Dyeing mechanism and photodegradation kinetics of gardenia yellow natural colorant

In this study, gardenia yellow solution is used to dye 100% cotton fabric. The dyeing rate curve and adsorption isotherms were recorded to explore the thermodynamic model and to calculate the corresponding parameters. A definite concentration of gardenia yellow solution was placed under the xenon arc lamp for irradiation to test its photodegradability. Absorbance of the solution was measured at different degradation times and the corresponding varying curve of the absorbance was drawn to explore the photodegradation reaction order of the natural colorant and consistent parameters were calculated. The experimental results proved that the dyeing of cotton fabric with gardenia yellow colorant followed the pseudo second order kinetic model whereas adsorption isotherm followed the Langmuir model and the photodegradation process followed the second order kinetic model. Values of different parameters were calculated: reaction rate constant k = 2.26 x 10(-3) (mg center dot L-1)(1-m) h(-1), the correlation coefficient R-2 = 0.994, and half decay time t(1/2) = 5.82 h.

Automated summary

The study found that dyeing cotton fabric with gardenia yellow solution follows the pseudo second order kinetic model, while adsorption follows the Langmuir model and photodegradation follows the second order kinetic model. Various parameters were calculated, with values such as reaction rate constant and half decay time determined.