Lithium isotope selectivities of lithium-specific adsorbents

制备了3种锂专用吸附剂，并对其锂同位素选择性进行了研究。分别是从前驱体LiMn_2O_4中提取锂离子制备的锰基吸附剂MnO_2（Li）和从Mg_2MnO_2中提取镁离子与从LiSbO_3中提取锂离子制备的锑酸HSbO_3中提取单斜结构的锰基吸附剂HMnO（2Mg）。在制备MnO_2（Li）和HMnO（2Mg）过程中，过氧二硫酸铵是一种较好的锂离子和镁离子萃取剂。同位素分析表明，三种吸附剂均具有^6Li特异性。在前驱体浸锂过程中，随着锰溶解程度的增加，MnO_2（Li）的锂同位素效应强度略有下降，随着前驱体中锂锰摩尔比在Li/Mn=0.5 ~ 0.8之间的增加，MnO_2（Li）的锂同位素效应强度也略有下降。MnO_2（Li）对锂同位素的最大分离系数为1.014。HMnO（2Mg）的各种性能取决于其制备过程中镁的提取程度。随着镁萃取度的增加，锂离子的吸收率增加，对锂离子的选择性增加，但分离因子值降低。三种吸附剂中，HSbO_3的锂同位素效应最大，吸收率与其他两种吸附剂相当。在25℃时，HSbO_3的最大分离因子为1.025。然而，吸附在HSbO3上的锂离子很难被提取出来，这是HSbO3作为锂同位素分离器的一个严重缺陷。

Three lithium specific adsorbents have been prepared and their lithium isotope selectivity has been investigated. They were a manganese oxide-based adsorbent designated as MnO_2(Li) prepared by extracting lithium ions from the precursor, LiMn_2O_4, another manganese oxide-based adsorbent, HMnO(2Mg) prepared by extracting magnesium ions from Mg_2MnO_2 and antimonic acid, HSbO_3, with the monoclinic structure prepared by extracting lithium ions from LiSbO_3. Ammonium peroxodisulfate was found to be an excellent extractant of lithium and magnesium ions in the preparation of MnO_2(Li) and HMnO(2Mg). Isotopically, the three adsorbents examined were all ^6Li specific. The magnitude of the lithium isotope effect of MnO_2(Li) slightly decreased with the increase in the degree of manganese dissolution in the process of lithium extraction from the precursor and also decreased with the increase in the lithium/manganese molar ratio in the precursor between Li/Mn=0.5 and 0.8. The maximum separation factor for the lithium isotopes with MnO_2(Li) was 1.014 at 25ﾟC.Various properties of HMnO(2Mg) depended on the degree of magnesium extraction in the process of its preparation. With the increase in the degree of magnesium extraction, the lithium uptake increased, selectivity for the lithium ions increased, but unfortunately the separation factor value decreased. HSbO_3 showed the largest lithium isotope effect among the three adsorbents examined while the amount of lithium uptake was comparable to those of the other two adsorbents. The maximum separation factor value of HSbO_3 was 1.025 at 25ﾟC.However, it was very difficult to extract lithium ions adsorbed in HSbO3, which seemed a serious drawback of HSbO_3 as a lithium isotope separator.