Wang Yue, Zhang Jinlong, Du Cong, Jin Yaofeng, Wu Xiaoyang, He Kunyu, Yang Yuxin, Li Xiaoyun
Department of Environmental Science, School of Geography and Tourism, Shaanxi Normal University, Xi'an 710119, China.
Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Sci Total Environ. 2024 Jan 15;908:168375. doi: 10.1016/j.scitotenv.2023.168375. Epub 2023 Nov 10.
Charge-assisted hydrogen bond (CAHB) is a key mechanism that affects the environmental behavior of pharmaceutical pollutants (PCs). However, the strength and stability of various CAHBs, and their effects on the co-sorption behavior of PCs are still unclear. Herein, DFT calculation with different solvent models including two implicit solvent model (PCM and SMD), and one explicit solvent model (ESM) were applied in this study, to investigate the effects of different CAHBs on the sorption and co-sorption behavior of four PCs (e.g., clofibric acid, p-aminobenzoic acid, acetaminophen, and sulfamerazine) on three model carbonaceous materials. First, the appearance of new peaks in the very low field of H NMR, and the blue shift of OH and NH peaks in FTIR indicated that CAHBs were indeed formed between PCs and carbonaceous materials. Next, according to the principal component analysis and correlation analysis of parameters (e.g., ΔE, bond length, bond angle, E, and ΔG) of these CAHBs calculated by the DFT with different solvent models, the results showed that SMD is the optimal model for calculating the strength and stability of CAHBs by DFT, and the strength and stability of CAHBs formed between PCs and carbonaceous materials in this study were in the order of homonuclear [O⋯H⋯O] CAHB > heteronuclear [O⋯HN]/[N⋯HO] type of CAHB > homonuclear [N⋯H⋯N]. Also, the co-sorption behavior of different PCs co-existing in binary systems further confirmed that, all above types of CAHBs formed between PCs and carbonaceous materials can produce obvious competition effect on the co-existing PCs that only OHB formed between them. This study not only reveals the environmental behavior of co-existing PCs, but also provides a theoretical basis for the design of obligate sorption materials for PCs in the natural environment.
电荷辅助氢键（CAHB）是影响药物污染物（PCs）环境行为的关键机制。然而，各种CAHB的强度和稳定性及其对PCs共吸附行为的影响仍不清楚。在本研究中，应用了包括两种隐式溶剂模型（PCM和SMD）和一种显式溶剂模型（ESM）在内的不同溶剂模型的密度泛函理论（DFT）计算，以研究不同CAHB对四种PCs（即氯贝酸、对氨基苯甲酸、对乙酰氨基酚和磺胺甲嘧啶）在三种模型碳质材料上的吸附和共吸附行为的影响。首先，1H NMR极低场出现新峰，FTIR中OH和NH峰蓝移，表明PCs与碳质材料之间确实形成了CAHB。其次，根据不同溶剂模型DFT计算的这些CAHB的参数（如ΔE、键长、键角、E和ΔG）的主成分分析和相关性分析，结果表明SMD是通过DFT计算CAHB强度和稳定性的最佳模型，本研究中PCs与碳质材料之间形成的CAHB的强度和稳定性顺序为同核[O⋯H⋯O] CAHB > 异核[O⋯HN]/[N⋯HO]型CAHB > 同核[N⋯H⋯N]。此外，二元体系中不同PCs共存的共吸附行为进一步证实，PCs与碳质材料之间形成的上述所有类型的CAHB对仅在它们之间形成OHB的共存PCs都会产生明显的竞争效应。本研究不仅揭示了共存PCs的环境行为，还为天然环境中PCs专用吸附材料的设计提供了理论依据。
