Investigation Of The Extraction Of Vegetable Dyes And Their Applications

With the improvement of environmental consciousness and the security issues brought by synthetic dyes,vegetable dyes,natural extract,renewable and biodegradable,environmental compatibility,and health functions,attract people's attention.Leather and wool are made up of protein fibers,which is compatible to human body and biodegradable,belonging to green fiber.It is particularly important to research the preparation of vegetable dyes and leather or wool dyeing.Tannin was extracted from Chestnut thorn shell and Walnut green husk.The content of tannin was roughly estimated when extracted by ultrasonic and water leach extracting.The vegetable extracts of chestnut thorn shell was modified by the reaction of sulfite.Then it was used in leather dyeing with the exist of ferric salt.Factors,such as the amount of mordant,fatliquoring agent and pH of neutralization were investigated on the dyeing property of leather.The tannin extracts from walnut green husk was used in leather dyeing,with the discussion of tombarthite,chitosan and surfactants that affected the property of dyeing.Dyeing solution,mixed of tannin extraction of walnut green husk,ferrous salt and pyrogallic acid,was applied to dyeing wool in different dyeing methods.The mordant dosage,dyeing time and temperature.liquor ratio,and dyeing pH were studied on the impact of the dyed black wool,and the dyeing process was optimized by orthogonal test.The results showed that the rate of tannin from chestnut thorn shell was up to 14.78%when the ultrasonic temperature of 65?.ultrasonic time of 20 min,and the liquor ratio of 1:20.The leather was dyed into blue-black using modified chestnut thorn shell extracts.With the increase of mordant,the wet and dry rub fastness decreased.The apparent depth of leather that was mordanted by ferrous sulfate was deeper than the one by ferric sulfate.Taking all factors into account,the dyeing depth and wet and dry rub fastness are good when the amount of mordant was about 2%.The color of dyed leather was shallowed when the fatliquor was added.The pH of the neturalization had little effect on the property of dyed leather,and the optimal pH was 6.5.The optimum conditions of tannin extracts from walnut green husk was for the extraction temperature of 65 ?,extraction time of 4.5h,liquor ratio of 1:40,and the extraction rate was up to 2.94%.Leather was dyed brown useing the extraction of walnut green husk.The dyeing rate was improved with the adding of tombarthite or chitosan.Tthe joining of the surfactant plays a certain degree of acceleration effect.By the method of pre-mordanting,we could get closer to black wool,and the optimized dyeing process was for the dyeing temperature of 70 ?,liquor ratio of 1:40,mordant dosage of 8%,neturalization pH of 5.5,dyeing time of 60min.