We are enthused about the ease of use and power of MINTEQA2 for Windows. The ability to specify a variety of sensitivity analyses and to immediately see the impact on the equilibrium due to changing a thermodynamic constant or other system parameter gives the user much greater insight into the chemistry than is available using the DOS version.

MINTEQA2 for Windows comes with sorption databases prepared for hydrous ferric oxide and goethite surfaces for use with the MIT Two-Layer (diffuse-layer) sorption model as described by David Dzombak and Samir Mathur. The model is provided with an extensive HTML help system and a comprehensive user guide especially useful for the sorption models.

• Computes equilibrium composition of aqueous systems
• Uses the U.S. EPA MINTEQA2 computational engine and database
• Allows user-specified equilibrium constraints including pH, pe, and multiple gas and solid phases
• Includes empirical and surface complexation (constant capacitance, MIT Two-Layer (diffuse-layer) and triple-layer) sorption models with screens and menus that make specifying treatment of electrostatic terms easier
• Automates sensitivity analyses over pH, pE, the concentration of any species, the log K of any species, the partial pressure of a gas, ionic strength, or temperature
• Presents results graphically; can plot the concentration of any species versus the sensitivity parameter

MINTEQA2 Introduction

MINTEQA2 is a geochemical equilibrium speciation model capable of computing equilibria among the dissolved, adsorbed, solid, and gas phases in the laboratory or in natural aqueous systems. MINTEQA2 includes an extensive database of reliable thermodynamic data.  The data required to predict the equilibrium composition in MINTEQA2 consists of a chemical analysis of the sample to be modeled giving total dissolved concentrations for the components of interest and any other relevant invariant measurements for the system of interest, possibly (but not necessarily) including pH, pe, or the partial pressures of one or more gases. A measured value of pH and/or pe may be specified as equilibrium values or MINTEQA2 can calculate equilibrium values. Also, a mineral may be specified as presumed present at equilibrium, but subject to dissolution if equilibrium conditions warrant, or definitely present at equilibrium and not subject to complete dissolution.

MINTEQA2 Database

MINTEQA2 has an extensive thermodynamic database that is adequate for solving a broad range of problems without need for additional user-supplied equilibrium constants. The standard database can be easily modified if it is found to be incomplete or inadequate for a particular problem. The empirical nature of the available metal adsorption data reflects the fact that natural adsorbent phases often occur as mixtures of impure amorphous substances that vary widely in chemical behavior from site to site. For this reason, adsorption data are left to the discretion and problem-specific knowledge of the user. Seven adsorption models are available in MINTEQA2 to match the type of data available for specific problems:

(1) the activity Kd model
(2) the activity Langmuir model
(3) the activity Freundlich model
(4) the ion exchange model
(5) constant capacitance model
(6) the triple-layer model
(7) the diffuse-layer model

Thermodynamic database files of surface reactions are generally not provided for these models as for aqueous and solid species; the user must provide the set of surface reactions and their equilibrium constants. An exception is a database of several surface reactions relevant to the diffuse-layer model for trace metal adsorption onto an iron oxide surface.

MINTEQA2 Requirements

 MINTEQA2 for Windows runs under Windows 95 and later. Requires IBM compatible machine with 486 or faster processor and at least 8 Mb memory.

MINTEQA2 for Windows

A Versatile Tool for Aqueous Geochemistry

We are pleased to announce the release of a user-friendly version of MINTEQA2 designed for Windows 95/98/2000/XP systems. MINTEQA2 for Windows can do all of the calculations that the official U.S.EPA DOS version can do and it uses the same thermodynamic database. It provides an intuitive graphical user interface using the familiar Windows conventions. MINTEQA2 for Windows computes the equilibrium composition of a multi-component aqueous system including the mass of each component in solution, sorbed, or precipitated.