Comparative adsorption performance of ibuprofen and tetracycline from aqueous solution by carbonaceous materials

Adsorption of ibuprofen and tetracycline onto a commercial granular activated carbon, multi-walled carbon nanotubes, and two low-cost activated carbons synthesized in the laboratory, has been investigated. The kinetic experimental data obtained at 30 degrees C and 250 r.p.m. were fitted to pseudo-first, pseudo-second and Elovich models, obtaining a high accuracy between the experimental data and the pseudo-second order equation. Therefore, the equilibrium adsorption data were analyzed by using Langmuir, Freundlich, Sips, Guggenheim-Anderson-de Boer, and Tempkin models. The highest ibuprofen adsorption capacity was obtained for AC-RH activated carbon, 239.8 mg g(-1), and in the case of tetracycline removal was of 845.9 mg g(-1) onto the peach stones activated carbon. These results are linked to the textural and chemical surface properties of the adsorbents. Fixed-bed experiments allowed obtaining good removal efficiencies at breakthrough time, 97.2% for ibuprofen and 96.1% for tetracycline onto activated carbon from rice husk. Desorption efficiencies were moderate in all systems, being higher by using NaOH solution at high concentration as elution agent. Finally, the important role of the acidic functionalities in the adsorption process was demonstrated by the accomplishment of FTIR studies of the adsorbents before and after the adsorption of both pharmaceutical compounds. (C) 2015 Elsevier B.V. All rights reserved.