Dyeing process principles

Earlier we found that the addition of alkyl-modified poly(propylene imine) dendrimers to polypropylene leads to fibers which can be dyed in conventional acid or disperse dyeing processes [3]. The alkyl chains make the additive compatible with the polypropylene matrix, while the polar core of the dendrimer can act as a receptor for the dye molecules. This host-guest behavior is analogous to the principle of the dendritic box as described by Meijer et al. [30] and elaborated by Baars et al. for dye extraction processes [31]. 

The beginnings of basic research at BASF were somewhat hesitant and still related to the needs of dyestuffs chemistry. In collaboration with Hans Fikentscher, Curt Schuster and W. Biilow, K.H. Meyer established the physical and chemical principles of the dyeing process of cellulose acetate and nitrate, silk, and wool. This research ran parallel to the efforts of the laboratory to invent dyestuffs for the new artificial fibres, such as cellulose acetate (rayon). 

In principle, for separation of salt from concentrated brine solutions, desahnation techniques common for seawater are suitable. Koyuncu et al. (2004) reported studies on reactive dye/sodium chloride separation using nanofiltration membranes made from polysulfone-polyamide. The emphasis of this research, however, was more directed towards the quality of the purified water than on reclamation of salt or dye. Wenzel et al. (1996) suggested re-use of the bath of a reactive dyeing process containing all auxiliaries after the hydrolyzed reactive dye has been removed by adsorption on activated carbon. The dyes were degraded in an anaerobic digester. 

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