ACID ACTIVATION OF A PALYGORSKITE WITH HCL - DEVELOPMENT OF PHYSICOCHEMICAL, TEXTURAL AND SURFACE-PROPERTIES

A palygorskite from Bercimuel (Segovia, Spain) was treated with 1.0, 3.0, 5.0 and 7.0 N solutions of KCI for 1 hour under reflux. The solids obtained were characterized by XRD, FT-IR spectroscopy, thermal analyses, TEM and nitrogen adsorption-desorption isotherms at 77 K. The acid treatment runs with the removal of the octahedral cations -Mg(II), Al(III) -and the formation of amorphous silica from the tetrahedral sheet. An important increase in the specific surface area was observed during treatment, reaching a maximum of 286 m(2)/g in the sample treated with 5.0 N HCl. The silica obtained after the treatments maintains the fibrous morphology of natural palygorskite. No creation of microporosity is observed during the treatment.