Design of Novel Reactive Dyes Containing Cationic Groups: Mechanism and Application for Environmentally Friendly Cotton Dyeing

In this work, four novel, high fixation reactive dyes containing cationic groups were synthesized using m-aminophenyltrimethylammonium salt or 4-(ethylsulfurate sulfonyl) aniline as the diazo component, 3-(N,N-diethylamino) acetanilide or 3 '-aminoacetanilide as the coupling component and m-aminophenyltrimethylammonium salt or N-(2-aminoethyl) pyridinium chloride as the cationic group. The synthesized dyes containing multiple cationic groups were characterized by FT-IR and H-1-NMR spectroscopy. The spectral properties were measured by UV-Vis absorption spectroscopy. Compared with conventional reactive dyes containing cationic groups, the synthesized dyes exhibited good water solubility upon introduction of a quaternary ammonium into the chromophore. The structural design of synthetic azo dyes allows enhanced the water solubility due to the introduction of a cationic group. The dyeing properties of the synthesized dyes to cotton fabric were explored at various temperatures and salt and alkaline concentrations. The results showed that the synthesized dyes possessed good dyeing properties with nearly 80% fixation and good color fastness on cotton (3-5) in the absence of salt. The success of the salt-free dyeing of cotton fabric with these dyes is an excellent example of environmentally friendly cotton dyeing. This study provides an important platform for the design of novel reactive dyes for cotton dyeing to reduce effluent pollution.