Bisphenol A was used as representative ionizable organic compounds (IOCs) to investigate their adsorption on graphene oxide (GO). To explore the pH-dependent adsorption of IOCs on GO, analysis of electrostatic interaction energy, hydrophobicity, and π-electron densities of benzene rings under different pH conditions was carried out employing molecular dynamics (MD) simulations and density functional theory (DFT) calculations. Six configurations of H-bond were witnessed during the adsorption process: (1) intramolecular H-bond between functional groups of GO; (2) GO…water H-bond; (3) GO…water…GO H-bond; (4) IOC…GO H-bond; (5) IOC…water…GO H-bond; and (6) IOC…water H-bond. MD results indicated more H-bonds appeared between GO (or IOC) and water than that between IOC and GO, indicating the water-mediated H-bond acted as a steering force in the adsorption process. Upon the adsorption, configurations of IOCs and GO were changed, and the hydrophilicity was decreased, which may in turn affect their fate and toxicity in the environment. The change of π-electron density of several common IOCs were provided, which may help to understand the pH-dependent behaviour of IOCs in future studies.

中文翻译：

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使用分子动力学模拟了解pH依赖的可氧化化合物在氧化石墨烯上的吸附

双酚A被用作代表性的可离子化有机化合物（IOC），以研究其在氧化石墨烯（GO）上的吸附。为了探索IOC在GO上的pH依赖性吸附，利用分子动力学（MD）模拟和密度泛函理论（DFT）计算，对不同pH条件下苯环的静电相互作用能，疏水性和π电子密度进行了分析。 。在吸附过程中观察到六种H键结构：（1）GO官能团之间的分子内H键；（2）GO…水氢键；（3）去…去水…去氢键；（4）IOC…GO氢键；（5）IOC…水…GO H键；（6）IOC…水氢键。MD结果表明，GO（或IOC）与水之间的氢键比IOC与GO之间的氢键多，表明水介导的氢键在吸附过程中起了转向作用。吸附后，IOC和GO的构型发生改变，亲水性降低，这又可能影响其在环境中的命运和毒性。提供了几种常见IOC的π电子密度的变化，这可能有助于在以后的研究中了解IOC的pH依赖性行为。