Adsorption of Pharmaceuticals onto Smectite Clay Minerals: A Combined Experimental and Theoretical Study

The adsorption of two pharmaceuticals, carbamazepine and paracetamol, onto the expandable clay mineral saponite has been studied through combination kinetic experiments, X-ray diffraction, theoretical modeling. Kinetic experiments indicate low for paracetamol on smectite clay. Accordingly, diffraction show that neither compound enters interlayer space. Molecular dynamics simulations were carried out to understand interactions between pharmaceuticals basal surface in presence Na+ cations. Calculations reveal almost does not coordinate solution cations, whereas a rather coordination cation is observed carbamazepine. As result, results mainly from van der Waals both pharmaceuticals. Carbamazepine adsorb via configurations, one involving coordination, which corresponds stable compared paracetamol. This confirmed by structural analyses completed with desorption free energy profile.