Agnihotri Sandeep, Mota José P B, Rostam-Abadi Massoud, Rood Mark J
Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996-2010, USA.
J Phys Chem B. 2006 Apr 20;110(15):7640-7. doi: 10.1021/jp060040a.
Hexane adsorption on single-walled carbon nanotube (SWNT) bundles is studied by both simulation and experimentally using a previously developed computer-aided methodology, which employed a smaller physisorbed probe molecule, nitrogen, to explore the porosity of nanotube samples. Configurational-bias grand canonical Monte Carlo simulation of hexane adsorption on localized sites of the bundles is carried out to predict adsorption on their external surface and in their internal sites. These localized isotherms are then combined into a global isotherm for a given sample by using knowledge of its tube-diameter distribution and structural parameters, such as the fraction of open-ended nanotubes and the external surface area of bundles in samples, which have been independently determined from the standard nitrogen adsorption isotherm. The near-perfect replication of experimental isotherms demonstrates the validity of our method for structural characterization of SWNT samples. The effect of temperature on adsorption is also studied and the simulation results are extrapolated to predict the limiting hexane adsorption capacity of the samples. The similarity between the hexane adsorption isotherms and those of other organic molecules demonstrates that the adsorption mechanisms explored here are not specific to hexane, and that the proposed methodology can be potentially applicable to other sorbates with equal success.
通过模拟和实验，采用先前开发的计算机辅助方法研究了己烷在单壁碳纳米管束上的吸附情况。该方法使用较小的物理吸附探针分子氮气来探测纳米管样品的孔隙率。进行了己烷在管束局部位置吸附的构型偏置巨正则蒙特卡罗模拟，以预测其外表面和内部位置的吸附情况。然后，通过使用已知的管径分布和结构参数（如开口端纳米管的比例以及样品中管束的外表面面积，这些参数已从标准氮气吸附等温线独立确定），将这些局部等温线组合成给定样品的全局等温线。实验等温线的近乎完美复制证明了我们用于单壁碳纳米管样品结构表征方法的有效性。还研究了温度对吸附的影响，并外推模拟结果以预测样品的极限己烷吸附容量。己烷吸附等温线与其他有机分子的吸附等温线之间的相似性表明，这里探索的吸附机制并非己烷所特有，并且所提出的方法可能同样成功地适用于其他吸附质。
