(377y) Using Lithium-Aluminum Layered Hydroxide As an Efficient Adsorbent to Recover Lithium from Brine

Jing Zhong¹, Sen Lin^1,2,*, Jianguo Yu^1,2,*

1.National Engineering Research Center for Integrated Utilization of Salt Lake Resources, East China University of Science and Technology, Shanghai, China, 200237.

2.State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai, China, 200237.

Abstract:

Lithium-aluminum layered double hydroxide (Li/Al-LDH) has been proved an efficient adsorbent for lithium recovery from high Mg/Li ratio brine^[1,2]. Additionally, Li/Al-LDH after adsorption could be regenerated just by neutral water with no dissolution compared to other lithium adsorbents, including manganese ion-sieve and titanium ion-sieve.

In this study, Li/Al-LDH was prepared by co-precipitation and tested by various methods. The XRD spectrum showed that the prepared adsorbent was exactly the layered double structure where Li⁺ entered the vacancies in the Al(OH)₃ layers and Cl^- and water molecules occupied the interlayer space^[3]. The SEM images and BET results demonstrated the adsorbent was hexagonal platelet-shaped and had a large specific surface area of 161 m²/g, respectively. The adsorption experimental results reflected that lithium adsorption capacity of Li/Al-LDH was more than 7.2 mg/g at 25℃and the adsorption equilibrated after 2 h. Adsorption capacity was slightly affected by pH (3-11) during the lithium extraction process. Meanwhile, the lithium adsorption capacity rose by near two times when MgCl₂ concentration increased from 0 to 395.8 g/L, which indicated that the existence of Mg²⁺ would promote the lithium adsorption.

Besides, the lithium ions adsorbed on Li/Al-LDH could be eluted via pure water or low concentration lithium solutions and the desorption ratio was more than 90% without significant decrease in adsorption capacity after 30 adsorption/desorption cycles. Consequently, the as-prepared Li/Al-LDH had enormous potential for lithium recovery from high Mg/Li brine in China.

Keywords: Lithium recovery; Adsorption; Li/Al-LDH; Mg/Li separation.

References:

[1] Paranthaman M P , Li L , Luo J , et al. Recovery of Lithium from Geothermal Brine with Lithium–Aluminum Layered Double Hydroxide Chloride Sorbents[J]. Environmental Science & Technology, 2017, 51(22):13481-13486.

[2] Wu L , Li L , Evans S F , et al. Lithium Aluminum Layered Double Hydroxide Chlorides (, LDH, ): Formation Enthalpies and Energetics of Lithium Ion Capture[J]. Journal of the American Ceramic Society, 2018.

[3] Britto S , Kamath P V . Polytypism in the Lithium–Aluminum Layered Double Hydroxides: The [LiAl₂(OH)₆]⁺ Layer as a Structural Synthon[J]. Inorganic Chemistry, 2011, 50(12):5619-5627.