Identification of Reactive Dye Transfer Source and Comparison of Two Types of Dye Transfer Inhibitors

The source for reactive dye transfer of cotton fabric varies in different studies, and there is limited information on the washing factors. This study explored the source of Reactive Red 195 colored cotton fabric dye transfer and reported the effects of three key washing factors and their interactions with two types of dye transfer inhibitors. First, the high-performance liquid chromatography results show that the peak of completely hydrolyzed Reactive Red 195 matches the peak of the washing residue of the fabric colored by Reactive Red 195. The dye transfer process is positively related to the hydrolyzed dyes. Based on this, response surface method models for the three factors, water consumption, water hardness, and dye transfer inhibitors concentration for polyvinylpyrrolidone and lauryl betaine were built. Both response surface method models show that due to the presence of Ca ²⁺ and Mg ²⁺ , the increase in water hardness reduces the zeta potential on the fabric surface, and causes a decrease of electrostatic repulsion between the dye and the fabric. The dye transfer inhibiting effect is reduced. The increase in dye transfer inhibitor concentration strengthened the effect of inhibiting the transfer of hydrolyzed Reactive Red 195. In addition, there is a cross effect between water hardness and dye transfer inhibitor concentration. There is optimal water hardness and dye transfer inhibitor concentration to maximize the inhibition of hydrolyzed Reactive Red 195 dye transfer. The water consumption shows a limited effect because the washing time is long enough to reach a balance in the fabric and washing fluids. Polyvinylpyrrolidone with many hydrophilic groups is easy to combine with hydrolyzed dyes. While lauryl betaine is a small molecule surfactant, the structural differences make the response surface method model show that polyvinylpyrrolidone has a better effect than lauryl betaine. The discoveries can be used to guide dye transfer inhibitor development. Further investigations, including dye transfer inhibitor synthesis and modification, are needed.