Thermodynamic parameters of disperse dyeing on several polyester fibers having different molecular structures

Eco-friendly dyeing of wool and nylon using madder as a natural dye: kinetic and adsorption isotherm studies

“…It is observed that with increase in temperature, saturation point occurred at shorter times. Similar trends have been reported in previous studies (Farizadeh et al 2010;Kim et al 2005). The reason for this behavior relies possibly on the limited number of sites available (primary amine groups) for dye adsorption in the nylon (0.036 equiv kg ) as compared to that of wool (0.82 equiv kg -1 ), resulting in faster saturation of nylon (Lewis and Rippon 2013).…”

“…These phenomena demonstrated that the adsorption of the madder natural onto nylon and wool was an exothermic reaction process; consequent higher dyeing temperature provided a negative result on the thermodynamic adsorption (Kim et al 2005;Chairat et al 2005). Nevertheless, in the practical aspect, since the dyeing process was commonly completed in the restricted period by additional volumes of dyes, higher adsorptions were achieved at higher application temperatures.…”

“…This factor is defined as a difference between the chemical potential of the dye in the dyeing solution and the chemical potential of the dye in the textile substrate, in which the obtained rate is the criterion of the affinity of the dye to transfer from dye bath solution toward textile (Kim et al 2005;Chairat et al 2005). Prior to reach the saturation point, the relations between [Dye] solution and [Dye] fiber are assumed to be linear.…”

Use of 4-vinylpyridine and 2-hydroxyethylmethacrylate monomer mixture grafted poly(ethylene terephthalate) fibers for removal of congo red from aqueous solution

“…The k p of the 4-VP/HEMA grafted PET fibers is 0.6546 mg g -1 min -1 (figure not shown, correlation coefficient 0.97). It may be seen that the increasing linear is attributed to the bulk diffusion [38,39].…”

“…The second step, the actual adsorption process is generally assumed to be much more rapid than either of the other diffusion steps. Of the two diffusion steps the diffusion into the inner layer is much slower than the movement of dye through the aqueous solution due to the physical obstruction of dye diffusion presented by the network of fiber molecules [38].…”