| Natural plant dyes can be used not only textile dyeing but also medicine, leather processing, food coloring, handicrafts and other fields for its nontoxic, harmless, no polluted and having a good compatibility with the environment. A layer of green peel outside of the mature walnuts, which is a kind of agricultural waste, brought a certain amount of pollution to the environment. However, walnut green husk contains rich natural pigment which having a good property in pigmenting. It will make waste profitable and economic benefits in the walnut industry if these resources can be utilized reasonably. In this research, we regarded the waste walnut green husk as raw material, and discussed the antioxidant activity and the dyeing ability by ethanol and subcritical water extraction, respectively. The main research contents as follows:Random-Centroid Optimization(RCO) methodology was employed to optimize the extraction technology combining with ultrasonic-assisted to extract tannin and anthraquinone by alcohol in walnut green husks, and the antioxidant activity was evaluated in both extraction procedure. Optimized the process conditions of direct dyeing by alcohol extraction, with the measurement of color characteristic values, we further studied 14 different kinds of single metal salt on fabric color value by different mordant dyeing methods, and screened a better dyeing effect with double metal salt.The results showed that the optimized extraction conditions were as follows:extraction temperature 58 ℃, heating time 81 min, ultrasonic time 21 min,solid-liquid ratio 0.08, particle size 40 mesh, ethanol concentration 36%(v/v) for tannin, and extraction temperature 64 ℃, heating time 114 min, ultrasonic time 24 min, solid-liquid ratio 0.09, particle size 20 mesh, ethanol concentration 60%(v/v) for anthraquinone, respectively. Both of them had a certain antioxidant activity. The results of the single factor design and orthogonal experiment showed that the optimal direct dyeing condition was dyeing temperature 90 ℃, pH value 4.0, mass concentration 71.40 g/L, and dyeing time 140 min. In this condition, pre-mordanting,meta-mordanting and post-mordanting dyeing method was compared with fourteen kinds of single metal salts such Fe3+, Fe2+, Cu2+, Al3+, Cr6+, Ti4+, Mn2+, Zn2+, Sr2+, Sn2+,Mg2+, Li+, K+, Na+ as a mordant method on cotton fabric. The results showed that the shade of the dyed cotton fabrics were different with neither different mordant and mordant dyeing methods, nor same mordant and different mordant dyeing methods,but the range of color changed by post-mordanting dyeing method is larger. The color chromatography range of cotton fabric could be increased by post-mordanting dyeing method of double metal-complex salt.The extraction technology with subcritical water from Walnut Green Husks were optimized according to the total extraction yield of Flavonoids, tannin and anthraquinone. Meanwhile, the antioxidant activity was evaluated in different extraction temperature. The results showed that the optimal extraction conditions were as follows: extraction temperature 194 ℃, extraction time 55 min and particle size 80 mesh. In this condition, the yield of total extraction yield was up to(147.87±0.65) mg/g. All extracts with different degree had the ability to remove of the hydroxyl free radicals and DPPH free radicals, and with the improvement of extraction temperature, they had higher scavenging activities and showed a positively related relationship to the sample mass concentration, and the scavenging activities are higher compared with their respective reference substance of Vc and rutin. The results of the single factor design and orthogonal experiment showed that the optimal direct dyeing condition was dyeing temperature 70 ℃, mass concentration 71.40 g/L,pH value 4.0, dyeing time 120 min. In this condition, the dyeing effect of 14 kinds of metal salt mordant dyeing different mordant dyeing method was compared with each other. The results showed that the certain differences of fabric color were existence by dyeing with different mordant methods, and the range of color change by post-mordanting dyeing method is the largest. Different bimetallic metal-complex salt could make the color chromatography range of cotton fabric increased. Comparedwith two methods of extraction, the active constituents of subcritical water extraction were increased in the content, and the extraction yield of tannic acid increased twice.With measurement of tannic acid mass concentration, half removal rate of DPPH free radical of alcohol extract was equivalent to subcritical water extracts of 160-180 ℃.And from dyeing properties, the brightness of cotton fabric dyeing by subcritical water extract is brighter; color is brighter-colored, Furthermore, two kinds of extracts had different dyeing range of chromatography, which will expand the pigment dyeing chromatography of walnut green husk.And then, the color fastness of the alcohol extract and subcritical water extraction from walnut green husk on cotton fabric were compared, and modern technical analysis methods on fiber material were used to test the change of internal structure of the fabric before and after dyeing by two kinds of extracts. Results show that the friction fastness is good basically; soaping fastness on single metal salt mordant dyeing of cotton fabric is post-mordanting ? pre-mordanting ?meta-mordanting ? direct dyeing. Double metal-complex salt and Fe3+, Fe2+, Cu2+,Al3+, Cr6+ single metal salt mordant such as soaping fastness can reach level 3 above.On the ultraviolet resistance, the cotton fabrics could have a good ultraviolet resistance after dyed by alcohol extracts from walnut green husk dye with Fe3+, Fe2+,Cr6+, Sr2+, Na+, K+ single metal salt mordant and double metal-complex salt Fe2+/Cu2+,Fe2+/Ti4+, Cu2+/Ti4+, Cu2+/Sn2+, Al3+/Cr6+, Cr6+/Ti4+ and Cr6+/Sn2+ mordant dyeing, the subcritical water extracts of walnut green husk dye only had good UV resistance in composite metal salt Fe3+/Sn2+, Cu2+/Sn2+ and Cr6+/Sn2+. By infrared spectroscopy and X-ray diffraction analysis showed that the internal structure of cotton fiber was not affected in the process of direct dyeing and metal salt mordanting by walnut green husk extracts. |
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