EXPERIMENTAL-STUDY OF ALUMINUM-ACETATE COMPLEXING BETWEEN 60-DEGREES-C AND 200-DEGREES-C

The solubilities of bayerite and boehmite were measured as a function of pH and acetate concentration at temperatures from 60 to 200 degrees C, to determine the stoichiometries and stability constants of aluminum-acetate complexes. Analysis of these solubility data indicate that the three aluminum-acetate complexes, AlAcO2+, Al(OH)AcOC+, and A1(AcO)(2)(+) are significant. The logarithm of the stability constants of these complexes are found to be linearly related to the reciprocal of temperature over the range 60-200 degrees C. The slopes of these relationships yield association enthalpies of approximate to 75 kJ/mol. Thermodynamic calculations indicate that acetate can markedly enhance the solubility of Al-bearing minerals in sedimentary basin fluids over the temperature range from 100 to 200 degrees C, at pH < 5, but have little effect in solutions having higher pHs.