Highlighting the single and binary adsorption mechanism of amoxicillin and doripenem on copper benzene-1,3,5-tricarboxylate MOF via experiments, characterization, statistical physics modelling and DFT simulation

The adsorption of amoxicillin (AMX) and doripenem (DRPNM) on copper benzene-1,3,5-tricarboxylate (HKUST-1) in single and binary systems is analyzed in this paper. The experimental results showed that the adsorption capacities of this MOF for the removal of these pharmaceuticals reduced from single to binary solutions. A monolayer adsorption model and its extended competitive version were successfully applied to analyze the adsorption data. The modeling results showed that the reduction of AMX and DRPNM adsorption capacities was explained by a competitive effect of these adsorbates generating an antagonistic behavior for both molecules where the same adsorption site was involved during their removal. The statistical physics model was also utilized to estimate the AMX and DRPNM adsorption orientation on the HKUST-1 surface. Adsorption energies were calculated confirming an exothermic removal process for both molecules and DFT simulations allowed to determine the role of hydrogen bonding in the adsorption mechanism. It was concluded that the interactions for the adsorption of DRPNM on this MOF were higher than those for AMX removal. Particularly, the oxygens linked to the cupper ions on MOFs structure played a crucial role during the adsorption mechanisms of these organic compounds. Overall, this paper presents a combination between experiment results and two different theoretical approaches to provide a new explanation of the mechanism of adsorption of two relevant antibiotics on HKUST-1 MOF.