title: Significance and systematic analysis of metallic impurities of carbon nanotubes produced by different manufacturers.
abstract: Commercially available carbon nanotubes (CNT) often contain some quantities of metallic and carbonaceous impurities. These impurities influence their physicochemical properties and performance, and accordingly a number of potential applications. The lack of information of metal impurities may also preclude accurate environmental and health risk assessments for specific CNT materials. To address these needs, a quantitative analysis of the metal contents has been made in a number of commercial carbon nanotubes produced by different manufacturers. More than 20 metals or metalloids were determined by neutron activation analysis. The results indicate arranging from 0.44 to 3 wt% of catalyst residues remained although the producers claim to provide a catalyst-free product. Most of the impurity elements are transition metals, such as Fe, Ni, Mo, Y, Co and Cr. In addition to the expected catalyst residues, other unexpected impurity elements were detected including As, Gd, W, Yb, Sm and so on. Metallic impurities in carbon nanotube materials should come from the large-scale production procedures, post fabrication and post-purification treatments. The analytical results determined by inductively-coupled plasma mass spectrometry show that a further deep purification using conventional acid reflux cannot completely remove the metallic impurities from carbon nanotubes. Post-production clean up is difficult and often incompletely.
authors: CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics and National Center for Nanoscience and Technology of China, Beijing 100190, PR China.
authors: Cuicui
authors: C
authors: Ge
authors: Wei
authors: W
authors: Li
authors: Yufeng
authors: Y
authors: Li
authors: Bai
authors: B
authors: Li
authors: Jiangfeng
authors: J
authors: Du
authors: Yang
authors: Y
authors: Qiu
authors: Ying
authors: Y
authors: Liu
authors: Yuxi
authors: Y
authors: Gao
authors: Zhifang
authors: Z
authors: Chai
authors: Chunying
authors: C
authors: Chen
mesh_terms: D004340:Drug Contamination; D007221:Industry / Q000379:methods; D008422:Materials Testing; D008670:Metals / Q000032:analysis*; D037742:Nanotubes, Carbon / Q000032:analysis* / Q000737:chemistry*
chemical_list: D008670:Metals; D037742:Nanotubes, Carbon