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Stockschläder J, Quicker P, Baumann W, Wexler M, Stapf D, Beckmann M, Thiel C, Hoppe H. Thermal treatment of carbon-fibre-reinforced polymers (Part 2: Energy recovery and feedstock recycling). WASTE MANAGEMENT & RESEARCH : THE JOURNAL OF THE INTERNATIONAL SOLID WASTES AND PUBLIC CLEANSING ASSOCIATION, ISWA 2022; 40:685-697. [PMID: 34387139 PMCID: PMC9016680 DOI: 10.1177/0734242x211038192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/17/2021] [Indexed: 06/13/2023]
Abstract
The use of carbon fibre (CF)-reinforced plastics has grown significantly in recent years, and new areas of application have been and are being developed. As a result, the amount of non-recyclable waste containing CF is also rising. There are currently no treatment methods for this type of waste. Within this project different approaches for the treatment of waste containing CF were investigated. Main subject of the research project were large-scale investigations on treatment possibilities and limits of waste containing CF in high temperature processes, with focus on the investigation of process-specific residues and possible fibre emission. The results showed that the two conventional thermal waste treatment concepts with grate and rotary kiln firing systems are not suitable for a complete oxidation of CFs due to the insufficient process conditions (temperature and dwell time). The CFs were mainly discharged via the bottom ash/slag. Due to the partial decomposition during thermal treatment, World Health Organization (WHO) fibres occurred in low concentrations. The tests run in the cement kiln plant have shown the necessity of comminution for waste containing CF. With respect to the short testing times and moderate quantities of inserted CF, a final evaluation of the suitability of this disposal path was not possible. The use of specially processed waste containing CF (carbon-fibre-reinforced plastic (CFRP) pellets) as a carbon substitute in calcium carbide production led to high carbon conversion rates. In the unburned furnace dust, which is marketed as a by-product of the process, CFs in relevant quantities could be detected.
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Affiliation(s)
| | - Peter Quicker
- Unit Technologies of Fuels, RWTH Aachen
University, Aachen, Germany
| | | | | | - Dieter Stapf
- Karlsruhe Institute of Technology,
Karlsruhe, Germany
| | - Michael Beckmann
- Institute of Process Engineering and
Environmental Technology, Technische Universität Dresden, Dresden, Germany
| | - Christopher Thiel
- Institute of Process Engineering and
Environmental Technology, Technische Universität Dresden, Dresden, Germany
| | - Helmut Hoppe
- Research Institute of the Cement
Industry, VDZ Technology gGmbH, Duesseldorf, Germany
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Kumoi J, Ikegami A, Fujitani Y, Morikawa K, Ichihara G, Yano T, Ichihara S. Factory site analysis of respirable fibers generated during the process of cutting and grinding of carbon fibers-reinforced plastics. Int Arch Occup Environ Health 2022; 95:1557-1565. [PMID: 35212801 DOI: 10.1007/s00420-022-01840-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/01/2022] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Carbon fibers are used in a variety of industrial applications, based on their lightweight and high stiffness properties. There is little information on the characteristics and exposure levels of debris generated during the factory processing of carbon fibers or their composites. This study revisits the general assumption that carbon fibers or their debris released during composite processing are considered safe for human health. METHODS The present interventional study was conducted at a factory located in Japan, and involved on-site collection of debris generated during the industrial processing of polyacrylonitrile (PAN)-based carbon-fiber-reinforced plastic (CFRP). The debris were collected before being exhausted locally from around different factory machines and examined morphologically and quantitatively by scanning electron microscopy. The levels of exposure to respirable carbon fibers at different areas of the factory were also quantified. RESULTS The collected debris mainly contained the original carbon fibers broken transversely at the fiber's major axis. However, carbon fiber fragments morphologically compatible with the WHO definition of respirable fibers (length: > 5 μm, width: < 3 μm, length/width ratio: > 3:1) were also found. The concentrations of respirable fibers at the six examined factory areas under standard working conditions in the same factory were below the standard limit of 10 fibers/L, specified for asbestos dust-generating facilities under the Air Pollution Control Law in Japan. CONCLUSIONS Our study identified potentially dangerous respirable fibers with high aspect ratio, which was generated during the processing of PAN-based CFRP. Regular risk assessment of carbon fiber debris is necessary to ensure work environment safety.
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Affiliation(s)
- Jun Kumoi
- Graduate School of Regional Innovation Studies, Mie University, 1577 Kurimamachiya-cho, Tsu, 514-8507, Japan
| | - Akihiko Ikegami
- Department of Environmental and Preventive Medicine, Jichi Medical University School of Medicine, 3311-1 Yakushiji, Shimotsuke, 329-0498, Japan
| | - Yuji Fujitani
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506, Japan
| | - Kota Morikawa
- Department of Occupational and Environmental Health, Tokyo Univeristy of Science, 2641 Yamazaki, Noda, 278-0022, Japan
| | - Gaku Ichihara
- Department of Occupational and Environmental Health, Tokyo Univeristy of Science, 2641 Yamazaki, Noda, 278-0022, Japan
| | - Takeo Yano
- Graduate School of Regional Innovation Studies, Mie University, 1577 Kurimamachiya-cho, Tsu, 514-8507, Japan
| | - Sahoko Ichihara
- Graduate School of Regional Innovation Studies, Mie University, 1577 Kurimamachiya-cho, Tsu, 514-8507, Japan.
- Department of Environmental and Preventive Medicine, Jichi Medical University School of Medicine, 3311-1 Yakushiji, Shimotsuke, 329-0498, Japan.
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Lovreglio P, Stufano A, Mele D, Acquafredda P, Cottica D, Gardinali F, Vimercati L, Soleo L, De Palma G. Occupational exposure to carbon fibers impregnated with epoxy resins and evaluation of their respirability. Inhal Toxicol 2020; 32:63-67. [PMID: 32197573 DOI: 10.1080/08958378.2020.1735582] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Objectives: The study aims to investigate occupational exposure to carbon fibers impregnated with epoxy resins (carbon fiber reinforced [CFR]) in workers at an airplane fuselage section construction plant, by environmental and biological monitoring.Materials and methods: Determination of airborne CFR was done by environmental sampling with active samplers, 11 of which were stationary and 19 personal samplings. The subsequent analyses were performed in the scanning electron microscope fitted with an X-ray microanalysis system (SEM-EDXA). Biological monitoring was carried out by determining CFR in exhaled breath condensate (EBC) collected from 19 male workers who wore personal environmental samplers (exposed workers) and from 10 male workers at the same factory who had no occupational exposure to CFR (internal controls). CFR analysis was done by SEM, applying the method used for determining asbestos fibers in aqueous samples.Results: The airborne CFR concentrations were found to be significantly higher (p = 0.03) at personal samplings (median value 7.01 ff/L, range 1.24-11.16 ff/L) than stationary samplings (median value 1.93 ff/L, range 0.55-10.09 ff/L). The aerodynamic diameters calculated starting from the length and geometric diameter of the sampled CFRs were always higher than 20 µm. CFR was not found in any of the EBC samples collected from the exposed workers and controls.Conclusions: Despite the evidence of occupational exposure to low concentrations of CFR, the absence of such fibers in the EBC in the exposed workers confirms their non-respirability, as expected based on their aerodynamic diameter.
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Affiliation(s)
- Piero Lovreglio
- Interdisciplinary Department of Medicine, Section of Occupational Medicine, University of Bari, Bari, Italy
| | - Angela Stufano
- Interdisciplinary Department of Medicine, Section of Occupational Medicine, University of Bari, Bari, Italy
| | - Daniela Mele
- Department of Earth and Geo-Environmental Sciences, University of Bari, Bari, Italy
| | - Pasquale Acquafredda
- Department of Earth and Geo-Environmental Sciences, University of Bari, Bari, Italy
| | - Danilo Cottica
- Environmental Research Center, Clinical Scientific Institutes Maugeri SpA SB, Pavia, Italy
| | - Francesco Gardinali
- Environmental Research Center, Clinical Scientific Institutes Maugeri SpA SB, Pavia, Italy
| | - Luigi Vimercati
- Interdisciplinary Department of Medicine, Section of Occupational Medicine, University of Bari, Bari, Italy
| | - Leonardo Soleo
- Interdisciplinary Department of Medicine, Section of Occupational Medicine, University of Bari, Bari, Italy
| | - Giuseppe De Palma
- Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, Section of Public Health and Human Sciences, University of Brescia, Brescia, Italy
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Wang J, Schlagenhauf L, Setyan A. Transformation of the released asbestos, carbon fibers and carbon nanotubes from composite materials and the changes of their potential health impacts. J Nanobiotechnology 2017; 15:15. [PMID: 28219381 PMCID: PMC5319145 DOI: 10.1186/s12951-017-0248-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 02/10/2017] [Indexed: 12/11/2022] Open
Abstract
Composite materials with fibrous reinforcement often provide superior mechanical, thermal, electrical and optical properties than the matrix. Asbestos, carbon fibers and carbon nanotubes (CNTs) have been widely used in composites with profound impacts not only on technology and economy but also on human health and environment. A large number of studies have been dedicated to the release of fibrous particles from composites. Here we focus on the transformation of the fibrous fillers after their release, especially the change of the properties essential for the health impacts. Asbestos fibers exist in a large number of products and the end-of-the-life treatment of asbestos-containing materials poses potential risks. Thermal treatment can transform asbestos to non-hazardous phase which provides opportunities of safe disposal of asbestos-containing materials by incineration, but challenges still exist. Carbon fibers with diameters in the range of 5–10 μm are not considered to be respirable, however, during the release process from composites, the carbon fibers may be split along the fiber axis, generating smaller and respirable fibers. CNTs may be exposed on the surface of the composites or released as free standing fibers, which have lengths shorter than the original ones. CNTs have high thermal stability and may be exposed after thermal treatment of the composites and still keep their structural integrity. Due to the transformation of the fibrous fillers during the release process, their toxicity may be significantly different from the virgin fibers, which should be taken into account in the risk assessment of fiber-containing composites.
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Affiliation(s)
- Jing Wang
- Institute of Environmental Engineering, ETH Zurich, 8093, Zurich, Switzerland. .,Advanced Analytical Technologies, Empa, Ueberlandstrasse 129, 8600, Dübendorf, Switzerland.
| | - Lukas Schlagenhauf
- Institute of Environmental Engineering, ETH Zurich, 8093, Zurich, Switzerland.,Advanced Analytical Technologies, Empa, Ueberlandstrasse 129, 8600, Dübendorf, Switzerland
| | - Ari Setyan
- Institute of Environmental Engineering, ETH Zurich, 8093, Zurich, Switzerland.,Advanced Analytical Technologies, Empa, Ueberlandstrasse 129, 8600, Dübendorf, Switzerland
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