# The Optimized Production of 5-(Hydroymethyl)furfural and Related Products from Spent Coffee Grounds
## 3 Results
### Lignin Enriched Fraction (LEF)
Additionally, carbohydrates were also observed in some of the samples, demonstrating some contamination from molecules that should have been deposited in one of the other fractions. Species common to both feedstock include, alkyl-aryl groups, methoxyls, guaiacyl and p-hydroxyphenyl units, usually found in lignin. Finally, the samples obtained using MW solvent system showed a higher number of unidentified peaks, when compared to the samples obtained using MEW and MAW. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{3}{*}{**Solvent**} & \multirow{3}{*}{**Bio-Mass**} & \multicolumn{3}{c}{**HHV\({}_{\text{exp}}\)**} & \multicolumn{3}{c}{**Theoretical HHV (I)**} & \multicolumn{3}{c}{**Theoretical HHV (2)**} & \multicolumn{3}{c}{**Theoretical HHV (3)**} \\ \cline{3-11}  & & \multicolumn{1}{c}{[J/g]} & \multicolumn{1}{c}{**Btu/lb**} & \multicolumn{1}{c}{**J/g**} & \multicolumn{1}{c}{**Error**} & \multicolumn{1}{c}{**Btu/lb**} & \multicolumn{1}{c}{**J/g**} & \multicolumn{1}{c}{**Error**} \\  & & & & & **(\%)** & **Btu/lb** & \multicolumn{1}{c}{**J/g**} & \multicolumn{1}{c}{**(\%)**} & \multicolumn{1}{c}{**Btu/lb**} & \multicolumn{1}{c}{**J/g**} & \multicolumn{1}{c}{**(\%)**} \\ \hline \multirow{3}{*}{MEW} & Pist & 14,854 & 5,720 & 13,036 & 11.6 & 5,938 & 13,812 & 7.5 & 5,541 & 12,889 & 15.2 \\  & SCG & 22,038 & 11,201 & 26,053 & 15.4 & 11,402 & 26,521 & 16.9 & 11,158 & 25,953 & 15.1 \\  & Pist & 19,339 & 8,299 & 19,304 & 0.2 & 8,499 & 19,768 & 2.2 & 8,147 & 18,950 & 2.1 \\  & SCG & 25,818 & 13,093 & 30,455 & 15.2 & 12,969 & 30,167 & 14.4 & 13,107 & 30,487 & 15.3 \\  & Pist & 10,792 & 12,767 & 29,695 & 63.7 & 12,821 & 29,822 & 63.8 & 12,887 & 29,976 & 64.0 \\  & SCG & 11,081 & 13,340 & 31,030 & 64.3 & 13,265 & 30,854 & 64.1 & 13,543 & 31,500 & 64.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Experimental and theoretical high heating value (HHV) with respective errors to the experimental values. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Solver**} & \multirow{2}{*}{**Biomass**} & \multicolumn{6}{c}{**Elemental Analysis (\%)**} \\ \cline{3-10}  & & **C** & **H** & **N** & **S** & **O** & **Total Metals** & **Total** \\ \hline \multirow{2}{*}{MEW} & Pist & 31.54 & 3.64 & 1.35 & 0.28 & 14.65 & 46.15 & 97.61 \\  & SCG & 57.14 & 6.93 & 5.69 & 0.59 & 18.47 & 9.51 & 98.33 \\ \hline \multirow{2}{*}{MAW} & Pist & 44.52 & 5.05 & 1.54 & 0.34 & 17.05 & 29.47 & 97.97 \\  & SCG & 61.84 & 8.56 & 2.57 & 0.81 & 16.03 & 8.60 & 98.41 \\ \hline \multirow{2}{*}{MW} & Pist & 64.86 & 7.66 & 0.26 & 2.55 & 19.62 & 5.44 & 100.39 \\  & SCG & 62.82 & 9.17 & 0.74 & 3.81 & 21.13 & 0.15. & 97.82 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Elemental analysis results performed to LEF samples. The “total metals” column is a sum of all the metals present in the respective sample obtained from ICP-OES, and the “total” column is the sum of the elemental analysis and the “total metals” column. Figure 4: Two-Dimensional Nuclear Magnetic Resonance (2D-NMR) analysis of LEF obtained using MEW. See Table 5 for label assignments. Figure 5: A 2D NMR analysis of LEF samples obtained using MAW. See Table 5 for label assignments. GC-MS was also used to identify the LEF fraction (see Appendix A, Figures A1-A6); this analysis confirmed the presence of smaller lignin units, and of fatty acids, which are produced by the hydrolysis of triglycerides in the coffee oil. This would account for the higher HHV of the SCG samples. This confirms that the major two components in this phase are the lipids and lignin fragments from the SCG. Figure 6: A 2D NMR analysis of LEF samples obtained using MW. See Table 5 for label assignments. Figure 7: Main structures identified using 2D NMR: (A) \(\beta\)-O-4\({}^{\prime}\) alkyl-aryl ethers with acylated \(\gamma\)-OH; (G) guiaacyl unit; (H) p-hydroxyphenyl unit; (PCA) p-couamates; (FA) ferulates; (T) tricin; (S) syringyl unit.