Kinetics of the Reaction between Reactive Dyes and Cotton in Dyeing from Long Liquors

Abstract

For a fibre–reactive dichloroquinoxaline carbonamide dye, the amounts of dye substantively and chemically bound to cotton fibre in dyeing from a long liquor have been determined. The reaction between dye and fibre was neither pseudo first– nor second–order. The relative rate of reaction (based on the amount of dye substantively bound and still reactive) was a function of the total amount of dye present on the fibre, and was about twenty–five times smaller than the corresponding rate constant for the reaction with sorbitol. An interpretation of the results implies that effects of heterogeneity slow down the reaction and that dye molecules can be bound substantively in different kinds of link (by adsorption in special topochemical positions or by association) so as to differ in their probability of reacting with the fibre.

The role of inorganic electrolyte (salt) in cellulosic fibre dyeing: Part 2 theories of how inorganic electrolyte promotes dye uptake

“…From the perspective of cellulosic fibre dyeing and the role of added NaCl or Na 2 SO 4 in dye uptake, the vast majority of kinetic studies have focussed on direct dyes, as demonstrated by the results presented in Figure 6 and, to a lesser extent, reactive dyes, 36,38,39,[55][56][57][58][59][60][61][62][63] though the kinetics of vat dye adsorption have received attention, as illustrated by the findings shown in Figure 7.…”

“…For example, the diffusion of reactive dyes in cellulosic fibres is a heterogeneous process insofar as the essentially mechanical physisorption of dye anions onto an appropriate adsorption site located on pore walls can be accompanied by the simultaneous chemisorption of the reactive dye anion onto an ionised hydroxyl group, Cell-O − . 59,60,[80][81][82][83][84] (2) However, in view of the limited, idealised and simplifying experimental conditions that are often typically employed in kinetic analyses of dyeing processes, which, for the most part, are unrepresentative of those encountered in real dyeing processes, it seems reasonable to once again pose the fundamental question as to exactly what type of information does the kinetic analysis of dye adsorption provide that is of relevance to the role of inorganic electrolytes in cellulosic fibre dyeing? The answer to this simple question is the same as that given above in the case of the thermodynamic analysis of aqueous dye adsorption processes, namely, not very much actually.…”

The role of auxiliaries in the immersion dyeing of textile fibres: Part 6 analysis of conventional models that describe the manner by which inorganic electrolytes promote reactive dye uptake on cellulosic fibres

“…As such, the kinetics of dyeing cellulosic fibres with reactive dyes is very complicated because of the marked heterogeneous nature of the diffusional process. Consequently, mathematical interpretations of the kinetics of reactive dyeing are necessarily complex as they must account for both physical diffusion and simultaneous dye-fibre reaction [eg (22,(93)(94)(95)(96)(97)(98)(99)(100)].…”