Equilibrium sorption of direct dye on polyamide

In this paper, the equilibrium sorption of dyeing polyamide 6.6 fabric with direct dye is presented. Polyamide is a chemical fiber obtained from synthetically produced polymers, while direct dyes are most often sulfonated azo compounds: which are derived from bendisidine and its derivatives. Samples of 100% raw polyamide 6.6 fabric were used in the experiment. The direct used dye is called Solophenyl blue 4GL. The samples were dyed at different dye concentrations: 5, 10, 20, 30, 40, 50 mg/l. The temperature at which the samples were dyed was 40, 60 and 98 °C. Citric acid was added to the dye solution to achieve a certain pH of the solution. A spectrophotometer (Cary 100 Conc UV-VIS, Varian) was used to measure the absorbance of aqueous stained solutions and to calculate the unknown dye concentration in the solution and to construct a calibration curve. The degree of dye exhaustion and the amount of absorbed dye were calculated. Two models of adsorption isotherms were used: Langmuir and Harkin-Jura. The high functionality of the variable was observed in the Langmuir model.