Separating and recovering lithium from brines using selective-electrodialysis: Sensitivity to temperature

Accepted Manuscript Title: Separating and recovering lithium from brines using selective-electrodialysis: Sensitivity to temperature Authors: Li-Ming Zhao, Qing-Bai Chen, Zhi-Yong Ji, Jie Liu, Ying-Ying Zhao, Xiao-Fu Guo, Jun-Sheng Yuan PII: DOI: Reference:

S0263-8762(18)30531-8 https://doi.org/10.1016/j.cherd.2018.10.009 CHERD 3379

To appear in: Received date: Revised date: Accepted date:

18-6-2018 6-10-2018 9-10-2018

Please cite this article as: Zhao, Li-Ming, Chen, Qing-Bai, Ji, Zhi-Yong, Liu, Jie, Zhao, Ying-Ying, Guo, Xiao-Fu, Yuan, Jun-Sheng, Separating and recovering lithium from brines using selective-electrodialysis: Sensitivity to temperature.Chemical Engineering Research and Design https://doi.org/10.1016/j.cherd.2018.10.009 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Separating and recovering lithium from brines using selective-electrodialysis: Sensitivity to temperature

Li-Ming Zhaoa,b,c,1, Qing-Bai Chen a,b,c,1, Zhi-Yong Jia,b,c*, Jie Liua,b,c, Ying-Ying Zhaoa,b,c, Xiao-Fu Guoa,b,c, Jun-

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Sheng Yuana,b,c*

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(a. Engineering Research Center of Seawater Utilization of Ministry of Education, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China; b. National-Local Joint Engineering

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Laboratory of Chemical Energy Saving Process Integration and Resource Utilization, School of Chemical

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Engineering and Technology, Hebei University of Technology, Tianjin 300130, China; c. Hebei Collaborative

*

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Innovation Center of Modern Marine Chemical Technology, Tianjin 300130, China)

Corresponding authors. Address: Box 307, Hebei University of Technology, No.8, Guangrong Road, Tianjin PRC.

authors contributed equally to the work.

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1These

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E-mail:[email protected], [email protected] (Z-Y JI); [email protected] (J-S YUAN)

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Graphical Abstract

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Little variation of lithium separation property in binary cations systems with rising

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temperature and its reason analysis based on a micro-model.

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Highlights

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 Lithium recovery ratio in various brines increased with rising temperature in

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S-ED.

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 In binary cations systems, FM―Li has little variation with temperature rise.  Arrhenius plots, and variation of membrane pore and hydrated ion was

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analyzed with temperature up.

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 The results obtained from a Li+-Na+-Mg2+ cation system was similar to that

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in binary systems.

ABSTRACT

This work was to investigate the lithium ion fractionation from various binary cation systems at various operating temperatures by electrodialysis (ED) with monovalent selective ion exchange

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membranes (usually called selective-electrodialysis, S-ED). Then a ternary cation system was selected to verify the results obtained from the binary cation systems. In Li+-Mn+ (Mn+: Na+, K+, Mg2+, Ca2+) brines containing only one kind of anion-Cl-, higher efficient recovery of lithium was obtained at higher temperature than at lower one, and the separation coefficients (FM―Li) at the same lithium

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recovery ratio were found to be changed slightly with temperature ranging from 10 °C to 30 °C. The results indicate the relationship between transport enhancement/interionic separation effects and

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temperature could be preliminarily expressed by Arrhenius-type equation. Moreover, the pore size of membrane and the cationic hydration number were analyzed with temperature increase, and then that

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FM―Li had little variation caused by temperature was explained. It should attribute to the swelling of

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membrane and a small reduction of cationic hydration numbers. Further verification was done in Li+-

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Na+-Mg2+ cation system, and the same results were obtained. The investigation experimentally

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demonstrates that S-ED technology is feasible for separating and recovering lithium from brines in

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different regions with different environment temperatures.

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Keywords: lithium; brine; selective-electrodialysis; coexisting cation; temperature

1. Introduction

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The charming growth in renewable energy is vital for the global economic sustainability. Lithium

ion batteries (LIBs) with their superior technical parameters, such as superior specific density (100– 265 W h/kg) and long life cycles (400–1200), have largely revolutionized the market demand of the renewable energy (Wagner, 2006; Choubey et al, 2016). Lithium has been found applications in LIBs

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as a remarkable cathode material. And the demand of lithium in global energy is growing in the energy age of tomorrow (Critical Materials Strategy, 2010). Nowadays, lithium recovery from mineral resources has been weakened and the movement of lithium exploitation in brines has surged (Kesler et al, 2012). And lithium recovery from brines (mainly including salt lake and concentrated seawater)

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should be part of sustainable engineering for a long period. At present, there are lots of technologies to recover lithium from brines, for instance, precipitation (Risacher et al, 2003), extraction (Xiang et

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al, 2016; Ooi et al, 2016), adsorption (Zhu et al, 2014; Chitrakar et al, 2014) and nanofiltration (Wen et al, 2006; Yang et al, 2011; Somrani et al, 2013; Sun et al, 2015). These techniques are effective for

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extracting lithium from low Mg2+/Li+ ratio brines (Mg2+/Li+ mass ratio < 8 (Yu et al, 2013)). However,

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further improvement of lithium recovery is needed and expected for high Mg2+/Li+ ratio brines using

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the methods mentioned above. So, high-efficiency method for recovering lithium from high Mg2+/Li+

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ratio brines should be further developed and investigated.

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Electrodialysis (ED), a useful and eco-friendly electric drive membrane process for the separation and desalination of electrolyte solutions, has aroused great concerns (Luiz et al, 2017; Ran et al, 2017).

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In many field of dissoluble resources utilization, such as preparation of liquid salt (greater than 160

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g/L NaCl) from seawater (Liu et al, 2016; Zhang et al, 2017), separation of mineral salt and organic acid (Huang et al, 2007; Zhang et al, 2009), recovery of some heavy metals (Reig et al, 2018; Mahmoud and Hoadley, 2017), acid and base produced from salinity wastewater by bipolar membrane

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electrodialysis (BMED) (Lin et al, 2015) and other applications, ED has been widely used. As a member of the ED processes, selective-electrodialysis (S-ED) technique also has been successfully applied to some special field of desalination, and has partly solved the separation of monovalent/multivalent ions from mixed electrolyte solutions. In S-ED process, the monovalent ions

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can penetrate the corresponding monovalent selective ion exchange membranes, but multivalent ions are intercepted in desalting cells in theory. Then, the separation of monovalent- and multivalent ions is achieved. Based on aforementioned theory, Van der Bruggen et al investigated the separation of monovalent/divalent ions from aqueous solution by electrodialysis with monovalent selective ion

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exchange membrane (Van der Bruggen et al, 2004). Lambert et al researched the separation of Na+ from Cr3+ by S-ED process, and it demonstrated that the separation between Cr3+ and Na+ was possible

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(Lambert et al, 2006). Meanwhile, an application of S-ED technology with five repeating units was designed to obtain NaCl-rich brine from concentrated seawater by Zhang et al (Zhang et al, 2017).

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At present, there is a little information about extracting lithium from brines by S-ED technique.

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The relevant studies still lack deep theoretical analysis and experimental data support. Parsa et al

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studied the lithium ion fractionation from sodium ion by S-ED process, and the results present the

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change of the ion fractionation of lithium and sodium using S-ED membrane technology (Parsa et al,

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2015). Meanwhile, extracting lithium from high Mg2+/Li+ brines by S-ED has been researched previously, and the separation of Li+ and Mg2+ was partly carried out (Ji et al, 2017). Different from

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lithium recovery techniques mentioned above, Mg2+/Li+ ratio has less impact for the S-ED technology

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on recovering lithium. But the competitive transport of coexisting cations shows a certain disadvantageous effect on the separation and purification of Li+. For example, the migration of the target Li+ can be influenced obviously by the coexisting Na+ in S-ED process (Parsa et al, 2015).

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Meanwhile, it is well-known that the performance of ionic transport in ED process could be certain temperature dependent. So, temperature should have some influence on the migration and purification of Li+. Therefore, considering on the practical lithium recovery process, the temperature of salt lake brines should be reckoned and then investigated. Some information about temperature in some known

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brines is listed in Table 1. It is obvious that there is great difference in salt lake brines all over the world. Moreover, feed temperature plays a key role in the lithium migration process, and the efficiency of lithium separation and recovery is temperature-dependent to some extent. However, the effectiveness of separating and recovering lithium from brines in different areas or in an area with four

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distinct seasons is not clear. So, further clarity is needed. In this work, the impact of temperature on lithium ions and major coexisting cations transport

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through the monovalent ion exchange membrane in S-ED process are studied systematically, using different binary cation systems and one ternary system. The different binary cations systems which

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selected in the study were used to preliminary explore the effect of coexisting cations on lithium at

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actual brines temperature. Meanwhile, the ion ionic composition of salt lake brines is usually more

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complex. It is necessary to evaluate the separation of lithium ions from various coexisting cations.

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Otherwise, considering the temperature of brines, and the tolerant temperature of the membrane, the

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experimental temperature ranges from 10 °C to 30 °C in this work. Meanwhile, a micro-model is depicted to illustrate the effects of membrane pore size and cationic hydration number at lower- and

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higher temperatures on lithium separation. The aim is to gain intuition on how the separation effect of

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lithium is influenced by temperature, and then the feasibility of S-ED technology for recovering and separating lithium from brines is discussed in a certain temperature range.

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2. Experimental section

2.1 Experimental setup and operating conditions

The S-ED experimental facility can be seen in Fig. 1. This setup was built by reforming the device provided by Beijing Huanyulida Environmental Products Ltd., China. Its compositions are listed in 6

Table 2. The schematic diagram and configuration of S-ED stack was depicted in Fig. 2. As the core module of S-ED setup, this stack comprises 11 monovalent selective cation exchange membranes (CIMS) and 10 monovalent selective anion exchange membranes (ACS). The additional cation exchange membrane was set to the anode surface to prevent Cl- from entering the anolyte. This

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is used for avoiding the damage to the selectivity of ion exchange membrane from the influence of electrode reaction. The size of each membrane is 30×10 cm, and the effective size of each membrane

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is 21.6 cm×6.5 cm and its electrical resistance is 2.4-3.0 Ω·cm2. The thickness of plastic sheet mesh spacer is 0.90 mm. In addition, the temperature control module (a low constant temp bath) is composed

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of the coiled condensing tube with a thermostat (Gongyi Yuhua instrument Ltd.). The error of the

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operating temperature is less than ± 0.5 °C.

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The major object of this part experiments is to explore the influence of temperature on the lithium

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separation and recovery. So, the discussion of optimized voltage in different brine systems is not our

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primary mission here. Referring to our previous research (Ji et al, 2017) and considering the limit current in all the experiments, the applied voltage of 5 V was selected, and the flow rates of the

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desalting stream/concentrating stream/electrolyte scream were fixed at 130, 130 and 80 L/h

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(corresponding to linear feed velocities of 6.2, 6.2 and 3.8 cm/s), respectively. Meanwhile, in order to eliminate gas bubbles in S-ED stack, it is necessary to circulate the solutions in each tank for a certain time (about 15 min) before the experiments. It can prevent gathering the heat of gas bubbles in the

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membrane stack and then eliminate its impact on the conductivity of membrane stack (Wang et al, 2013). Then the magnetic pumps conveyed corresponding solution into the respective compartment. All experiments are run equal to 120 min, sampling once every 20 minutes.

2.2 Chemicals 7

The experiments were carried out in batch S-ED process at different temperatures. Therein, 1.5 L NaCl solution of 0.5 mol/L was added to the concentrating compartment, and 2.5 L Na2SO4 solution of 5 % was added to the electrolyte compartment. In this work, artificial brines of chloride type including four kinds of binary cation and one kind

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of ternary cation were used to explore the influence of temperature on the separation and recovery of lithium by S-ED. And the various compositions representing different brines in desalting chamber (2.5

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L) are listed in Table 3.

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2.3 Analysis methods

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The concentration of Li+ was analyzed by Atomic Absorption Spectrometry (TAS-990, Beijing

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Purkinje General Instrument Co., Ltd.), Mg2+ and Ca2+ concentrations were determined by EDTA

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titration method, and K+ concentration was ascertained by Sodium Tetraphenylborate (NaTPB)-

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Quaternary Ammonium Salt (ACQ) titrimetric method. Cl- concentration was tested by “Silver Nitrate Titration” (ASTM D512-89 (1999) “Standard Test Methods for Chloride Ion in Water”). Na+ amount

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2.4 Data analysis

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was calculated by electrical balancing of total ions in the solution.

2.4.1 Ion flux

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The ion flux (mmol/ (m2·min)) was calculated using equation (1):

Flux (mmol/(m2 ∙ min))=

Cct Vct −Cc0 Vc0

(1)

A∙N∙t

where Cct and Vct are the electrolytic concentration (g/L) and solution volume (L) at time t in the concentrating tank; Cc0 and Vc0 are the initial ion concentration (mmol/L) and volume (L) of the

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solution in concentrating tank; N is the number of membrane pairs in S-ED stack (10); t is the operating time (min), and A is the effective area of each membrane (0.01407 m2).

2.4.2 Recovery ratio of lithium

RLi (%)=

Vct (Cct -Cc0 ) Vd0 Cd0

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The recovery ratio of lithium (RLi) was calculated as follows. ×100%

(2)

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where Vd0 and Cd0 represent the initial solution volume (L) and concentration of Li+ (mg/L) in the desalting compartment; Vct and Cct are those at time t in the concentrating compartment.

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2.4.3 Separation coefficient

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The separation coefficient (FM―Li) was defined as the quotient between the concentration ratio of

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coexisting cation and Li+ at time t and the corresponding initial ratio in the desalting tank. (C ∕C ) M

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FM−Li = (CM ∕CLi )t Li i

(3)

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where CM is the concentration of coexisting cation and CLi is that of Li+ (mol/L); the subscripts t and i represents the time t and the initial moment, respectively.

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FM―Li=1 means that lithium ion could not be separated effectively from coexisting cations.

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FM―Li>1 means lithium ion is prior to other ion in the view of passing through the ion exchange membrane, and the separation effect of coexisting cation and lithium ion increases with the increase of FM―Li. If FM―Li＜1, it implies the coexisting cation will get through the membrane preferentially

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than lithium ion.

2.4.4 Arrhenius plots The standard means of defining temperature effects is calculated by the Arrhenius method (Choi et al, 2014; Kimura et al, 2018). 9

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k = A × exp ( RTa )

(4)

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lnk = lnA − RTa

(5)

where k is reaction rate (representing the migration to concentrating cell from desalting cell, hence as positive rate); A is the pre-exponential factor; Ea is the apparent activation energy (kJ/mol); R is the

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gas constant (8.314 J/(mol·K)), and T is temperature (°C).

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3. Results and discussion

Temperature might influence the separation of Li+-Mn+. In one side, both the electrical

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conductivity and permeation flux of ion exchange membrane increase significantly with temperature,

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due to the swelling of the polymer matrix. However, the working temperature scope of ion exchange

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membrane is urged to restrict, because the active groups in ion exchange membrane phase would be

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damaged at a high operating temperature such as over 40 °C. On the other side, the viscosity of feeding

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solution would be decreased with the increasing of temperature, which is conducive to ion diffusion. Then, the cumulative effect of ions in membrane phase should be weakened due to the increasing of

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ionic migration rate. Furthermore, temperature has some different effects on the apparent migration

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rate of coexisting cation and Li+ in different solutions. So, the lithium recovery from brines with different binary cation systems was investigated at various operating temperatures.

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3.1 Effect of temperature on the migration and separation of lithium in different binary cation systems

3.1.1 Effect of temperature in Li+, Na+//Cl-—H2O system The average fluxes of Na+ and Li+ ion at a certain time are illustrated in Fig. 3(a). As time periods extend, the Na+ flux as a whole has a slight downward trend, and the Li+ flux mostly remains the same

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value. This is mainly due to the advantage of sodium ion in concentration and hydrated radius. Then the current in S-ED stack is mainly loaded by sodium ions, and sodium ions should be transferred preferentially comparing with lithium ions. Therefore, the molar content of sodium ions in desalting tank decreases obviously under batch mode. Due to the intense competition of coexisting sodium ions,

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lithium molar content in desalting tank reduces more smoothly, leading to a well maintenance of average lithium ions flux. Meanwhile, the average ionic fluxes of the two ions (Na+ and Li+) in the

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corresponding time periods show an upward trend with the increase of temperature, especially above 25 °C, and the Li+ flux at relative low temperature (20 °C) is close to the same level. Fig. 3(b) reveals

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that the lithium recovery ratio (RLi) also increases with the operating temperature rise. And the RLi

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value rises from 21.47 % to 39.2 % in the range of 10-30 °C after 120 min. This attributes to both the

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permeability of ion exchange membrane and the enhancing of ionic Brownian movement at a higher

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temperature. In fact, there is only a slightly change of lithium recovery ratio when the temperature

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increased from 15 °C to 20 °C. The little influence of temperature on the lithium and sodium ion flux and lithium recovery ratio is mainly determined by two competing mechanisms: the change of

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membrane pore and the hydration radius of ion. Firstly, the variation of this temperature range is belong

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to a very narrow range, indicating that the pore size of the ion exchange membrane does not change so much in the normal temperature variation range. Based on the little variation of membrane pore, the transport rate of Li+ and Na+ at 20 °C is not much faster than that at 15 °C. Besides, the hydrated ionic

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radius tends to decrease with the increase of temperature in the Li+, Na+//Cl-—H2O system, making Na+ and Li+ easy to realize electro-migration (Brodhol, 1998; Yamaguchi, 2010). But the increment of lithium recovery ratio is not obvious due to the fact that the coexisting sodium ions are abundant, which will exert more obvious inhibition on lithium migration to some extent.

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In regard to the influence of temperature on the migration of ions in electro-driven ion exchange membrane process, some studies indicated that higher temperature contributed to enhance the ionic mass transfer (Benneker et al, 2018). The operating temperature mainly affected the ionic migration rate, thus the ionic recovery ratio could be enhanced by rising temperature at the same operating time.

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However, there is little information about how the separation effect between different ions was affected by the variation of temperature. Moreover, the separation effect of lithium and sodium at various

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temperatures, which is vital in this research, was required attention.

In order to explore the effect of temperature on lithium and sodium separation, the separation

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coefficient of sodium and lithium (FNa—Li) at the same lithium recovery ratio (21.47 %) of different

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temperatures were drawn in Fig. 4(a). It is obvious that the FNa—Li values at various temperatures are

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approximately close, which is a very interesting phenomenon in the separation process of sodium and

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lithium at various temperatures. This seems to indicate that the change of temperature could not

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remarkably affect the separation coefficient of sodium and lithium. The rising of temperature could only shorten the ionic migration time in the experiments.

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To illustrate above phenomenon in theory, it is worthy to note that temperature dependency of

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ionic transport is dominated by Arrhenius plot (Eq. (4)). The apparent activation energy (Ea) for ion transport can be ascertained with a linear Arrhenius relationship between lnk and 1/T, as shown in Eq. (5) (Choi et al, 2014; Kimura et al, 2018). The Arrhenius plots of Li+ and Na+ transporting to the

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concentrating compartment are presented in Fig. 4(b). And the ionic mole transport rates represent the transfer from the desalting tank to the concentrate one. It can be seen that the lnk value at higher temperature is greater than that at lower temperature, indicating that lithium transfer was enhanced with temperature rise. It also illustrates that the two straight slopes are very close to one another. So,

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the Ea values of the Li+ and Na+ migration is very approximate. This indicates that whatever happens to lithium ion, the same to sodium ion. Thus, under the same lithium recovery ratio, there is no significant difference in the separation coefficient of sodium and lithium at different temperatures.

3.1.2 Effect of temperature in Li+, K+//Cl-—H2O system

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Because of the close microstructure of K+ and Na+, they have a similar effect on the migration of Li+. However, there should be a subtle distinction between the influence of K+ and Na+ with different

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hydrated ionic radius on the migration of Li+, especially at different temperatures. So, the influence of temperature on the lithium recovery in Li+, K+//Cl-—H2O system should not be ignored. The variation of migration rate of lithium (Mr) and lithium recovery ratio (RLi) with time are shown in Fig. 5, using

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Li+, K+//Cl-—H2O system of experimental brine. Li+ and K+ fluxes are shown in Fig. 5(a), and their

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trends in the data diagram are very similar to that of above coexisting sodium ions. So, the reason for

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the change of curves versus time is not repeated here. Overall, it can be seen that the K+ and Li+ fluxes rise with the temperature up. Fig. 5(b) shows a linear increase of lithium recovery ratio versus time in

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the concentrating compartment. The RLi value rises from 18.9 % to 40.3 % in the range of 10-30 °C

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after 120 min. It is similar to that in Li+, Na+//Cl-—H2O system. However, compare with the curves in Fig. 5(b) and Fig. 3(b), it also can be seen from that the same variation of temperature (15-20 °C) affects lithium recovery more sensitive in the Li+, K+//Cl-—H2O system. This is mainly because that

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the hydration ionic radius of potassium (0.331 nm) is smaller than that of sodium (0.358 nm), causing a stronger competitive migration of potassium ion at the same temperature condition. Then the

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influence of coexisting potassium ion induced by the little temperature change on lithium migration is relatively sensitive.

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The separation coefficient (FK—Li) at the same lithium recovery ratio (18.98 %) during different

temperatures are drawn in Fig. 6. Like the temperature effect in sodium system, the FK—Li values at various temperatures also have little irregular fluctuation in Fig. 6(a). In further theoretical explanation, Arrhenius plot was used and the Arrhenius relationship between lnk and 1/T in Li+, K+//Cl-—H2O system is illustrated in Fig. 6(b). It can be seen that the slopes of two curves are very close to each 13

other under the different test temperature conditions, which means the ion migration rates of lithiumand potassium ion are also close to each other. So, it further demonstrates that the temperature does not have a significant influence on the separation of Li+/K+ at the same lithium recovery ratio.

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3.1.3 Effect of temperature in Li+, Mg2+//Cl-—H2O system Considering the reality that the salt lake brines in China always have a higher Mg2+/Li+ ratio, and

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the initial concentrations of Li+ and Mg2+ ions were about 0.05 and 1.50 mol/L, the Mg2+/Li+ mole ratio of the feed solution was set at 30 during this part experiments. The curves of the ion flux of Li+/ Mg2+ and the recovery ratio of Li+ with different temperatures are shown in Fig. 7.

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Fig. 7(a) represents the ion fluxes of Li+ and Mg2+ in the Li+, Mg2+//Cl-—H2O systemic

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experiments at various temperatures. Unlike section 3.1.1 and 3.1.2, it is clear that both Li+ and Mg2+

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flux curves show a certain downward trend versus time. This phenomenon should be caused by monovalent selectivity of cation exchange membrane. That is to say, monovalent cations can realize

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transmembrane electric transfer preferentially. And compared with the experiments of coexisting

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monovalent cations, the amount of lithium ions in the desalting tank reduces rapidly. Moreover, Li+ and Mg2+ fluxes increase with temperature, which indicates that ionic migration rate is promoted with

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the increase of temperature. Fig. 7(b) shows the lithium recovery ratio also increases with temperature and reaches to 59.63 % after 120 min at 30 °C. Therefore, the effect of temperature on the separation

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performance of Li+ and Mg2+ is positive at the same operating time.

As shown in Fig. 8(a) about the trend of curves at the same lithium recovery ratio (37.00 %), there is a more interesting phenomenon that the separation coefficient of magnesium and lithium (FMg—Li) does not show a significant change as well. The linear Arrhenius relationship between lnk and 1/T in 14

Li+, Mg2+//Cl-—H2O system is given in Fig. 8(b). It implies that the reactive apparent activation energy of lithium and magnesium is extremely close to each other at the same lithium recovery ratio in the SED process.

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3.1.4 Effect of temperature in Li+, Ca2+//Cl-—H2O system The presence of calcium in feed solution is a traditional problem for concentrating brines. Some

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studies showed a certain incursion of calcium occurs on the surface of cation exchange membrane (Bazinet and Araya-Farias, 2005; Hayes and Severin, 2016). A rapid decline of current will present once the calcium fouling appears on the ion exchange membrane toward to electrode and the electrode.

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It can be derived from not only the rise of the membrane cell voltage and the specific energy

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consumption, but also the splitting of water (Firdaous et al, 2007; Tanaka et al, 1986), even though

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there is a small quantity of calcium in natural brines because of low solubility product of CaSO4. So, it is meaningful in practice for exploring the effect of temperature on lithium recovery in Li+-Ca2+

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binary cation system. In order to explore the influence of temperature on lithium separation and

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recovery in Li+, Ca2+//Cl-—H2O system, the solution with a certain Ca2+/Li+ of 5 was used as the feedstock in this section, referring to calcium concentration in some actual salt lake (Yu et al, 2013).

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The migration rates (Mr) and the recovery ratios of lithium (RLi) at different temperatures are

shown in Fig. 9. Fig. 9(a) shows the variation of Li+ flux and Ca2+ flux with time at various

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temperatures. Both Li+ flux and Ca2+ flux decline with time, and it is similar to that in Fig. 7(a). However, Li+ flux in this experiment is greater than that in section 3.1.3 on account of lower coexisting cation strength. On the other side, the two cations fluxes increase with the temperature up. On the other side, the curves of RLi are on the rise with time in Fig. 9(b), and the value of RLi increases with temperature rising. The values of RLi at temperatures of 10, 15, 20, 25 and 30 °C are 56.8 %, 61.8 %, 15

67.4 %, 69.1 % and 73.3 % after 120 min, respectively. These experimental data illustrate that higher temperature is favorable to the recovering lithium process in Li+-Ca2+ binary cation system. Fig. 10 shows the variation of separation coefficient of calcium and lithium (FCa—Li) with temperature, and Arrhenius plot of Li+/Ca2+ transport to the concentrating compartment at different

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temperatures under the same lithium recovery ratio (56.79 %). As shown in Fig. 10(a), it reveals that the change of FCa—Li value is not significant as the temperature rising from 15 to 30 °C. However, the

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experimental data at 10 °C is slightly higher than those at other temperature conditions. The further explanation for this phenomenon should be based on Fig. 10(b). Unlike the section 3.1.3, the curve

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trend of calcium is not like that of magnesium in Fig. 8(b), there is a certain difference in the linear

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Arrhenius relationship between lnk and 1/T of lithium and calcium. The main reason is that lithium

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ions in the feed containing coexisting ion with lower Ca2+/Li+ ratio, are preferable migrated because

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of the permselectivity of monovalent cation exchange membrane in S-ED stack. Another reason is that

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the ionic strength in the calcium containing system is extremely low comparing with that in above magnesium containing system, which leads to the competitive mobility of coexisting ions (Ca2+)

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increasing and the leakage of calcium ions enhancing greatly.

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3.2 Effect of temperature in different binary cation systems with a micro perspective analysis and the experimental verification in ternary cation system

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3.2.1 Effect of temperature in different binary cation systems (Li+, Mn+//Cl-—H2O) with a micro perspective analysis

The lithium recovery ratio (RLi) and the separation coefficient of each coexisting cation and lithium (FM—Li) are two significant parameters of S-ED process in separating and recovering lithium 16

from brines with different feed characteristics. In the section 3.1, on the one hand, temperature has some positive influence on the lithium recovery with time; on the other hand, the effects of temperature on the separation of lithium and coexisting ions are not significant at the same lithium recovery ratio. It indicates that raising temperature is more conducive to increase the migration rate of lithium and

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promote the lithium recovery ratio at the same operating time in batch S-ED mode. However, it seems that there are still some differences among the FM—Li values at various temperatures.

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According to the experimental data of FM—Li value at low and high temperatures (10 °C and 30 °C), the quantity difference of FM—Li values between 10 °C and 30 °C are described in Fig. 11. It could be

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clearly found that the variation of FM—Li between the two temperatures is very small except the change

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in Li+, Ca2+//Cl-—H2O system. Fig. 11 also shows that ΔFCa—Li is larger than ΔFMg—Li between 10 °C

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and 30 °C, and then ΔFK—Li and ΔFNa—Li in turn. These cannot be clearly explained only with the

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existing experimental data. Thus, a microscopic analysis was considered to explain the feeble

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differences.

Generally, the influence of temperature on S-ED process in a microscopic level is derived from

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two aspects: the expansion of the macromolecule function layer in ion exchange membrane, and the

CC E

diffusion of ion. As the temperature rise, the activity of high polymer chain is enhanced and the pore size of ion exchange membrane shows a swelling in a certain extent, which results in the increasing size of the membrane aperture (Amar et al, 2007). For the influence of the diffusion of solute and

A

solvent, it can be investigated by the diffusion coefficient in Stokes-Einstein equation: 𝑘𝑇

𝐷𝐴𝐵 = 6𝜋𝜇

(6)

𝐵 𝑟𝐴

where k is Boltzmann constant (0.1380 J/K), T is thermodynamic temperature (K), μB is the kinetic viscosity of the solvent (mPa∙s), rA is the radius of the solute molecule (m).

17

As the operating temperature (T) rises, the kinetic viscosity (μB) declines. Then the diffusion coefficient (DAB) increases, and the molecular diffusion is enhanced. So, the lithium recovery ratios in all brine systems increase with temperature rise. But the values of FM—Li have somewhat difference between monovalent coexisting ion- and divalent coexisting ion systems with the variation of operating

sizes of cation exchange membrane and the hydrated ions with temperature.

IP T

temperature, which is also observed from Fig. 11. This should be attributed to the variations of pores

SC R

Fig. 12 shows the influence of temperature on the variations of pores sizes of cation exchange membrane and the hydrated ions. Firstly, certain swelling presents in the cation exchange membrane

U

with increasing operating temperature. This is mainly because of the swelling behavior (induced by

N

temperature) of the high polymer chains in the membrane (Ying et al, 2003; Roy et al, 2017). The

A

swelling principally affects the migration of hydrated ions, then results in the migration rate of

M

monovalent cations (both sodium/potassium and lithium) synchronous changing from low to high

ED

relatively. So the separation coefficient of sodium/potassium and lithium has little change at the same lithium recovery ratio with increasing temperature. For the difference between ΔFNa—Li (or ΔFK—Li)

PT

and ΔFMg—Li (or ΔFCa—Li), the main reason is the selective permeation mechanism of monovalent

CC E

cation exchange membrane for monovalent cations. This mechanism includes the pore action of membrane and its electrostatic interaction. Compared with the target ion Li+, as shown in Table 4 (Nightingale, 1959; Shannon, 1976; Volkov et al, 1997), the multivalent cation with a larger hydrated

A

ionic radius is suffered strong electrostatic repulsion from the membrane surface. Therefore, the quantity of lithium migration is much more at higher temperature conditions, then causing greater FMg—Li (or FCa—Li) value. Secondly, the hydrated number of ions decreases with temperature, which has been proved

18

through many X-ray and neutron diffraction studies (Brodhol,1998; Yamaguchi et al, 2010), i.e., water molecules in hydrated shell of the ion Mn+ could be partial relieved in higher temperature feed solution. Then, the hydrated ionic radius of Mn+ maybe decrease with increasing temperature, which strongly affects the migration of M+. Based on the partial dehydration mechanism of cation transport in S-ED

IP T

process, a little variation of FNa—Li and FK—Li appears because the hydrated radius of sodium/potassium ion is close to that of lithium ion. Similarly, the water molecule number controlled by magnesium and

SC R

calcium ions is also low in higher temperature, but both the hydrated radius of Mg2+ and Ca2+ are larger than that of Li+. So, there are some difference between the value of ΔFNa—Li (or ΔFK—Li) and that of

U

ΔFMg—Li (or ΔFCa—Li) with the increasing of temperature in feed solution. Meanwhile, the main reason

N

for the greater ΔFCa—Li comparing with ΔFMg—Li is that the calcium content is extremely low versus

A

magnesium (about 1/6).

M

To sum up, it is just that temperature do not have a significant influence on the separation of

ED

coexisting cations and lithium, but have more influence on the recovery ratio of lithium. 3.2.2 Effect of temperature in ternary cation system (Li+, Na+, Mg2+//Cl-—H2O) with a view to

PT

experimental verification

CC E

For further provide some theory and information instruction to recover and separate lithium from actual brines, a ternary cation brine (Li+, Na+, Mg2+//Cl-—H2O) was selected to study at two temperature conditions (15, 25 °C). The selection of coexisting cations (Na+, Mg2+) was based on the

A

major cations in actual brines (Yu et al, 2013), and the experimental temperatures were determined by referring to the actual brines from different region all over the world. In accordance with Table 1, the maximal temperature range in some actual brine is from 20 to 28 °C, indicating that 25 °C should be more appropriate in this study. On the other hand, the minimum temperature (15 °C) in this section

19

was selected based on the average temperature ranging from 9 to 20 °C. The migration rate (Mr) and the recovery ratio of lithium (RLi) at different temperatures are shown in Fig. 13. It shows that the curves of Na+ and Li+ fluxes in Fig. 13(a) take on slightly downtrend with time. However, the Mg2+ flux curves almost remain a constant value at two different temperatures.

IP T

This is co-determined by both the monovalent selectivity of the cation exchange membrane and the continuous ion migration in batch mode. For monovalent cations (Li+ and Na+), the ionic strength

SC R

decreases significantly because they can be permselectively transferred from desalting cell to concentrating cell. As for Mg2+, its leakage rate is extremely low when there is a large amount of

U

monovalent ions in feed solution. Nonetheless, the fluxes of all cations are enhanced with rising

N

temperature. In Fig. 13(b), with temperature rising from 15 °C to 25 °C, the value of R Li increases

A

from 22.69 % to 31.99 % after 120 min. And the slopes of the RLi curves rise with the operating

M

temperature up. It illustrates that the recovering lithium process in the cation system is better at a higher

ED

operating temperature.

The separation coefficients of sodium/magnesium and lithium at the same lithium recovery ratio

PT

under the temperature of 15 and 25 °C are shown in Fig. 14(a). It is found that the two separation

CC E

coefficients show little relationship with the increasing of operating temperature. So, the result obtained in section 3.1 is also suitable for the solution with polybasic cation system. That is to say, the effect of temperature on the separation coefficient of each coexisting cation and lithium in actual brine

A

is not significant at the same lithium recovery ratio. Therefore, from a macro point of view, it only enhances the migration rate of various ions in solution simultaneously. In a theoretical perspective from Fig. 14(b), the slope of sodium is very similar to that of the lithium. It also can be seen that the slope of magnesium seems to a little difference from that of lithium/sodium. This is probably because

20

that the leakage rate of Mg2+ should be enhanced based on swelling of the monovalent permselectivity cation exchange membrane pore size at higher temperature, although the increasing of sodium ion flux should restrain magnesium transfer in a certain extent. In other words, the positive effect of temperature on magnesium transfer is stronger than the inhibiting effect of the increasing of coexisting

IP T

sodium ions flux (result from rising temperature) on magnesium transfer. However, the effect of

(both FNa—Li and FMg—Li) is not obvious (as shown in Fig. 14(a)).

U

4. Conclusions

SC R

temperature going up on lithium separation is not great, and this effect on the separation coefficient

N

In this research, electrodialysis process with monovalent selective ion exchange membranes was

A

used to recover and separate lithium from various binary/ternary cation systems. The sensibility of

M

brine temperature on the migration of Li+ and the separation of coexisting cations and lithium ions

ED

were investigated. The results of this study were as follows. (1) For various binary cation systems, it indicated that raising temperature is favorable for

PT

recovering lithium process. But the change of temperature could not remarkably affect the separation

CC E

coefficient of coexisting cations and lithium under the same lithium recovery ratio. The transfer enhancement/interionic separation effects with increasing temperature could be explained by Arrhenius plots. Larger lnk value was obtained at a higher temperature, indicating that the lithium

A

transfer was enhanced; the Arrhenius straight slopes (for Li+ and Mn+) were very close to one another, indicating that the separation coefficients had little change with temperature rise. For the greater value of ΔFCa—Li between lower- and higher temperature in calcium containing system, the ionic strength in this system was extremely low comparing with that in other coexisting cation containing systems,

21

which led to the competitive mobility of Ca2+ increased and the leakage of Ca2+ enhanced greatly. (2) The influence of temperature on recovering and separating lithium from brines with different binary feed characteristics in S-ED process could be attributed as follows: the swelling of the high polymer chains on cation exchange membrane surface and the decreasing of the water molecule

IP T

numbers controlled by hydrated ions in feed during their electro-transport process. For further experimental verification in a ternary cation system (Li+, Na+, Mg2+//Cl-—H2O) at two temperature

SC R

conditions (15, 25 °C), the better lithium recovery ratio was obtained at 25 °C. However, similar to binary systems, there was also no significant difference in the separation coefficients of

U

sodium/magnesium and lithium at the same lithium recovery ratio under the two temperatures. It turned

N

out that those claims obtained in binary cation systems are still applied to relative actual salt lake brines

A

with high Mg2+/Li+.

M

This paper highlights a slightly sensibility to temperature (within the scope of electrodialysis) for

ED

separating lithium from brines by separation coefficient and Arrhenius plot. And based on the experimental and micro-model analyzed, it indicates that the S-ED technology is applicable for

PT

recovering and separating lithium from brines in a certain temperature range. These results should be

CC E

useful to select the method for extracting lithium from different regional brines, and also conducive to

A

investigate electrodialytic separation process in future.

Acknowledgment

The research was financially supported by Program for the Top Young Innovative Talents of Hebei Province, Tianjin Research Program of Application Foundation and Advanced Technology

22

(12JCQNJC03300), Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT, IRT14R14), National Natural Science Foundation of China (20806019), and Hebei

A

CC E

PT

ED

M

A

N

U

SC R

IP T

Provincial Natural Science Foundation (B2009000024; B2017202246).

23

References

Amar N. Ben, Saidani H., Deratani A., Palmeri J., Effect of temperature on the transport of water and neutral aolutes across nanofiltration membranes, Langmuir 23 (2007) 2937–2952.

IP T

Bazinet L., Araya-Farias M., Effect of calcium and carbonate concentrations on cationic membrane fouling during electrodialysis, J. Colloid Interf. Sci. 281 (2005) 188–196.

SC R

Benneker A.M., Rijnaarts T., Lammertink R.G.H., Wood J.A., Effect of temperature gradients in (reverse) electrodialysis in the Ohmic regime, J. Membr. Sci. 548 (2018) 421–428.

Brodhol J.P., Molecular dynamics simulations of aqueous NaCl solutions at high pressures and temperatures, Chem.

N

U

Geol. 151(1998) 11–19.

A

Chitrakar R., Makita Y., Ooi K., Sonoda A., Synthesis of iron-doped manganese oxides with an ion-sieve property:

M

lithium adsorption from Bolivian brine, Ind. Eng. Chem. Res. 53 (2014) 3682–3688. Choi J., Byun Y.J., Lee S.Y., Jang J.H. , Henkensmeier D., Yoo S.J., Hong S.A., Kim H.J., Sung Y.E., Park J.S., Poly

ED

(arylene ether sulfone) with tetra (quaternary ammonium) moiety in the polymer repeating unit for application in

PT

solid alkaline exchange membrane fuel cells, Int. J. Hydrogen Energy 39 (2014) 21223–21230. Choubey P.K., Kim M.S., Srivastava R.R., Lee J.C., Lee J.Y., Advance review on the exploitation of the prominent

CC E

energy-storage element: Lithium. Part I: From mineral and brine resources, Miner. Eng. 89 (2016) 119–137. Critical Materials Strategy, US Department of Energy December, 2010.

A

Crosman E. T., Horel J. D., MODIS-derived surface temperature of the Great Salt Lake, Remote Sens. Environ. 113 (2009) 73–81.

Firdaous L., Malériat J.P., Schlumpf J.P., Quéméneur F., Transfer of monovalent and divalent cations in salt solutions by electrodialysis, Sep. Sci. Technol. 42 (2007) 931–948. Haferburg G., Gröning J.A.D., Schmidt N., Kummer N.A., Erquicia J.C., Schlömann M., Microbial diversity of the 24

hypersaline and lithium-rich Salar de Uyuni, Bolivia, Microbiological Research 199 (2017) 19–28. Hayes T.D., Severin B.F., Electrodialysis of highly concentrated brines: effects of calcium, Sep. Purif. Technol. 175 (2016) 443–453. Huang C.H., Xu T.W., Zhang Y.P., Xue Y.H., Chen G.W., Application of electrodialysis to the production of organic

IP T

acids: State-of-the-art and recent developments, J. Membr. Sci. 288 (1–2) (2007) 1–12. Ji Z.Y., Chen Q.B., Yuan J.S., Liu J., Zhao Y.Y., Feng W.X., Preliminary study on recovering lithium from high

SC R

Mg2+/Li+ ratio brines by electrodialysis, Sep. Purif. Technol. 172 (2017) 168–177.

Kampfa S.K., Tylerb S.W., Ortizc C.A., Munozc J.F., Adkinsd P.L., Evaporation and land surface energy budget at

U

the Salar de Atacama, Northern Chile, J. Hydrol. 310 (2005) 236–252.

N

Kesler S.E., Gruber P.W., Medina P.A., Keoleian G.A., Everson M.P., Wallington T.J., Global lithium resources:

A

relative importance of pegmatite, brine and other deposits, Ore Geol. Rev. 48 (2012) 55–69.

M

Kimura T., Akiyama R., Miyatake K., Inukai J., Phase separation and ion conductivity in the bulk and at the surface

375 (2018) 397–403.

ED

of anion exchange membranes with different ion exchange capacities at different humidities, J. Power Sources

PT

Lambert J., Avila-Rodriguez M., Durand G., Rakib M.. Separation of sodium ions from trivalent chromium by

CC E

electrodialysis using monovalent cation selective membranes, J. Membr. Sci. 280(1-2) (2006) 219–225. Liang Q.S., Han F.Q., Geological characteristics and lithium distribution of east Taijinar salt lake in Qaidam basin, J. Salt Lake Res. 21 (2013) 1–9.

A

Lin J., Ye W., Huang J., Ricard B., Baltaru M.C., Greydanus B., Balta S., Shen J., Vlad M., Sotto A., Luis P., Van der Bruggen B., Toward resource recovery from textile wastewater: dye extraction, water and base/acid regeneration using a hybrid NF-BMED process, ACS Sustain. Chem. Eng. 3(9) (2015) 1993-2001. Liu J., Yuan J.S., Ji Z.Y., Wang B.J., Hao Y.C., Guo X.F., Concentrating brine from seawater desalination process by

25

nanofiltration–electrodialysis integrated membrane technology, Desalination 390 (2016) 53–61. Luiz A., McClure D.D., Lim K., Leslie G., Coster H.G.L., Barton G.W., Kavanagh J.M., Potential upgrading of biorefinery streams by electrodialysis, Desalination 415 (2017) 20–28. Mahmoud A., Hoadley A.F.A., An evaluation of a hybrid ion exchange electrodialysis process in the recovery of

IP T

heavy metals from simulated dilute industrial wastewater, Water Res. 46 (10) (2012) 3364–3376. Nightingale E.R., Phenomenological theory of ion salvation-effective radii of hydrated ions, J. Chem. Phys. 63 (1959)

SC R

1381–1387.

Ooi K., Makita Y., Sonoda A., Chitrakar R., Tasaki-Handa Y., Nakazato T., Modelling of column lithium adsorption

U

from pH-buffered brine using surface Li+/H+ ion exchange reaction, Chem. Eng. J. 288 (2016) 137–145.

N

Parsa Nazila, Moheb Ahmad, Mehrabani-Zeinabad Arjomand, Masigol Mohammad Ali, Recovery of lithium ions

A

from sodium-contaminated lithium bromide solution by using electrodialysis process, Chem. Eng. Res. Des.

M

98(2015) 81-88.

ED

Ran J., Wu L., He Y.B., Yang Z.J., Wang Y.M., Jiang C.X., L. Ge, Bakangura E., T.W. Xu, Ion exchange membranes: new developments and applications, J. Membr. Sci. 522 (2017) 267–291.

PT

Reig M., Vecina X., Valderrama C., Gibert O., Cortina J.L., Application of selectrodialysis for the removal of As

CC E

from metallurgical process waters: Recovery of Cu and Zn, Sep. Purif. Technol. 195 (2018) 404–412. Risacher F., Alonso H., Salazar C., The origin of brines and salts in Chilean salars: a hydrochemical review, EarthSci. Rev. 63 (2003) 249–293.

A

Roy Y., Warsinger D.M., Lienhard J.H. , Effect of temperature on ion transport in nanofiltration membranes: Diffusion, convection and electromigration, Desalination 420 (2017) 241–257. Schmidt N., Hydrogeological and hydrochemical investigations at the Salar de Uyuni (Bolivia) with regard to the extraction of lithium, FOG 26 (2010) 1–131.

26

Shannon R.D., Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides, Acta Crystallogr. A 32 (5) (1976) 751–767. Somrani A., Hamzaoui A.H., Pontie M., Study on lithium separation from salt lake brines by nanofiltration (NF) and low pressure reverse osmosis (LPRO), Desalination 317 (2013) 184–192.

IP T

Sun S.Y., Cai L.J., Nie X.Y., Song X.F., Yu J.G., Separation of magnesium and lithium from brine using a Desal nanofiltration membrane, J. Water Process Eng. 7 (2015) 210–217.

SC R

Tanaka Y., SenōM., Concentration polarizationn and water dissociation in ion-exchange membrane electrodialysis: mechanism of water dissociation, J. Chem. Soc. Faraday Trans 82 (1) (1986) 2065–2077.

U

Van der Bruggen B., Koninckx A., Vandecasteele C., Separation of monovalent and divalent ions from aqueous

N

solution by electrodialysis and nanofiltration, Water Res. 38 (2004) 1347–1353.

A

Volkov A.G., Paula S., Deamer D.W., Two mechanisms of permeation of small neutral molecules and hydrates ions

M

across phospholipid bilayers, Bioelectrochem, Bioenergy 42 (1997) 153–160

ED

Wagner R., Battery Fuel Gauges: Accurately Measuring Charge Level, https://www.maximintegrated.com/en/appnotes/index.mvp/id/3958, 2006.

PT

Wang X.L., Wang Y.M., Zhang X., Feng H.Y., Li C.R., Xu T.W., Phosphate recovery from excess sludge by

CC E

conventional electrodialysis (CED) and electrodialysis with bipolar membranes (EDBM), Ind. Eng. Chem. Res. 52 (2013) 15896−15904.

Wen X.M., Ma P.H., Zhu C.L., He Q., Deng X.C., Preliminary study on recovering lithium chloride from lithium-

A

containing waters by nanofiltration, Sep. Purif. Technol. 49 (2006) 230–236.

Xiang W., Liang S.K., Zhou Z.Y., Qin W., Fei W.Y., Extraction of lithium from salt lake brine containing borate anion and high concentration of magnesium, Hydrometallurgy 166 (2016) 9–15. Yamaguchi T., Ohzono H., Yamagami M., Yamanaka K., Yoshida K., Wakita H., Ion hydration in aqueous solutions

27

of lithium chloride, nickel chloride, and caesium chloride in ambient to supercritical water, J. Mol. Liq. 153 (2010) 2–8. Yang G., Shi H., Liu W.Q., Xing W.H., Xu N.P., Investigation of Mg2+/Li+ separation by nanofiltration, Chinese. J. Chem. Eng. 19 (4) (2011) 586–591.

IP T

Ying L., Kang E.T., Neoh K.G., Characterization of membranes prepared from blends of poly (acrylic acid)-graftpoly (vinylidene fluoride) with poly (N-isopropylacrylamide) and their temperature- and pH-sensitive

SC R

microfiltration, J. Membr. Sci. 224 (2003) 93–106.

Yu J.J., Zheng M.P., Wu Q., Research progress of lithium extraction process in lithium-containing salt lake, J. Chem.

U

Ind. Eng. Prog. 32 (2013) 13–21.

N

Zhang Y.F., Liu L., Du J., Fu R.Q., Van der Bruggen B. , Zhang Y., Fracsis: Ion fractionation and metathesis by a NF-

A

ED integrated system to improve water recovery, J. Membr. Sci. 523 (2017) 385–393.

M

Zhang W., Miao M.J., Pan J.F., Sotto A., Shen J.N., Gao C.J., Van der Bruggen B., Process economic evaluation of

5(2017)5820–5830.

ED

resource valorization of seawater concentrate by membrane technology, ACS Sustainable Chem. Eng.

PT

Zhang Y., Van der Bruggen B. , Pinoy L., Meesschaert B., Separation of nutrient ions and organic compounds from

CC E

salts in RO concentrates by standard and monovalent selective ion-exchange membranes used in electrodialysis, J. Membr. Sci. 332 (1–2) (2009) 104–112. Zhu G., Wang P., Qi P.F., et al, Adsorption and desorption properties of Li+ on PVC-H1.6Mn1.6O4 lithium ion-sieve

A

membrane, Chem. Eng. J. 235 (2014) 340–348.

28

DC Power supply +

SED Stack

Concentrating solution

Desalting solution

Electrolyte solution

Anode

Cathode

Electrolyte solution tank

Desalting solution tank Pump 3

Pump 2

Pump 1

Low constant temp bath

ED

M

A

N

U

SC R

Fig. 1- Schematic diagram of the S-ED setup in batch mode.

IP T

Pump 4 Concentrating solution tank

Fig. 2 Schematic diagrams and configuration of S-ED stack.

60 40 5 4

Na+: Li+:

10 °C 10 °C

15 °C 15 °C

10 °C 15 °C 20 °C 25 °C 30 °C

40

30 20 °C 20 °C

25 °C 25 °C

30 °C 30 °C

20

21.47 %

10

A

3

CC E

80

(b)

RLi(%)

(a)

100

50

PT

Ion flux of Li+ and Na+ (mmoL/(m2·min))

120

2 1

0

0

0

20

40

60

80

100

120

140

20

Time (min)

40

60

80

Time (min)

Fig. 3 -Ion fluxes and recovery ratio of lithium in Li+-Na+ system at various temperatures

29

100

120

-6

1.2

(b)

(a)

Li+ Na+

-7

1.0

-8 -9

0.8

lnk

FNa—Li

-10

0.6

-11 -12

0.4

-13

0.2

-15

0.0 10

15

20

25

0.00330

30

0.00340

0.00335

0.00345

0.00350

1/T (K-1)

Temperature (°C)

IP T

-14

0.00355

transport to the concentrate Ion flux of Li+ and K+ (mmoL/(m2·min))

120

50

(a)

(b) 10 °C 15 °C 20 °C 25 °C 30 °C

100

40

60

U

80

4

15 °C 15 °C

20 °C 20 °C

25 °C 25 °C

30 °C 30 °C

3

20

N

10 °C 10 °C

18.98 %

A

K+: Li+:

RLi(%)

30

5

SC R

Fig. 4- Separation coefficient in Li+-Na+ system at a same lithium recovery ratio and Arrhenius plot of Li+/Na+

1 0 0

20

40

60

80

100

M

10

2

120

0 20

140

40

Time (min)

60

80

100

120

ED

Time (min)

Fig. 5- Ion fluxes and recovery ratio of lithium with Li+-K+ system at different temperatures 1.2 1.0

-7

(b)

Li+ K+

-8 -9

CC E

0.8

-10

0.6

lnk

FK—Li

-6

PT

(a)

0.4

-11 -12 -13

A

0.2

-14

0.0

-15 10

15

20

25

30

0.00330

Temperature (°C)

0.00335

0.00340

0.00345

0.00350

0.00355

1/T (K-1)

Fig. 6- Separation coefficient in Li+-K+ system at a same lithium recovery ratio and Arrhenius plot of Li+/K+ transport to the concentrate

30

(a) Li : +

(b)

2+

Mg : 16

60

12

12

10 °C 15 °C 20 °C 25 °C 30 °C

70

8

8

4

4

50

RLi(%)

30 °C 25 °C 20 °C 15 °C 10 °C

Ion flux of Mg2+ (mmoL/(m2·min))

30 °C 25 °C 20 °C 15 °C 10 °C

16

Ion flux of Li+ (mmoL/(m2·min))

80

20

20

40

37.00 %

30 20

0 0

0 0

20

40

60

80

100

120 0

20

40

60

80

100

Time (min)

Time (min)

SC R

Fig. 7-Ion fluxes and recovery ratio of lithium in Li+-Mg2+ system at different temperatures -6

2.5

(a)

-7

2.0

(b)

Li+ Mg2+

-8 -9

U

-10

lnk

-11

1.0 -12 -13

A

0.5

N

FMg—Li

1.5

120

100

80

60

40

20

120

IP T

10

-14 -15

0.0 15

20

25

30

M

10

Temperature (°C)

0.00330

0.00335

0.00340

0.00345

0.00350

0.00355

1/T (K-1)

ED

Fig. 8- Separation coefficient in Li+-Mg2+ system at a same lithium recovery ratio and Arrhenius plot of Li+/ Mg2+

PT

Li+: 30 °C 25 °C 20 °C 15 °C 10 °C

12

8

70

30 °C 25 °C 20 °C 15 °C 10 °C

16

12

8

4

A

4

0

0 0

20

40

60

80

100

120 0

20

40

60

(b)

Ca2+:

CC E

16

Ion flux of Li+ (mmoL/(m2·min))

80

20

(a)

80

100

Ion flux of Ca2+ (mmoL/(m2·min))

20

60

56.79 %

50

RLi(%)

transport to the concentrate

40 10 °C 15 °C 20 °C 25 °C 30 °C

30 20 10 20

120

40

60

80

Time (min)

Time (min)

Fig. 9-Ion fluxes and recovery ratio of lithium with Li+-Ca2+ system at different temperatures

31

100

120

-6

4.0

(a) -7 3.2

(b)

Li+ Ca2+

-8 -9

2.4

lnk

FCa—Li

-10 -11

1.6

-12 -13

0.8

-15 25

20

15

10

30

0.00330

0.00335

Temperature (°C)

0.00340

0.00345

1/T (K-1)

IP T

-14 0.0

0.00350

0.00355

SC R

Fig. 10-Separation coefficient in Li+-Ca2+ system and Li+/Ca2+ transport to the concentrate Arrhenius plot at same lithium recovery ratio

U

2.0

N

1.5

A

1.0

0.5

0.0 Na

K

Mg

M

between 10 °C and 30 °C

The quantity of ΔFM—Li

2.5

Ca

ED

Coexisting cations (Mn+)

A

CC E

PT

Fig. 11-The quantity difference of FM—Li between 10 °C and 30 °C

32

IP T SC R U

50

80 60

Li+, 15 °C Li+, 25 °C

Na+, 15 °C Na+, 25 °C

Mg2+, 15 °C Mg2+, 25 °C

M

(a)

(b)

15 °C 25 °C

40

20

PT

2.5 2.0 1.5 1.0 20

40

60

80

30

RLi(%)

ED

40

CC E

Ion flux of Li+, Na+ and Mg2+ (mmoL/(m2·min))

temperatures

A

N

Fig. 12- Microanalysis of variation of cation exchange membrane pore sizes and hydrated ions at different

22.69 %

20

10

0 100

20

120

40

60

80

100

Time (min)

Time (min)

A

Fig. 13- Ion fluxes and recovery ratio of lithium with Li+-Na+-Mg2+ system at different temperatures

33

120

-5

2.5

(a)

-6

FNa—Li 2.0

(b)

-7

FMg—Li

Li+ Na+ Mg2+

-8 -9

lnk

FM—Li

1.5

-10 -11

1.0

-12 -13

0.5

-14

10

15

20

25

30

-15 0.003340.003360.003380.003400.003420.003440.003460.00348

1/T (K-1)

Temperature (°C)

IP T

0.0

SC R

Fig. 14-Separation coefficient in Li+-Na+-Mg2+ system at a same lithium recovery ratio and Arrhenius plots of

A

CC E

PT

ED

M

A

N

U

Li+/Na+/Mg2+ transport to the concentrate

34

Table 1 Properties of segmental known brine temperature in the world Temp. (°C) State

Location

Salt lake

Ref. Min

Max

Avg

China

Qinghai-Tibet plateau

East Taijinar

-23

28

/

Bolivia

South American altiplano

Uyuni

4-5

20

9

(Liang and Han, 2015)

IP T

(Schmidt, 2010; Haferburg et al, 2017) Atacama

8

22

USA

North American

Great Salt Lake

0.5

26.7

14

N A M ED PT CC E A

35

(Kampfa et al, 2005)

SC R

Andean plateau

10-20

U

Chile

(Crosman and Horel, 2009)

Table 2 Compositions of S-ED setup Name

Type

Direct current (DC) power JS3020D

Manufacturer

State

Wuxi ANS Electronic Technology Ltd.

China

supply Electrode

Titanium coated Shanxi Elade New Material Technology China Co.,Ltd.

Cation exchange membrane

CIMS

ASTOM Corporation

Anion exchange membrane

ACS

ASTOM Corporation

Magnetic pumps

DP-100

Shanghai Xinxishan Industrial Ltd.

China

Low constant temp bath

DFY-20/20

Gongyi Yuhua instrument Ltd.

China

A

CC E

PT

ED

M

A

N

U

SC R

IP T

with ruthenium

36

Japan Japan

Table 3 Various compositions in desalting chamber Mn+/Li+ (mole ratio)

Na+

Li+, Na+//Cl-—H2O

Na+/Li+=15

K+

Li+, K+//Cl-—H2O

K+/Li+=15

Mg2+

Li+, Mg2+//Cl-—H2O

Mg2+/Li+=30

Ca2+

Li+, Ca2+//Cl-—H2O

Ca2+/Li+=5

Na+, Mg2+

Li+, Na+, Mg2+//Cl-—H2O

Na+/Li+=15; Mg2+/Li+=30

IP T

0.05 mol/L

System of brine

SC R

Conc. of Li+ Coexisting cations

A

CC E

PT

ED

M

A

N

U

Note: “Mn+” represents coexisting cation ion.

37

Table 4 Hydrated ionic radii (rh) of various ions contained in natural brines

Li+

Na+

K+

Mg2+

Ca2+

rh (nm)

0.382

0.358

0.331

0.428

0.412

A

CC E

PT

ED

M

A

N

U

SC R

IP T

Ions

38