Table 1.
Experimental design matrix and treatments for Ca(OH)2 pretreatment at 95°C. Composition of rice straw, delignification, and enzymatic hydrolysis performance after corresponding treatments.
| Treatment no. | Experimental factors | Solid recovery (% wt/wt) | Composition of treated sample (% wt/wt of dry biomass) | Delignificationb | Enzymatic hydrolysis | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Ca(OH)2 loading (% wt/wt) | Time (h) | Lignin content | Total glucose | Total sugar | Pretreated and unwashed biomass | Pretreated and washed biomass | |||||
| Glucose conversion ratioc | Glucose yieldd | Glucose conversion ratioc | Glucose yieldd | ||||||||
| 1 | 0 | 1 | 83.6% | 14.5% | 33.1% | 58.6% | 10.7% | 33.3% | 121.1 | 30.2% | 100.0 |
| 2 | 5 | 3 | 80.7% | 12.7% | 32.8% | 57.6% | 21.8% | 41.4% | 150.4 | 43.2% | 141.8 |
| 3 | 5 | 2 | 82.4% | 13.3% | 32.4% | 57.6% | 18.0% | 36.2% | 131.6 | 33.8% | 109.5 |
| 4 | 5 | 3 | 80.7% | 13.1% | 31.6% | 55.8% | 19.1% | 41.4% | 150.5 | 39.9% | 126.0 |
| 5 | 0 | 2 | 82.3% | 14.2% | 32.1% | 57.0% | 12.6% | 32.9% | 119.6 | 29.8% | 95.5 |
| 6 | 10 | 3 | 80.1% | 11.9% | 31.4% | 54.8% | 27.0% | 48.5% | 176.3 | 41.8% | 131.3 |
| 7 | 5 | 2 | 81.7% | 13.5% | 32.9% | 56.3% | 16.8% | 47.6% | 173.0 | 42.6% | 140.2 |
| 8 | 10 | 1 | 80.7% | 13.1% | 31.3% | 54.3% | 19.7% | 32.4% | 117.7 | 37.7% | 117.9 |
| 9 | 10 | 2 | 80.5% | 12.7% | 30.1% | 53.2% | 21.9% | 43.1% | 156.4 | 54.1% | 162.9 |
| 10 | 10 | 3 | 80.4% | 12.3% | 31.4% | 54.9% | 24.4% | 46.8% | 170.1 | 56.6% | 177.5 |
| 11 | 0 | 3 | 82.5% | 13.9% | 32.3% | 56.2% | 14.5% | 36.6% | 132.9 | 35.9% | 115.9 |
| 12 | 5 | 1 | 84.2% | 14.1% | 33.7% | 58.1% | 13.5% | 42.2% | 153.1 | 35.9% | 120.8 |
| 13 | 0 | 3 | 83.1% | 14.0% | 26.9% | 47.1% | 14.1% | 32.9% | 119.5 | 34.0% | 91.6 |
| 14 | 10 | 2 | 79.0% | 12.3% | 31.7% | 54.8% | 24.3% | 35.5% | 128.8 | 49.9% | 158.1 |
| 15 | 0 | 1 | 83.9% | 14.5% | 32.2% | 56.4% | 10.6% | 29.6% | 107.6 | 21.6% | 69.5 |
| 16 | 0 | 2 | 84.4% | 14.6% | 32.9% | 57.6% | 9.9% | 34.7% | 125.9 | 30.9% | 101.7 |
| 17 | 10 | 1 | 81.6% | 12.8% | 33.2% | 57.1% | 20.9% | 37.2% | 135.1 | 55.0% | 182.8 |
| 18 | 5 | 1 | 84.4% | 14.1% | 34.0% | 58.3% | 13.1% | 40.4% | 146.7 | 37.7% | 128.3 |
| 19a | – | – | 85.8% | 16.2% | 35.2% | 60.0% | – | 30.5% | 110.8 | 28.0% | 98.7 |
| 20a | – | – | 85.9% | 16.3% | 34.7% | 59.1% | – | 32.7% | 118.9 | 27.2% | 94.4 |
aTreatments 19 and 20 are parallel wash-only experiment sets
bDelignification is calculated relative to average lignin removed in the wash only treatments
cGlucose conversion ratio is calculated as % wt/wt of glucose released from the solid fraction of pretreated biomass glucose content
dGlucose yield is calculated as mg glucose released from pretreatment and enzymatic hydrolysis per g raw biomass. It does not include glucose lost during washing