In-situ magnetization of porous carbon beads for lithium-ion adsorption from strongly acidic solution

Abstract

To enhance the feasibility and cost-effectiveness of hydrometallurgy of spent lithium-ion batteries, it is crucial to achieve the recycling of strong acids employed in electrode dissolution. The current method of directly adding precipitants into strongly acidic electrode filtrate to obtain lithium results in contamination and renders it non-reusable. Therefore, an adsorption method was proposed for the capture and adsorption of lithium-ion from a strongly acidic solution. Subsequently, the porous, magnetic, and spherical carbon adsorbents were used for magnetic separation after reaching saturation during the adsorption process. In this work, the porous carbon beads were prepared using coal tar pitch as a precursor material, and the different magnetization methods of as-prepared carbon beads were investigated, including in-situ and impregnated magnetization. The results demonstrate a significant increase in mesopore volume from 0.0610 cm3/g to 0.2120 cm3/g by in-situ magnetization, thereby enhancing the availability of transport channels for lithium-ion adsorption. The graphitization degree of porous carbon beads is improved by magnetization, which is attributed to the catalytic graphitization effect of Fe. The ID/IG value of porous carbon beads decreases the most from 2.68 to 2.48 by impregnated magnetization, while the content of iron retained after activation is low, and the remanent magnetism of PCB-FeCl3 is far less than that of PCB-Fe3O4 (25.1103 emu/g). The result implies that the in-situ magnetization technique enables the utilization of porous carbon beads for magnetic separation recovery technology. The in-situ magnetized porous carbon beads have a high adsorption capacity for lithium-ion (79.8 mg/g) and still maintain excellent adsorption performance after 5 cyclic times of lithium-ion adsorption from a strongly acidic solution.