Abstract: | The solubility of potassium sulphate in sulphuric acid at 293°K has been determined. The effects of traces of Fe2+, Fe3+ and Cr3+ ions on the recrystallisation of potassium sulphate from both neutral and acidic solutions have been studied. While Fe2+ ions had no significant effect, concentrations of 0.07 g Fe3+ or 0.02 g Cr2+ per 100 g H2O inhibited crystallisation of potassium sulphate from 100% supersaturated solutions. A method for purifying potassium sulphate contaminated with Fe3+ and Cr3+ ions, by means of fractional crystallisation, is outlined. |