Potentiality of banana peel for removal of Congo red dye from aqueous solution: isotherm, kinetics and thermodynamics studies

Potentiality of fruit peel (banana peel) was evaluated by adsorption of Congo red (CR) dye from aqueous solution. The adsorption study was performed by varying operating variables such as pH, initial concentration of CR, adsorbent dose, contact time and temperature. The dust of banana peel was characterized by different instrumental techniques such as point of zero charge, scanning electron microscopy and Fourier transformed infrared spectroscopy. The results revealed that the dye adsorption is favorable at higher pH (10). The equilibrium of dye adsorption was assessed by Freundlich and Langmuir isotherm models. Similarly, kinetics of CR adsorptions was assessed by pseudo-first-order and pseudo-second-order kinetics. Results revealed that isotherm and kinetics of dye adsorption fit well with Langmuir isotherm and pseudo-second-order kinetics, respectively. The dye adsorption capacity was recorded as 1.727 mg/g. The thermodynamics of the dye adsorption revealed that the adsorption is thermodynamically favorable, spontaneous and exothermic in nature. The regeneration study suggested that 97.3% dye removal can be achieved by regenerating the spent adsorbent with 0.1 N NaOH solution. Finally, it can be concluded that banana peel could be an efficient adsorbent for removal of Congo red from aqueous medium.