Effect of chemical heterogeneity on interactive solute dispersion into fixed beds

Abstract

The paper aims to establish the relationship between chemical heterogeneity and linearly adsorbed solute dispersion into fixed beds. For simplifying reasons, we considered the heterogeneity where the active sites are uniformly distributed over  grains which are  mixed with non active grains. Following the approach of continuous media. We have developed a transport model for describing the breakthrough point as a function of the chemical heterogeneity from the classical advection-dispersion equation of water transport to which we add a function describing the bed heterogeneity. The establishment of the model is based on assumptions which are: Fluid phase equilibria established,  linear adsorption equilibrium and BERNOULLI  chemical heterogeneity distribution. The differential equation obtained is solved by the numerical method of finite volumes based on the Thomas algorithm.

First, hydrodynamics study shows the same dispersion for all heterogeneous medium studied. This behavior provides to observe the evolution of the dispersion with chemical heterogeneity.

Also the Result shows an important effect of chemical heterogeneity on the spread of the breakthrough curve. The more intense the chemical heterogeneity of the medium is, the more important the solute dispersion is. Also low dispersion of the breakthrough curves obtained at less flow rate compared with high flow rate.