Kinetics and isotherm modeling of phenol adsorption by immobilizable activated carbon

Abstract

For the present study, activated carbon–epoxidized natural rubber–poly(vinyl)chloride composite was fabricated on the glass plates to remove phenol from the aqueous solution. The best fitting of kinetics and isotherm modeling was established using the nonlinear and linear regression analyses. The statistical functions such as R2, χ2 and RMSE were used to determine the best-fitting of the adsorption modeling. It was found that the adsorption data best-fitted the PSO kinetics model for both nonlinear and linear regression analyses. The best-fitting isotherm models for both analyses was the Freundlich model with the highest R2 and lowest χ2 and RMSE values among all models. The intraparticle diffusion was the sole rate-controlling step during the phenol uptake onto the immobilized AC composite. The plot exhibited multilinear portions, which corresponded to three stages of adsorption. The nonlinear regression modeling for kinetics and isotherm achieved higher R2 with lower χ2 and RMSE values as compared to the linear regression showing that the former analysis is more robust, accurate and consistent than the latter approach. Based on the results of the analysis, it is highly recommended to use nonlinear regression when dealing with the adsorption data for the specific and accurate fitting of kinetics and isotherm models.