Lithium extraction by extractant confined in Pickering emulsion
Enze Li, Zelong Li, Qiancheng Xia, Feiyu Zhang, Zhangqi Liang, Zhaozan Xu, Guandao Gao, Hu Li, Fangqin Cheng
Abstract
The global energy transformation towards electrification and decarbonization urgently requires a sustainable lithium supply. However, current solvent extraction technology suffers from extractant dissolution and low efficiency. Herein, we develop an oil-in-water (O/W) Pickering emulsion with high stability using amphipathic SiO2 nanoparticles to confine tributyl phosphate (TBP) extractant within the oil phase for enhancing lithium extraction from salt-lake brine. Resultantly, the Pickering emulsion achieves a lithium recovery of 91.7% with Li-Mg separation factor (βLiMg) of 101.9 after only three-stage extraction and Li+ mass transfer rate (k) of 4.57 × 10−8 m/s, greatly outperforming the traditional TBP system (52.8% recovery, βLiMg = 12, k = 7.50 × 10−9 m/s). We propose that the tiny gaps between SiO2 particles serve as Li+ transport channels, in which the interfacial electric field generated by surface charges of SiO2 particles and the confinement effect within these gaps synergistically enhance Li+ dehydration and diffusion. Efficient and sustainable lithium supply is increasingly important, but solvent extraction techniques are not yet practical. Here, the authors report the development of a Pickering emulsion for lithium extraction from salt-lake brine.