salt-lake

With the rapid expansion of the new energy industry and electronics market, the demand for lithium is growing rapidly, leading to a significant increase in the price of the metal. There has been great interest in lithium extraction from salt lakes. The powdered lithium ion-sieve (LIS) suffers from poor dispersion and difficult recovery. Composite polyvinyl alcohol (PVA) nanofiber mats with H1.6Mn1.6O4 (HMO) were prepared by electrostatic spinning and radiation induced cross-linking. HMO was immobilized in the nanofiber mats by covalent attachment, cross-linking and entrapment. Hydrophilicity of PVA, high porosity of nanofiber and cross-linked 3D network endow the HMO/PVA nanofiber mats good mechanical strength, excellent Li+ adsorption performance and long service life. 1/1-HMO/PVA nanofiber mats exhibit Li+ adsorption capacity of 30.1 mg g-1 in salt-lake brine, which was superior to most LIS-containing adsorbents. Even in real salt-lake water with very low Li concentration of 15.45 mg L-1 and high Mg/Li ratio of 1260/1, the nanofiber mats have an excellent adsorption capacity of 24.2 mg g-1 and high distribution coefficient of 9713.34 mL g-1, which was close to that of HMO powder. After ten adsorption and elution repetitions Li+ adsorption capacity decreased less than 10%, which indicates the long-term stability of the HMO/PVA nanofiber mats. The loss rate of Mn is less than 5% and gradually decreases with the increase of the number of cycles. The present study demonstrates the potential application of HMO/PVA nanofiber mats for direct recovery of Li+ from salt-lake especially in low-grade high Mg/Li ratio liquid lithium ore where holds a large proportion of the typical salt-lakes in China.