Thermodynamic properties of cotton dyeing with indigo dyes in non-aqueous media of liquid paraffin and D5

Abstract

On the basis of investigation into the dyeing equilibrium of cotton fibers with indigo dyes in decamethylcyclopentasiloxane (D5), liquid paraffin and water, the thermodynamic properties of cotton dyeing with indigo dyes in non-aqueous medium systems were studied in comparison with aqueous dyeing. The main works involved are as follows: firstly, the adsorption isotherms were created; then, the three theoretical adsorption models of Nernst, Langmuir and Freundlich were used to fit the adsorption isotherms created; finally, the thermodynamic parameters were calculated. The results showed that the adsorption isotherms were all in line with the Freundlich model. The order of dyeing affinity was in the sequence: liquid paraffin > D5 > water. The dyeing entropy in the three media showed positive values, which is mainly attributed to the adsorption of both indigo-leuco and water onto cotton fibers, thus reducing the ice-like structure formed among the water molecules in the dyeing system and the hydrophobic bonding structure formed among the non-aqueous medium molecules, then leading to an increase in the system disorder. The dyeing heat in the three media also showed positive values, due mainly to the absorption of thermal energy to “melt” the ice-like structure and to “break” the hydrophobic bonding structure. These dyeing thermodynamic properties are conducive to understanding and interpreting the dyeing performance and behavior of indigo dyes in non-aqueous dyeing systems.

Cleaner Dyeing Technology for Denim Fabrics with Excellent Utilization of Indigo Based on Inert Gas Protection

“…There must be energy gain or loss in the dyeing process regardless of the dyeing liquor or fibers used. Dyeing thermodynamics has a direct influence on the changes in the dyeing system …”

“…Dyeing thermodynamics has a direct influence on the changes in the dyeing system. 25 A thermodynamic analysis of cotton fibers dyed in different dyeing processes is conducted in order to better understand the behavior of indigo. The thermodynamic parameters of dyeing cotton with indigo are calculated, and these parameters are summarized in Table1.…”

Single box dyeing of denim yarns under nitrogen protection with high indigo concentration

“…A high roller pressure resulted in a low liquid volume, the fiber was unable to fully swell, and the leuco-indigo remained on the surface of the fiber rather than penetrating it, resulting in a lower dyeing uptake and K/S value. 31 Figure 3(c) shows the variation of dyeing performances with temperature under the conditions of 99% N 2 , 0.5 MPa roller pressure, and 22 m/min yarn speed. When the temperature reached 45 C, the K/S value and dyeing uptake of denim yarns were at their peak.…”

Sustainable dyeing of ramie fiber with ternary reactive dye mixtures in liquid ammonia

“…1,2 In this regard, over the past several years, technologies such as adsorption, 3,4 Fenton catalytic systems, 5,6 and membranes [7][8][9] have been applied to treat these complex wastewater effluents; however, these methods are still questionable in terms of sustainable development in the textile industry. Therefore, waterless dyeings, such as dyeing in supercritical uid, [10][11][12] silicone oil, [13][14][15][16][17] liquid paraffin oil, [18][19][20] plant oil, 21,22 and ethanol, 23,24 have been studied as an example of a cleaner dyeing method to reduce water pollution.…”