A Study On Extraction And Terahertz Spectra Of Lignin And Fiber From Midribs Of Tobacco

In this work, lignin in the midribs of tobacco leaves was extracted through high boiling solvent-1,4-butylene-glycol (90 % or so). The optimum condition of extraction lignin from midribs of tobacco leaves was found through orthogonal design. The result shows that: the yield of lignin was the highest under the condition of 90 % 1,4-butylene-glycol solution, temperature of 220℃, time of 120 minutes and catalyst C. Another effective catalyst A was also found. Catalyst A was recommended to be used during production practice due to its lower cost.Raman spectrum of lignin from midribs from tobacco leaves was detected by using 785 nm laser for the first time. The Raman intensities of HBS-lignin was measured through a high resolution Raman systems (JY-HR-800) with confocal microscopy. A 100 X microscopy objection lens was used for focusing the laser beam and the collection of the scattered light. The spot diameter of the focused laser beam on the sample is about 1μm. A solid-state diode laser was used as an excited source 785 nm. The laser power on the sample was kept at 0.5 mw and typical spectrum acquisition time was 100 s. If the source power is over 4 mW, lignin would be burned. The bands in Raman spectrum were assigned; the especial 2048 cm-1 band was assigned to overtones and/or combinations.Terahertz spectra of lignin from midribs of tobacco leaves were measured through terahertz-TDS at frequency of 0.3~2.0 THz. The results show that: the data of refractive index of lignin can be fit using a line with negative slope, while the data of absorption coefficient about lignin can fit using a line with positive slope. Furthermore, the difference on the slope values of absorption coefficient is caused by the difference of lignin's molecular weight.Terahertz spectra of midribs from different chemical treatments were also measured through terahertz-TDS at terahertz range of 0.3~1.5 THz. The results show that: the data of refractive index about alcohol midribs can be fit by a line with negative slope, which is Y =1.84857-5.23397E-14 X, at this frequency range but the data of the other 3 samples i.e. original, expanded and water midribs can be fit by polynomial equations; at the same time, the data of absorption coefficients from the 4 samples of midribs can all be fit by lines with different slopes.A new method to detect tobacco leaves and cigarette products was developed using terahertz techniques.