Agriculture Reference
In-Depth Information
Fig. 3.4
Effect of compost-
ing time of lignin samples on
the results of thermogravi-
metric analysis carried out in
an inert atmosphere. (Data
replotted from Bernabé et al.
2013
)
However, as shown by Bernabé et al. (
2013
), that kind of stability does not imply
greater thermal stability. Typically thermodegradation of the lignin component of
biomass requires higher temperatures to be reached in an inert atmosphere, com-
pared to hemicellulose and cellulose. The thermogravimetric analysis results in
Fig.
3.4
reveal a significant decrease in the decomposition temperature of lignin
samples as a function of their time of composting.
It is important to keep in mind that components of lignocellulosic materials other
than lignin also can play a role in resistance to biodegradation. For instance, the
substantially crystalline nature of cellulose in its natural form can be expected to
slow down its biodegradation relative to the amorphous zones within the cellulose
component (Hubbe et al.
2010
). Thus, the inclusion of microcrystalline cellulose in
certain bio-composites can be expected to slow down their biodegradation (Maiti
et al.
2011
). Caricasole et al. (
2011
) showed that pine needles are particularly dif-
ficult to degrade, presumably because of a high content of terpene-related com-
pounds.
3.4.3
Detoxification in the Course of Composting
As shown by Hu et al. (
2011
), composting has potential to be used as a tool for de-
composition of toxic waste products. Addition of the toxic substance tetracycline to
a compost pile was shown to have little if any effect on such parameters as tempera-
ture or the main chemical transformations. Meanwhile, most of the tetracycline was
decomposed, presumably through enzymatic action. The decomposition of toxic
components during ordinary composting has been noted in recent studies (Hachicha
et al.
2012
; Karadag et al.
2013
).
