Microenvironment-Modulating Adsorption Enables Highly Efficient Lithium Extraction under Natural pH Conditions.

Han, Yu; Ma, Jiaxiang; Liu, Dongqing; Yang, Yan; Zhang, Tao; Wang, Min; Liang, Daxin; Wen, Liping et al. · ACS Nano · 2024

basic_science · Level V

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Abstract

Ion-sieve adsorbents are effective materials in practical applications for extracting liquid lithium. However, it is greatly suppressed in adsorption capacity and selectivity (Li/Mg) under natural near-neutral conditions of seawater or salt lakes, due to the interference of <i>in situ</i> released H<sup>+</sup> and Mg<sup>2+</sup> impurity. This paper proposes an adsorbent with a microenvironment-modulating function as a solution. The introduction of quaternary ammonium groups into the carrier accelerates the migration of H<sup>+</sup>, while preventing the diffusion of Mg<sup>2+</sup> by electrostatic repulsion. Besides, it can also prestore OH<sup>-</sup>, effectively consuming the generated hydrogen ions <i>in situ</i>. Based on the rational design, the alkali consumption of the microenvironment-modulating strategy is dramatically reduced to 1/144 of the traditional alkali-adding method. Additionally, adsorption performance is significantly promoted under natural pH conditions, with a maximum 33 times higher separation factor (selectivity) and 4 times higher adsorption capacity than commercial ion-sieve adsorbents. This development indicates the feasibility of using microenvironment modulation for effective lithium extraction and inspires the development of next-generation high-performance adsorbents.