Adsorption and Desorption Behavior of Lithium Ion in Spherical PVC–MnO2 Ion Sieve

Abstract

A spherical PVC–MnO 2 ion sieve of 2.0–3.5 mm diameter was prepared by the antisolvent method using synthesized Li 4 Mn 5 O 12 ultrafine powder as the precursor, poly(vinyl chloride) as the binder, and N -methyl-2-pyrrolidone as solvent. Batch experiments of the adsorption capacity (isotherm) and adsorption rate of Li + on the spherical PVC–MnO 2 ion sieve were studied. Spherical PVC–MnO 2 had a high adsorption capacity for Li +, and the isotherm data were well fitted by the Langmuir model; the adsorption kinetics were well described by the Lagergren equation. Furthermore, a mathematical model was set up to calculate the film mass transfer coefficient ( k f ) and pore diffusivity ( D p ) of the adsorbent. Continuous flow experiments for study of Li + adsorption breakthrough and the subsequent desorption (elution) in a PVC–MnO 2 packed column were carried out employing six feed solutions of various pH values and concentrations of Li +, Na +, K +, and Mg 2+ for simulating brine samples of various salt lakes and/or seawaters. After the adsorption treatment to concentrate the Li + on PVC–MnO 2, the column was regenerated by 1.0 mol/L HCl which supplied H + to accomplish elution of the adsorbed Li + by ion exchange. The experimental results demonstrate that PVC–MnO 2 had high selectivity for Li + and that its adsorption of Li + from the feed were little affected by Na +, K +, and Mg 2+ also present in the feed solution. Spherical PVC–MnO 2 is an attractive medium for large scale lithium extraction from brine or seawater.