Zur thermodynamisch‐phänomenologischen Beschreibung der Färbevorgänge I. Diskontinuierliches Modellsystem

The essential characteristics of a simple, discontinuous model system for mass transfer between two phases are discussed. It is shown that for dyeing processes that conform to this model it is possible, with the aid of the methods of non‐equilibrium thermodynamics, to give an unambiguous definition of the concepts «rate of dyeing» and «affinity of dyeing», at any stage of dyeing. It is clear from the derived phenomenological equations that dyeing systems rarely reach a true equilibrium state ( i.e. a stationary state of zero order), but that in general an osmotic or a D ONNAN equilibrium is attained.