Correcting errors in the thermodynamic database for the equilibrium speciation model MINTEQA2 Original Research Article

The thermodynamic database distributed with the widely used equilibrium speciation model MINTEQA2 contains errors in reactions involving organic ligands. Users of this model should check the log equilibrium constants (log K) supplied with the modelʹs database against constants from critically reviewed compilations. The comparison of constants is not straightforward and may involve one or more data reduction steps, such as correcting the log K to zero ionic strength and to a temperature of 25°C. More importantly, it is necessary to reformulate the reaction from the literature in terms of the same components (reactants) used in MINTEQA2 before making the comparison. Use of the MINTEQA2 model without correcting errors in the database can lead to significantly erroneous results as is shown here for copper-EDTA speciation.