Kinetic modelling of photocatalytic removal of Rhodamine 6G by ZnS/CNFs composite

According to the literature review, Langmuir–Hinshelwood (L-H) kinetics model is the most common model in the dyes photocatalysis studies. So, non-linear regression analysis was used to development a kinetics model based on L–H model in photocatalytic removal of Rhodamine 6G (Rh-6G) by Zinc sulfide/Carbon nanofibers (ZnS/CNFs) composite and an empirical equation was obtained for estimation of apparent pseudo first- order rate constant (kap) as a function of the operational variables. Semi-logarithmic graphs of the Rh-6G concentration versus irradiation time at different values of operational variables (Rh-6G concentration, ZnS/CNFs amount, pH and intensity of UV light irradiation) were drawn, which achievement of direct lines in all of the experiments confirmed the fitting of this process by pseudo first-order kinetics model. Non-linear relationship of kap with each of the operational variables was plotted and results showed that kap increased with increment of ZnS/CNFs amount, pH and UV light intensity, whereas kap decreased with increasing initial Rh-6G concentration. Also, findings indicated a high similarity was between the model prediction and experimental results.