Relation between the absorption spectra and the chemical constitution of dyes: XXIX. Interaction of direct azo dyes in aqueous solution

Interaction of dyes in aqueous solution results in differences in the spectrum of t h e mixture when compared wit h the SLlm of the spectra of t he individual dy s.A general s urvey, chiefly with azo dyes, was made to deter mine the effect of dye struc t ure on this interaction.The eff ect of other factors on t he interaction of direct azo dyes was investigated.The addit io n of alcohol or non-ionic dctergent prevents th is interaction , while the presence of inorganic salts or an increase in dyc concentration appears to increa e t he extent of interaction.Th e effect of acids and bases is dependent upon the nature of t he dyes in t hc mixture.The results obtained arc consistent with the assumption that the forees involved in the interaction of direct azo dyes in mixtures are the same as those causing the aggregation of individual dyes and those binding these dyes to fib ers.