Abstract

Disperse dyes are non-water soluble specialized dyes used for the dyeing of polyethylene terephthalate fibers. Typically, the quantification of their effective content is achieved through a color comparison method subsequent to the dyeing of polyester fiber textiles. However, this conventional method is notably complex, labor-intensive, and economically inefficient. This article explores the feasibility of using spectrophotometry to determine the effective content of dispersed dyes, using a mixture of dispersed blue 291G filter cake, different proportions of dispersant MF, sodium lignosulfonate dispersant, and corresponding commercial dispersed dyes as examples. The results demonstrate that optimizing the DMF/ water solvent ratio, calibrating the dye’s spectral absorption curve, and executing linear regression on “dye absorbance-dye concentration” yields a maximum deviation of +0.8314% and a minimum of +0.016% in the effective dye content measured by spectrophotometry, as compared to the color comparison method. This underscores the substantial consistency between the two methodologies. The spectrophotometry approach not only offers high precision but also significantly reduces testing duration. For large-scale assessment of effective dye content in disperse dyes, spectrophotometry provides significant advantages including rapid analysis, elevated accuracy, and enhanced environmental sustainability.

Keywords: UV visible absorption spectrophotometry; Disperse dyes; Effective content; Rapid determination; Lambert-Beer law