The main technical problems of reactive dyes are as follows
(1) the utilization rate is not high enough, generally 60%~70%, producing a large number of colored sewage, its color is more than thousands of times, the COD value is generally in the 0.8 million ~ 30,000 PPM, the COD value of concentrated wastewater is more than 50,000 PPM.
(2) in order to restrain the charge on the surface of the fiber, a considerable amount of electrolyte is required for the use of reactive dyes, which not only increases the labor intensity, but also causes the chloride ion concentration in the wastewater up to more than 100,000 PPM, which greatly increases the difficulty in the treatment of reactive dye dyeing wastewater.
(3) some color fastness cannot meet the market requirements, such as sweat fastness to sunlight, wet rubbing fastness, and sunlight fastness of azo red dyes and azo blue dyes in light color, etc.
(4) few dark varieties can replace vulcanized materials and VAT dyes.