Abstract
In this paper, a study was conducted on the method of recovering potassium from sea water andbrine by using zirconium polyphosphate (ZPP) and zirconium phosphate (ZP), and then crystallinezirconium phosphate (CZP) as an inorganic ion exchanger.
For preparing polyphosphate, there were used Na-tripolyphosphate, Na-hexametaphosphate, andNa-polyphosphate which was prepared by heating NaH2PO4·2H2O for three hours at 550°C and 650°C, respectively.
1. The total ion exchange capacity of the resulting ZPP was in the range of 4 to 5mg-equiv, /gof exchanger, and that of ZP exchanger was enhanced with an increase in the molar ratio ofPO4/Zr of the initial solution. It was about 5 mg-equiv./g when the molar ratio was 2.5: 1.
2. It was possible to selectively adsorb the potassium dissolved in sea water and brine by ZPand ZPP exchangers.The amount of adsorbed potassium for the zirconiumpyrophosphate and zirconium-hexametaphosphate was larger than that of sodium, and in selective adsorption, potassiumproved to be the best of all exchangers used.
3. Also, chromatographical separation was possible between sodium and potassium by which theconcentration and volume of desorbent for the column were exchanged. Therefore, thepercentage of potassium ion against the total cation (Na+K+Mg+Ca) in the desorbent was enhanced to about 80%.
