A Kinetic and Thermodynamic Study of CI Fluorescent Brightener 113 on Cotton

Fluorescent brightening agents are dyestuffs in which adsorption is the primary mechanism involved in the dyeing process. They are commonly used to improve the brightness in various industrial products, especially textiles. FBA 113 is widely used in the dyeing process for cotton. This study aims to evaluate the optimum dyeing process of FBA 113 on cotton to assess the dyeing behavior, the adsorption isotherm model, and thermodynamic parameters. The study examined various parameters, including dyeing times, dyeing temperature, the amount of dye, and auxiliary. Variations in conditions were observed to define the dyeing equilibrium time, the Langmuir and Freundlich adsorption isotherm, the pseudo-first-order, pseudo-second-order dyeing kinetic model, and the thermodynamic parameters, such as enthalpy (DH0), entropy (DS0), and Gibb's energy (DG0). The results show that the appropriate dyeing was FBA 113 0.25 % owf with 20 g/L KCl as an auxiliary, the best dyeing temperature was 323 K, and the equilibrium time was 120 min. This dyeing reflected an adsorption behavior that displayed multilayer adsorption that corresponded to the Freundlich isotherm. Also, the adsorption model had a pseudo-second-order of 0.9874 using linear regression. The dyeing reaction was exothermic, with DH0 -26.58 kJ/mol, DS0 34.19 J/mol, and the spontaneous process had a negative DG0 value. The fiber and dye interacted physically. The study can enhance our understanding of FBA 113 dyeing behavior and identify situations in which it can be used in other dyeing process models, which will help optimize further dyeing studies.