Combined Neutron and X-Ray Diffraction Study of Ibuprofen and Atenolol Adsorption in Zeolite Y

TL;DR

This study explores how ibuprofen and atenolol bind to zeolite Y, revealing how their structures and interactions influence adsorption for environmental cleanup.

Contribution

A novel combined neutron and X-ray diffraction approach with symmetry reduction reveals distinct adsorption mechanisms for two pharmaceuticals in zeolite Y.

Findings

Ibuprofen is stabilized by steric confinement and dispersive interactions in zeolite Y.

Atenolol's adsorption is driven by electrostatic charge compensation within the zeolite framework.

Adsorption geometry depends on functional group orientation and host-guest proximity, not molecular chirality.

Abstract

The widespread occurrence of pharmaceutical residues in aquatic environments necessitates the development of advanced porous materials for efficient remediation. This study investigates the adsorption mechanisms of ibuprofen and atenolol within the high-silica zeolite Y. Batch adsorption experiments demonstrated significant uptake, with loading capacities of 191.6 mg/g for ibuprofen and 273.0 mg/g for atenolol, confirming the material’s effectiveness. Using a combination of neutron and X-ray powder diffraction, complemented by Rietveld refinement and simulated annealing algorithms, we achieved the exact localization of the guest molecules. While the pristine zeolite maintains cubic symmetry Fd3¯, the incorporation of pharmaceutical molecules induces significant residual nuclear density and anisotropic lattice distortions. To accurately model these perturbations, a systematic symmetry reduction to the acentric triclinic space group F1 was implemented. This approach enabled an ab initio refinement of the structure, revealing that drug uptake of each guest is governed by distinct chemical drivers. Ibuprofen is stabilized via steric confinement and long-range dispersive interactions. In contrast, atenolol stability is governed by electrostatic charge compensation within the zeolitic voids. Our results suggest that the final adsorption geometry is dictated by the spatial orientation of functional groups and host–guest proximity rather than molecular chirality. These results provide a microscopic model describing the fundamental host–guest interactions in FAU zeolites. This structural understanding is an essential step towards the potential use of zeolitic materials in environmental remediation and complex guest sequestration.

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