Lithium octanoate assisted sol–gel route to improve hydrophilicity of H2TiO3 for enhanced lithium extraction

The addition of surfactants during synthesis enhances the hydrophilicity of the lithium adsorbent H 2 TiO 3 (HTO), thereby facilitating lithium extraction. In this work, lithium octanoate (C 7 H 15 COOLi) was used as a raw material to prepare the precursor Li 2 TiO 3 (LTO), in which it also acted as a surfactant to assist the sol–gel process. The optimal calcination temperature was determined based on powder X-ray diffraction (PXRD) patterns, scanning electron microscope (SEM) images and equilibrium adsorption capacity ( Q e ) of Li + . The corresponding sample HTO-2 was examined by contact angle measurement, whose water contact angle was much smaller than that of HTO-0 synthesized from lithium acetate (CH 3 COOLi). The enhanced hydrophilicity improved the interaction between HTO-2 and hydrated Li + complexes, resulting in the increased Q e for HTO-2 compared to HTO-0. The adsorption of Li + by HTO-2 was well described by Langmuir isotherm model and pseudo-second-order kinetic model, and Q e only showed a slightly decrease after ten cycles. Moreover, its excellent adsorption selectivity for Li + was demonstrated in simulated desalination brine. This work reveals the dual role of C 7 H 15 COOLi and the critical role of hydrophilicity in enhancing lithium extraction.