Table 10.
Proposed experiments by Box-Behnken method and the predicted and experimental values of sugar derivatives obtained by subcritical water extraction of chestnut bark.
| Run | Temp. (X1), °C | Time (X2), min | Solvent-Solid Ratio (X3), mL/g | 5-HMF Yield, mg/g of Bark | Furfural Yield, mg/g of Bark | Levulinic Acid Yield, mg/g of Bark | ||
|---|---|---|---|---|---|---|---|---|
| Experimental | Predicted | Experimental | Predicted | Experimental | ||||
| 1 | 150 (−1) | 10 (−1) | 20 (0) | 0.2 | 0.1 | 0.1 | 0.1 | 0 |
| 2 | 250 (1) | 10 (−1) | 20 (0) | 8.0 | 6.8 | 9.5 | 7.8 | 18.6 |
| 3 | 150 (−1) | 60 (1) | 20 (0) | 0.9 | 1.0 | 0.8 | 1.0 | 0 |
| 4 | 250 (1) | 60 (1) | 20 (0) | 3.5 | 3.7 | 2.3 | 2.4 | 25.0 |
| 5 | 150 (−1) | 35 (0) | 10 (−1) | 0.7 | 0.7 | 0.7 | 0.6 | 0 |
| 6 | 250 (1) | 35 (0) | 10 (−1) | 5.1 | 5.2 | 4.0 | 4.0 | 22.3 |
| 7 | 150 (−1) | 35 (0) | 30 (1) | 0.3 | 0.3 | 0.2 | 0.2 | 0 |
| 8 | 250 (1) | 35 (0) | 30 (1) | 7.8 | 8.2 | 6.3 | 7.0 | 20.1 |
| 9 | 200 (0) | 10 (−1) | 10 (−1) | 4.1 | 5.1 | 9.3 | 11.6 | 0 |
| 10 | 200 (0) | 60 (1) | 10 (−1) | 11.0 | 10.1 | 21.6 | 20.3 | 20.2 |
| 11 | 200 (0) | 10 (−1) | 30 (1) | 3.5 | 4.0 | 8.6 | 9.1 | 0 |
| 12 | 200 (0) | 60 (1) | 30 (1) | 8.5 | 7.9 | 18.5 | 16.0 | 19.4 |
| 13 | 200 (0) | 35 (0) | 20 (0) | 9.0 | 8.2 | 17.3 | 16.8 | 16.9 |
| 14 | 200 (0) | 35 (0) | 20 (0) | 9.2 | 8.2 | 18.1 | 16.8 | 15.6 |
| 15 | 200 (0) | 35 (0) | 20 (0) | 8.1 | 8.2 | 16.3 | 16.8 | 13.5 |
| 16 | 200 (0) | 35 (0) | 20 (0) | 9.1 | 8.2 | 19.4 | 16.8 | 14.8 |
| 17 | 200 (0) | 35 (0) | 20 (0) | 7.4 | 8.2 | 15.2 | 16.8 | 11.4 |