Removal of Lead (II) from Aqueous Solution using Banana (Musa Paradisiaca) Stalk-Based Activated Carbon

Abstract

Banana Stalk Activated Carbon (BSAC) chemically prepared was used as adsorbent to remove Pb (II) from aqueous solution in a batch mode. BSAC was characterized using physicochemical properties, proximate analysis, pH_pzc, and Fourier Transform Infrared (FTIR) spectroscopy. Effects of initial concentration, contact time, temperature, adsorbent dose and pH on adsorption of Pb (II) were evaluated. FTIR showed that BSAC is rich in carboxyl, hydroxyl and phenolic functional groups. The maximum percentage removal of Pb (II) was 97.90% at equilibrium time of 120 minutes. The kinetic data of Pb (II) were analyzed using pseudo-first-order, pseudo-second-order and intra-particle diffusion models but the pseudo-second-order kinetic model gave the best fit. Langmuir, Freundlich, Temkin and Dubinin – Radushkevich (D–R) isotherm models were used to analyze the equilibrium adsorption data, but the Langmuir isotherm model provided the best correlation (R²) of 0.998 and maximum adsorption capacity (q_max) of 200 mg/g.  The thermodynamic properties of the adsorption process, such as the Gibbs free energy, enthalpy and the entropic change have been evaluated and established that the process was spontaneous, feasible and endothermic in nature. BSAC is efficient and effective in removing Pb(II) from its aqueous solution.

Keywords: Banana stalk, adsorption, kinetics, isotherm, equilibrium