Experimental and modeling studies of methylene blue adsorption onto Na-Bentonite clay

Abstract

This study aimed to investigate methylene blue (MB) adsorption onto Na-bentonite as adsorbent. Individual effects of operating factors including initial MB concentration, pH, contact time and temperature on the performance of adsorption were firstly investigated. Results showed that these factors had significant effects on adsorption of MB solution. The adsorption rate was rapid at the initial stage and it reached equilibrium in a few minutes. For kinetic and equilibrium studies, pseudo-first, pseudo-second order and Langmuir models were able to fit experimental data with the maximum adsorption capacities ranging from 398.28 -465.28 mg/g. Also, thermodynamic studies showed that the process under study was the spontaneous and endothermic reaction. Finally, the surrogate-based model was developed to study interaction effects of operating factors and to examine the optimal condition. The optimal conditions for this study were found at the initial concentration of 634 mg/L, a pH of 10, and atemperature of 55oC.

Keywords

• adsorption
• surrogate-based models
• langmuir isotherm
• optimization
• kinetics
• thermodynamics