A new sorption mechanism of polyester dyeing with disperse dyes in water is proposed. It is considered dye aggregates could not be sorbed unless they turn into single molecules. However, this theory could not explain numerous sorption phenomena: sorption continues when equilibrium dye concentration exceeds its solubility; dyeing at long liquor ratio, using microencapsulated or crystal-modified dyes do not change concentration of single dye molecules or dye solubility, but increase sorption rate and quantity in a fixed time. We demonstrate that both single and aggregated dye molecules could be sorbed using CI Disperse Blue 56. Because of the large size and low diffusion rate, dye aggregates could temporarily block sorption channel and prevent entry of other dyes. Therefore, only using extra more dyes could get a dark colour. Series of approaches could be proposed to reduce or eliminate the sorption problems caused by aggregates using the new sorption mechanism.
ASJC Scopus subject areas
- Chemistry (miscellaneous)
- Chemical Engineering(all)
- Materials Science (miscellaneous)