## 3 Results and Discussion
### CNC and LNP Characterization  
The obtained HS and HP CNC showed broad particle size distributions that can be explained by considering the tendency of the nanofibrils to cluster and the presence of residues due to the extraction method employed (Figure 3). In particular, either HS or HP extracts displayed colloidal populations between 150 and 200 nm, compatible with reported CNC fibrils size and smaller populations at around 30-50 nm possibly ascribableto fragments or impurities [22; 77; 78]. Moreover, micrometric clusters are observed in both extracts, with a prevalence of HS. Figure 1: CNC production scheme from different hazelnut lignocellulosic biomasses: (**a**) pruning shoots; (**b**) shells. Figure 2: LNP production scheme from different hazelnut lignocellulosic biomasses: (**a**) pruning shoots; (**b**) shells. Spectroscopic analysis confirmed the cellulosic nature for all extracts since both IR and Raman spectra displayed typical signals. However, the comparison of HS and HP profiles highlighted the higher presence of foreign substances in HS CNC. In fact, while IR profiles were identical, with evidence of water stretching and bending signals at 3300 and 1640 cm\({}^{-1}\), respectively (Figure 4a), Raman spectra pointed to the presence of impurities in HS CNC, as shown by the band between 1600 and 1650 cm\({}^{-1}\), which are likely due to C-N stretching of amide compounds (Figure 4b). The spectroscopic observations were confirmed by morphological analysis, from which the presence of impurities was depicted (Figure 5). SEM images clearly show the typical  
Figure 4: IR-ATR (**a**) and Raman (**b**) spectra of CNC extracted from HS and HP. Extracts were freeze-dried and directly analyzed. The Raman profiles highlighted the presence of impurities in HS compared to HP extracts. Figure 3: Size distributions of CNC extracted from HS and HP, obtained by light scattering analysis. HP extracts show colloidal populations compatible with classical CNC size. HS extracts show a higher degree of aggregated populations, which are partially due to impurities. elongated structure of cellulose nanofibrils, with size slightly higher than 100 nm, which is compliant with DLS measurements. No relevant macroscopic differences emerged from SEM observations because HS and HP CNC were apparently similar in shape and size. On the other hand, X-rays analysis evidenced structural differences in the inner crystal organization and nature of the nanofibrils. Insightful investigation of HS and HP CNC crystalline nature is displayed in Figure 6 and Table 1. The X-rays profiles of HP CNC revealed two cellulose crystalline phases I\(\beta\) and II, whereas HS CNC were characterized by the I\(\beta\) phase only. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**CNC Extract** & **Crystalline Phase** & **Main Peaks (\%20)** & **Crystalline Content (\%)** & **Amorphous Content (\%)** \\ \hline \multirow{4}{*}{HP} & \multirow{4}{*}{I\(\beta\)} & 14.8 & \multirow{4}{*}{42} & \multirow{4}{*}{30} \\  & & 16.5 & 20.2 & \\ \cline{1-1}  & & 12.3 & & \\ \cline{1-1}  & & II & 20.1 & 28 & \\ \cline{1-1}  & & 22.0 & & \\ \hline \multirow{2}{*}{HS} & \multirow{2}{*}{I\(\beta\)} & 14.9 & \multirow{2}{*}{71} & \multirow{2}{*}{29} \\ \cline{1-1}  & & 16.4 & 22.2 & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Calculated crystalline and amorphous contents in CNC extracted from HP and HS. Data was obtained by fitting of the profiles in Figure 6.  
Figure 5: SEM microphotographs of CNC extracted from (**a**) HS and (**b**) HP. Samples were prepared by diluting the extracts \(\times\)1000 in water and overnight drying at room temperature. Typical elongated shape and size of CNC is highlighted. A higher presence of impurities in HS extracts is depicted. Bars = 100 nm. In particular, the I\(\beta\) and II phases contributed to HP CNC crystallinity for the 42% and 28%, respectively (Table 1). Crystalline cellulose is known to exist as cellulose I, II, III, and IV crystal forms [79].