表面修饰碳纳米管通过土柱运输
Summary
Surface properties of a nanoparticle are important for their interaction with the surrounding medium. Therefore the surface modification of carbon nanotubes can be critical for their transport and retention through porous media. Here, lab scale column experiments are used to understand the possible transport and retention of these nanoparticles.
Abstract
Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, electronics and biomedical applications. Due to their accelerating production and use, CNTs constitute a potential environmental risk if they are released to soil and groundwater systems. It is therefore essential to improve the current understanding of environmental fate and transport of CNTs. The transport and retention of CNTs in both natural and artificial media have been reported in literature, but the findings widely vary and are thus not conclusive. There are a number of physical and chemical parameters responsible for variation in retention and transport. In this study, a complete procedure of selected multiwalled carbon nanotubes (MWCNTs) is presented starting from their surface modification to a complete set of laboratory column experiments at critical physical and chemical scenarios. Results indicate that the stability of the commercially available MWCNTs are critical with their attached surface functional group which can also influence the transport and retention of MWCNT through the surrounding medium.
Introduction
随着在使用不同类型的纳米粒子，以改善一些技术行业，如信息技术，能源，环境科学，医学，国土安全，食品安全，交通纳米技术的最新发展;深入了解纳米颗粒在土壤和地下水的运输和保存的是风险评估，以及工程纳米颗粒1-3环境应用的关键。碳纳米管（CNT）是最产生的碳基纳米颗粒2,4中的一个。碳纳米管是石墨烯的长和圆筒形，其直径典型地低于100nm和50μm的长度为100毫微米的范围内。它们具有独特的性能，这加速了它们的使用在许多应用中，例如电子，光学，化妆品和生物医学技术（ 例如 ，复合材料）5。具有增加的使用，也有一个加强研究ISK到人类接触和作用，对健康以及以下CNT与其他基碳纳米材料的处置对环境的5-8不利的生态影响。
与无表面改性（官能化），CNT是极其疏水并倾向于聚集在水溶液中。官能化碳纳米管可以，但是，保持分散和稳定在水溶液中，并用于生物医学用途，例如药物递送9。这里很重要的是该碳纳米管保持分散和动员，使药物能够在人体10内被递送。另一方面，为了减少对环境的风险，有必要进行研究集中于如何以固定的CNT，以避免其进入含水层和饮用水资源11。最近的研究已经报道CNT的毒性作用在活的生物体以及在CNT的进入和积聚在食物链术语风险对生态系统，因为CNT是难以生物降解5,8。甚至与屏障系统中含有碳纳米管堆填区，有可能对碳纳米管穿过屏障。在这种情况下，碳纳米管会进入地下水和水库地表水体。由于CNT处置法规没有明确定义和传输机制了解甚少，碳纳米管的流动性有更好的了解要制定和设计相应的处理系统12。因此，学习和了解的命运和碳纳米管的多孔介质运输和通常存在于表面上的地下环境中的物理和化学因素的影响是很重要的修改CNT保留。
若干研究已进行了大约的集电极粒度13-15的影响，对纳米颗粒的多孔介质中传输流的晶粒17的速度16，和表面性能。然而，SOLUT效果系统研究离子化学（如pH和离子强度）就可能沉积在集电器表面上仍然有限18-20。另外，物理因素，介质的溶液化学和碳纳米管的表面性质的综合影响是不能很好地理解和不同，在不同的文献。在这项研究中，对于多壁碳纳米管的表面改性的制备方法将用填充有酸清洗石英砂有系统实验室规模的柱显示出沿将被用于研究表面改性的碳纳米管在饱和多孔介质的传输，保留和再活化。
Protocol
Representative Results
Discussion
碳纳米管功能化的影响。
正如图2证实了官能化碳纳米管的稳定性，在多壁碳纳米管的溶出量的观察到的差异是由于官能化和特别是由于加入的羧基（-COOH）基团的多壁碳纳米管的表面上（ 图3和4）。在类似的官能化的过程中，氧的存在下通过X射线光电子能谱法14中得到证实。已经较早发现添加表面活性剂的纳米颗粒…
Offenlegungen
The authors have nothing to disclose.
Acknowledgements
The authors would like to acknowledge the support from the Department of Earth Sciences, Uppsala University for supporting part of this research.
Materials
| Name of Material/ Equipments | Company | Catalog Number | Comments/Description |
| MWCNT | Cheap Tubes Inc., USA | sku-03040304 | Purchased as semi-functionlized powder |
| Quartz sand | Sibelco Nordic, Baskarp, Sweden | B44 | Purchased with more than 91% silica sand |
| H2SO4 | VWR | 1.01833.2500 | 95-97% purity |
| HNO3 | VWR | 1.00441.1000 | 70% purity |
| HCl | VWR | 1.00317.2500 | 37-38% purity |
| H2O2 | VWR | 23615.248 | 30% purity |
| NaCl | VWR | 1.06404.0500 | 99.5% purity |
| NaOH | Sigma-Aldrich | S8045-500G | 99.99% pur pellets |
| Ultrasonic Homogenizer | Biologics Inc. Manassas, Virginia | Model 3000, 0-127-0002 | Operated for fix time interval |
| Sonicator (bath) | Kerry Ultrasonic Ltd | 1808 | Common bath sonicator |
| Peristaltic pump | Ismantec, Glattbrugg, Switzerland | ISM931 | Work with tygon tubing in the pump |
| Spectrophotometer | Hach Lange | DR500, LPV408.99.0001 | Operate with manual cuvette as well as automated sampling |
| pH meter | Metrohm | 781 | pH analysis |
| Glass column | Chromaflex | 420830-1510 | Column with adjustable cap |
| Fraction collector | Spectrum Labs Europe | CF-2, 124846 | Fixed at regular interval of time |
| Fraction collector tubes | VWR | 212-9599 | 6 ml volume glass tube |
| Hot plate stir | Thermo Scientific | SP131320-33 | Adjustable tempurature |
| Oven | Elektro Helios | 259 | For oven dry of sand |
| Balance | Mettler Toledo | AE 160 | For accurate weight |
Referenzen
- Maynard, A. D., et al. Safe handling of nanotechnology. Nature. 444, 267-269 (2006).
- Mauter, M., Elimelech, M. Environmental applications of carbon-based nanomaterials. Environ. Sci. Technol. 42 (16), 5843-5859 (2008).
- Darka-Kagy, K., Khodadoust, A. P., Reddy, K. R. Reactivity of aluminum lactate-modified nanoscale iron particles with pentachlorophenol in soils. Environ. Eng. Sci. 27 (10), 861-869 (2010).
- Lin, D., et al. Fate and transport of engineered nanomaterials in the environment. J. Environ. Qual. 39 (6), 1896-1908 (2010).
- Petersen, E. J., et al. Potential release pathways, environmental fate, and ecological risks of carbon nanotubes. Environ. Sci. Technol. 45 (23), 9837-9856 (2011).
- Wiesner, M., Bottero, J. Y. . Environmental nanotechnology. , (2007).
- Klaine, S. J., et al. Nanomaterials in the environment: Behavior, fate, bioavailability, and effects. Environ. Toxicol. Chem. 27 (9), 1825-1851 (2008).
- Wang, C., et al. Toxicity effects of four typical nanomaterials on the growth of Escherichia coli, Bacillus subtilis and Agrobacterium tumefaciens. Environ. Earth Sci. 65 (6), 1643-1649 (2012).
- Shen, M., et al. Polyethyleneimine mediated functionalization of multi-walled carbon nanotubes: Synthesis characterization, and in vitro toxicity assay. J. Phys. Chem. C. 113 (8), 3718-3724 (2009).
- Sahithi, K., et al. Polymeric conposites containing carbon nanotubes for bone tissue engineering. Int. J. Biol. Marcomol. 46 (3), 281-283 (2010).
- Petersen, E., Huang, Q., Weber, W. Bioaccumulation of radio-labeled carbon nanotubes by Eisnia Foetida. Environ. Sci. Technol. 42 (8), 3718-3724 (2008).
- Gottschalk, F., et al. Modeled Enrionmental concentrations of engineered nanomaterials for different regions. Enrviron. Sci. Technol. 43 (24), 9216-9222 (2009).
- Liu, X., et al. et al.Mobility of multiwalled carbon nanotubes in porous media.Environ. Sci. Technol. 43 (21), 8153-8158 (2009).
- Tian, Y., Gao, B., Ziegler, K. J. High mobility of SDBS-dispersed single-walled carbon nanotubes in saturated and unsaturated porous. J. Hazard. Mater. 186 (2-3), 1766-1772 (2011).
- Mattison, N. T., et al. Impact of porous media grain size on the transport of multi-walled carbon nanotubes. Environ. Sci. Technol. 45 (22), 9765-9775 (2011).
- Kasel, D., et al. Limited transport of functionlized multi-walled carbon nanotubes in two natural soils. Environ. Pollution. 180, 152-158 (2013).
- Yu, S., et al. Effects of humic acid and Tween-80 on behavior of decabromodiphenyl ether in soil columns. Environ. Earth Sci. 69 (5), 1523-1528 (2013).
- Jaisi, D. P., et al. Transport of single-walled carbon nanotubes in porous media: filtration mechanisms and reversibility. Environ. Sci. Technol. 42 (22), 8317-8323 (2008).
- Tiraferri, A., Tosco, T., Sethi, R. Transport and retention of microparticles in packed sand columns at low and intermediate ionic strengths: experiments and mathematical modeling. Environ. Earth Sci. 63 (4), 847-859 (2011).
- Tian, Y., et al. Deposition and transport of functionalized carbon nanotubes in water-saturated sand columns. J. Hazard. Mater. 213-214, 265-272 (2012).
- Mekonen, A., Sharma, P., Fagerlund, F. Transport and mobilization of multiwall carbon nanotubes in quartz sand under varying saturation. Environ. Earth Sci. 71 (8), 3751-3760 (2014).
- Sharma, P., Bao, D., Fagerlund, F. Deposition and mobilization of functionalized multiwall carbon nanotubes in saturated porous media: effect of grain size, flow velocity and solution chemistry. Environ. Earth Sci. , (2014).
- Phenrat, T., Lowry, G. V., Hotze, E. M. Nanoparticle aggregation: challenges to understanding transport and reactivity in the environment. J. Environ. Qual. 39 (6), 1909-1924 (2010).
- Crist, J. T., et al. Transport and retention mechanisms of colloids in partially saturated porous media. Vadose Zone J. 4 (1), 184-195 (2005).
- Jaisi, D. P., Elimelech, M. Single-walled carbon nanotubes exhibit limited transport in soil columns. Environ. Sci. Technol. 43 (24), 9161-9166 (2009).
- Corapcioglu, M. Y., Choi, H. Modeling colloid transport in unsaturated porous media and validation with laboratory column data. Water Resour. Res. 32 (12), 3437-3449 (1996).
- Wan, J., Wilson, J. L. Colloid transport in unsaturated porous media. Water Resour. Res. 30 (4), 857-864 (1994).
- Wan, J., Wilson, J. L. Visualization of the role of the gas-water interface on the fate and transport of colloids in porous media. Water Resour. Res. 30 (1), 11-24 (1994).
- Bradford, S. A., et al. Physical factors affecting the transport and fate of colloids in saturated porous media. Water Resour. Res. 38 (12), (2002).
- Bradford, S. A., Torkzaban, S., Walker, S. L. Coupling of physical and chemical mechanisms of colloid straining in saturated porous media. Water Res. 41 (13), 3012-3024 (2007).
