Titanium-based lithium ion sieve adsorbent H2TiO3 with enhanced Li+ adsorption properties by magnetic Fe doping

Abstract

The titanium-based lithium ion sieve adsorbent H2TiO3 (HTO), known for its structural stability and high adsorption capacity, emerges as a highly promising material. Nonetheless, its precursor, the Li2TiO3 powder (LTO), synthesized via the high-temperature solid-phase method, tends to agglomerate and poses challenges in separation. This agglomeration compromises the adsorption sites and, consequently, its adsorption capacity. To counter this, we employed a strategy of doping LTO with magnetic Fe3O4 nanoparticles as a Fe source, aiming to mitigate the agglomeration issue. Subsequently, Fe-doped H2TiO3 (HFTO) was obtained by acid washing and used to adsorb lithium ions from an aqueous solution. Experimental results revealed that HFTO's equilibrium adsorption capacity for lithium in LiCl solution peaked at 34.27 mg/g. Moreover, even after five cycles of adsorption–desorption, HFTO maintained an adsorption capacity exceeding 32.00 mg/g. Investigations into HFTO's adsorption mechanism, utilizing Raman spectroscopy, FT-IR, and XPS, uncovered that the adsorption of Li+ by HFTO occurs through the dissociation of O–H bonds and the subsequent formation of O-Li bonds.