Visual MINTEQ is a freeware chemical equilibrium model for the calculation of metal speciation, solubility equilibria, sorption etc. for natural waters. It combines state-of-the-art descriptions of sorption and complexation reactions with easy-to-use menus and options for importing and exporting data to/from Excel. Chemical equilibrium modelling has never been easier!
The code, originally built on USEPA’s MINTEQA2 software, is maintained by Jon Petter Gustafsson at SLU, Sweden, since 2000.
Visual MINTEQ will run on most Windows platforms and relies on .NET Framework. For more details, see here. The current versions are 3.1 and 4.0.