Abstract
In order to increase the adsorption rate of lithium, a method for preparing granular adsorbent with high porosity was examined using sodium chloride as the porous agent. Porous granular adsorbent was prepared using the following procedure. A precursor (Li1.33Mn1.67O4) and NaCl powder were mixed for 30 minutes, and the homogeneous mixture was added to a DMF solution containing PVC. The suspension was mixed sufficiently, placed in a granulation apparatus, and subsequently dropped into a water-methanol solution. The granular precursor obtained was washed with water to remove NaC1 for pore generation. It was treated in a 0.5M HCl solution for three days. Consequently, H-type porous granular adsorbent was obtained.
The lithium adsorption rate was improved considerably when NaCl above 3 wt% was added to the precursor. The granule diameter influenced the adsorption rate of lithium. The lithium uptakes reached 20, 18 and 16mg/g through adsorption for 31 days with granules showing diameters of 0.50-0.71 mm, 0.71-1.00 mm and 1.00-1.40 mm, respectively.
The porous adsorbents showed an adsorption rate about 1.2 times higher than those prepared without NaCl. A preliminary calculation suggested that recovery cost can be reduced to 58% by a doubling of the adsorption rate, and about 80% by an increase of up to 1.2 times.
