Dimensionless groups for the description of sorption equilibria in dyeing with anionic dyes. I. Inorganic co‐ion exclusion

Abstract

SynopsisThe equations of a general Donnan Model have been simplified and used to describe the equilibrium sorption of anionic dyes by fibers containing acidic and basic groups. By examining simple situations, the dependence of the sorption behavior on specific dimensionless groups of variables has been clarified. This approach emphasizes common features of different ionic dyeing systems, it can be applied in graphical methods of data analysis, and it has potential applications in process control.

Dimensionless groups for the sorption of dye and other ions by polymers. II. Hydrochloric acid, C.I. acid blue 25, and polyamides with an excess of basic groups

“…The analysis in Part I considered several partial treatments of the topic which have received much attention in the l i t e r a t~r e .~.~ Here the treatment is extended to include specific ion binding, zwitterion formation, anion exchange competition, and electrolyte sorption, without restricting the discussion to limited regions of the sorption isotherms, and without restricting the ratio of the concentrations of acidic and basic end groups in the polymer, as has long been c u s t~m a r y .~.~ Sumner has recently offered a general approach to the theory of dyeing which is closely related to the present because the same basic thermodynamic ideas underlie both analyses of the problem.' Crespo et al have also ( 1 ) where X is the Donnan distribution coefficient which takes account of electrical effects, zi is the electrical charge on ion i including sign, and the ionic distribution coefficient K i includes chemical and osmotic effects on the ion distribution. Ct is the concentration of ion i in the fiber, and Cf is the concentration in solution.…”

Dimensionless Groups for the Equilibrium Sorption of Polysulfonated Acid Dyes by Polyamides

“…He estimated KD = 2.5 X 10 +3 1 / kg for this dye. Our as-_ signment in row 1 of Table II for Kcj = 0.07 I / kg is formally equivalent to Grieder's internal volume assignment, so that for this monosulfonated dye, we find that In a previous analysis [6] using independent data for hydrochloric acid sorption by nylon 66 fibers and data for sorption of CI Acid Blue 25 by two different . nylon 6 fibers, both containing an excess of acidic groups, we obtained the following average estimate for the &dquo;relative affinity:&dquo;…”

“…This agreement is remarkably good, since we made no prior assumption about Kc, in obtaining Equation 28 [ 6 ] . In both studies, the same sort of phosphate buffer system was used.…”

“…In an earlier paper [ 6 ] , we derived dimensionless equations and dimensionless sorption parameters for the equilibrium sorption of singly charged anions by fibers containing acidic and basic groups. We also used this approach to describe the equilibrium sorption of hydrochloric acid and a monosulfonated dye Cl Acid Blue 25 by polyamide fibers after extension to permit analyses of specific ion binding, zwitterion formation, anion-exchange competition, and electrolyte sorption [ 7 ] .…”