Empa-Swiss Federal Laboratories for Materials Science and Technology, St. Gallen, Switzerland.
Environ Pollut. 2012 Oct;169:64-73. doi: 10.1016/j.envpol.2012.05.004. Epub 2012 Jun 8.
The colloidal stabilities of ten carbon nanotubes (CNTs) having varying physico-chemical properties were compared in long-term experiments. The presence of Suwannee River Humic Acid (SRHA) increased the fraction of CNTs in the supernatants (4-88% for the various CNT types) after addition in pre-dispersed form and 20 days of shaking and 5 days of settling. These suspensions were monomodal, containing individually suspended CNTs with highly negative surface charges. Calcium (2 mM) removed most of the CNT types from the supernatant, due to CNT-agglomerate formation initiated by reduction in surface charge. The amount of SRHA adsorbed to the different CNT types did not correlate (r(2) < 0.1) with the percentage of CNTs remaining in suspension. Multiple linear regression analysis revealed that the oxygen content and the diameter of the CNTs significantly influenced the percentage of stabilized CNTs, resulting in an increased fraction of functionalized and large-diameter CNTs that remained in suspension.
十种具有不同理化性质的碳纳米管（CNT）的胶体稳定性在长期实验中进行了比较。在预分散形式添加后，添加苏万尼河腐殖酸（SRHA）会增加上清液中 CNT 的分数（各种 CNT 类型的 4-88%），并在 20 天的摇晃和 5 天的沉降后增加。这些悬浮液是单模态的，含有具有高度负表面电荷的单独悬浮 CNT。由于表面电荷减少引发 CNT 团聚体形成，钙离子（2 mM）将大多数 CNT 类型从上清液中去除。不同 CNT 类型吸附的 SRHA 量与悬浮液中剩余 CNT 的百分比没有相关性（r(2) < 0.1）。多元线性回归分析表明，CNT 的氧含量和直径显著影响稳定 CNT 的百分比，导致功能化和大直径 CNT 的分数增加，从而在悬浮液中保留下来。
