Effect of Counterions and Ureas on Adsorption of Direct Dye on Cellulose

Abstract

The differences in behavior on adsorption of direct dyes with different kinds of counterions on cellulose in the absence of an electrolyte are indicated, and an alternative role for electrolytes on adsorption of the dye on cellulose is proposed. In addition, an interesting effect of urea on the dye adsorption on cellulose at various temperatures is revealed.

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

“…From the perspective of the five dye classes used for cellulosic fibre dyeing, studies of electrolyte-induced aggregation have focussed predominantly on direct dyes 158,[188][189][190][191][192][193][194][195][196][197] and reactive dyes [198][199][200][201][202][203][204] ]. For example, the extent of aggregation of direct dyes increases with increasing amount of inorganic electrolyte, as illustrated by the data presented in Figure 18.…”

Developments in direct dyes for cellulosic materials

“…Thus concentrated solutions of direct dyes can be stabilised using non-ionic additives but the adsorption of the dyes by cellulose is decreased when non-ionic agents are present The adsorption of CI Direct Yellow 12 (5) by cotton has been studied in the presence of additions of sodium alginate representing a range of degrees of polymerisation [61]. The effects of urea additions and various types of counter-ions in the absence of conventional electrolytes were investigated for three typical direct dyes: CI Direct Yellow 12, Red 2 (18) and Blue 15 (13), on cotton fibres and viscose film [62].…”