Synthesis of Titanium Ion Sieves and Its Application for Lithium Recovery from Artificial Indonesian Geothermal Brine

Indonesia is one of the countries in the world that has been utilizing geothermal as a renewable energy source to generate electricity. Depending on the geological setting, geothermal brine possesses critical elements worthwhile to extract. One of the critical elements is lithium which is interesting in being processed as raw material for the battery industries. This study thoroughly presented titanium oxide material for lithium recovery from artificial geothermal brine and the effect of Li/Ti mole ratio, temperature, and solution pH. The precursors were synthesized using TiO2 and Li2CO3 with several variations of the Li/Ti mole ratio mixed at room temperature for 10 min. The mixture of 20 g of raw materials was put into a 50 mL crucible and then calcined in a muffle furnace. The calcination temperature in the furnace was varied to 600, 750, and 900 °C for 4 h with a heating rate. of 7.55 °C/min. After the synthesis process, the precursor is reacted with acid (delithiation). Delithiation aims to release lithium ions from the host Li2TiO3 (LTO) precursor and replace it with hydrogen ions through an ion exchange mechanism. The adsorption process lasted for 90 min, and the stirring speed was 350 rpm on a magnetic stirrer with temperature variations of 30, 40, and 60 °C and pH values of 4, 8, and 12. This study has shown that synthetic precursors synthesized based on titanium oxide can absorb lithium from brine sources. The maximum recovery obtained at pH 12 and a temperature of 30 °C was 72%, with the maximum adsorption capacity obtained was 3.55 mg Li/gr adsorbent. Shrinking Core Model (SCM) kinetics model provided the most fitted model to represent the kinetics model (R2 = 0.9968), with the constants kf, Ds, and k, are 2.2360 × 10-9 cm/s; 1.2211 × 10-13 cm2/s; and 1.0467 × 10-8 cm/s.