Chemical characterization of particulate emissions from diesel engines: A review

The Raman spectra of carbonaceous material (CM) from 19 metasediment samples collected from six widely separated areas of Southwest Japan and metamorphosed at temperatures from 165 to 655°C show systematic changes with metamorphic temperature that can be classified into four types: low-grade CM (c. 150–280°C), medium-grade CM (c. 280–400°C), high-grade CM (c. 400–650°C), and well-crystallized graphite (> c. 650°C). The Raman spectra of low-grade CM exhibit features typical of amorphous carbon, in which several disordered bands (D-band) appear in the first-order region. In the Raman spectra of medium-grade CM, the graphite band (G-band) can be recognized and several abrupt changes occur in the trends for several band parameters. The observed changes indicate that CM starts to transform from amorphous carbon to crystallized graphite at around 280°C, and this transformation continues until 400°C. The G-band becomes the most prominent peak at high-grade CM suggesting that the CM structure is close to that of well-crystallized graphite. In the highest temperature sample of 655°C, the Raman spectra of CM show a strong G-band with almost no recognizable D-band, implying the CM grain is well-crystallized graphite. In the Raman spectra of low- to medium-grade CM, comparisons of several band parameters with the known metamorphic temperature show inverse correlations between metamorphic temperature and the full width at half maximum (FWHM) of the D1- and D2-bands. These correlations are calibrated as new Raman CM geothermometers, applicable in the range of c. 150–400°C. Details of the methodology for peak decomposition of Raman spectra from the low to medium temperature range are also discussed with the aim of establishing a robust and user-friendly geothermometer.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/iar.12057

A new approach to develop the Raman carbonaceous material geothermometer for low-grade metamorphism using peak width

Impact of exhaust gas recirculation (EGR) on the oxidative reactivity of diesel engine soot

Changes in electrical and microstructural properties of microcrystalline cellulose as function of carbonization temperature

A high performance exfoliated biochar carbon with a layered nanosheet structure was prepared from a low cost agricultural residue (corn cob) via a novel synthesis strategy involving biomass pre-treatment, nitrogen pyrolysis, and a high temperature thermal–chemical flash exfoliation. The exfoliation strategy resulted in porous carbon nanosheets with BET specific surface area of 543.7 m2 g−1, far higher than the 7.9 m2 g−1 of the natural biochar produced without any pre- or post-treatment modifications. The exfoliated material also showed increased oxygen functionality in the form of electrochemically active quinone and pyrone surface groups. This combination of high specific surface area and highly active surface functional groups resulted in very promising capacitive performance, demonstrating a high capacitance of 221 F g−1, over 100 times greater than the natural biochar. The exfoliated biochar electrodes fabricated without any conductive or organic additives showed outstanding high rate capability retaining 78% of their low rate capacitance at a fast 40 A g−1 discharge. This combination of high capacitance and fast charge–discharge capability distinguishes this material from most other high surface area activated carbons; in fact, the electrochemical behaviour more closely resembles that of designer nanomaterials such as graphene and carbon nanotubes. The biochar electrodes were also extremely durable showing only a 3% reduction in capacitance after 5000 successive potential cycles. The exfoliation strategy developed here could provide a novel route for the low cost production of high performance energy storage materials from a variety of waste biomass feedstocks.

J. J. Sloan

Papers

Raman spectroscopy of carbon-containing particles