Adsorption of rhodamine b dye from aqueous solution using an eco-friendly biosorbent from musa paradisiaca peels: Equilibrium and kinetics studies

The eco-friendly biosorbent derived from Musa paradisiacal (MPB) was assessed for its capacity to adsorb Rhodamine B (RhB) from aqueous media. To achieve this, the influence of key operational parameters-including biosorbent mass, contact time, initial dye concentration, and solution pH-was systematically investigated.Adsorption was carried out in batch tests. After adsorption the supernatant was analysed by UV-Vis spectrophotometry to determine the residual concentration of the RhB solution.Adsorption modeling was done with the surface reaction kinetic model and Langmuir and Freundlich equilibrium models. The obtained results showed that MPB has a pHZPC of 5.51, a specific surface area of 292.52 m2 g-1 and a maximum observed capacity (Qmo) of 90.00 mg g-1. The results demonstrated that the adsorption capacity of MPB increases with time and initial dye concentration, confirming a time-dependent uptake mechanism. Interestingly, the adsorption was only slightly influenced by pH, suggesting that electrostatic interactions are not the dominant driving force, and that other mechanisms such as hydrophobic interactions or specific binding sites may be involved. The optimal operating pH was determined to be 5.50, with a maximum adsorption capacity (Qm) of 4.97 mg/g and a peak adsorption percentage of 79.48%.Kinetic modeling revealed that the pseudo-second-order model (Rg² = 0.9002) provided a better fit than the pseudo-first-order model (Rg² = 0.8975), indicating that chemisorption likely governs the adsorption process. Equilibrium data were best described by the Freundlich isotherm (Rg² = 0.9384), compared to the Langmuir model (Rg² = 0.9049), suggesting heterogeneous surface adsorption and the possibility of multilayer coverage. Overall, MPB proved to be an effective and stable biosorbent for Rhodamine B removal under varied conditions. Its compatibility with the pseudo-second-order kinetic model and Freundlich isotherm reinforces its potential for practical applications in wastewater treatment.