School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China.
Beijing Higher Institution Engineering Research Center of Energy Conservation and Environmental Protection, Beijing 100083, China.
Int J Mol Sci. 2019 Feb 3;20(3):665. doi: 10.3390/ijms20030665.
The adsorption of three typical polycyclic aromatic hydrocarbons (PAHs), naphthalene, phenanthrene, and pyrene with different ring numbers, on a common mesoporous material (MCM-41) was simulated based on a well-validated model. The adsorption equilibriums (isotherms), states (angle distributions and density profiles), and interactions (radial distribution functions) of three PAHs within the mesopores were studied in detail. The results show that the simulated isotherms agreed with previous experimental results. Each of the PAHs with flat molecules showed an adsorption configuration that was parallel to the surface of the pore, in the following order according to the degree of arrangement: pyrene (Pyr) > phenanthrene (Phe) > naphthalene (Nap). In terms of the interaction forces, there were no hydrogen bonds or other strong polar forces between the PAHs and MCM-41, and the O⁻H bond on the adsorbent surface had a unique angle in relation to the PAH molecular plane. The polarities of different H atoms on the PAHs were roughly the same, while those of the C atoms on the PAHs decreased from the molecular centers to the edges. The increasing area of the π-electron plane on the PAHs with the increasing ring number could lead to stronger adsorption interactions, and thus a shorter distance between the adsorbate and the adsorbent.
基于经过充分验证的模型，模拟了三种具有不同环数的典型多环芳烃（PAHs）萘、菲和芘在常见介孔材料（MCM-41）上的吸附。详细研究了介孔内三种 PAHs 的吸附平衡（等温线）、状态（角分布和密度分布）和相互作用（径向分布函数）。结果表明，模拟的等温线与先前的实验结果吻合。具有平面分子的每种 PAH 都表现出与孔表面平行的吸附构型，按排列程度的顺序为：芘（Pyr）>菲（Phe）>萘（Nap）。在相互作用力方面，PAHs 和 MCM-41 之间没有氢键或其他强极性力，吸附剂表面上的 O⁻H 键与 PAH 分子平面具有独特的角度。不同 H 原子在 PAHs 上的极性大致相同，而 PAHs 上 C 原子的极性则从分子中心向边缘逐渐降低。随着环数的增加，PAHs 的π-电子平面面积增加，导致吸附相互作用增强，因此吸附质与吸附剂之间的距离缩短。
