Kinetic models for adsorption on mineral particles comparison between Langmuir kinetics and mass transfer

• A theoretical model for batch adsorption process based on the Langmuir rate equation is presented.
• A closed form mathematical solution is used to obtain the theoretical adsorption curves.
• The effects of the various adsorption parameters are presented and discussed.
• The model is used to fit experimental results for the adsorption of chromium on stone particles.
• Results obtained from this model are compared to those obtained from a mass transfer model.

This paper presents a parametric study of kinetic adsorption model, for treating industrial wastewater contaminated with heavy metals by mineral particles, using Langmuir kinetics. It also compares the model with a mass transfer model, as a mathematical limiting case. Theoretical adsorption curves are presented in a simple form of fractional removal of pollutant as a function of time. They are obtained from the mathematical solution of ordinary differential equations, derived from differential mass balance and Langmuir kinetic rate equation. The effects of dimensionless process parameters on the fraction removal are presented. These include: equilibrium constant, particle dosage, ratio of the initial mass of pollutant to the maximum adsorbed mass, and Langmuir rate coefficient. The model provides a good fit to experimental results for adsorption of Cr(III) on both marl stone and stone cutting particles. A simplified fitting approach is presented.

Figure optionsDownload as PowerPoint slide