Reactive dyes have been industrialized for more than 40 years. Because of its bright color, simple synthesis, convenient application, wide use and excellent performance, it is the fastest growing dyestuff today. The traditional reactive dye production process is to add inorganic salt to the dye slurry after chemical synthesis, use the salting out to make the dye supersaturated out, and then filter the dye beating, spray drying, so as to obtain the product.
In synthetic dyes, due to the complexity of the organic reaction, in addition to the finished dyes, there are a variety of dye isomers, homologues and incomplete primary and secondary materials in the synthetic slurry. How to separate inorganic salt and accessory dyes while concentrating, separating and purifying the crude dye slurry has been a hot topic in dye industry. Because the presence of inorganic salt not only affects the stability of the dye, but also reduces the coloring strength and color fastness of the dye, and the presence of the accessory dye affects the final color of the dye. At the same time, its liquid products, solid content is relatively low, the use of spray drying energy consumption is too high.
The advantages of using membrane separation technology to treat dyes are as follows:
1, remove small molecular inorganic salts, improve the dye coloring strength 40-60%;
2, replace the salting-out pressure filtration process to reduce wastewater discharge and shorten the process;
3, save raw and auxiliary materials, recycled products;
4, increase the solid content of dye slurry 20-30%, reduce the drying cost;
5, suitable for reactive dyes, acid dyes, direct dyes and whitening agents and other water-soluble dyes.