Aggregation of o,o-dihydroxyazo dyes¯1. Concentration, temperature, and solvent effect

The variation of the average number of molecular aggregation for C.I. Direct Red I has been studied in aqueous solutions as a function of the dye concentration, temperature and solution pH. The objective of this paper is to evaluate the optimal conditions and dye structure in the dyeing process. Electrochemical and VIS spectrophotometrical methods have been used to calculate molecular aggregation. The electrochemical calculation uses the reduction process of the dye, and previous calculations by other authors have been reported at a given pH and varying the solution concentration. Molecular aggregation also depends on pH, and an understanding of the reduction mechanism at several pH values is therefore necessary.