Elsevier

Hydrometallurgy

Volume 174, December 2017, Pages 21-28
Hydrometallurgy

Selective adsorption of lithium from high Mg-containing brines using HxTiO3 ion sieve

https://doi.org/10.1016/j.hydromet.2017.09.009Get rights and content

Highlights

  • The maximum lithium adsorption capacity of HxTiO3 reached the 36.3 mg/g in the high Mg containing brines of China.

  • HxTiO3 exhibited high selectivity between Li+ and Mg2 +, and the separation factors of Li+ to Mg2 + reached 4783.

  • HxTiO3 possessed stable lithium adsorption capacity during six adsorption-desorption.

Abstract

The prepared titanium type lithium ion sieve HxTiO3 are characterized and tested as adsorbents for selective adsorption of lithium from high Mg-containing brine. The maximum adsorption capacities of Li+, Na+, K+, Ca2 + and Mg2 + ions onto HxTiO3 reached 36.34, 1.93, 1.99, 2.58 and 3.53 mg/g, respectively, under the initial pH 8.8 at 25 °C for 24 h. Adsorption isotherms and kinetic analysis indicated that the adsorption of Li+ ions and other cations onto HxTiO3 followed Langmuir isotherm model and pseudo-second order kinetic equation. A diffusion model simulation showed that the Li+ ions had the highest external diffusion coefficients (7.7 × 10 2 cm s 1) while the other cations had small effect on the adsorption rate of Li+. The Biot number was > 100 signified that these ions adsorption onto HxTiO3 were controlled by the internal diffusion. The separation factors (α) of Li+ over other cations were much > 1. In particular, the α value of Li+ over Mg2 + reached 4783, indicating the high selectivity for Li+. In addition, the Li+ ion adsorption capacity kept constant during the six adsorption-desorption cycles and molar ratio of Mg to Li of eluents was as low as 0.08, indicating that the HxTiO3 ion sieve could effectively extract Li+ from the enriched brine.

Introduction

Lithium has found application in many industries such as ceramics, pharmaceuticals, and rechargeable batteries in mobile information and electric vehicles (Peiró et al., 2013; Ziemann et al., 2012). With the rapid expansion of the worldwide lithium battery market, the demand for lithium has increased to around 28, 000 tons of total global demand in 2012. > 80% of lithium is normally extracted from salt lake brine which are found in Bolivia, Chile, Argentina (Kesler et al., 2012). Although the salt lake brine of China has the huge lithium reserves, lithium production technology are currently under developing stage due to the unfavorable conditions of high magnesium (Mg) concentrations and complex elements in the brine, making it unsuitable for being extracted by the ripped precipitation method used in the majority of global salt lake brine (An et al., 2012; Moazeni et al., 2015).

The reported lithium extraction methods from the brine with high magnesium concentrations focus on extraction, electrodialysis, nanofiltration, membrane, and adsorption (Dang and Steinberg, 1978; Chitrakar et al., 2014a; Pasta et al., 2012). Adsorption method, as an efficient and cost-effective alternative, has become one of most popular domains in lithium extraction from the brine. Two main kinds of adsorbents including spinel manganese type lithium ion sieve with quick adsorption rate,(Ooi et al., 1990; Chitrakar et al., 2001; Ariza et al., 2006; Chitrakar et al., 2000a; Nishihama et al., 2011; Chitrakar et al., 2014b; Chitrakar et al., 2000b) and titanium type lithium ion sieve with low loss which were extensively studied by many researchers,(Moazeni et al., 2015; Chitrakar et al., 2014a; Wang et al., 2016; He et al., 2015; Tang et al., 2015; C-L et al., 2014) possessed the similar maximum lithium adsorption capacity of 45–50 mg/g under the constant conditions (~ 2 g of Li+ ions, pH 12) in the Li-containing solutions. As to the actual Li-containing brine, the manganese type lithium ion sieve (Zandevakili et al., 2014) and titanium type lithium ion sieve (Chitrakar et al., 2014a) have been proved to effectively extract the Li+ from the low Mg-containing brine of Urmia Lake and Bolivia, and the lithium adsorptive capacities were 15 mg g 1 and 32.7 mg g 1, respectively. However, lithium adsorption by lithium ion sieve especially titanium type lithium ion sieve from the high Mg-containing brine was seldom researched.

This research aimed at studying the adsorption extraction of lithium from the high Mg containing brine using laboratory prepared titanium ion sieve (HxTiO3), with the reported maximum lithium adsorption capacity so far (76.7 mg g 1) in LiOH solutions (~ 2 g L 1 of Li+ ions, pH 12) at 30 °C for 24 h. The structural characteristics of HxTiO3 and adsorption behavior, isotherms, thermodynamics, kinetics and recyclability in the brine were determined. In addition, the Li+ adsorption selectivity between Li+ and other cations were also preliminary investigated, considering their potential negative influence on lithium adsorption capacity.

Section snippets

Synthesis of HxTiO3

All of the chemical reagents were of analytical grade without further purification. The titanium dioxide (TiO2), lithium hydroxide (LiOH·H2O) and tetrabutylamine (TBA) were supplied by the Sinopharm Chemical Reagcal Co, Ltd., China. The enriched Qaidam basin salt lake brine of China collected by Beijing General Research Institute of Mining and Metallurgy was used for the lithium adsorption experiments in the present study. With the addition of Ca(OH)2 solutions, the pH of the enriched brine was

Texture properties

Fig. 1a showed that the XRD patterns of synthesized precursors matched well with the monoclinic β-Li2TiO3 phase (Fig. S1). Several peaks of sample were further characterized by using Cu Kα radiation (λ = 1.5418 Å) with a step of 0.02o to determine the lattice parameters, and the obtained results were good agreement with the reported values (a = 5.13 Å, b = 8.83 Å, c = 9.78 Å, β = 99.94°). (Chitrakar et al., 2014a) After hydrochloric acid pickling, (− 133), (− 206) and (062) diffraction peaks of the β-Li2TiO3

Conclusions

The HxTiO3 as lithium ion sieve has been successively prepared and used to adsorb Li+ from the high Mg-containing brine. The maximum adsorption capacities of Li was 36.34 mg/g and the separation factors of Li+ to Mg2 + reached 4783 in the brine which contained Na+, K+, Li+ (~ 1.56 g/L), high Mg2 + (~ 58.5 g/L), high Ca2 + (~ 55 g/L) and high concentrated anions at the initial pH 8.8, 25 °C for 24 h. After six adsorption-desorption cycles, the Li+ ion adsorption capacity maintained at ~ 33 mg g 1, indicating

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 51574212, U1403195).

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