## 3 Results and Discussion
### Treatment with Acetone
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline  & \multicolumn{4}{c}{**Real Values**} & \multicolumn{4}{c}{**Coded Values**} & \multicolumn{2}{c}{**Composition**} & \multicolumn{2}{c}{**\% Elimination**} \\ \cline{2-11}
**Test** & **c** & **t** & **T** & **s/L** & **c** & **t** & **T** & **s/L** & **Cellulose, \%** & ** Lignin, \%** & **Cellulose** & ** Lignin** \\ \cline{2-11}  & **\%** & **min** & \({}^{\circ}\)**C** & **_w/v_ & **c** & **t** & **T** & **s/L** & **Cellulose, \%** & ** Lignin** \\ \hline ETA-1 & 45 & 10 & 150 & 1/15 & \(-\)1 & \(-\)1 & 0 & 0 & 85.6 & 4.5 & 30.6 & 92.6 \\ ETA-2 & 65 & 10 & 150 & 1/15 & \(+\)1 & \(-\)1 & 0 & 0 & 87.5 & 5.3 & 33.3 & 95.5 \\ ETA-3 & 45 & 30 & 150 & 1/15 & \(-\)1 & \(+\)1 & 0 & 0 & 84.8 & 9.1 & 36.6 & 89.8 \\ ETA-4 & 65 & 30 & 150 & 1/15 & \(+\)1 & \(+\)1 & 0 & 0 & 89.1 & 4.6 & 38.3 & 93.1 \\ ETA-5 & 55 & 20 & 130 & 1/10 & 0 & 0 & \(-\)1 & \(-\)1 & 86.2 & 8.5 & 25.3 & 90.1 \\ ETA-6 & 55 & 20 & 170 & 1/10 & 0 & 0 & \(+\)1 & \(-\)1 & 86.1 & 10.6 & 36.5 & 91.5 \\ ETA-7 & 55 & 20 & 130 & 1/20 & 0 & 0 & \(-\)1 & \(+\)1 & 85.6 & 8.4 & 34.5 & 91.6 \\ ETA-8 & 55 & 20 & 170 & 1/20 & 0 & 0 & \(+\)1 & \(+\)1 & 88.4 & 3.9 & 46.6 & 92.4 \\ ETA-9 & 45 & 20 & 150 & 1/10 & \(-\)1 & 0 & 0 & \(-\)1 & 84.6 & 10.5 & 31.7 & 88.8 \\ ETA-10 & 65 & 20 & 150 & 1/10 & \(+\)1 & 0 & 0 & \(-\)1 & 87.7 & 4.8 & 35.1 & 94.8 \\ ETA-11 & 45 & 20 & 150 & 1/20 & \(-\)1 & 0 & 0 & \(+\)1 & 85.8 & 4.1 & 37.9 & 93.0 \\ ETA-12 & 65 & 20 & 150 & 1/20 & \(+\)1 & 0 & 0 & \(+\)1 & 87.9 & 4.9 & 40.9 & 93.6 \\ ETA-13 & 55 & 10 & 130 & 1/15 & 0 & \(-\)1 & -1 & 0 & 85.1 & 7.9 & 28.5 & 92.6 \\ ETA-14 & 55 & 30 & 130 & 1/15 & 0 & \(+\)1 & \(-\)1 & 0 & 86.2 & 9.7 & 31.9 & 89.9 \\ ETA-15 & 55 & 10 & 170 & 1/15 & 0 & \(-\)1 & +1 & 0 & 86.7 & 6.6 & 39.1 & 92.3 \\ ETA-16 & 55 & 30 & 170 & 1/15 & 0 & +1 & +1 & 0 & 87.4 & 9.1 & 44.3 & 90.6 \\ ETA-17 & 45 & 15 & 130 & 1/15 & \(-\)1 & 0 & \(-\)1 & 0 & 84.1 & 9.5 & 26.5 & 89.3 \\ ETA-18 & 65 & 15 & 130 & 1/15 & \(+\)1 & 0 & \(-\)1 & 0 & 86.3 & 7.0 & 30.0 & 92.7 \\ ETA-19 & 45 & 15 & 170 & 1/15 & \(-\)1 & 0 & +1 & 0 & 86.1 & 8.1 & 43.1 & 90.3 \\ ETA-20 & 65 & 15 & 170 & 1/15 & \(+\)1 & 0 & +1 & 0 & 88.5 & 6.5 & 43.2 & 93.5 \\ ETA-21 & 55 & 10 & 150 & 1/10 & 0 & \(-\)1 & 0 & \(-\)1 & 84.9 & 6.3 & 23.4 & 93.8 \\ ETA-22 & 55 & 30 & 150 & 1/10 & 0 & \(+\)1 & 0 & \(-\)1 & 86.7 & 8.3 & 38.8 & 90.5 \\ ETA-23 & 55 & 10 & 150 & 1/20 & 0 & \(-\)1 & 0 & +1 & 86.7 & 3.0 & 42.6 & 93.7 \\ ETA-24 & 55 & 30 & 150 & 1/20 & 0 & \(+\)1 & 0 & +1 & 86.6 & 5.8 & 36.9 & 92.6 \\ ETA-25 & 55 & 15 & 150 & 1/15 & 0 & 0 & 0 & 0 & 0 & 86.5 & 6.1 & 33.1 & 93.0 \\ ETA-26 & 55 & 15 & 150 & 1/15 & 0 & 0 & 0 & 0 & 86.3 & 6.2 & 34.3 & 92.5 \\ ETA-27 & 55 & 15 & 150 & 1/15 & 0 & 0 & 0 & 0 & 86.3 & 6.1 & 33 Second-order models for the selected response variables are shown in Table 6. It can be seen that the corresponding values of the regression coefficients confirm that the fits are sufficiently well adjusted. After the optimization process, the best values of the variables, in order to maximize the percentage of cellulose and the value of \(Y_{I}\) and minimize the content of lignin and \(Y_{c}\), were found to be 66.5% acetone over 8.4 min at 155 \({}^{\circ}\)C and a \(s/L\) ratio of 1/19.5. To verify the model, at least three repetitions of the experiment were conducted under the determined optimum conditions, obtaining the results shown in Table 7. It can be seen that both the values predicted by the model and those obtained experimentally coincide, which confirms the goodness of fit of the model.