In-situ self-assemblied HTO/MXene/PSF hybrid membrane for high efficiency and selective lithium extraction from shale gas wastewater

H₂TiO₃ (HTO) emerges as a highly promising lithium-ion sieve (LIS) material for selectively and efficiently extracting lithium from liquid-phase systems. However, the practical use of conventional powdered HTO adsorbents is hindered by difficulties in recovery and titanium leaching, which limits their reusability. Herein, we design a novel HTO/MXene/polysulfone (HTO/MXene/PSF) hybrid membrane, where two-dimensional (2D) MXene nanosheets bridge PSF and HTO via enhanced hydrogen bonding and enable the in-situ self-assembly of HTO into spindle-like nanostructures. As anticipated, the hybrid membrane exhibits selective lithium adsorption, achieving a capacity of 25.80 mg·g⁻¹ from shale gas wastewater (SGW). Moreover, it maintains remarkable cyclic stability with a negligible decrease in adsorption capacity of merely 0.25% after ten consecutive adsorption–desorption cycles. Besides, filtration studies demonstrate that a membrane with a surface area of 12.56 cm² can effectively process 230 mL of SGW. Theoretical calculations reveal that hydrogen bonding and electronic interactions drive the self-assembly of HTO on MXene and further elucidate the adsorption strength and spatial hindrance mechanisms for selective lithium ion adsorption. This study introduces an innovative concept of in-situ self-assembled LIS in a hybrid membrane for lithium recovery from SGW, which is expected to inspire further research on self-assembled sieve-based adsorbents.