## 3 Results
### Treatment Using ZnCl\({}_{2}\)-4H\({}_{2}\)O
Therefore, they were taken to a rotary evaporator where a third solid was obtained, recovered, and characterized. The recovery was similar in all cases (between 60 and 70%) with respect to the cellulose, hemicellulose, and lignin composition of the starting material. It is observed that the amount of recovered biomass is inversely proportional to the amount of hemicellulose present in the original biomass. The amount of Solid I recovered was similar in all cases (between 35 and 50%) but was much higher than expected if the recovered Solid I contained only non-solubilized lignin. This was especially the case for barley straw, which is the biomass with the lowest lignin (Table 1). These data indicate that in addition to lignin, part of the structural carbohydrates remained insoluble in Solid I. \begin{table}
\begin{tabular}{c c c c} \hline
**Dissolution** & \
\begin{tabular}{c} **Solid I** \\ **(wt.\% of Initial** \\ **Biomass)** \\ \end{tabular} &
\begin{tabular}{c} **Solid II** \\ **(wt.\% of Initial** \\ **Biomass \({}^{\text{a}}\)** \\ \end{tabular} \\ \hline
60 \({}^{\circ}\)C & 84.3 & 7.9 & 92.2 \\
70 \({}^{\circ}\)C & 49.1 & 18.4 & 70.1 \\
80 \({}^{\circ}\)C & 57.5 & 11.0 & 68.5 \\
90 \({}^{\circ}\)C & 61.3 & 8.0 & 69.3 \\ \hline \end{tabular} a \({}^{\text{a}}\) % of biomass recovered based on the initial mass of main compounds present in pruning waste.  
\end{table} 
Table 2: Mass balance results of pruning waste after treatment with ISH between 60 and 90 \({}^{\circ}\)C after 24 h of reaction (solids dried at 105 \({}^{\circ}\)C). In summary, in all three cases, morphological changes compatible with those observed in X-ray diffraction were observed. Samples of Solid I indicated a partial dissolution of the starting material but still contain part of the original structure; this structure seems more accessible for hydrolysis reagents. The structures of Solid II and Solid III are completely different from the structure of the original biomass [10; 17] because the process of dissolution and recovery produces amorphous solids that favor greater accessibility to the components of the biomass, which is expected to result in the higher reactivity of this material. FTIR spectroscopy was used to study the functional groups of the samples. The region of 3800-2600 cm\({}^{-1}\) for the original biomass and the obtained solids from the dissolution/recovery after treatment is shown in Figure 3. The spectra showed an intense and broad band of OH groups and interactions with water molecules through hydrogen bridging bonds [42]. There are overlapping peaks between 3000 and 2800 cm\({}^{-1}\) that can be assigned to the stretching vibrational modes of C-H bonds. The intensity of these peaks increased in Solid I and Solid III with respect to the spectra of the corresponding lignocellulosic biomass and Solid II, indicating a higher proportion of C-H bonds than in other samples. This fact could be attributed to an enrichment in lignin, the component that contains more C-H bonds. In contrast, Solid II showed a different intensity in all cases, indicating enrichment of cellulose and hemicellulose. For this reason, the comparison of both Solid I and Solid III with a commercial lignin reference and Solid II with commercial cellulose and hemicellulose references will be carried out. \begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Sample**} & **Solid I** & **Solid II** & **Solid III** & **\% Total** \\  & **(wt.\% of Initial** & **(wt.\% of Initial** & **(wt.\% of Initial** & **Recovered** \\  & **Biomass)** & **Biomass)** & **Biomass \({}^{\bullet}\)** \\ \hline Barley Straw & 35.9 & 24.1 & 3.1 & 63.1 \\ Pruning Waste & 49.1 & 18.4 & 2.6 & 70.1 \\ Vine shoot & 43.6 & 15.3 & 8.4 & 67.3 \\ \hline \end{tabular} a % of biomass recovered based on the initial mass of main compounds present in biomass.  
\end{table} 
Table 3: Mass balance results of pruning waste after treatment with ISH at 70 \({}^{\circ}\)C after 24 h of reaction (solids dried at 105 \({}^{\circ}\)C).