Abstract
Acrylonitrile fibre can be dyed with acid dyes by the cuprous ion technique, and cuprous ion be produced by the reduction of cupric salt. In the case of applying hydroxylamine sulphate as most suitable reducing agent, acid dye in the bath is reduced simultaneously, and decomposed. Acid dyes used in the present experiment are monoazo dyes, and following results are obtained:
When dyes are reduced in boiling solution containg hydroxylamine sulphate, aromatic amines are formed according to the theoretical rate of the third order reaction. However, the rate of reaction and the order of rate are strongly dependent on the temperature and at 90° or 80°C. occurs the reaction of the second order or succesive reactions. The experiments indicated that the number of sulphonic groups in the chemical structure of dye and its substitute position have a large effect on the rate of reaction. The rate constant increases rapidly as the number of sulphonic group is raised, and the concentration of hydroxylamine sulphate has an effect on decomposition of dye. But the pH of the solution has a relatively little effect, if the solution has a pH of less than 5.0.
