Instantaneous Equilibrium Approximation Analysis

Abstract

The issue of “how fast” reversible chemical reactions must be before “instantaneous equilibrium” may be assumed in ground‐water contamination problems is investigated. An example multicomponent model is used to study the requirements that must be placed on a system's Damkohler numbers to guarantee that reaction mechanisms are not kinetically limited. Analysis is presented for multicomponent transport problems using soluble complexation, ion exchange, and surface complex formation reactions. Results are presented to illustrate that instantaneous equilibrium is an excellent approximation when nondimensionalized reaction rates exceed 100.