Kato Nobuyuki, Nagaya Taiki, Matsui Yasuto, Yoneda Minoru
Department of Environmental Engineering, Graduate School of Engineering, Kyoto University.
Agency for Health, Safety and Environment, Kyoto University.
J Occup Health. 2017 Nov 25;59(6):521-528. doi: 10.1539/joh.17-0002-OA. Epub 2017 Oct 7.
The application of multiwall carbon nanotubes (MWCNTs) currently extends to various fields. However, it has been reported that exposure to CNT causes hazardous effects on animals and cells. The purpose of this study was to quantify the exposure to MWCNT in MWCNT/polymer composites for exposure assessment. We focused on catalytic metals included in the MWCNT and the diameter of dust released during the working processes. Although the Co in MWCNTs is not a common catalyst, it was used as a tracer in this study.
A field survey was conducted in a MWCNT/polymer composite pilot factory. Airborne MWCNTs were monitored using black carbon monitors (BCMs) and optical particle sizers (OPSs) and collected on a filter. The MWCNT powder, all polymer resins used during the working processes, and the filter were analyzed in our lab using inductively coupled plasma mass spectrometry (ICP-MS) and electron microscopic observation.
The mean concentration of airborne MWCNT contained in the collected dust was 0.92 μg/m a few meters away from the extruder during the working processes (using elemental analysis). The maximum concentration measured using BCMs was shown to be seven times higher than the base concentration during the pelletizing process of polycarbonate (PC) and MWCNT composites. However, free, isolated, and unbound agglomerated MWCNTs were not detected using scanning electron microscopic (SEM) observation.
The result obtained by elemental analysis indicated it was possible to quantify MWCNT in composites. The mean concentration at this factory was lower than the recommended exposure limit. However, additional studies during the pelletizing process are required in the future.
多壁碳纳米管（MWCNTs）目前已应用于各个领域。然而，据报道，接触碳纳米管会对动物和细胞产生有害影响。本研究的目的是对MWCNT/聚合物复合材料中的MWCNT暴露进行量化，以进行暴露评估。我们关注MWCNT中所含的催化金属以及工作过程中释放的粉尘直径。尽管MWCNTs中的钴不是常见的催化剂，但在本研究中用作示踪剂。
在一家MWCNT/聚合物复合材料中试工厂进行了现场调查。使用黑碳监测仪（BCMs）和光学粒子计数器（OPSs）监测空气中的MWCNTs，并收集在滤膜上。在我们的实验室中，使用电感耦合等离子体质谱（ICP-MS）和电子显微镜观察对MWCNT粉末、工作过程中使用的所有聚合物树脂以及滤膜进行了分析。
在工作过程中，距离挤出机几米处收集的粉尘中，空气中MWCNT的平均浓度为0.92μg/m³（使用元素分析）。在聚碳酸酯（PC）和MWCNT复合材料的造粒过程中，使用BCMs测量的最高浓度比基础浓度高7倍。然而，使用扫描电子显微镜（SEM）观察未检测到游离、孤立和未结合的团聚MWCNTs。
元素分析结果表明，可以对复合材料中的MWCNT进行量化。该工厂的平均浓度低于推荐的暴露限值。然而，未来需要在造粒过程中进行更多研究。
