Solubility of ammonium aluminum sulfate dodecahydrate in the aluminum sulfate plus ammonium sulfate plus sulfuric acid plus water system at (25, 30, 40, and 50) °C

Solubilities of NH4Al(SO4)(2)center dot 12H(2)O in mixed aqueous Solutions of Al-2(SO4)(3) and (NH4)(2)SO4 were determined at (25 30 40, and 50) degrees C. At the same temperatures, solubilities of NH4Al(SO4)(2)center dot 12H(2)O in the (NH4)(2)SO4 + Al-2(SO4)(3) + H2SO4 + H2O system and densities of the equilibrium solutions were measured for sulfuric acid mass fraction on the salt-free basis, w', equal to 0.1. The measured solubilities were compared with available literature data. Ammonium alum solubilities are only moderately influenced by the sulfuric acid addition up to w'(H2SO4) = 0.1. The addition of sulfuric acid to the ternary (NH4)(2)SO4 + Al-2(SO4)(3) + H2O Solution increases the ammonium alum solubility in solutions with a NH4/Al molar ratio close to 1. In contrast, at either low or high NH4/Al molar ratios, the ammonium alum solubility is suppressed by the sulfuric acid addition.