# The Optimized Production of 5-(Hydroymethyl)furfural and Related Products from Spent Coffee Grounds
## 3 Results
### Cellulose Enriched Fraction (CEF)  
#### 3.3.1 CEF Characterization  
CEF was characterized using four types of solid-state analysis: Fourier-transform infrared spectroscopy (FT-IR), solid state NMR (ssNMR), elemental analysis and thermogravimetric analysis (TGA). For FT-IR, the elemental analysis and TGA, the CEF samples were compared to pure cellulose. In the FT-IR analysis, the samples were divided according to the solvent system, allowing the comparison between pure cellulose and CEF from pistachio hull and SCG (Figure 8). A large well-defined peak around 1000-1100 cm\({}^{-1}\) was observed in all the spectra. This peak is characteristic of a C-O bond in the glucose monomer in cellulose. Additionally, another peak was observed around 3000 cm\({}^{-1}\), characteristic of an alkyl group from the glucose ring was observed for all the fractions. All the CEF fractions that were obtained from pistachio and SCG differed depending on the solvent system used. While distinctive peaks were observed for CEF in the MEW extraction, there were a number of other peaks suggesting esters and possibly proteinous species in both the MEW solid fractions derived from the pistachio and SCG. The cellulose fraction isolated using MAW was the most similar to pure cellulose with few other species observable for the SCG other than those for cellulose. The spectra relating to the pistachio CEF were highly similar for both MEW and MAW solvent extraction. The CEF samples obtained using MW, pistachio in particular, show some more unidentified peaks between 1200 and 1800 cm\({}^{-1}\). Once more, this may be an indicator that the fractionation using this solvent led to samples with higher level of impurities. This correlates with the purity of the LEF fraction in the MAW samples and demonstrates the poor fractionation potential of the MW system. To assess the samples in more detail, the solids were analyzed by solid state NMR (ssNMR). A \({}^{13}\)C and \({}^{1}\)H spectra were obtained for each sample (Figure 9). In the \({}^{13}\)C spectra for the pistachio CEF, peaks characteristic of cellulose were observed between 60 and 100 ppm, although further downfield peaks assignable to acid or ester linkages were also present. The proton spectrum showed a broad, unresolved peak, which is typical of amorphous solid materials in this type of analysis. The \({}^{13}\)C and \({}^{1}\)H spectra for the SCG CEF were far better resolved. These narrower peaks are either associated with highly crystalline material, such as cellulose or a \"soft\" (mobile) component. Both of these spectra demonstrate a high level of cellulose has been extracted but that it is heavily contaminated with non-aromatic components such as fatty acids/esters or amino acid/proteins material. The elemental analysis of the CEF fraction confirms this likely contamination to be protein for both the SCG and  
Figure 8: Fourier-transform infrared spectroscopy (FT-IR) spectra of the CEF samples. pistachio (Table 6). Compared to pure cellulose all the CEF fractions had elevated carbon, N and S while have lower O. To estimate the amount of cellulose in the samples, thermogravimetric analysis was performed on all the six samples of CEF (Figure 10). By comparing the reduction in weight in the sample to that of pure cellulose, the total cellulose in the samples was estimated (Table 7). The percentage of cellulose in the CEF fractions produced from pistachio hulls is higher than CEF from SCG, irrespective of the solvent system used. This is presumably due to the higher level of cellulose and lower protein and other nitrogen species in the hulls. Additionally, the lower percentage of cellulose in the MW fraction demonstrates the poor separation afforded by the MW system.