Study On The Application Of Hollow Fiber Membrane In Preparing Of Vegetable Dyes

Catechu and Sappan Wood are both widespread in nature, with low cost of production, and good medicinal properties. The topics main research is the application of hollow fiber membrane in plant dyes Catechu and Sappan Wood.First of all, using PVDF hollow fiber microfiltration membrane of the pore size 0.2um for purification catechu, compared the turbidity of catechu dyes before and after membrane separation , compared the characteristics of value on dyeing of wool fabrics and cotton fabrics , and tested the relationship between flux and run-time in the separation , as well as the relationship between pigment concentration and running time. And then studied the membrane fouling process and cleaning methods when Catechu dye purification. It shows that the application of the micro-filtration membrane can decrease the turbidity values of the permeated catechu dye liquids and also can improve the dyeing properties of catechu dye on wool, cotton fabrics. The catechu permeate flux and its content of dye are both decreased after the membrane separate system has been run for 1 hour. Then, the membrane system need to be washed. It is better that NaOH solution is used as detergent. Ultrasonic cleaning can be used to improve membrane flux when the membrane is polluted.The traditional method of refined Sappan Wood Dye (SWD) is vacuum distillation and then powder .It consumes time and energy. In this article hollow fiber membrane is used to refine and Sappan Wood dyes. First, study the preparation before the extraction ,optimize the extraction temperature, time, frequency, test the placement stability of Sappan Wood dye and acid-base stability, its conductivity of the dye liquid with the different content. The dyeing method of SWD and Brazilin (one of the main chemical of SWD) is also discussed. Then extract the best extraction process, using micro-filtration membrane separation and purification, and finally concentrated by ultrafiltration. It shows that Sappan Wood should be crushed to the appropriate particle size to ensure the uniform mixing of raw materials before the extraction; Extraction processes: 100℃, 1h every time and 3 times; Sappan Wood Dye liquid is more stable under acidic conditions, and it is instable under alkaline conditions and it changes greatly; In the liquid content of 0~0.8%, its electrical conductivity is directly proportional to the concentration of SWD and the coloration molecular of SWD can exists stably in water; Pre-mordant dyeing method with mordant aluminum is suitable for dyeing wool fabrics with SWD; Besides the major components Brazilin can dye wool fabric, the other components in SWD can also dye wool fabric. Vacuum filtration can remove the majority of impurities in Sappan wood dye, and the membrane separation technology can further separate the impurity in the dye liquor. After hollow fiber membrane MOF-503 separation the pigment of Sappan wood dye liquor is reduced not many. So its separation is good. In the concentration process of Sappan wood, Hollow fiber membrane UEOS-503 continuous running 2.5 hours, but will not polluted seriously. After continuous running 3 hours, the membrane flux still might achieve 85% of the initial. The membrane concentration is conserve energy and save water than conventional enrichment methods. The results of the study on the separation and purification, concentrated vegetable dyes, as well as the application of membrane has a practical significance and reference value.