• adsorption;
  • lead;
  • acid activated clay;
  • isotherm models


The natural local deposits of montmorillonite-illite type of clay (MIC) were susceptible for acid activation. Raw clay was taken for experimentation, disintegrated on acid activation with sulfuric acid, which showed a particle size distribution. The montmorillonite and illite phases in the raw clay disappeared on acid activation and the activated clay, MIC(AA), showed with sodium-aluminum-silicate and beidellite phases apart from quartz (low) phase. The raw and acid-activated clays were characterized using X-ray powder diffractometry, X-ray fluorescence, Fourier transform infrared spectrometry, and energy dispersive X-ray, and their adsorption capacities were compared. When tested for adsorption of Pb(II) in aqueous solutions, the acid-activated clay showed about 50% increased adsorption than raw clay. Sips adsorption isotherm and pseudo-second-order kinetic models were found to be best for the batch adsorption data. Kinetic studies showed the existence of film diffusion and intraparticle diffusion. A two-stage batch adsorber was designed for the removal of Pb(II) from aqueous solutions. © 2010 American Institute of Chemical Engineers AIChE J, 2010