Experimental study of aluminum-acetate complexing between 60 and 200°c

The solubilities of bayerite and boehmite were measured as a function of pH and acetate concentration at temperatures from 60 to 2OO"C, to determine the stoichiometries and stability constants of aluminum-acetate complexes. Analysis of these solubility data indicate that the three aluminum- acetate complexes, AlAcO *+ Al(OH)AcO+, and Al(Ac0); are significant. The logarithm ofthe stability constants of these complexei are found to be linearly related to the reciprocal of temperature over the range 60-200°C. The slopes of these relationships yield association enthalpies of -75 kJ/mol. Ther- modynamic calculations indicate that acetate can markedly enhance the solubility of Al-bearing minerals in sedimentary basin fluids over the temperature range from 100 to 2OO"C, at pH < 5, but have little effect in solutions having higher pHs.