Novel LIS-doped mixed matrix membrane absorbent with high structural stability for sustainable lithium recovery from geothermal water

Lithium-ion sieves (LIS) have gained significant interest in lithium recovery from geothermal water . However, the severe loss and low recyclability of the powder adsorbents restrict their practical application. Here, the symmetric mixed matrix membranes adsorbents of LIS (MMMs-LIS) were prepared after doping the dopamine-modified LIS into polysulfone (PSf) matrix by breath figure approach with the characters of low thickness, high exposure area of H 2 TiO 3 (HTO) and high structural stability. The hydrophilic dopamine (DA) would probably promote the condensate water droplets to penetrate PSf matrix and make the smaller HTO/DA preferably emerge on the pore surfaces, accelerating the intercalation of Li + into the vacancies of HTO on the premise of the strengthened interfacial interaction between HTO/DA and PSf matrix. Therefore, the well-designed MMMs processed a comparable Li + adsorption capacity of 25.01 mg·g −1 and an equilibrium adsorption time of 45 min to powdery HTO during the dynamic adsorption process at 298.15 K (C 0  = 25.78 mg·L −1 , pH = 12.0). Moreover, Ti 4+ loss rate of HTO in MMMs decreased from 10.5% down to 1.1% after the first desorption and then gradually alleviated after multiple cycles until stabilized at 2.3%, indicating the excellent structural stability. These results suggest the great potentials of MMMs for highly efficient and sustainable lithium recovery from geothermal water .