The performance of an eco-friendly adsorbent for methylene blue removal from aqueous solution: Kinetic, isotherm, and thermodynamic approaches

Abstract

The current study aims to determine how well pomegranate peel can remove Methylene Blue (MB) from an aqueous solution. For this purpose, kinetic, isotherm, and thermodynamic adsorption studies were performed in a batch system. The rate of MB adsorption was rapid and reached equilibrium at about 60 minutes. The adsorption capacity reached approximately 42.71 mg g-1 at the initial dye concentration of 100 mg L-1. The kinetic modeling of MB adsorption was conducted using pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models. The pseudo-second-order model was found to be the most adequate for fitting the kinetic data based on R2, RMSE, ARE, and χ2 values. It was also discovered that MB adsorption onto pomegranate peel is not simply rate-limited by intraparticle diffusion. The isotherm approach showed a maximum adsorption capacity of 67.78 mg g-1 at 298 K using 2 g L-1 of pomegranate peel. Equilibrium modeling was also conducted. The four statistical values highlighted the better fit of the Langmuir model than the Freundlich model. Additionally, the exothermic and spontaneous nature of the adsorption process was revealed by thermodynamic research. These findings demonstrate the effectiveness of pomegranate peel as an eco-friendly absorbent for MB removal.

Keywords

• adsorption
• kinetic
• pomegranate peel
• methylene blue
• isotherm
• thermodynamic