A comprehensive study on paracetamol and ibuprofen adsorption onto biomass-derived activated carbon through experimental and theoretical assessments

Abstract

The paper reports an experimental and theoretical work about the adsorption of paracetamol (PCM) and ibuprofen (IBP) onto a new activated carbon synthesized starting from the tree pods deriving from Erythrina speciosa. The adsorbent shows good porous properties, with a BET surface area of 795.1 m2/g, and an average pore volume of 0.422 cm3 g−1. Adsorption tests are carried out by varying the most important operating parameters. The adsorption capacity of both IBP and PCM results to be maximum at pH = 3, i.e., where the adsorbate molecules are found in neutral form. Adsorption isotherms indicated that IBP adsorption capacity increases with temperature up to 96.28 mg g−1, while an opposite trendwas retrieved for PCM, which decreased until 50.40 mg g−1. For a theoretical analysis, a double layer model (DLM) is adopted in order to provide an interpretation of the occurring adsorption mechanisms. The theoretical approach indicates that both IBP and PCM are adsorbed bya multi-molecular way, i.e. each functional group on the adsorbent surface accommodates more than one molecule at the same time. Finally, the adsorption energy reveals that a physical adsorption is responsible for both IBP and PCM adsorption on the synthesized adsorbent.