Han Zhantao, Zhang Fawang, Lin Daohui, Xing Baoshan
Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Environ Sci Technol. 2008 Sep 15;42(18):6869-75. doi: 10.1021/es801150j.
Carbon nanotubes (CNTs), because of their wide application, will inevitably enter aquatic systems, but the fate and transport of their suspensions in the environment are largely unknown. Clay minerals are expected to interact with CNT suspensions, affecting their fate and bioavailability. This study investigated the influence of clay minerals (kaolinite and montmorillonite) on the stability of surfactant (SDBS, CTAB, and TX100) facilitated multiwalled CNT (MWCNT) suspensions. Adsorption of the surfactants by MWCNTs and clay minerals was also examined. This is a first study on the interaction between clay minerals and surfactant-CNT suspensions. Sorption of SDBS by clay minerals and MWCNTs followed the order MWCNTs >> montmorillonite approximately kaolinite; but sorption of CTAB and TX100 followed the order montmorillonite > MWCNTs > kaolinite. For SDBS suspended MWCNTs, introduction of montmorillonite and kaolinite could not change their stability; for CTAB suspended MWCNTs, both montmorillonite and kaolinite greatly deposited the suspended MWCNTs; for TX100 suspended MWCNTs, montmorillonite could partially deposit the suspended MWCNTs, whereas kaolinite showed minimal effect. Two mechanisms of clay minerals affecting MWCNT suspensions are (1) removal of surfactants by clay minerals from solution and MWCNT surface and (2) bridging between clay mineral and MWCNTs by surfactant.
碳纳米管（CNTs）由于其广泛应用，不可避免地会进入水生系统，但其悬浮液在环境中的归宿和迁移情况在很大程度上尚不清楚。预计粘土矿物会与碳纳米管悬浮液相互作用，影响其归宿和生物可利用性。本研究考察了粘土矿物（高岭土和蒙脱石）对表面活性剂（十二烷基苯磺酸钠、十六烷基三甲基溴化铵和吐温100）促进的多壁碳纳米管（MWCNT）悬浮液稳定性的影响。还研究了表面活性剂在多壁碳纳米管和粘土矿物上的吸附情况。这是关于粘土矿物与表面活性剂-碳纳米管悬浮液之间相互作用的首次研究。粘土矿物和多壁碳纳米管对十二烷基苯磺酸钠的吸附顺序为多壁碳纳米管>>蒙脱石≈高岭土；但对十六烷基三甲基溴化铵和吐温100的吸附顺序为蒙脱石>多壁碳纳米管>高岭土。对于十二烷基苯磺酸钠悬浮的多壁碳纳米管，引入蒙脱石和高岭土不会改变其稳定性；对于十六烷基三甲基溴化铵悬浮的多壁碳纳米管，蒙脱石和高岭土都会使悬浮的多壁碳纳米管大量沉淀；对于吐温100悬浮的多壁碳纳米管，蒙脱石会使悬浮的多壁碳纳米管部分沉淀，而高岭土的影响最小。粘土矿物影响多壁碳纳米管悬浮液的两种机制是：（1）粘土矿物从溶液和多壁碳纳米管表面去除表面活性剂；（2）表面活性剂在粘土矿物和多壁碳纳米管之间形成桥连。
