Carbon Nanotubes in Soils: Transport, Filtration, and Impact on Soil Microbial Community

CBET-0828795 Elimelech碳纳米管（CNT）在电子、光学、医疗和结构复合材料技术等各种应用中不断涌现。 由于它们在大规模工业生产中的预期作用，毫无疑问，碳纳米管最终将进入我们的水生环境。 与其他纳米颗粒相比，CNT的不寻常的物理化学特性，特别是非常大的纵横比和在水溶液中的高度成束（聚集）状态，排除了它们的聚集和运输行为的有意义的理论预测。 此外，由于缺乏实验室数据的CNT运输在多孔介质中，很少有人知道他们的潜在流动性和命运在地下环境。 特别令人感兴趣的是，需要评估碳纳米管对地下水蓄水层的潜在污染。 CNT对地下水的污染可能来自垃圾填埋场渗滤液、废水渗透和土地应用。 因此，了解CNT在土壤中的迁移程度将是预测地下水含水层污染风险的关键。 此外，由于碳纳米管保留在土壤剖面，其对土壤微生物生态的影响，必须考虑在最近的研究表明碳纳米管的抗菌效果。拟议研究的总体目标是评估碳纳米管在土壤中的运输和保留的程度以及保留的碳纳米管对土壤微生物群落的影响。 将确定碳纳米管在土壤中迁移的最坏情况，这将使他们能够预测地下水蓄水层受污染的可能性。 此外，他们将建立条件下，保留碳纳米管影响土壤微生物生态。两个假设指导他们的研究：（i）碳纳米管在土壤中的流动性将相对有限，因为碳纳米管的大纵横比和它们的高度聚集（捆绑）状态将促进通过物理化学过滤和过滤的广泛去除，和（ii）由于它们的有效保留，特别是通过过滤，碳纳米管将在土壤中积累，从而影响土壤微生物群落。 为了完成拟议的工作，他们将：（1）选择和表征单壁碳纳米管（SWNT）和多壁碳纳米管MWNT，（2）选择和表征土壤和模拟多孔介质，（3）评估CNT在填充柱中的运输和保留，（4）评估通过溶液化学中的扰动保留的CNT的移动（释放），（5）评估保留的碳纳米管对土壤微生物学的影响，（6）评估最坏情况和对土壤和地下水的潜在影响。该研究计划将包括一名博士生和两名本科生的培训。 将在本科课程中增加关于纳米材料在环境中的迁移以及纳米材料对地下环境的地质微生物学的潜在影响的特别单元。 他们将与耶鲁大学皮博迪博物馆合作，为博物馆的学校项目和教师研讨会开发适当的模块，介绍纳米技术对环境和社会的影响。

CBET-0828795ElimelechCarbon nanotubes (CNTs) are emerging in a variety of applications, including electronic, optical, medical, and structural composite technologies. Because of their anticipated role in large-scale industrial production, there is little doubt that CNTs will ultimately find their way into our aquatic environment. The unusual physicochemical characteristics of CNTs compared to other nanoparticles, particularly the very large aspect ratio and highly bundled (aggregated) state in aqueous solutions, preclude meaningful theoretical predictions of their aggregation and transport behavior. Furthermore, because of the lack of laboratory data on CNT transport in porous media, very little is known about their potential mobility and fate in subsurface environments. Of particular interest is the need to assess the potential contamination of groundwater aquifers by CNTs. Contamination of groundwater with CNTs may originate from landfill leachates, wastewater infiltration, and land applications. Therefore, understanding the extent of CNT transport in soils will be the key to predicting the risk of contamination of underlying groundwater aquifers. Furthermore, because of CNT retention within the soil profile, its impact on soil microbial ecology must be considered in light of recent studies indicating antibacterial effects of CNTs. The overall objective of the proposed research is to assess the extent of transport and retention of CNTs in soils and the impact of retained CNTs on the soil microbial community. Worst case scenarios for CNT transport in soils will be established, which will then enable them to predict the potential for contamination of underlying groundwater aquifers. Furthermore, they will establish the conditions under which retained CNTs influence the soil microbial ecology. Two hypotheses guide their research: (i) the mobility of CNTs in soils will be relatively limited as the large aspect ratio of the nanotubes and their highly aggregated (bundled) state will promote extensive removal by physicochemical filtration and straining, and (ii) because of their effective retention, particularly via straining, CNTs will accumulate in soils and thus will influence the soil microbial community. To complete the proposed work, they will: (1) select and characterize single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes MWNTs, (2) select and characterize soils and model porous media, (3) evaluate transport and retention of CNTs in packed columns, (4) evaluate mobilization (release) of retained CNTs by perturbations in solution chemistry, (5) assess the impact of retained CNTs on soil microbiology, and (6) evaluate worst case scenarios and potential effects on soil and groundwater. The research program will include the training of a doctoral student and two undergraduate students. Special modules on transport of nanomaterials in the environment and on the potential implications of nanomaterials on the geomicrobiology of subsurface environments will be added to undergraduate courses. They will work with the Yale Peabody Museum to develop appropriate modules for the museum's School Programs and Teacher's Workshops on environmental and societal impacts of nanotechnology.