Table 4 Segal crystallinity index (CrI), crystal size, degree of polymerization (DP), water retention value (WRV) and direct orange dye adsorption of raw poplar, steam-pretreated poplar and cellulose-rich pulp from the four two-stage pretreatments
Sample | Segal CrI (%) | Crystal size (nm) | DP | WRV (%) | Adsorption of direct orange (mg g−1) |
|---|---|---|---|---|---|
Raw poplar | 51.5 | 1.8 | – | – | – |
SP2 | 63.7 | 2.7 | 622 | 177 | 47.6 |
DES-SP2 | 65.1 | 2.9 | 615 | 226 | 71.4 |
Organosolv-SP2 | 74.2 | 3.8 | 212 | 262 | 72.5 |
Soda/AQ-SP2 | 68.6 | 3.5 | 479 | 207 | 81.9 |
Hydrotrope-SP2 | 71.0 | 2.9 | 523 | 200 | 63.6 |