Abstract
The authors conducted a test on the feasibility of recoverring potassium from brine by using MgHPO4·3H2O. They first examined conditions under which MgHPO4·3H2O was formed, and they next examined the absorbing character and mechanism of potassium by using materials produced under various conditions.
1. Potassium was absorbed by the alkaline area and eluded from the acidic side. When it was absorbed, pH did not show any remarkable change even if alkali was added. This suggested that absorption of potassium might be caused by exchange reaction.
2. Although the rate of potassium absorption differed in accordance with the particle size of MgHPO4·3H2O, the complete equilibrium was obtained within about 30 minutes. As compared with this rate, the rate of dissolution of MgHPO4 was lower.
3. As the concentration of the added potassium solution increased, the amount of absorbed potassium increased. The amount of absorbed potassium was 0.5 and 0.9 meq/g when K+ concentration was 0.15 and 0.2 mole/l, respectively.
4. As compared with potassium, the amount of absorbed sodium was very small.
5. The solubility of MgHPO4·3H2O possessing an average particle size of 120μ, amounted to 24mg in 100g water at 20°C and to 14mg in brine (16°Bé) produced by ion exchange membrane method.
