抄録
Novel spinel type manganese dioxide adsorbents have been developed for selective recovery of Li+ from seawater. LiMn2O4 (Li/Mn molar ratio = 0.5) and Li1.5Mn2O4 (Li/Mn molar ratio = 0.75) were prepared, as an intermediate product, by sintering the mixture of Mn3O4 and LiOH, and the λ-MnO2 adsorbents were then obtained by ion exchange of Li+ to H+ with diluted hydrochloric acid. The characterization of the adsorbent with X-ray powder diffraction revealed that the adsorption of Li+ with both adsorbents progresses via cation exchange, and that the expansion-shrinking behavior of b axis in the crystal structure occurs during the adsorption-desorption of Li+. The adsorption ability of the adsorbent prepared from Li/Mn = 0.75 is higher than that from Li/Mn = 0.5, especially in high pH region of the aqueous solution. Since this adsorbent has also high selectivity on Li+/Na+ in the aqueous solution, the selective recovery of Li+ from the artificial seawater can be achieved by the chromatographic operation. From the practical experiments with the pilot plant in IOES, we elucidate that the chromatographic operation using the developed absorbent could be applied to large scale lithium recovery system from seawater.
