Liquid Phase Adsorption of Rhodamine B Dye onto Acid-treated Raphia hookeri Fruit Epicarp: Isotherms, Kinetics and Thermodynamics Studies

Abstract

Novel adsorbent was prepared from the waste of Raphia hookeri fruit via acid treatments (ARH). The Brunauer-Emmett-Teller (BET) surface area of ARH was obtained to be 1.86 m² g-1. Large surface pores evidently exposed by the scanning electron microscopic studies characterized ARH. Active surface functional groups were also revealed by the infrared spectroscopic studies. These characteristics resulted in ARH effectiveness in Rhodamine B (RhB) dye removal, with 98.46 % dye removal from 50 mg L-1 RhB solution. Maximum adsorption was obtained at pH of 3. Equilibrium adsorption data fitted best into the Langmuir adsorption isotherm, with maximum monolayer adsorption capacity of 166.67 mg g-1. Pseudo-second-order kinetics best describe the RhB-ARH adsorption kinetic data. Energy of adsorption obtained from the D-R model was greater than 8 kJ mol-1, suggesting that the uptake of RhB onto ARH was chemical in nature. Desorption efficiency followed the order CH3COOH > HCl > H2O with highest desorption percentage of 36.36 %.