Titanium-based ion sieve with enhanced post-separation ability for high performance lithium recovery from geothermal water

The improvement of post-separation performance of powdery lithium ion sieve with the guarantee of high adsorption capacity and fast kinetics remains to be a huge challenge. Herein, a novel granular and porous titanium-based lithium ion sieve (PIS) was developed using agar-assisted strategy and used for lithium recovery from geothermal water. The agar acted as both spherality-shaping and sacrificial porogenic agent. As a result, PIS had a 64-fold larger diameter (2.8 mm) than powdery ion sieve (IS), which could be easily separated by filtration and then reused with a steady performance. Due to its loose microstructures and rich porosity, PIS showed high adsorption capacity (25.8 mg/g) and rapid kinetic (equilibrium time 6 h) in geothermal water. In addition, the separation factors of competitive ions related to Li+ were 1162.3, 273.7 and 328.5 for Na+, K+ and Ca2+, respectively, exhibiting benign selectivity in natural geothermal water. Thus, this granular PIS with enhanced post-separation ability, high capacity and fast kinetic could be considered as a promising candidate for lithium recovery from geothermal water. Moreover, this simple and green method could be easily popularized to prepare other porous adsorbents.