State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
College of Resources and Environmental Engineering, Guizhou University, Guiyang, Guizhou 550025, China.
Environ Sci Technol. 2024 Sep 10;58(36):16175-16185. doi: 10.1021/acs.est.4c03365. Epub 2024 Aug 9.
Carbon materials are regarded as a promising adsorbent for the adsorption of volatile organic compounds (VOCs). However, their adsorption behaviors are usually compromised at ambient conditions, attributed to the competitive VOCs adsorption with water vapor. In this study, we demonstrated that the selectivity for toluene than water of carbon can be effectively enhanced by introducing more sp-carbon with two-dimensional nanosheets stacked. The multilayer carbon nanosheets enriched with sp-carbon (CNS-MCA) exhibit a 151° HO-contact angle, indicating hydrophobicity. Dynamic adsorption behaviors revealed that CNS-MCA retain 71% of their toluene adsorption capacity (91 mg/g) even at 60% relative humidity. Density functional theory (DFT) calculations, static adsorption studies, in situ Raman spectroscopy, and time-resolved in situ nuclear magnetic resonance (NMR) spectroscopy collectively indicate that toluene exhibits enhanced adsorption and selectivity due to π-π* interactions between its aromatic rings and the sp-carbon. Conversely, water adsorption is attenuated, attributed to the reduced availability of surface-exposed hydrogen bonds associated with sp-carbon and the inherent hydrophobic nature of multilayer graphene. This study extends a novel solution for the enhancement of VOCs adsorption under humid conditions.
碳材料被认为是一种很有前途的吸附剂，可用于吸附挥发性有机化合物（VOCs）。然而，它们在环境条件下的吸附性能通常会受到影响，这是因为它们与水蒸气的竞争吸附。在这项研究中，我们证明了通过引入二维纳米片堆叠的更多 sp 碳，可以有效地提高碳对甲苯的选择性，而不是水。富含 sp 碳的多层碳纳米片（CNS-MCA）表现出 151°的 HO 接触角，表明其疏水性。动态吸附行为表明，即使在相对湿度为 60%的情况下，CNS-MCA 仍保留其甲苯吸附容量的 71%（91mg/g）。密度泛函理论（DFT）计算、静态吸附研究、原位拉曼光谱和时间分辨原位核磁共振（NMR）光谱共同表明，由于甲苯的芳香环与 sp 碳之间的π-π*相互作用，其吸附和选择性得到增强。相反，水的吸附被削弱，这归因于与 sp 碳相关的表面暴露氢键的可用性降低以及多层石墨烯固有的疏水性。这项研究为在潮湿条件下增强 VOCs 吸附提供了一种新的解决方案。
