Tunega Daniel, Gerzabek Martin H, Haberhauer Georg, Totsche Kai U, Lischka Hans
Institute of Soil Research, University of Natural Resources and Applied Life Sciences, Vienna, Peter-Jordan-Strasse 82, A-1190 Vienna, Austria.
J Colloid Interface Sci. 2009 Feb 1;330(1):244-9. doi: 10.1016/j.jcis.2008.10.056. Epub 2008 Oct 28.
A systematic DFT study of interactions between a set of mono- and polyaromatic hydrocarbons (PAHs) and the (110) goethite surface have been performed in this work. It was found that PAHs form relatively weak surface complexes having their molecular plane practically parallel to the surface plane. The origin of the interactions is in the polarization of the pi-system by polar OH groups and in the formation of weak hydrogen bonds where the pi-system acts as a proton acceptor. The computed perpendicular distances of the molecular plane of PAHs to the hydrogen atoms of the surface OH groups range from 2.3 to 2.7 A. Computed interaction energies regularly increase for the linearly shaped molecules from benzene to anthracene. Two other PAHs with a nonlinear shape, phenanthrene and pyrene, are less strongly bound to the surface although they have a similar (phenanthrene) or even larger size (pyrene) than anthracene. These differences were explained by the specific configuration of the surface hydroxyl groups of goethite. The three types of OH groups, mu-OH, mu(3)-O(II)H, and OH, form a valley, the width of it fits very well the molecular shape of the linear PAHs. It was found that with anthracene as example the linear PAHs can easily slide along the valley of OH groups with practically no barrier. In summary it is concluded from our results that the (110) goethite surface will withhold linear PAHs significantly better than nonlinear ones.
在这项工作中，对一组单环和多环芳烃（PAHs）与（110）针铁矿表面之间的相互作用进行了系统的密度泛函理论（DFT）研究。研究发现，PAHs形成相对较弱的表面配合物，其分子平面实际上与表面平面平行。相互作用的起源在于极性OH基团对π体系的极化以及弱氢键的形成，其中π体系充当质子受体。计算得出的PAHs分子平面到表面OH基团氢原子的垂直距离在2.3至2.7埃之间。对于从苯到蒽的线性分子，计算得出的相互作用能有规律地增加。另外两种非线性形状的PAHs，菲和芘，与表面的结合较弱，尽管它们的尺寸与蒽相似（菲）甚至更大（芘）。这些差异可以用针铁矿表面羟基的特定构型来解释。三种类型的OH基团，μ-OH、μ(3)-O(II)H和OH，形成一个凹槽，其宽度与线性PAHs的分子形状非常吻合。研究发现，以蒽为例，线性PAHs可以很容易地沿着OH基团形成的凹槽滑动，几乎没有障碍。总之，从我们的结果可以得出结论，（110）针铁矿表面对线性PAHs的保留能力明显优于非线性PAHs。
