Pyrolysis is a well-known process for biomass upgrading, and a great deal of works are available about it. However, they focus on conventional lignocellulosic samples, and the information about any other less common samples, while still valuable, is very difficult to find. For instance, Brazilian ginseng (Pfaffia glomerata) is a feedstock without hemicellulose and a profitable source of target compounds (like beta-ecdysone) via an extraction process, also generating an exhausted solid. However, there is not much information about this biomass in the literature. For this reason, this work deals for the first time with the effect of different pretreatments on the thermal degradation behavior of Brazilian ginseng. To do so, thermogravimetric analysis (TGA) of the raw material and post-treated samples was done in a synthetic air atmosphere (20% oxygen). The thermograms were fitted via an autocatalytic model (deviation of 4.22%), and the calculated kinetics were used to analyze how the pretreatment modifies the volatilization and char formation for each individual compound (cellulose and lignin) in all the samples. Additionally, structural changes were observed performing XRD and DSC, explaining why different kinetic parameters were required for each sample. Regarding XRD, a variable crystalline index that ranged from 51% to 75% was obtained. Concerning DSC, the pretreatment produced an endothermic peak between 150 and 200 °C.
Figure 1: Thermograms of ginseng roots treated with ethyl acetate at 120 bar at 60 °C. W, water mass fraction; O, oil mass fraction; HC, hemicellulose mass fraction; C, cellulose mass fraction; L, lignin mass fraction; XHC, hemicellulose char mass fraction; XC, cellulose char mass fraction; XL, lignin char mass fraction; and TOTAL, simulated behavior
The whole work can be found at: http://pubs.acs.org/doi/abs/10.1021/acs.energyfuels.7b00695