Surface Modification and Spatial Optimization of Pre-Lithiation Tio2 Ion Sieves for Efficient Extraction of Lithium

Abstract

The closed pores and slow kinetics of conventional Ti-based adsorbents (HTO) hinder their industrial application in the selective adsorption of Li+ from wastewater. Herein, a surface modification and spatial optimization strategy was developed to improve the adsorption performance of HTO for Li+. The FTIR, TEM-EDS and XPS analyses reveal that heteroatoms introducing to the adsorbent from cetyltrimethylammonium chloride (CTAC) favors the directional migration of Li+ towards adsorption sites. The contact angle and FTIR analyses indicate that surface hydrophilicity of the modified HTO has been improved, which accelerates the de-solvation process of hydrated Li+ into activated Li+ that is readily into the adsorbents. The SEM, TEM and HRTEM analyses confirm that the size of adsorbent particles is decreased after the modification, reducing the transfer pathway and resistance of Li+. The BET analysis shows that the rich-pore structure of the modified HTO exposes specific Li+ adsorption sites and creates adsorption space for Li+ due to partial decomposition and volatilization of CTAC. The adsorption process corresponds to the pseudo-second-order kinetic model and Langmuir isotherm model. The experimental results show that the Li+ adsorption rate is increased from 0.37mg·g-1·min-1 of HTO to 0.82mg·g-1·min-1 of modified HTO, and its adsorption capacity is 49.05mg·g-1. The adsorption capacity of the modified adsorbent remains 96.7% after 5 cycles, indicating that it has excellent recyclability. This study provides a new strategy for effectively extracting Li+ from low concentration lithium-ion solutions.

Keywords: adsorption, Hydrophilicity, Lithium-ion sieve, surface modification, Spatial optimization