PH influence in cephalexin adsorption onto SBA-15 mesoporous silica

S. LEGNOVERDE; S. SIMONETTI; E. BASALDELLA

APPLIED SURFACE SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 300 p. 37 - 42

0169-4332

Cephalexin adsorption from aqueous solutions using SBA-15 mesoporous silica as adsorbent and theinfluence of pH solution on drug adsorption were studied. In order to have a better knowledge aboutthe way the drug molecules interact with the inorganic matrix, the adsorption process was estimatedby applying the computational chemistry software YAeHMOP (Yet Another extended Hückel Molecular Orbital Package). A strong correlation between the theoretical calculations and the experimentalresults was established, showing that the adsorbate adsorbent interaction is pH dependent. Calculatedcephalexin horizontal adsorption energy was almost 9 eV more stable than the one corresponding tovertical adsorption, and also the lowest enthalpy of contact and the maximum adsorption percent werefound for the cationic cephalexin-silica system. Cephalexin adsorption through the NH3+ group is 8 eVstronger than the molecule adsorption through the COO- group. In agreement with these theoreticalpredictions, experimental results indicate that the electrostatic attraction between CPX ions and the surface of mesoporous silica is favored at pH values between 2 and 2.56, the maximum being for cephalexin adsorption obtained at pH 2.3.