Preparation And Performance Of The Partial Titanate Lithium Adsorbent

Lithium and its compounds have been applied widely in the areas of medicine, ceramics, glass, industrial melting, nuclear energy, aviation and so on. In our country, there is adundant of lithium resources, in which lithium content is very low and the ratio of Mg/Li is very large. Therefore, Traditional methods, except adsorption method, are not suitable for extracting lithium from this salt lake brine. It is necessary to exploit a new kind of lithium adsorbent, which can separate lithium from the salt lake/brine effectively. The details are as follows:1. The H2Ti03-type lithium adsorbent was prepared by a simple solid-phase reaction between TiO2 and Li2CO3, with Anhydrous ethanol as the dispersion medium. The precursors were investigated from the extraction ratio of Li+, the extraction ration of Ti4+ and the adsorption properties of relative lithium adsorbent. The structure and surface morphology of the products were characterized by XRD and SEM. The results showed that pure monoclinic Li2Ti03 was synthesized under the condition:Li/Ti 2, calcined temperature 850℃, calcined time 24h.2. Lithium adsorbent was prepared via acid-modifying the lithium adsorbent precursor. The factors affecting the properties of lithium adsorbent were investigated from acid-modifying temperature, Concentration of hydrochloric acid, acid-modifying time, ratio of liquid to solid.the result showed that the lithium adsorbent was prepared via extracting the Li+ from the lithium adsorbent precursor under the condition:acid-modifying temperature 60℃,0.25M HCl, acid-modifying time 24h, ratio of liquid to solid 100:1, when the extraction ration of Li+ and Ti4+ were 85.62% and 0.17%.3. The adsorption properties of lithium adsorbent in the Li+ solution were investigated from adsorption time, ratio of liquid to solid, pH and adsorption temperature. The results showed that the saturated adsorption capacities of the lithium adsorbent in 694mg·L-1 LiOH solution,87.5 mg·L-1 and 282.5 mg·L-1 LiCl solution (pH=10.1, NH3-NH4C1 buffer system) were 39.8 mg·L-1,30.9 mg·L-1,28.63 mg·L-1. The adsorption process obeyed pseudo-second-order rate equation, indicating that the process can be seen as chemical adsorption. The equilibrium data could be described well by the Langmuir isotherm equations, indicating that the process was monolayer adsorption.4. Regeneration of the lithium adsorbent was investigated from acid-modifying temperature, Concentration of hydrochloric acid, acid-modifying time. The results showed that the lithium adsorbent can be regenerated by acid-modifying under the condition:acid-modifying temperature 60℃,0.25M HCl, acid-modifying time 2h, ration of liquid to solid 100:1, when the extraction ration and Li+ and Ti4+ were 88.68% and 1.21%.5. The lithium adsorbent was researched via adsorption properties, cycle performance and the selectivities to metal ions in the salt lake brine. The results showed that the adsorptive capacity of the lithium adsorbent in the salt lake brine can reach 20.78 mg·g-1 after 10 days. The structure of the lithium adsorbent in the salt lake brine have little change after 8 cycles, with the adsorption capacity maintaining at about 14mg·g-1, the desorption capacity maintaining at about 14.5 mg·g-1, the extraction ratio of Ti4+ maintaining at about 1.2%. the selectivity sequence for metal ions on the first adsorption process was:Li+>Mg2+>Na+>K+. During the cycle process, the KdLi became larger, while the KdMg, KdNa and KdK became smaller. At the same time,αKLi,αNaLi andαMgLi became larger. At the 8th cycle, KdLi, KdMg,KdNa and KdK were 142.42,1.39.4.83.4.60 respectively,αKLi,αNaLi andαMgLi were 30.98,29.46,102.4 respectively.