Enhanced lithium extraction from aqueous solutions using multi-scale modified titanium adsorbent

[Display omitted] •Ni replaces Li in the (Li) layer to create stable NiO bonds, improving stability.•Ni enhances the electronic transition ability and promotes adsorption.•EVOH is first used for adsorbent granulation, resulting in high hydrophilicity and rapid equilibrium.•Multi-scale modifications could significantly improve adsorbent performance of H2TiO3. It is highly appealing to use titanium-based adsorbents (like H2TiO3 (HTO)) that have a high capacity and selectivity to directly extract Li+ from an aqueous solution. However, HTO still faces the problems of low actual adsorption capacity and dissolution of Ti4+, and the application of powder adsorbents is limited by poor fluidity and poor recyclability. In this work, a multi-scale modification strategy was adopted. At the atomic-scale, we prepared Ni-doped HTO-Ni-2 % powder which exhibited higher adsorption capacity (33.27 mg/g) and lower dissolution rate of Ti4+ (2.2 %) compared to undoped HTO (29.73 mg/g and 2.63 %). Computational studies showed that Ni doping replaced Li in the (Li) layer, resulting in more stable NiO bonds and enhanced electronic transition ability. At the micro-scale, we have achieved successful granulation of HTO-Ni-2 % using ethylene vinyl alcohol (EVOH) as a binder for the first time. Owing to the increased hydrophilicity by EVOH, the spherical adsorbents exhibited impressive performance, achieving adsorption equilibrium in a short time while maintaining a considerable adsorption capacity (24 h, 10.2 mg/g), and having lower Ti4+ dissolution. These results have significant implications for developing efficient adsorbents for lithium extraction.