Biochar characterization of invasive Pennisetum purpureum grass: effect of pyrolysis temperature

Abstract

Pennisetum purpureum is one of the most invasive perennial grasses of the Poaceae family, which are abundant in southeast Asia including Brunei Darussalam. The pyrolysis process at a slow heating rate proved to be highly promising for biochar production. The production and characterization of different Pennisetum purpureum biochars have been investigated at the pyrolysis temperatures of 400 °C, 500 °C and 600 °C with a heating and nitrogen flow rate of 5 °C/min and 0.5 L/min, respectively. The observed higher heating values were 22.18 MJ/kg, 23.02 MJ/kg, 23.75 MJ/kg, and the alkaline pH were 9.10, 9.86, 10.17 for the biochar at 400 °C, 500 °C, 600 °C temperatures, respectively. The water holding capacity was one hundred percent for all biochars and continued to increase for higher pyrolysis temperature. SEM images show that the porosity of the biochars has been enhanced with increased temperatures due to the rearrangement of crystallinity and aromaticity. On the other hand, the yields of biochar have been decreased from 35.13% to 23.02% for the increase of pyrolysis temperature from 400 °C to 600 °C. Energy dispersive X-ray analysis shows that the O/C atomic ratios were 0.15, 0.08 and 0.06 for the biochar of 400, 500 and 600 °C which validates the improvement in heating values. FT-IR analysis revealed that the available functional groups in the biochars were CO , C=C, and C-H. Thermogravimetric analysis (TGA) under pyrolysis condition showed residue of 46.56%, 51.13% and 55.67% from the biochar at 400, 500, and 600 °C, respectively. The derivative thermogravimetry (DTG) graph indicates that the degradation rate is higher for 400 °C biochar than the 600 °C biochar.

Wildfire history of the boreal forest of south-western Yakutia (Siberia) over the last two millennia documented by a lake-sediment charcoal record

“…Although it has been shown that larger charcoal particles originate generally within a few hundred metres of a lake archive (Clark et al, 1998;Higuera et al, 2007;Ohlson and Tryterud, 2000), they have also been observed to travel further depending on vegetation and fire conditions (Peters and Higuera, 2007;Pisaric, 2002;Tinner et al, 2006;Woodward and Haines, 2020). As wildfires in the Siberian boreal forest are predominantly considered low-intensity surface fires (de Groot et al, 2013;Rogers et al, 2015), the potential of the resulting convection to transport large charcoal particles is probably limited compared to high-intensity crown fires. We therefore assume a charcoal source area between a few hundred metres directly around the lake for low-intensity fires (Conedera et al, 2009) and increasing distance of up to several kilometres for more intense fires producing stronger convection, resulting in a total source area estimate of up to ca.…”

“…Aakala et al, 2018;Feurdean et al, 2017;Molinari et al, 2020;Wallenius, 2011). However, comparisons across boreal study sites are complicated by the differing predominant fire regimes in North America (high-intensity crown fires) and Eurasia (lower-intensity surface fires) (de Groot et al, 2013;Rogers et al, 2015).…”

“…The main fire regimes in the European and western Siberian evergreen boreal forest also differ markedly from those of its larch-dominated, deciduous counterpart in eastern Siberia. Many prevalent evergreen conifers (Pinus sibirica, Picea obovata, Abies sibirica) are commonly seen as fire avoiders and are more susceptible to crown fires (Dietze et al, 2020;Isaev et al, 2010;Rogers et al, 2015). The predominant eastern Siberian larches (Larix gmelinii, L. cajanderi, L. sibirica), on the other hand, can resist fires with an insulating bark protecting the cambium from heat, while their deciduous and self-pruning nature restricts fires from reaching the crown (Wirth, 2005).…”

Analysis on Preparation, Application, and Recycling of Activated Carbon to Aid in COVID-19 Protection

“…The carbonaceous materials are prepared by eliminating the volatile matters through thermal decomposition in this stage. Temperature, heating rate, gas flow rate, and the residence period are the main parameters [17]. As biochars show lower adsorption capability, an activation procedure is important to develop the pore volume and the surface areas.…”

Advanced Applications of Fuel Cells during the COVID-19 Pandemic

“…Solid oxide fuel cell (SOFC) offers relatively very high competence among all the types of fuel cells, fuel flexibility (hydrogen, natural gas, biogas from biomass [28][29][30][31][32], and gases made from coal), and low emissions, which led to the use of SOFCs as future power generation technology [33,34]. It shows high efficiency (>60% efficiency) with clean environment credentials [35].…”