Fabrication of Porous Capsules Encapsulating Lithium Adsorbent Using Polyethylene Glycol and Evaluation of Adsorption Performance

Abstract

We enclosed lithium ion adsorbent of several micrometer in diameter in microcapsules with larger diameter than the adsorbent to achieve ease of handling. We selected hydrophobic polymethyl methacrylate (PMMA) as the wall material of the capsules based on Hansen solubility parameter. PMMA has excellent mechanical strength. However, the hydrophobicity inhibit permeation of water and lithium ions. Therefore, polyethylene glycol (PEG) was incorporated into the PMMA microcapsules and then, removed to make water channels in the capsules. The created micropores promote the diffusion of lithium ions, and adsorption performance of lithium ions was improved by adding the PEG. When evaluated in terms of adsorption kinetics, the pseudo-second-order kinetics were in good agreement with the experimental data. The Langmuir adsorption isotherm model was in good agreement when the equilibrium adsorption amount of lithium ions was evaluated using adsorption isotherms.