The terminal hydroxyl groups (−OH) can serve as dyeing sites, but PET is difficult to dye because the individual chains pack tightly.
"Cotton is actually fairly difficult to dye and there is a lot of associated pollution," says Michael Harari, president and co-founder at ColorZen.
However, leaving in the grease can make it difficult to dye and can ruin the carding cloth on a drum carder.
As dyeing of nylon is particularly difficult, acid dyes, fixing agents, thickeners, finishing agents, are required for successful colouration and cause major problems with the plant's effluent disposal in terms of chemical oxygen demand (COD).
However, a limited number of dyes and pigments for pure green color filters have been introduced because it is difficult to synthesize dye and pigment molecules which simultaneously absorb the light of both violet (<450 nm) and red (>600 nm) regions, but not that of around 500-nm region.
The removal of synthetic dyes from wastewaters is especially difficult when reactive dyes are present, for which conventional wastewater treatment plants give low removal efficiency (Kumari and Abraham 2007).
It is rather difficult to treat dye effluents because of their synthetic origins and their mainly aromatic structures, which are biologically non-degradable [2].
However, the accurate delineation of the tumor area is often difficult because the dye simply contrasts the surface irregularity of the tumor [ 18].
Therefore, removal of dyes is an important aspect of wastewater treatment before discharge, as it is difficult to remove dyes from effluent because they are not easily degradable and are generally not removed from wastewater by the conventional wastewater purification systems (Abd El-Latif et al. 2010; Kargi and Ozmihci 2004; Chen et al. 2001).
Black hair dye is difficult to remove without frying your hair - go to a hairdresser to avoid accidents.
