Adsorptive removal of Pb(II) ions from groundwater samples in Oman using carbonized Phoenix dactylifera seed (Date stone)

Abstract

ObjectiveIn the present work, the potential use of raw date stone as an inexpensive carbonized adsorbent material for removal of Pb(II) has been demonstrated. MethodsThe adsorption of Pb(II) ions onto carbonized date stone has been studied by batch adsorption method. The variables (pH, adsorbent dose and initial concentration of Pb(II) ions) of the adsorption process were optimized by response surface methodology via Box-Behnken design (BBD). ResultsThe optimum values of pH, adsorbent dose and initial concentration were 5.0, 0.3 g and 5.0 mg L−1, respectively to achieve 88.50% removal efficiency. The adsorption data fitted well to both Langmuir and Freundlich isotherm models with coefficient of correlation (r) ˃0.9999. The maximum adsorption capacity of the described adsorbent material for Pb2+ ions with Langmuir model was found to be 9.03 mg g−1. Kinetic data obtained at different concentrations have been analysed using pseudo-first-order and pseudo-second-order kinetic models. The experimental data obeyed pseudo-second-order kinetic model. Gibb’s free energy change (ΔG°) was evaluated and resulted with −17.91 kJ mol−1 at 298 K, hence indicated favourable adsorption process. ConclusionNeghal carbonized date stone was found to be a promising natural adsorbent for removal of Pb(II).