**7. Lithium ion-sieve**

In fact, two types of chemical elements can be used, such as LISs, lithium manganese oxide type (LMO type) and lithium titanium oxide type (LTO type). LMO-type LISs are the most popular selective lithium adsorbents at present because of superior lithium absorption abilities, magnificent regeneration performance and high lithium selectivity. In addition, the extraction of lithium from aqueous solutions has recently improved significantly through the use of electrochemical methods. However, the LISs type suffers from the dissolution of manganese in aqueous solutions, which in industrial conditions can lead to serious water contamination. In this regard, LISs type LTO can overcome this problem, can be easily removed from the aqueous solution, and titanium compounds are not harmful to the aquatic environment [136–138]. In addition, LTO-type LISs has much more stable molecular structures due to the high energy of the titaniumoxygen bond compared with LMO-type LISs. But when an electrical potential is applied LISs of type LTO have limited use in extracting lithium from an aqueous solution. This restriction may prevent future industrial use of LISs type LTO. Thus, LMO-type and LTO-type LISs have their own unique benefits and

**203**

Li<sup>+</sup>

**Figure 3.**

*Schematic representation of LIS process.*

*Lithium Recovery from Brines Including Seawater, Salt Lake Brine, Underground Water…*

problems. Therefore future research to meet large scale industrial applications

With research [44], several LMO-type LISs have been well developed by many scientists [48]. As a rule, their precursors demonstrate a spinel structure. Because of multiple valence states of manganese, several lithium manganese oxides with different crystal structures can be formed. At 25°C, the phase diagram Li-Mn-O shows

In the blue area in **Figure 4a**, the stoichiometric spinel phase defect is defined by the triangle Mn3O4·Li4Mn5O12·λ-MnO2. Using the general formula LixMn3−xO4 (0 ≤ x ≤ 1.33), one can imagine the stoichiometric spinel phases lying on the bond between Mn3O4 and Li4Mn5O12. According to the general formula Mn3−xO4 (0 ≤ x ≤ 1) defective spinels of manganese oxides located between Mn3O4 and λ-MnO2 are presented. In accordance with the general formula Li2O·yMnO2 (y > 2.5), the defect of lithium-manganese-oxide spinel is expressed and the communication line lies between Li4Mn5O12 and λ-MnO2. At this point, in LiMn2O4·Li2Mn4O9·Li4Mn5O12 the blue triangle in **Figure 4b** is the active area for preparing the precursors of LMO-type LISs. Therefore, it is possible to obtain high Li-Mn precursors such as Li5Mn4O9 and Li7Mn5O12 in principle, implying that high

adsorption capaci-

may focus on minimizing their respective disadvantages.

**7.1 Lithium recovery by LMO type lithium-ion sieves**

*7.1.1 Study of ternary phase diagram of Li-Mn-O*

the isothermal cross-section **Figure 4** [139–143].

capacity LISs may be obtained in the future.

constructed by Chitrakar et al. [47].

absorption of lithium from aqueous solutions.

Currently, only a few LMO-type LIS precursors with high Li<sup>+</sup>

ties such as λ-MnO2, MnO2·0.31H2O and MnO2·0.5H2O, which are derived from LiMn2O4, Li4Mn5O12 and Li1.6Mn1.6O4, respectively, were prepared. As shown in **Figure 5**, a phase diagram consisting of additional proton-type manganese oxides depending on the valence state of manganese, molar Li/Mn and H/Mn ratios

As shown in the figure, LIS precursors of the LMO-type can be classified into two types of reactions and are represented in two perpendicular planes: the vertical plane represents the redox reaction region, and the horizontal plane represents the ion exchange region. **Table 3** mainly summarizes their main properties for the

*DOI: http://dx.doi.org/10.5772/intechopen.90371*

*Lithium Recovery from Brines Including Seawater, Salt Lake Brine, Underground Water… DOI: http://dx.doi.org/10.5772/intechopen.90371*

**Figure 3.** *Schematic representation of LIS process.*

*Thermodynamics and Energy Engineering*

distillation [114].

**6. Lithium ion-sieve effect**

called "LIS effect" [131–135].

**7. Lithium ion-sieve**

has the smallest ionic radius among all metal ions.

a membrane process [112, 113]. Lithium extraction from seawater was selectively achieved by dialysis using a lithium ion superconducting membrane. For appropriate industrial lithium mass production applications, the dialysis process can be energy efficient and easily scalable [111]. Recovery of lithium by membrane desalination followed by crystallization was reported by Quist-Jensen et al. [114]. Extraction of lithium chloride and comparison of membrane crystallization in direct contact, vacuum and osmotic configuration were carried out. In their environment, the necessary supersaturation for crystallization was achieved for the simultaneous production of pure water and lithium by vacuum-membrane

In 1971, ion-sieve oxides were first prepared by Volkhin et al. [125] since ionsieve oxides have received increasing attention in the last few decades due to the special properties and performance as metal ions [126–130]. To extract specific metal ions with effective ion-sieve characteristics, ion-sieve oxides are fine adsorbents. Ion-sieve oxide adsorbents are obtained from corresponding precursors containing ions of the target metal. Characteristically, precursors are stable molecular structures, even if target ions are removed from their crystal sites, free crystal sites can still be retained. Thus, the resulting free crystal regions can only contain ions whose ionic radii are less than or equal to the radii of the target ions. In fact, only lithium ions can re-enter the free spaces of lithium ion sieves because lithium

The study shows that only lithium ions can be adsorbed when LISs are placed in aqueous solutions containing different kinds of metal ions. **Figure 3** shows how LIS works. The main stage is the formation of LIS with hydrogen filled state [LIS (H)] by removing lithium ions from the lithium filled state [LIS (Li)], principally through Li-H ion exchange, then the adsorption isolation of lithium ions LIS from


In fact, two types of chemical elements can be used, such as LISs, lithium manganese oxide type (LMO type) and lithium titanium oxide type (LTO type). LMO-type LISs are the most popular selective lithium adsorbents at present because of superior lithium absorption abilities, magnificent regeneration performance and high lithium selectivity. In addition, the extraction of lithium from aqueous solutions has recently improved significantly through the use of electrochemical methods. However, the LISs type suffers from the dissolution of manganese in aqueous solutions, which in industrial conditions can lead to serious water contamination. In this regard, LISs type LTO can overcome this problem, can be easily removed from the aqueous solution, and titanium compounds are not harmful to the aquatic environment [136–138]. In addition, LTO-type LISs has much more stable molecular structures due to the high energy of the titaniumoxygen bond compared with LMO-type LISs. But when an electrical potential is applied LISs of type LTO have limited use in extracting lithium from an aqueous solution. This restriction may prevent future industrial use of LISs type LTO. Thus, LMO-type and LTO-type LISs have their own unique benefits and

**202**

Li+

problems. Therefore future research to meet large scale industrial applications may focus on minimizing their respective disadvantages.
