Lithium Extraction from Aqueous Systems by λ-MnO₂-Deposited PU Electrospun Mats

Abstract

There has been a strong increase in demand for lithium, so the extraction of lithium from natural water resources has become a remarkable remedy to reduce the harmful environmental impact of conventional lithium extraction processes. One of the most effective methods of separating lithium from natural water sources is adsorption using lithium ion sieves as adsorbents. However, the powdered nature of the adsorbents makes them challenging to process. In this study, flexible and free-standing polyurethane (PU) electrospun mats associated with lambda-MnO2 particles were fabricated to extract lithium from aqueous systems. Bead-free and smooth nanofibers were electrospun from a volumetric mixture of DMF:THF (1:2) at 30 wt % of PU solution. lambda-MnO2 powder was deposited on the electrospun mat by vacuum-assisted deposition. The lithium extraction performance of the mats was found to be 21% using single-layer filtration and increased to 77% with multistage filtration. Moreover, using the optimized conditions, lithium extraction achieved up to 14% in a spiked brine sample taken from Lake Tuz (Central Anatolia, Turkey), where the Mg2+/Li+ ratio is higher than 85.