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fiber-like and irregular shape, rough surface, various particle sizes, and uneven dispersion (Lee et al. 2016). Table 1. D 10 , D 50 , D 90 and Surface Area for Each Fraction of Populus alba Dust Size fraction 0-63 μm 63-125 μm 125-250 μm 250-500 μm Particle size D 10 (μm) 12.91 30.25 56.84 164.62 Particle size D 50 (μm) 38.06 89.44 180.78 565.78 Particle size D 90 (μm) 94.91 204.33 418.62 1402.98 Surface area (m 2 /g) 0.27 0.11 0.06 0.02 Table 2. D 10 , D 50 , D 90 and Surface Area for Each Fraction of Pinus massoniana Dust Size fraction 0-63 μm 63-125 μm 125-250 μm 250-500 μm Particle size D 10 (μm) 12.77 18.12 29.78 66.67 Particle size D 50 (μm) 34.16 57.21 120.09 219.04 Particle size D 90 (μm) 77.90 154.14 279.06 459.90 Surface area (m 2 /g) 0.28 0.18 0.10 0.05 Table 3. D 10 , D 50 , D 90 and Surface Area for Each Fraction of Cinnamonum campora Dust Size fraction 0-63 μm 63-125 μm 125-250 μm 250-500 μm Particle size D 10 (μm) 10.29 17.76 52.25 138.30 Particle size D 50 (μm) 29.76 66.50 161.86 303.23 Particle size D 90 (μm) 66.78 157.51 313.18 568.19 Surface area (m 2 /g) 0.35 0.19 0.07 0.04 Besides, the dust of P. massoniana and C. camphora had similar shapes, being oval and slender, and the dust of P. alba and P. massoniana had a relatively uniform and normal particle size. All the samples had particles of 1000 μm, not only P. massoniana and C. camphora , and even P. alba reached the 1500 μm size. National Fire Protection Association (NFPA) Standard 68 defines combustible dust as particles less than 420 μm in diameter and believes that these particles have a potential to cause a fire or explosion when dispersed and ignited in the air. In this paper, wood dust from three species is considered to be combustible dust because the particles less than 420 μm in diameter account for about 50% of all dust samples for each species. Elemental and Thermogravimetric Analysis of Wood Dust Table 4 shows the carbon, hydrogen, nitrogen, and sulfur content in the dust of C. camphora , P. alba, and P. massoniana . The H/C ratio of P. alba, P. massoniana , and C. camphora was 9.7%, 8.4%, and 9.1%, respectively. Compared with poplar and pine trees (Liao et al. 2004), the chosen wood dust samples in this paper had a lower hydrogen and nitrogen content, and a higher nitrogen and sulfur content. Figure 5 shows the TG and DTG curves for the wood dust samples. In general, the pyrolysis process of wood dust is divided into three main stages: water loss drying, devolatilization, and carbonization (Xu et al. 2010). For all dust samples, the water was dehydrated at 30 °C to 100 °C, and most cellulose and hemicellulose were decomposed at 220 °C to 400 °C (Yan 1997; Yang et al. 2000).
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Guo et al . (2019 ). “Explosion of wood d usts,” B io R esources 14(2), 3182-3199.
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