Adsorption of ibuprofen on cocoa shell biomass-based adsorbents: Interpretation of the adsorption equilibriumvia statistical physics theory

The adsorption of ibuprofen (IBP) on raw and functionalized cocoa shell biomasses was studied via the statistical physics theory assuming a double layer adsorption process. The impact of molecular aggregation, steric and energy investigations on the IBP adsorption mechanism were analyzed and discussed. The theoretical calculations indicated that the IBP molecule could be removed through an inclined orientation on the surfaces of cocoa shell biomass-based adsorbents. The adsorption of this pharmaceutical was an exothermic process linked to physical adsorption forces with adsorption energies ranging from 1.46 to 3.25 kJ/mol. Calculated saturation IBP adsorption capacities ranged from 16.67 to 23.81 mg/g for raw biomass and from 30.59 to 38.95 mg/g for the functionalized biomass. The density of adsorption sites and adsorption energies played an important role to explain the performances of these adsorbents for IBP removal from aqueous solutions. In particular, the cocoa shell biomass functionalized with plasma and glycine could be an alternative material for industrial applications and can outperform other adsorbents reported for IBP removal from water. (C) 2021 Elsevier B.V. All rights reserved.