Lithium sequestration from dilute solutions and sea bittern inspired by the self-assembled complexation

Abstract

The increasing demand for lithium and limited resources has attracted attention to challenging omnipresent resources like seawater, where the commonly used Li2CO3 precipitation method fails. Lithium-selective receptors could, in principle, circumvent these challenges but are plagued by poor extraction ability from dilute solutions. In this work, we report new anthraquinone-derived acyclic ionophores that undergo self-assembly to form a very stable binuclear lithium adduct, selective over sodium & potassium analogs, supported by DFT studies and crystal structures. Consequently, a high binding constant (Ka ∼ 105 M−1) and lithium recognition at a nanomolar concentration (LOD ∼ 90 nM) were observed. The high binding affinity and stability of lithium adduct efficiently drive lithium-ions transportation and solvent extraction from dilute solutions with a lithium concentration as low as 10 ppm and from sea bittern. This study opens an avenue to circumvent the limitations for future lithium sequestration even from natural resources.