Removal of Pb(II) ions from aqueous solutions by sulphuric acid-treated palm tree leaves

Abstract

The adsorption of Pb(II) ions on chemically activated carbon derived from palm tree leaves was investigated. The activated carbon (AC) was characterized by Infrared absorption spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) method and Scanning Electron Microscopic (SEM) analysis. The surface area (SBET), pore volume, and pore diameter of AC were determined by adsorption isotherms for N2. The effect of pH, equilibrated contact time, initial concentration of Pb(II), adsorbent dosage, and temperature were investigated. The maximum uptake of lead ion was obtained at pH 5.5 ± 0.3. The adsorption equilibrium was established after 180 min. The adsorption of lead ions by AC increased with its initial concentration in the medium, and reached a maximum at an approx. concentration of 100 mg Pb L−1. Pseudo-first order and pseudo-second order kinetic models were applied to study the kinetics of the adsorption process. The pseudo-second order kinetic model provided the best correlation (R2 > 0.9981) with the experimental data. It was found that the adsorption of Pb(II) on AC correlated better with the Langmuir than with the Freundlich isotherm equation in the concentration range studied. The study indicates that date palm derived AC could be used as an efficient adsorbent for the removal of lead ions from aqueous solutions. A maximum removal efficiency of 98.6% Pb(II) was obtained at a 4 g L−1 solid-to-liquid ratio and an initial heavy metal concentration of 50 mg L−1.