Department of Civil and Environmental Engineering, University of Waterloo, 200 University Avenue West, Waterloo, N2L 3G1, Ontario, Canada.
Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, N2L 3G1, Ontario, Canada.
Chemosphere. 2024 Jan;347:140639. doi: 10.1016/j.chemosphere.2023.140639. Epub 2023 Nov 7.
This study describes a novel application of the use of molecular modeling tools for investigating the adsorption of organic micropollutants (OMPs) from water by nanocomposites. The partitioning of pharmaceuticals onto β-Cyclodextrin (β-CD) functionalized adsorbents was investigated at the molecular level to explore the atomistic interactions of pharmaceutical contaminants in water systems with β-CD and to provide insight into possible approaches for removal of pharmaceuticals from water. Molecular electrostatic surface potential mapping of β-CD derivatives was employed to examine the impact of substitution degree of β-CD and type of grafting agent on host-guest complexation. The stability of the complexes of selected pharmaceuticals and β-CD derivatives were assessed via molecular dynamics simulations to evaluate competitive adsorption between organic micropollutants (OMPs) and between OMPs and fulvic acid, a representative natural organic material (NOM) component found in water systems. Molecular electrostatic surface potential maps showed that grafting agents with aromatic and amine functional groups were found to provide attractive interactions for negatively charged OMPs. In addition, optimization of substitution degree of β-CD is necessary to enhance adsorption of target OMPs. Furthermore, it was found that aromatic ring bearing grafting agents can provide additional electrostatic attractions by π-π interactions with the aromatic ring of the OMPs. The impact of common water quality characteristics on adsorption was assessed and it was revealed that the effect of pH and calcium on adsorption depends on the ionizable functional groups present on the grafting agent. Molecular dynamics simulations showed that adsorption of target OMPs does not solely depend on hydrophobicity but is affected by electrostatic interactions. The simulations revealed that fulvic acid which is commonly present in environmental waters can be a competitor with ibuprofen for the β-CD cavity. Ultimately, this study showed that molecular level simulation can be effectively employed to investigate adsorption of OMPs by β-CD functionalized adsorbents and could be employed to enhance their design and subsequent environmental applications.
本研究描述了一种将分子建模工具应用于研究纳米复合材料从水中吸附有机微量污染物（OMPs）的新方法。在分子水平上研究了药物在β-环糊精（β-CD）功能化吸附剂上的分配，以探索药物在水系统中与β-CD的原子相互作用，并为从水中去除药物提供可能的方法。采用β-CD 衍生物的分子静电表面电势映射来研究β-CD 的取代度和接枝剂类型对主客体络合的影响。通过分子动力学模拟评估了所选药物和 β-CD 衍生物的配合物的稳定性，以评估有机微量污染物（OMPs）之间以及 OMPs 与腐殖酸之间的竞争吸附，腐殖酸是水系统中发现的代表性天然有机物质（NOM）成分。分子静电表面电势图表明，具有芳香族和胺官能团的接枝剂被发现为带负电荷的 OMPs 提供了有吸引力的相互作用。此外，优化 β-CD 的取代度对于增强目标 OMPs 的吸附是必要的。此外，发现带有芳环的接枝剂可以通过与 OMPs 的芳环发生π-π相互作用提供额外的静电吸引力。评估了常见水质特性对吸附的影响，结果表明 pH 值和钙对吸附的影响取决于接枝剂上存在的可离子化官能团。分子动力学模拟表明，目标 OMPs 的吸附不仅取决于疏水性，还受静电相互作用的影响。模拟表明，在环境水中普遍存在的腐殖酸可能与布洛芬竞争β-CD 腔。最终，本研究表明，分子水平模拟可有效地用于研究β-CD 功能化吸附剂对 OMPs 的吸附，并可用于增强其设计和后续的环境应用。
