Abstract

This project aimed to assess the carbon nanotube (CNT) fiber emission and the potential exposure associated with grinding and brushing of CNT containing products for applications in construction. Specifically, we looked at applications of pre-dispersed CNT in a liquid phase, where the likelihood of exposure was evaluated. The CNT products to be evaluated were tested in two ways: As a dried-out film formed on the surfaces of concrete tiles to simulate a spill and embedded in concrete during mixing to simulate intended use. The surface film trial showed no loose and individual CNT fiber with aspect ratio higher than 3 to 1 released by the brushing motion, although larger particles containing CNT were found as airborne particles originating from the brushing of CNT containing tile surfaces. A few non-CNT straight fibers with sub-micrometer to a few micrometers in length were found from concrete cylinder grinding. This can potentially be related to the specific loading and concentration used or can be a consequence of the chemical pre-dispersion state of the liquid CNT prior to the trials taking place. According to the low number of CNT containing particles found, very trace amount of elemental carbon was contributed by CNTs. We also demonstrated the importance of confirming the presence of individual CNT and CNT containing substance using electron microscopy analysis and the efficiency of using direct sampling method as a result of comparisons among employed methods.

Copyright © 2021 American Association for Aerosol Research

摘要

该项目旨在评估碳纳米管 (CNT) 纤维排放以及与用于建筑应用的含 CNT 产品的研磨和刷洗相关的潜在暴露。具体而言，我们研究了预分散 CNT 在液相中的应用，并评估了暴露的可能性。待评估的 CNT 产品通过两种方式进行测试： 作为在混凝土瓷砖表面形成的干膜以模拟溢出，并在混合过程中嵌入混凝土中以模拟预期用途。表面膜试验显示没有松散和单个长宽比高于 3 比 1 的 CNT 纤维因刷牙运动而释放，尽管发现较大的含 CNT 颗粒是源自含 CNT 的瓷砖表面刷洗的空气传播颗粒。从混凝土圆柱体研磨中发现了一些亚微米到几微米长的非碳纳米管直纤维。这可能与所使用的特定负载和浓度有关，或者可能是试验发生前液体 CNT 的化学预分散状态的结果。根据发现的含碳纳米管颗粒的数量很少，碳纳米管贡献了非常微量的元素碳。我们还证明了使用电子显微镜分析确认单个 CNT 和含有 CNT 的物质存在的重要性，以及使用直接采样方法的效率作为所采用方法之间比较的结果。这可能与所使用的特定负载和浓度有关，或者可能是试验发生前液体 CNT 的化学预分散状态的结果。根据发现的含碳纳米管颗粒的数量很少，碳纳米管贡献了非常微量的元素碳。我们还证明了使用电子显微镜分析确认单个 CNT 和含有 CNT 的物质存在的重要性，以及使用直接采样方法的效率作为所采用方法之间比较的结果。这可能与所使用的特定负载和浓度有关，或者可能是试验发生前液体 CNT 的化学预分散状态的结果。根据发现的含碳纳米管颗粒的数量很少，碳纳米管贡献了非常微量的元素碳。我们还证明了使用电子显微镜分析确认单个 CNT 和含有 CNT 的物质存在的重要性，以及使用直接采样方法的效率作为所采用方法之间比较的结果。

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