Surface-Modified H2TiO3 for Enhanced Lithium Ion Adsorption: Dispersion Optimization and Regulation of Interfacial Mass Transfer Resistance

The lithium adsorption capacity of layered H2TiO3 (HTO) is constrained by particle aggregation, which results in substantial interfacial mass transfer resistance. This study employs phenylphosphonic acid (BPA) to modify HTO, achieving dual optimization of dispersion stability and adsorption kinetics. BPA grafting was confirmed (via P–O–Ti covalent bonds) and likely introduced steric and electrostatic repulsion and decreased the surface energy. Sedimentation tests showed that BPA-modified HTO (HTO-BPA) exhibited reduced particle aggregation, leading to faster Li+ adsorption equilibrium (5 h vs 13 h for HTO) and a higher capacity (54.58 mg·g–1 compared to 47.23 mg·g–1 for HTO). HTO-BPA also demonstrated reduced acid dependency during desorption, maintaining Ti dissolution below 2% over eight cycles. This work provides a scalable strategy for designing efficient lithium-ion sieves, critical for sustainable resource recovery.