Fabricating Ion Sieves by 3D Printing for Selective Lithium Adsorption from Brines

This work presents the formation of a stable 3D monolith based on manganese oxide for the adsorption of lithium from brine. The precursor phase was prepared by microwave-assisted hydrothermal synthesis and a subsequent calcination process to achieve the desired crystalline phase LiMn2O4. The monolith was formed using additive manufacturing, which allowed its size and shape to be controlled. Subsequently, this monolith was washed with a HCl solution to generate adsorption sites for lithium. The prepared materials were characterized by XRD, FTIR, TGA, N2 physisorption, and SEM-EDS. Analysis confirmed that the 3D monolith retained its crystalline structure throughout the process. The kinetic characteristics of the adsorption process were evaluated using pseudo-first and pseudo-second order equations, as well as Freundlich and Langmuir equations, to describe thermodynamic equilibrium. Monoliths were able to capture lithium up to 13.84 mg/g and the Freundlich equation described the equilibrium (R2=0.9751), while the second-order equation better described the kinetic behavior (R2=0.9130). Results showed that monoliths are selective towards lithium in the presence of competing cations. The stability of the materials was evaluated in adsorption-desorption cycles, demonstrating a competitive reuse after five cycles. This research presents a promising new approach for developing efficient lithium extraction methods from brine. In this study, a manganese oxide-based monolith for lithium recovery from brine has been synthesized and comprehensively characterized. The 3D-printed monoliths have good mechanical robustness and chemical stability. Their reusability was maintained after five lithium adsorption-desorption cycles. Kinetic and equilibrium experiments showed that the 3-D-printed monoliths have a competitive lithium adsorption capacity and high lithium selectivity. image