Application of walnut tree sawdust modified with KMnO4 for removal of methylene blue from aqueous solution in batch system: Isotherm, kinetic and thermodynamic studies

Abstract

In this study, the adsorption of methylene blue from aqueous solution by modifying sawdust with KMnO4 has been studied as an effective adsorbent. The surface and characteristics of the composite are studied by Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The result demonstrate, that by increasing pH, the amount of methylene blue adsorption also increases, and the amount of optimum removal of this dye (96.36%) was obtained at methylene blue dye pH aqueous solution equal to 6 with initial concentration 100 mg L-1. The studies have shown that the kinetics of the adsorption process follows the pseudo-second-order model with a correlation coefficient R2>0.999, and equilibrium data conform the Langmuir isotherm model with R2>0.9982 and a maximum capacity of single layer adsorption qe equal to 100 mgg-1. Thermodynamically, the reaction is endothermic and spontaneous. Consequently, the result has shown, that the modified sawdust can be used as a quick, inexpensive and effective adsorbent in order for removal of methylene blue dye from aqueous solution.