Sustainable lithium recovery from shale gas wastewater via a polydopamine modified Ni–H2TiO3/MXene/polysulfone composite membrane

The rapid expansion of the shale gas industry has led to the production of large volumes of wastewater containing valuable lithium resources. Although various lithium-ion sieve (LIS) materials have been developed for selective lithium recovery from shale gas wastewater (SGW), their adsorption capacity and selectivity are severely limited under natural near-neutral conditions. Here, a polydopamine (PDA)-modified Ni–H 2 TiO 3 (HTO)/MXene/polysulfone (PSF) composite membrane was developed for sustainable and selective lithium recovery from real SGW at its natural pH of 7.92. Surface polymerization of dopamine modulated the zeta potential of the membrane, effectively enhancing its Li + adsorption performance. The PDA/Ni-HTO/MXene/PSF membrane achieved a high adsorption capacity of 38.31 mg g −1 within 2 h, while maintaining excellent cycling stability and fouling resistance. Mechanistic analyses revealed that the synergistic effects between PDA and MXene enhanced the electronic capture ability of Ti–O and C–O coordination sites and activated interfacial π-electronic structures and charge redistribution, thereby promoting Li + adsorption and transport. The integrated membrane-based approach couples lithium recovery with wastewater treatment, offering a pathway for simultaneous resource recovery with reduced chemical input and secondary salinity loading.