Solid waste to biofuels and heterogeneous sorbents via pyrolysis of wheat straw in the presence of fly ash as an in situ catalyst

Heterogeneous biochars from agriculture residues and coal fly ash for the removal of heavy metals from coking wastewater

“…A full characterization of these FA and WS samples were published previously in the context of biofuel production, including an inorganic elemental analysis. 50 As necessary, ultimate analysis results are provided alongside the produced biochar samples to enable assessment of changes due to pyrolysis and activation. Similar to cautions over the wheat straw samples, coal is a heterogeneous solid and varies by region.…”

“…This suggests that the CO 2 activation removes volatile matter, forming a microporous structure as a result of the Boudouard reaction, 75 which in the case of the 5 wt% FA, may be catalyzed, as seen in prior work investigating pyrolysis gas yields of FA and clay mineral impregnated biomasses. 26,50 Table 1 also shows the results of elemental analysis performed by XPS (wide energy spectra of chars available in ESI †). The biochars and activated carbons fabricated in this study had oxygen contents of between 17 and 20% and elemental carbon contents between 69 and 75%.…”

“…In prior work, we demonstrated that during the extraction of pyrolytic biofuels from y-ash incorporated biomasses, the carbon dioxide in pyrolysis gas increases as the FA concentration increased. 50 3. XPS analysis showed the presences of these groups on the surface of all chars, conrming the existence of ketones, aldehyde, carboxyl acids, amides, esters and lactone groups 78,82 (spectra in ESI †).…”

“…85,86 Prior work demonstrates that such reactions are enhanced by the presence of in situ catalysts such as clay minerals and coal y ash. 26,50,85,87 3.3 Applicability of bio-sorbents to wastewater treatment Kinetic and isotherm studies were carried out to gauge the potential for these heterogeneous carbonaceous systems to be used for the adsorption of heavy metals from CW. The kinetic data shows a rapid initial uptake followed by asymptotic approach to equilibrium, reached within 24 h (example kinetic data in Fig.…”

“…49 Yet, WS pyrolysis is potentially catalyzed by the presence of such alkalis, and, as we recently demonstrated, is catalyzed further by the presence of FA in two critical ways. 50 First, the temperature at which many non-condensable gases are released was lower with the inclusion of the FA, which would be benecial to the net energy balance of the process. Second, the condensable pyrolysis bio-oil produced was lower in oxygenated components and the non-condensable fraction was higher in CH 4 when FA was used as an in situ catalyst.…”