Volatile organic compounds (VOCs) have been identified as highly toxic and carcinogenic pollutants threatening both human health and the living environment. Their recognition and removal are important issues. Carbon nanotubes (CNTs) have been proposed as a promising agent for the adsorption of detrimental VOC molecules. Due to the intrinsic nanoscale nature of such processes, details of molecular interactions and the adsorption mechanism remain to be clarified. This paper aims to provide a molecular perspective on the adsorption behavior of VOC molecules on both neutral and electrically charged CNTs by the means of molecular dynamics simulations. Simulation results indicate a strong correlation between the adsorption affinity and hydrophobicity of acetone, ether, methanol and toluene molecules. VOCs possessing a higher hydrophobicity demonstrate greater adsorption affinity. The adsorption of toluene and ether molecules is quite stable around the CNT surface. In contrast, hydrophilic molecules such as acetone and methanol can only be unstably adsorbed. For neutral CNTs, the van der Waals interaction is responsible for the adsorption affinity. For electrically charged CNTs, however, electrostatic attraction or repulsion with the charged groups in VOC molecules significantly affects the adsorption behavior. As a result, the introduction of charges on the CNT surface can help to optimize the adsorption process of VOC molecules. Calculations on the potentials of mean forces support the same reasonings. Simulation results about acetone, ether, methanol and toluene clearly indicate that customized strategies are needed for precisely controlling the adsorption of different VOC molecules on CNTs. The results reported in this work should be helpful for the better development of sensing and removal systems of detrimental VOC molecules.

中文翻译：

---

碳纳米管上挥发性有机化合物的电荷可调谐吸附的分子观点

挥发性有机化合物（VOC）已被确认为具有高毒性和致癌性的污染物，威胁着人类健康和生活环境。它们的识别和删除是重要的问题。已经提出碳纳米管（CNT）作为吸附有害VOC分子的有前途的试剂。由于这种方法的内在的纳米尺度性质，分子相互作用和吸附机理的细节仍有待澄清。本文旨在通过分子动力学模拟，为VOC分子在中性和带电CNT上的吸附行为提供分子视角。模拟结果表明，丙酮，乙醚，甲醇和甲苯分子的吸附亲和力和疏水性之间具有很强的相关性。具有较高疏水性的VOC表现出更大的吸附亲和力。甲苯和醚分子在CNT表面周围的吸附非常稳定。相反，亲水分子如丙酮和甲醇只能被不稳定地吸附。对于中性CNT，范德华相互作用是吸附亲和力的原因。但是，对于带电的CNT，VOC分子中带电基团的静电吸引或排斥会显着影响吸附行为。结果，在CNT表面上引入电荷可以帮助优化VOC分子的吸附过程。对平均力潜力的计算也支持相同的推理。关于丙酮，乙醚，甲醇和甲苯清楚地表明，需要使用量身定制的策略来精确控制不同VOC分子在CNT上的吸附。这项工作中报告的结果应有助于更好地开发有害VOC分子的传感和去除系统。