Simultaneous and individual adsorption of ibuprofen metabolites by a modified montmorillonite

Abstract In this work, the applicability of a modified montmorillonite (C18 Mt) to remove ibuprofen (IBU) and its main metabolites, 1-hydroxyibuprofen (1-OH IBU), 2-hydroxyibuprofen (2-OH IBU) and carboxyibuprofen (CBX-IBU), simultaneously or separately, from aqueous samples has been evaluated. First, the material was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy and zeta potential measurements. And then, the effect of the experimental conditions (initial concentration, time, temperature and pH) on the adsorption capacity was assessed. A statistical analysis of the adsorption isotherms reveals that Langmuir was the best model in fitting the experimental adsorption data. Maximum adsorption capacities were estimated to be 64, 20, 63 and 19 mg/g for IBU, 1-OH IBU, 2-OH IBU and CBX-IBU, respectively. These values were significantly lower for the mixture solution due to the competition effect for the active sites. Moreover, it was observed that the removal time is quite fast ranging from 20 to 30 min and the adsorption kinetics was predominantly based on the pseudo-second-order model. Characterization studies showed that the main driving force of adsorption was a combination of electrostatic interaction and partitioning. It was also observed that pH had very important effects on the adsorption. C18 Mt had proven to be an excellent adsorbent capable to remove new generation pollutants, even at low adsorbent dose making their application economic.