Abstract
Lithium-specific adsorption and lithium isotope separation characteristics were investigated on adsorbents, HMnO (Mg), prepared by treating MgMn2O4with hydrochloric acid or hydrochloric acid-ammonium peroxodisulfate ((NH4)2S2O8) mixture solution. Lithium-specific adsorption was observed for the adsorbents with the spinel structure and magnesium extractability of more than about 90%. The use of (NH4)2S2O8with an appropriate concentration may reduce the degree of manganese dissolution in acid treatments while keeping high extractability of magnesium.
Lithium isotope fractionation between the adsorbent thus prepared and a supernatant in equilibrium with each other was observed. The lighter isotope, 6Li, was found to be preferentially fractionated into the adsorbent phase and the value of the single-stage separation factor minus one was 5.4-7.4×10-3at 25°C. No apparent relation was found between acid treatment conditions andthe lithium isotope effect as long as the adsorbent retained the spinel structure and had magnesium extractability more than about 90%
