Adsorption of Carbamazepine in All-Silica Zeolites Studied with Density Functional Theory Calculations

The anticonvulsant drug carbamazepine (-) is an emerging contaminant of considerable concern due to its hazard potential and environmental persistence. Previous experimental studies proposed hydrophobic zeolites as promising adsorbents for the removal of carbamazepine from water, but only a few framework types were considered in those investigations. In the present work, electronic structure calculations based on dispersion-corrected density functional theory (DFT) were used to study the adsorption of CBZ in eleven all-silica zeolites having different pore sizes and connectivities of the pore system (AFI, ATS, BEA, CFI, DON, FAU, IFR, ISV, MOR, SFH, SSF framework types). It was found that some zeolites with one-dimensional channels formed by twelve-membered rings (IFR, AFI) exhibit the highest affinity towards CBZ. A good fit of CBZ into the zeolite pores that maximizes dispersion interactions was identified as the dominant factor determining the interaction strength. Further calculations addressed the role of temperature (for selected systems) and of guest-guest interactions between coadsorbed CBZ molecules. In addition to predicting zeolite frameworks of particular interest as materials for selective CBZ removal, the calculations presented here also contribute to the atomic-level understanding of the interaction of functional organic molecules with all-silica zeolites.

Automated summary

This study used electronic structure calculations to investigate the adsorption of carbamazepine (CBZ) in eleven all-silica zeolites. It was found that zeolites with one-dimensional channels formed by twelve-membered rings exhibited the highest affinity towards CBZ. The fit of CBZ into the zeolite pores, maximizing dispersion interactions, was identified as the dominant factor determining the interaction strength. The calculations also contributed to the understanding of the atomic-level interaction between functional organic molecules and all-silica zeolites.