Removal of Pb(II) in Aqueous Solutions Using Synthesized Zeolite X from Ecuadorian Clay

Zeolite X was synthesized from clay using the alkaline fusion method and hydrothermal treatment to remove Pb(II) in aqueous solutions. Clay and zeolite were characterized through X-ray diffraction and fluorescence (XRD, FRX), as well as through specific surface area (SSA). The adsorbents were prepared as cylindrical extrudates using clay and a clay-zeolite combination (60-40%, respectively). The effects of pH, isotherm, and adsorption kinetics on the removal of Pb(II) in solutions of 80 mg Pb(II)/L were studied. It was possible to obtain a zeolite X from clay, with an SSA of 376 m2/g, 30 times greater than that of clay (12 m2/g). In the combined extrudate was present the zeolitic structure, with an SSA 12 times higher compared to the clay extrudate. The adsorption capacity, at 30 ◦C and V/m ratio of 1 g/L, is almost double compared to the clay extrudate (24 mg Pb(II)/g vs. 13 mg Pb(II)/g). Adsorption follows second order kinetics, and the Langmuir isotherm equation showed a good fit with the experimental equilibrium data for the two extrudates. The Webber-Morris and Bangham-Burt’s models suggest that pore and film diffusion influence the kinetic mechanism.