• activated carbon;
  • adsorption;
  • isotherms;
  • kinetics;
  • Pb(II)

This article reports the removal of Pb(II) ions from aqueous solution by the surface modified Guazuma ulmifolia (SMGU) seeds as an adsorbent and this material was prepared by treating the Guazuma ulmifolia seeds with sulphuric acid. The effectiveness of the SMGU has been investigated as a function of solution pH, adsorbent dose, contact time, and initial Pb(II) ion concentration. The Pb(II) adsorption was favored with maximum adsorption at pH 6.0. The Pb(II) adsorption equilibrium was attained within 60 min. The experimental data were analyzed using the Langmuir and Freundlich isotherm equations. The equilibrium data fit wellthe Freundlich isotherm. The experimental data were analyzed using four adsorption kinetic models: the pseudo-first-order and pseudo-second-order equations, the Elovich equation, and intraparticle diffusion equation to determine the best fit equation for the adsorption of Pb(II) ions onto SMGU. The characteristic parameters for each kinetic model have been determined and the coefficient of determination have been calculated to assess which model provides the best fit predicted data with experimental results. The kinetic results show that the pseudo-second-order equation provides the best correlation for the adsorption process. The nature of the possible adsorbent and metal ion interactions was examined by the FTIR technique. Surface morphological study was also done using BET and scanning electron microcopy analysis. The equilibrium data were applied for a single-stage batch adsorber design. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 307-316, 2013