Monitor and Characterize Airborne Carbon Nanotube Particles

Details

• Personal Author:
  Xiong JQ
• Description:
  Carbon nanotubes (CNTs) are among the most dynamic and fast-growing engineered nanomaterials due to their novel properties. Now, they can be produced in bulk quantities by a number of established methods, such as, electric arc discharge, chemical vapor deposition, high pressure CO conversion, etc. Industrial scale production is expected in the near future. As production and application increase, the potential of human exposure to this new type material in the workplace as well as in the general environment are increasing, and their impacts on human health are of great concern by many researchers. There is a serious lack of information regarding the aerosol behavior and properties of such new and unique substances, as well as a lack of adequate detection and monitoring technologies. CNTs are highly agglomerated and often coexist with non-tubular type particles, such as amorphous carbon soot, metal catalysts as well as ambient particles. To identify agglomerated CNT particles in the presence of other airborne particles, and quantifying the number concentrations of a specific sub-size fraction, we developed a method for sampling, quantification and characterization of CNT particles in air, utilizing a 13-stage Electrical Low Pressure Impactor (ELPI) in parallel with a 6-stage Integrating Screen Diffusion Battery (ISDB). The system is capable of monitoring particle concentration and size distribution real-time and collecting size segregated particle samples for detection and quantification of CNT contents in each size fraction by Atomic Force Microscopy (AFM) and automated image analysis software (SIMAGIS(R) Nanotube Solutions). By applying an appropriate deagglomeration pretreatment, the sampled particles can be classified into two categories: tubular (individual nanotubes and/or their agglomerates) and non-tubular (soot, dust, metal catalysts, and other co-existing nano-particles). Physical size and shape characters of tubular particles can also be determined with respect to the diameter, length, aspect ratio and curvatures, respectively. The technology has been applied for monitoring and characterizing airborne unrefined CNT samples (raw materials). 7 industrial grade CNT samples of various types have been examined in this study, including single-walled, double-walled and multi-walled nanotubes. The experimental data demonstrated that all types of CNT raw materials examined can be dispersed into air to a significant extent with agitation. The sizes of particles generated were widely distributed and varied with the type of CNTs and with the methods by which they were manufactured. By using a 6-stage ISDB, we have also resolved the particle size mode under 3 nm, a size range that is not quantifiable by other current particle instruments. By number counts, the majority particles are in the respirable-size region (< 4 micro­m) for all types of CNT samples examined in this study; implying that CNTs can possibly become airborne during manufacturing and handling processes and expose humans via inhalation or dermal absorption. The image analysis results by AFM showed that the CNTs tend to agglomerate rather than to exist as single particles, physically. As deposition efficiency and sites of inhaled particles within the respiratory system largely depends on particle size distribution, the deposition pattern of agglomerated CNT should be similar to those equivalent sized non-agglomerated particles. Nevertheless, entrained particles depositing on/in the deep lung surfaces of the bronchioles or alveoli will contact pulmonary surfactants in the surface hypo phase and the agglomerated CNT are likely to be de-agglomerated. Therefore, to investigate human exposure to airborne CNTs, the characteristics of particles, such as, structure, size distribution and surface area, agglomeration state as well as purity of the samples, must be taken into account. [Description provided by NIOSH]
• Subjects:
  Aerosols Environmental Monitoring Occupational Health Particulate Matter Safety
• Keywords:
  Aerosol Particles Air Sampling Equipment Carbon Nanotubes CNT Exposure Assessment Humans Nanomaterials Nanoparticles Particle Counters Particle Size
• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  New York ; OSHA Region 2
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-29
• NIOSHTIC Number:
  nn:20058608
• NTIS Accession Number:
  PB2022-100271
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R01-OH-008807, 2013 May; :1-29
• Contact Point Address:
  Judy Q. Xiong, Ph.D., Department of Environmental Medicine, New York University School of Medicine, 57 Old Forge Road, Tuxedo, NY 10987
• Email:
  xiongj01@NYUMC.ORG
• CAS Registry Number:
  Carbon nanotubes (CAS RN 308068-56-6)
• Federal Fiscal Year:
  2013
• Performing Organization:
  New York University School of Medicine
• Peer Reviewed:
  False
• Start Date:
  20050801
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20090731
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:4d6dc2b47cd710a3824e3d8ffe774b767ceb01b32511c89f01d7a2c8a27605a9b5d8c79af72d2b714ddc21970b83a2665319b5a2a6108223548d80dbd70a4e46
• Download URL:
  https://stacks.cdc.gov/view/cdc/218948/cdc_218948_DS1.pdf
• File Type:
  [PDF - 1.11 MB ]