Views: 1000 Author: Site Editor Publish Time: 2022-03-30 Origin: Site
① The permeation peak decreased due to the absorption of the enzyme solution. For this purpose, we made the UV absorption spectrum of the pure enzyme solution as shown in Figure 8, and the enzyme concentration used was 8ml/l. It can be seen from Figure 7 that the transmittance of the enzyme solution between 330-800nm increases with the increase of the wavelength, and the increase is larger between 330-600n, and the 600-800nm is relatively flat; the absorption peaks of different enzyme concentrations The difference is larger in the previous wavelength band. Comparing the absorption curves of reactive red X-3B, direct yellow brown D3G and reactive blue KGL with different enzyme concentrations, the obvious difference in absorption before the maximum absorption wavelength band of these dyes, that is, between 330-500nm, reflects the different concentrations of enzymes here. The absorption difference in the wavelength range; while between 500-560nm, it is the maximum absorption wavelength band of reactive red X-3B dye. Due to the high absorption intensity of reactive red X-3B, the absorption of the enzyme is covered, which is shown as each absorption curve. There is no significant difference in this range, since the absorption intensities of reactive blue KGL and direct yellow brown D3G at the maximum absorption wavelengths (603nm and 447nm) are both lower than those of reactive red X-3B (maximum absorption wavelength is 523nm), so at their maximum The absorption wavelength range fails to cover the absorption of different concentrations of enzymes, which shows that there are still differences between the curves in this range; after the maximum absorption wavelength range of these dyes, the absorption of the dyes gradually decreases, and each absorption curve is slightly different. It just reflects the slight difference in the absorption of different concentrations of enzymes in this wavelength range.
② Another reason is that the enzyme may react with the dye. Some researchers speculate that a complexation reaction may have occurred between them, resulting in a complex that is less active than the enzyme. The formation of this complex will change the absorption spectrum of the dye solution and also change the maximum absorption wavelength of the dye. . However, we did not find significant changes in the maximum absorption wavelength of dyes in the absorption curves of dyes with different enzyme concentrations, and the absorption spectrum curves of these dyes-enzyme solutions hardly changed with the extension of the action time from 15min to 45min.
Therefore, we speculate that the first reason is very likely, that is, due to the absorption of the enzyme solution, resulting in the change of the absorption spectrum of the dye-enzyme solution; from the absorption spectrum, there is no sign of complex formation between the dye and the enzyme.
3.2 Effect of cellulase finishing on fabric dyeing chromaticity
Take the dyed fabric without enzymatic finishing as the standard sample, and take the dyed fabric after enzymatic finishing or the enzymatic finishing fabric as the sample, test the △E (total color difference), △L (lightness difference), △E (total color difference), △L (lightness difference), △ C (brightness difference), △H (color difference), △ (K/S) (surface depth difference), determine the effect of cellulase treatment before and after dyeing on the color of dyed fabrics. The results are shown in Table 5-8.
3.2.1 The effect of cellulase finishing on the surface depth of fabric dyeing
The surface depth of dyed fabrics is expressed by the surface depth value K/S. The larger the K/S value, the darker the color. K/S is a function of wavelength, and has different values at different absorption wavelengths. In general calculations, the K/S value at the maximum absorption wavelength is taken as the color depth value of dyeing.
Compared with the conventional dyeing process without enzyme finishing, the dyeing process after enzymatic finishing, except reactive red X-3B, when the dye dosage is 1%, the dyed fabric's △(K/S)>0, the rest dyed fabrics The Δ(K/S) values of the samples were all less than 0, which indicated that the dyeing shade became lighter after the enzyme treatment. It is generally believed  that due to the regular arrangement and compact structure of the crystalline region, the enzyme molecules are difficult to reach. Cellulase attacks the amorphous region of the cellulose matrix and promotes the hydrolysis of cellulose in the amorphous region. The dyes are dyed in cotton. Therefore, the color depth value of cotton fabric decreased after enzyme treatment; another possibility is that, similar to the alkali reduction results of polyester, after cotton fabric was treated with cellulase, the fiber became thinner, the specific surface increased, and the fabric Diffuse reflection of light increases, so the visual density of the dye becomes smaller.
Comparing the process of enzymatic finishing after dyeing with the conventional process of only dyeing, at the maximum absorption wavelength, except for direct yellow RS, reactive brilliant red M-8B, reactive blue KGR, and vat blue RSN when the dye dosage is 4%. The △(K/S) values of the other dye-dyed fabrics are all less than 0 except for the △(K/S)>0 of the fabrics. This shows that enzymatic treatment after dyeing will make the shade of most dyed fabrics lighter. Cotton fabrics dyed with common dyes have a certain retarding effect on the catalytic hydrolysis of cellulase, and there is little difference with the structure of dyes and the amount of dyes dyed, and the exception is the change of color depth value. The color depth value △ (K/S) of the remaining dyed fabrics is less than 0. The reason is as mentioned above. After the cotton fabric is treated with cellulase, the fibers become thinner, the specific surface increases, and the diffuse reflection of the fabric increases, so , the visual concentration of the dye becomes smaller; another reason, the enzyme treatment will have a stripping effect on the dyed fabric.