Effect of Ti-containing precursors on structure and adsorption performance of Li4Ti5O12 and Li2TiO3 oxides to Li plus ions

Using solid-phase synthesis method, Li4Ti5O12 and Li2TiO3 oxides were synthesized and used as adsorbents for Li+ ions. The physical-chemical properties were studied, using X-ray diffraction analysis, IR-spectroscopy, lowtemperature adsorption-desorption of nitrogen, and scanning electron microscopy. It was shown that, using anatase as a Ti-containing precursor, single-phase oxides Li4Ti5O12 (d 26.5 nm, a 8.401 angstrom, V 569.5 angstrom 3) and Li2TiO3 (d 26.5 nm, a 7.731 angstrom, V 462.1 angstrom 3) with macro-mesoporous structure (ABET 11 and 16 m2/g, VBJH des 0.03 and 0.03 cm3/g, DBJH des 6 and 6 nm, respectively) and spherical-like morphology were obtained. For the samples obtained from rutile, an impurity of unreacted Ti-containing precursor was detected. The effect of the nature of Ti-containing precursors, concentration and temperature of HCl regeneration solution, and contact time on the degree of conversion to H-form and adsorption capacity of the obtained adsorbents was studied. The highest efficiency of ion exchange of Li+ ions with H+ (gamma H+ 96.7-100 %) was reached in conversion of adsorbents to Hform, during treatment with 0.1 M HCl at temperature of 70 degrees C for 48 h. Adsorbents H4Ti5O12 and H2TiO3 prepared from anatase showed higher adsorption efficiency of Li+ ions (qe 95.1 and 84.0 mg/g, alpha 34.7 and 32.9 %, respectively) compared to samples obtained from rutile (qe 75.7 and 81.2 mg/g, alpha 23.8 and 29.9 %, respectively). After three cycles of acid regeneration, the adsorption capacity was maintained at 40.6-47.0 mg/g for Li4Ti5O12, and at 34.8-38.4 mg/g for Li2TiO3, respectively. The hydrogen demonstration during adsorption-desorption cycles increased from 8.4 to 10.8 for Li4Ti5O12, and from 8.0 to 11.2 for Li2TiO3. Anatase Ticontaining precursor recrystallization into rutile modification and further amorphization was determined. The presented results are interesting for developing highly efficient adsorbents for Li+ ions recovery from aqueous solutions.