The dye industry is a labor-intensive industry with relatively large resources and energy efficiency. The conventional dye preparation method has the weakness of the obtained dye having a large particle size and poor color fastness. If it is not purified, it will seriously affect the dyeing effect and color fastness of the dye. In addition, when the purification is carried out by the conventional evaporation concentration and salting out method, the quality of the obtained product is relatively poor. Not only the salt consumption should reach 10% to 15% of the mass fraction, but also the dye loss rate will reach 5% of the mass fraction, and the wastewater pollution caused by it is quite serious.
The membrane separation and desalination technology can not only effectively perform desalting and concentration of the crude dye, but also the obtained dye can be made into a liquid product or dried to form a solid powdery product. This greatly improves the weakness in the traditional dye preparation method and becomes a green clean production process in the dye industry.
Application of membrane separation technology in dye production and desalting purification
The process of desalting and concentration of the dye is carried out by membrane separation and desalination technology. The nanofiltration membrane technology in the membrane separation technology has a pore diameter of between 0.002 and 0.005 s, and can effectively separate substances that have a molecular weight of 200 to 1000, small molecules, inorganic salts and water. It can also increase the dye concentration by 30%, and the subsequent evaporation energy consumption can be reduced by a quarter compared to the conventional method. Therefore, the membrane separation technology not only reduces the salt content and production cost after purification of the product salt, but also improves the production efficiency of the product.