Department of Environmental Science, Zhejiang University , Hangzhou 310058, People's Republic of China.
Environ Sci Technol. 2014 May 6;48(9):4817-25. doi: 10.1021/es405227u. Epub 2014 Apr 8.
The adsorption of naphthalene, phenanthrene, and pyrene onto graphene (GNS) and graphene oxide (GO) nanosheets was investigated to probe the potential adsorptive sites and molecular mechanisms. The microstructure and morphology of GNS and GO were characterized by elemental analysis, XPS, FTIR, Raman, SEM, and TEM. Graphene displayed high affinity to the polycyclic aromatic hydrocarbons (PAHs), whereas GO adsorption was significantly reduced after oxygen-containing groups were attached to GNS surfaces. An unexpected peak was found in the curve of adsorption coefficients (Kd) with the PAH equilibrium concentrations. The hydrophobic properties and molecular sizes of the PAHs affected the adsorption of G and GO. The high affinities of the PAHs to GNS are dominated by π-π interactions to the flat surface and the sieving effect of the powerful groove regions formed by wrinkles on GNS surfaces. In contrast, the adsorptive sites of GO changed to the carboxyl groups attaching to the edges of GO because the groove regions disappeared and the polar nanosheet surfaces limited the π-π interactions. The TEM and SEM images initially revealed that after loading with PAH, the conformation and aggregation of GNS and GO nanosheets dramatically changed, which explained the observations that the potential adsorption sites of GNS and GO were unusually altered during the adsorption process.
研究了萘、菲和芘在石墨烯（GNS）和氧化石墨烯（GO）纳米片上的吸附，以探究潜在的吸附位点和分子机制。通过元素分析、XPS、FTIR、拉曼、SEM 和 TEM 对 GNS 和 GO 的微观结构和形态进行了表征。石墨烯对多环芳烃（PAHs）表现出高亲和力，而含氧基团附着在 GNS 表面后，GO 的吸附显著降低。在吸附系数（Kd）与 PAH 平衡浓度的曲线中发现了一个意外的峰。PAHs 的疏水性和分子大小影响了 G 和 GO 的吸附。PAHs 对 GNS 的高亲和力主要是由平面上的π-π相互作用和 GNS 表面褶皱形成的强大凹槽区域的筛分效应所主导。相比之下，GO 的吸附位点由于凹槽区域消失和极性纳米片表面限制了π-π相互作用而变为附着在 GO 边缘的羧基。TEM 和 SEM 图像最初表明，在加载 PAH 后，GNS 和 GO 纳米片的构象和聚集发生了显著变化，这解释了在吸附过程中 GNS 和 GO 的潜在吸附位点异常改变的观察结果。
