Abstract:

A dimethylformamide-tetrachloroethylene (DMF/TCE) solvent-nonsolvent mixture was used for the purification of monochloro-s-triazine, monofluoro-s-triazine and bis (monofluoro-s-triazine) reactive dyes. The question is important for dye-house practise in the textile industry, when using reactive dyes for dyeing cotton fabrics and expecting good dye stability after washing. Dye purity was tested by sodium analysis on the basis of the results of the inductively coupled plasma/atomic emission spectroscopy (ICP AES method). The stability of commercial and purified dyes in solutions of pH 7 and pH 12 at 20 °C (60 °C) was investigated by the HPLC method. The pseudo-first-order rate law was used to calculate the rate constants of hydrolysis of dyes in alkaline media. Neutral solutions of all dyes examined at 20 °C remained unchanged after 24 hours. No apparent difference was found between the rates of hydrolysis of all the commercial and purified reactive dyes studied.