A COMPARATIVE STUDY FOR CHOOSING THE BEST KINETIC MODEL USING DIFFERENT ERROR METRICS

Abstract

In the present investigations, a comparison of fly ash and cow dung ash was carried out to study the adsorption kinetics of Nickel ions present in aqueous solution. Various kinetic models are evaluated during these investigations, which include pseudo-first-order, pseudo-second-order, intra-particle diffusion, fractional power, and Elovich models. These models were exhaustively evaluated and compared using eighteen different error functions. An overall performance indicator metric has also been discussed that helps in ranking the different kinetic models for estimation of adsorption capacity (qt) based on the values of different error functions. After analysing these results, it was observed that the kinetic models can be ranked from best to worst with respect to qt determination for cow dung ash and are as follows: pseudo-first order, pseudo-second order, Intra-particle diffusion, Elovich, and Fractional power. Similarly, for fly ash adsorbent, the ranking of kinetic models from best to worst was found to be: pseudo-second-order, intra-diffusion particle, fractional power, Elovich, and pseudo-first-order.