Graphite Whiskers Derived from Waste Coffee Grounds Treated at High Temperature

Melvin, Gan Jet Hong; Wang, Zhipeng; Morimoto, Shingo; Fujishige, Masatsugu; Takeuchi, Kenji; Hashimoto, Yuichi; Endo, Morinobu

doi:10.1002/gch2.201800107

Cited by 8 publications

(3 citation statements)

References 11 publications

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“…In the CD-SA-G and CD-PL-G samples imperfect hexagonal graphite crystals were observed as discrete plates on the surface of particles (Figure 14). A wide variety of graphite forms were observed in CD-RO-G ( Figure 15), including platy, columnar, spherical, whiskers, cones, and chunk structures, which is in agreement with what is described for natural and synthetic graphite [83][84][85][86][87][88][89][90][91]. Some char particles present platy-structured walls ( Figure 15A) suggesting a full structural reorganization during the graphitization process.…”

Section: Characterisation Of Graphitized Demineralised Char Concentratessupporting

confidence: 86%

Assessment of Graphitized Coal Ash Char Concentrates as a Potential Synthetic Graphite Source

et al. 2020

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Coal ash char concentrates from four countries (Portugal, Poland, Romania, and South Africa) were prepared, characterised, and graphitized under the scope of the Charphite project (Third ERA-MIN Joint Call (2015) on the Sustainable Supply of Raw Materials in Europe). Coal ash chars may be a secondary raw material to produce synthetic graphite and could be an alternative to natural graphite, which is a commodity with a high supply risk. The char concentrates and the graphitized material derived from the char concentrates were characterised using proximate analysis, X-ray fluorescence, X-ray diffraction (structural), Raman microspectroscopy, solid-state nuclear magnetic resonance, scanning electron microscopy, and petrographic analyses to determine if the graphitization of the char was successful, and which char properties enhanced or hindered graphitization. Char concentrates with a lower proportion of anisotropic particles and a higher proportion of mixed porous particles showed greater degrees of graphitization. It is curious to see that embedded Al2O3 minerals, such as glass and clay, influenced graphitization, as they most likely acted as catalysts for crystal growth in the basal direction. However, the graphitized samples, as a whole, do not compare well against a reference natural graphite sample despite some particles in select char concentrates appearing to be graphitized following graphitization.

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Section: Characterisation Of Graphitized Demineralised Char Concentratessupporting

confidence: 86%

Assessment of Graphitized Coal Ash Char Concentrates as a Potential Synthetic Graphite Source

et al. 2020

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“…For carbonization temperatures ranging from 2000 °C to 2800 °C, the cylindrical fiber structure is still maintained, and a slight fusion between the surface grooves of the fibers is observed. Notably, LCFs prepared at 2800 °C exhibit the presence of nanometer–diameter whiskers 35 with micron length on their surface (Fig. 2c).…”

Section: Resultsmentioning

confidence: 99%

Highly conductive and porous lignin-derived carbon fibers

Jia,

Yu,

Wang

et al. 2023

Mater. Horiz.

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“…TEM image of CRH1500 graphitized carbon layers with planar distance, d = 0.35 nm, which is slightly larger than (002) plane of single crystal graphite ( d = 0.335 nm), is shown in Figure c. Larger d indicates the graphitized carbon is turbostratic carbon . TEM images of CRH1500 SiC whiskers are presented in Figure d,e, and CRH1500 SiC particles in Figure f.…”

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confidence: 96%

Electromagnetic Wave Absorption Performance of Carbonized Rice Husk Obtained at Various Temperatures

Melvin

Wang

2019

Global Challenges

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Agricultural wastes such as rice husks (RHs) are valuable due to their feasibility to be converted into carbon materials, low cost, and abundancy in contrast to the conventional carbon material sources. In this study, RHs are carbonized at various temperatures from low to high temperatures, and their electromagnetic (EM) wave absorption properties are evaluated. Carbon materials, silicon carbide (SiC) whiskers, and SiC particles are obtained from RHs carbonized at 1500 °C (CRH1500) for 0.5 h with presence of Ar gas at 1 atm. In order to evaluate their EM wave absorption performance, complex permittivity and permeability are measured by using vector network analyzer, and the values are utilized in the reflection loss (R.L.) calculation according to the transmission line theory. CRH1500, 40 wt% with thickness of 1.6 mm exhibits minimum R.L. of ≈−55.4 dB (>99.9997% absorption) at 11.37 GHz and response bandwidth (R.L. < 10 dB, > 90% absorption) of 4.21 GHz. Low‐cost and abundant RHs, carbonized at various temperatures, show significant absorption performance. Their absorption performance and response bandwidth are highly dependent on matching thickness, indicating that they can be easily modulated for promising electromagnetic wave absorber materials.

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Graphite Whiskers Derived from Waste Coffee Grounds Treated at High Temperature

Cited by 8 publications

References 11 publications

Assessment of Graphitized Coal Ash Char Concentrates as a Potential Synthetic Graphite Source

Assessment of Graphitized Coal Ash Char Concentrates as a Potential Synthetic Graphite Source

Highly conductive and porous lignin-derived carbon fibers

Electromagnetic Wave Absorption Performance of Carbonized Rice Husk Obtained at Various Temperatures

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