The adsorption of salicylic acid, acetylsalicylic acid and atenolol from aqueous solutions onto natural zeolites and clays: Clinoptilolite, bentonite and kaolin

In this study, adsorption of salicylic acid, acetylsalicylic acid and atenolol from aqueous solutions onto clinoptilolite modified with sorbed metallic cations (Cu(II), Zn(II), Ni(II) or Mn(II)) have been probed. Natural clays (kaolin and bentonite, pure or ion-exchanged by octadecyl dimethyl benzyl ammonium chloride) have been also probed as adsorbents. The adsorption was studied at 30 degrees C by titration microcalorimetry, employed to obtain the heats evolved as a result of adsorption. Adsorption experiments were performed under the same conditions, the equilibrium adsorbate concentrations were determined by fluorescence spectrophotometry. The maximal adsorption capacities of investigated solids against target pharmaceuticals lie in the range of 10(-5)-10(-6) mol/g. Modified minerals have shown different capacities in comparison with natural ones. The adsorption capacities are dependent on the characteristics of pharmaceutically active compound. The results obtained in this work show that natural materials can be used effectively in the removal of investigated pharmaceuticals by adsorption. (C) 2012 Elsevier Inc. All rights reserved.