Adsorption of pharmaceuticals and related compounds in cation-exchanged zeolites – A computational perspective

沸石是一种多孔无机骨架材料，由于晶体结构中存在孔洞或通道而具有固有的孔隙性。在铝硅酸盐沸石中，负电荷通过带正电荷的物质（主要是质子或金属阳离子）来平衡。阳离子交换已被确立为一种通用的技术来改变沸石材料的应用相关性质。除了已有的应用（如催化、气体分离），沸石还可用于药物和相关功能有机分子的吸附，目标应用于废水处理（去除“新出现的污染物”）或药物输送。然而，到目前为止，只有少数实验研究研究了阳离子交换沸石的这些用途，并且系统地了解阳离子类型对功能有机分子吸附的影响很大程度上缺乏。在这个项目中，在分散校正密度泛函理论（DFT）框架下的原子模拟将用于研究药物和相关化合物与含有不同阳离子的沸石吸附剂的相互作用。重点将放在两种与应用特别相关的大孔沸石上（FAU和MOR框架类型），考虑到含有不同基团阳离子的系统。该项目的第一部分将包括对DFT方法的彻底验证，包括优选阳离子位置和吸附能。在第二部分中，考虑到不同阳离子种类以及Si/Al比和框架类型（FAU/MOR）的变化，将系统地研究阳离子沸石与一组“模型化合物”（含有代表性官能团的相对简单的药物）之间的相互作用。第三部分将进行一组案例研究：在已发表的实验研究的基础上，将确定废水处理或药物输送方面特别感兴趣的有机物种。然后将使用DFT计算来研究它们与阳离子沸石的相互作用，不仅比较不同的阳离子类型，而且考虑与实际应用相关的各种其他方面，例如温度的影响和水的竞争性吸附。总之，在这个项目中进行的计算将使我们更好地了解功能性有机分子和阳离子沸石之间的相互作用，为开发定制沸石吸附剂提供有价值的见解。虽然该项目本身是纯粹的计算性质，但预计它将通过允许识别沸石-客体组合来刺激更多的应用研究活动，从而保证进行更全面的实验调查。

Zeolites are porous inorganic framework materials that possess an intrinsic porosity due to the presence of channels or cavities in the crystal structure. In aluminosilicate zeolites, the negative framework charge is balanced through positively charged species, mostly protons or metal cations. Cation exchange has been established as a versatile technique to modify application-relevant properties of zeolite materials. Beyond established applications (e.g., catalysis, gas separation), zeolites could also find use in the adsorption of pharmaceuticals and related functional organic molecules, targeting applications in wastewater treatment (removal of “emerging contaminants”) or in drug delivery. So far, however, only a few experimental studies have studied cation-exchanged zeolites for these uses, and systematic insights into the impact of the cation type on the adsorption of functional organic molecules are largely lacking. In this project, atomistic simulations in the framework of dispersion-corrected density functional theory (DFT) will be used to study the interaction of pharmaceuticals and related compounds with zeolite adsorbents containing different cations. Focus will be on two large-pore zeolites of particular relevance to applications (FAU and MOR framework types), considering systems containing cations from different groups. The first part of the project will comprise a thorough validation of the DFT methodology, both in terms of preferred cation sites and adsorption energies. In the second part, the interaction between cationic zeolites and a set of “model compounds”, relatively simple pharmaceuticals containing representative functional groups, will be studied systematically, considering different cation species as well as variations in Si/Al ratio and framework type (FAU/MOR). A set of case studies will be performed in the third part: On the basis of published experimental studies, organic species of particular interest in the context of wastewater treatment or drug delivery will be identified. DFT calculations will then be employed to study their interaction with cationic zeolites, not only comparing different cation types, but also considering various additional aspect of relevance for real-world applications, such as the impact of temperature and the competitive adsorption of water. Altogether, the calculations performed in this project will lead to a better atomic-level understanding of the interactions between functional organic molecules and cationic zeolites, delivering valuable insights for the development of tailored zeolite adsorbents. While the project itself is of a purely computational nature, it is anticipated that it will stimulate more applied research activities by allowing the identification of zeolite-guest combinations that warrant a more comprehensive experimental investigation.