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

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 the equilibrium at about 60 min. The adsorption capacity reached approximately 42.71 mg g^-1 at the initial dye concentration of 100 mg L^-1. The kinetic modelling of MB adsorp­tion was perofrmed 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. The equilibrium modelling was also conducted. The four statis­tical values highlighted the better fit of the Langmuir model than the Freund­lich model. Additionally, the exothermic and spont-aneous 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.