Department of Environmental Engineering and Earth Sciences, Clemson University, 342 Computer Court, Anderson, SC 29625, USA.
Water Res. 2011 Jan;45(3):1378-86. doi: 10.1016/j.watres.2010.10.023. Epub 2010 Oct 26.
Understanding the influence of natural organic matter (NOM) on synthetic organic contaminant (SOC) adsorption by carbon nanotubes (CNTs) is important for assessing the environmental implications of accidental CNT release and spill to natural waters, and their potential use as adsorbents in engineered systems. In this study, adsorption of two SOCs by three single-walled carbon nanotubes (SWNTs), one multi-walled carbon nanotube (MWNT), a microporous activated carbon fiber (ACF) [i.e., ACF10] and a bimodal porous granular activated carbon (GAC) [i.e., HD4000] was compared in the presence and absence of NOM. The NOM effect was found to depend strongly on the pore size distribution of carbons. Minimal NOM effect occurred on the macroporous MWNT, whereas severe NOM effects were observed on the microporous HD4000 and ACF10. Although the single-solute adsorption capacities of the SWNTs were much lower than those of HD4000, in the presence of NOM the SWNTs exhibited adsorption capacities similar to those of HD4000. Therefore, if released into natural waters, SWNTs can behave like an activated carbon, and will be able to adsorb, carry, and transfer SOCs to other systems. However, from an engineering application perspective, CNTs did not exhibit a major advantage, in terms of adsorption capacities, over the GAC and ACF. The NOM effect was also found to depend on molecular properties of SOCs. NOM competition was more severe on the adsorption of 2-phenylphenol, a nonplanar and hydrophilic SOC, than phenanthrene, a planar and hydrophobic SOC, tested in this study. In terms of surface chemistry, both adsorption affinity to SOCs and NOM effect on SOC adsorption were enhanced with increasing hydrophobicity of the SWNTs.
了解天然有机物 (NOM) 对碳纳米管 (CNT) 吸附合成有机污染物 (SOC) 的影响对于评估 CNT 意外释放和溢流入自然水体对环境的影响以及 CNT 作为吸附剂在工程系统中的潜在应用非常重要。在这项研究中，比较了三种单壁碳纳米管 (SWNT)、一种多壁碳纳米管 (MWNT)、一种微孔活性碳纤维 (ACF) [即 ACF10] 和一种双峰多孔颗粒活性炭 (GAC) [即 HD4000] 在存在和不存在 NOM 的情况下对两种 SOC 的吸附。发现 NOM 的影响强烈依赖于碳的孔径分布。MWNT 具有大孔，NOM 的影响最小，而 HD4000 和 ACF10 具有微孔，NOM 的影响严重。尽管 SWNTs 的单溶质吸附容量远低于 HD4000，但在存在 NOM 的情况下，SWNTs 的吸附容量与 HD4000 相似。因此，如果释放到自然水中，SWNTs 可以表现得像活性炭一样，能够吸附、携带和将 SOC 转移到其他系统。然而，从工程应用的角度来看，与 GAC 和 ACF 相比，CNT 在吸附容量方面并没有表现出明显的优势。还发现 NOM 的影响也取决于 SOC 的分子特性。在这项研究中，与平面疏水性 SOC 菲相比，非平面亲水性 SOC 2-苯苯酚的吸附，NOM 竞争更为激烈。就表面化学而言，随着 SWNTs 疏水性的增加，对 SOC 和 NOM 吸附的吸附亲和力以及 NOM 对 SOC 吸附的影响都增强了。
