Separation of Potassium from The Model Solution

Abstract

Potassium content in biomass ashes, especially empty fruit bunches was quite high and had not been utilized maximally. This research dealt with the development of a technique for recovering potassium salt from a solution of ash extraction. Experiments were carried out usung a solution model containing KCl, NaCl, MgCl2, and CaCl2 with concentrations of 164.19, 8.39, 7.44, dan 39.60 mg/L respectively. Results of a preliminary experiment indicated that the solubilities of KCl and NaCl were reversed: 280.4 and 280.4 (g/L in water) to 6.9 and 14.2 (g/L in absolute ethanol), while the solubilities of MgCl2 and CaCl2 were still high (68.7 and 383.5 g/L in ethanol). Using these values of solubility, a combined evaporation and adding ethanol was trialed firstly to increase the precipitation of KCl. Evaporation of KCl solution 164.19 g/L until an evaporation leves of 15% did not give any precipitation yet, while adding ethanol to the remaining solution (at solution ratios of 4/1 and 3/2 ethanol) yielded precipitations with the potassium recoveries of 60% and 48% respectively. At an evaporation level of 30%, the evaporation yielded a 5% potassium recovery, while the combined technique gave 60% and 50% recoveries for adding ethanol with ratios of 4/1 and 3/2 respectively. The application of the combined technique on the mixed salts solution was modified slightly. The precipitate from the evaporation (containing KCl and NaCl) was redissolved into water and followed by adding ethanol to precipitate only KCl. Thus, two precipitates were finally obtained: (i) precipitate from adding ethanol to filtrate of evaporation, and (ii) precipitate from dissolving precipitate from evaporation. At an evaporation level of 30%, the evaporation only gave a precipitate recovery of about 10%, while the application of combined technique gave bout 80% and 60% recoveries by adding ethanol with ratios of 4/1 and 3/2 respectively. Hopefully this technique could separate KCl from its mixture with NaCl, MgCl2, and CaCl2.