Abstract
Lithium extraction from natural waters by cation exchange chromatography was studied. The experimental conditions were: cation exchange resin, AG50W-X8 (200-400 mesh); resin bed, 30.0cm×2.0cmφ; eluent, 0.5M HCl; flow rate, 4.0cm3/min; temperature, 25.0°C. Under these conditions, lithium was perfectly separated from other cationic components within experimental errors and the degree of lithium recovery was 99%.
The isotopic ratio (7Li/6Li) of extracted lithium was measured with a double-filament surface ionization technique on a mass spectrometer. The 7Li/6Li value of seawater relative to that of a lithium isotope standard (CBNM-016; 7Li/6Li=12.289±0.052) was 1.0294 as the average of seven measurements, and the standard deviation was 0.0008.
The lithium isotopic compositions of the natural waters examined (one seawater and five hot spring waters) varied between +1.4 and +29.4 expressed in permil deviation from the isotopic ratio of the isotope standard. This indicates a possibility that lithium isotopic compositions of natural materials may be used as a tracer in geochemical studies.
