# Eco Valorization of _Eucalyptus globulus_ Bark and Branches through Liquefaction
## 3 Results and Discussion  
### Chemical Composition  
The studied materials are wastes of a Forest management company that efficiently separates _Eucalyptus globulus_ bark and branches before sending wood for the cellulose companies. The material dries in the sun and the initial samples had moisture around 17.5% and 10.6% for bark and branches, respectively. Since especially branches are mostly removed in the forest and afterwards transported to the company and chipped, there can be a vast diversity in the composition, such as bark, leaves, and possibly some sand, as mentioned before for _Pinus Sylvestris_ forest residues shredded chips [60]. Bark and branches are heterogeneous materials, consisting of non-structural and structural components. Among the macromolecular structural components, the main ones are cellulose, hemicelluloses, and lignin. The non-structural components are low molecular weight compounds, which include mainly the extractives and inorganic compounds. It is known that the chemical composition of branches and bark varies from species to species, changing in various parts of the same tree (trunk, branches, roots, bark, and needles) and is also affected by the trees growing conditions [61]. Other factors influencing the chemical composition of the bark and branches includes the age of trees, tree cutting season, and time elapsed between cutting and carrying out the analyses. The results on the chemical composition of bark and branches used in this study are depicted in Table 1. The major component for both samples is cellulose, with 40.5% and 41.3% for bark and branches, respectively. Similar results for the cellulose content were presented by [PERSON] et al. [62] for eucalyptus bark cellulose (41.6%) and [PERSON] et al. [5] for _Eucalyptus globulus_ branches (41.2%). [PERSON] et al. [63] reported a 62.6% of holocellulose content in eucalyptus bark, which is not much different from the 63.6% obtained in this study. The second most representative component are hemicelluloses, with values are of 23.1% and 22.3%, for bark and branches, respectively (Table 1). The hemicellulose content was determined indirectly by the difference between the total polysaccharides and cellulose, which might justify the differences from other studies. Most of the studies report some smaller amount of hemicelluloses for eucalyptus bark (e.g., 20.8% [62] or 7.0-19.6% [5]). [PERSON] et al. [5] reported 17.8% of pentosans for eucalyptus branches. Klason lignin represented of 17.9% and 15.6% for branches and bark, respectively. [PERSON] et al. [62] reported 16.7% of lignin in eucalyptus bark, which is quite similar to the data obtained in this work (Table 1). At the same time, [PERSON] et al. [5] obtained a lignin content of 21.8% for branches, which is considerably higher than that \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Bark Composition (\%)** & **Branches Composition (\%)** \\ \hline Ashes & 14.2 \(\pm\) 1.2 & 10.6 \(\pm\) 0.8 \\ Dichloromethane & 1.2 \(\pm\) 0.2 & 3.0 \(\pm\) 0.2 \\ Extract. & Ethanol & 2.9 \(+\) 0.3 & 3.1 \(\pm\) 0.2 \\ Hot water & 4.4 \(\pm\) 1.0 & 4.8 \(\pm\) 0.5 \\ Proteins a  & - & 0.3 \(\pm\) 0.1 \\ Tannins b  & 11.4 \(\pm\) 6.8 & 16.8 \(\pm\) 0.6 \\ Klason Lignin c  & 15.6 \(\pm\) 0.3 & 17.9 \(\pm\) 1.6 \\ Cellulose & 40.5 \(\pm\) 1.0 & 41.3 \(\pm\) 3.7 \\ Hemicelluloses & 23.1 & 22.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Chemical Composition of barks and branches of _Eucalyptus globulus_ (% dry material). found here. However, in that work, a contribution of tannins was not counted for the lignin content. Extractives were determined with dichloromethane (non-polar), ethanol (semi polar), and water (polar). Bark presented 1.2% of non-polar, 2.9% semi-polar, and 4.4% of polar extractives, representing 8.5% of total extractives. There are not so many studies for extractives from eucalyptus bark using the same solvents. Nevertheless, [PERSON] et al.