Self-assembled Fe-HTO/MXene/PSF lithium ion-sieve membrane for efficient lithium extraction from shale gas wastewater

The growing demand for electric vehicles and renewable energy has increased the need for efficient lithium extraction. Here, we introduce a novel Fe-doped H₂TiO₃/MXene/Polysulfone (Fe-HTO/MXene/PSF) lithium ion-sieve membrane (LISM) for lithium extraction from shale gas wastewater (SGW). The efficient and selective extraction of lithium from SGW was simultaneously accomplished during the low-pressure membrane filtration process. A self-assembly structure of Fe-HTO on the membrane surface was achieved by MXene nanosheet, which efficiently prevented the particle aggregation, and enhanced the adsorption capacity and structural stability. The Fe-HTO/MXene/PSF LISM achieved a lithium adsorption capacity of 28.50 mg/g within 8 h from SGW. The membrane retains 98.70 % of its initial performance after 10 adsorption/desorption cycles, demonstrating good cyclic stability. Furthermore, filtration experiments showed that a membrane with an area of 12.56 cm² could process 120 mL of SGW, demonstrating its potential for low-pressure filtration applications. Density functional theory (DFT) calculations indicated that Fe doping reduced lithium migration barriers and accelerated lithium adsorption rates, while the interfacial engineering of Fe-HTO with MXene enhanced lithium adsorption. The findings highlight the promising scalability of the Fe-HTO/MXene/PSF LISM for practical lithium extraction from SGW, with significant implications for sustainable lithium recovery.