Energy Conservation in Carpet Dyeing by Dyebath Recycling

ABSTMCT: Reduction in the requirements for water, energy, and chemicals have been achieved by changes in carpet beck dyeing procedures. Instead of discharging the dyebath following each dye cycle, in the new procedure the spent bath is analyzed, reconstituted to the desired concentration of dyes and auxiliary chemicals, and reused. Bench scale dyeings were conducted initially to define operational parameters for coloring commercial nylon carpet a variety of shades with both acid and disperse dyes. The procedures developed were employed in pilot scale equipment for dyeing carpets with reuse of the dye bath for up to f ive dyeings before dumping. Within sample end-to-end variations and between sample variations in color were assessed by instrumental techniques. Results suggest that commercially acceptable carpet dyeings can be achieved in recycled dyebaths. Compared with conventional carpet beck dyeing, the modified proceflures make possible savings of 33 percent in chemical costs, 58 percent in wafer re quirements, and 67 percent in energy requirements.