INTERACTION BETWEEN DIRECT DYES AND POLYOXYETHYLENE DODECYL ETHERS IN AQUEOUS SOLUTIONS BY FILTER PAPER CAPILLARY ANALYSIS

The interaction between three direct dyes and four nonionic surface active agents, polyoxyethylene dodecyl ethers, was investigated by means of filter paper capillary analysis. In particular, the effect of the polyoxyethylene chain length (n=5-8) of the surfactants, the chemical constitution of the dyes, and the temperatures (10-30°C) on the interaction was studied. The direct dyes interact with the polyoxyethylene dodecyl ethers to form complexes DSm. The stoichiometric number (m) was 1.4 to 2.0. The equilibrium constant (K) and standard affinity (-Δμ°) of the interaction increased with an increase in the temperature. K and -Δμ° increased in the order of penta-