Carbon nanotubes (CNTs) are widely used and may pose potential environmental risks to soil and groundwater systems. Therefore, it is important to improve current understanding of the fate and transport of CNTs in porous media. In this study, the transport behavior of multi-walled carbon nanotubes (MWCNTs) with different surface modifications were examined in water-saturated sand columns under different pH (5 and 7) and ionic strength (0.1, 1, and 5 mM) conditions. COOH-MWCNTs have the strongest mobility among the five types of MWCNTs, followed by pristine MWCNTs. NH₂-MWCNTs, Cu-MWCNTs, and Fe-MWCNTs have the weaker mobility. The transport of five types of MWCNTs decreased with the increase of ionic strength, while increased with the increase of pH value. The results suggested that the transport of MWCNTs can be affected by the electrostatic attraction between the functional groups on the surface of MWCNTs and quartz sand. Moreover, the pH and ionic strength of the solution also played an important role in enhancing the transport of MWCNTs, which have great significance for evaluating the transport and fate of MWCNTs in natural environment.

碳纳米管（CNTs）被广泛使用，可能对土壤和地下水系统构成潜在的环境风险。因此，重要的是提高当前对多孔介质中CNT的命运和传输的了解。在这项研究中，在不同的pH（5和7）和离子强度（0.1、1和5 mM）条件下，在水饱和砂柱中检查了具有不同表面改性的多壁碳纳米管（MWCNT）的传输行为。在五种类型的多壁碳纳米管中，COOH-多壁碳纳米管具有最强的迁移率，其次是原始多壁碳纳米管。NH ₂-MWCNT，Cu-MWCNT和Fe-MWCNT具有较弱的迁移率。五种碳纳米管的迁移率随离子强度的增加而降低，随pH值的增加而增加。结果表明，多壁碳纳米管的运输可能受到多壁碳纳米管表面官能团与石英砂之间静电吸引的影响。此外，溶液的pH值和离子强度在增强MWCNT的传输中也起着重要作用，这对于评估MWCNT在自然环境中的传输和命运具有重要意义。