Table 1
Chemicals and materials used in this work.
| Chemicals | Purities | Manufacturer |
|---|---|---|
| Ethylene glycol | A.R. | Macklin Company |
| n-hexane | A.R. | Tianjin Fuyu Company |
| Nicotine | 98% | USP Company |
| Solanesol | 95% | Aladdin Company |
| H2SO4 | A.R. | LuoYang Haohua Company |
| N2 | 99.999% | Bejing Praxair Company |
| Tobacco stem | – | China Tobacco Hunan Ind. Co. |
| Wheat straw | – | Henan, China |
| Corncob | – | Henan, China |
Figure 1
Removal efficiency of lignin for wheat straw, corncob and tobacco stem after ethylene glycol treatment, respectively.
Table 2
Lignin content of wheat straw, corncob and tobacco stem before and after ethylene glycol treatment.
| Material | Lignin content (wt/wt) Before treatment | Lignin content (wt/wt) After treatment |
|---|---|---|
| Wheat straw | 18.50 | 11.23 |
| Corncob | 14.15 | 7.91 |
| Tobacco stem | 5.15 | 4.44 |
Figure 2
Removal efficiency of lignin for wheat straw with addition of nicotine as well as solanesol after ethylene glycol treatment, respectively.
Table 3
Solanesol content of tobacco stem before and after n-hexane treatment.
| Material | Solanesol content (wt/wt) Before treatment | Solanesol content (wt/wt) After treatment |
|---|---|---|
| Tobacco stem | 0.18 | 0 |
Figure 3
Removal efficiency of lignin for tobacco stem with and without n-hexane pre-treatment after ethylene glycol treatment, respectively.
Figure 4
FT-IR spectra of tobacco stem sample before and after treatment with solanesol and ethylene glycol.
Table 4
Assignment of absorbance bands in FT-IR spectra.
| Wavenumber (cm−1) | Vibration | Assignment |
|---|---|---|
| 3405 | O–H | Phenolic OH + aliphatic OH |
| 2931 | C–H | CH3 + CH2 |
| 1737 | C=O | Unconjugated C=O |
| 1626 | C–C | Aromatic skeleton |
| 1515 | C–C | Aromatic skeleton |
| 1428 | C–C | Aromatic skeleton |
| 1322 | C–O | Syringyl unit of lignin |
| 1248 | C–O | Guaiacyl unit of lignin |
| 1063 | C–OH + C–O–C | Aliphatic OH + ether |
Figure 5
SEM images of tobacco stem sample before and after treatment with solanesol and ethylene glycol. (a) Tobacco stem before treatment with solanesol and ethylene glycol; (b) Tobacco stem after treatment with solanesol and ethylene glycol.