A discussion on linear and non-linear forms of Thomas equation for fixed-bed adsorption column modeling

The Thomas model is the most common equation to describe the dynamics of fixed-bed adsorption columns. However, its parameters’ validity strongly depends on the region of the breakthrough curve considered for the data fitting. A rigorous analysis based on different error functions was carried out to determine the accuracy of both linear and non-linear forms of the model. The non-linear equation proved to be more robust and less susceptible to experimental error, with less than 0.5% of deviation in qTh calculation. A complete statistical analysis should be carried out to determine the fitting region if linear regression is preferred.

Keywords: fixed-bed column, Thomas model, linear regression, non-linear regression, adsorption.