Mechanism and kinetics of reactive yellow 145 decolorization by catalytic nano zero-valent iron particles

In this study, the decolorization of Reactive Yellow 145 (RY-145) dye, which is commonly used in the textile industry, was investigated using nano zero-valent iron (nZVI) particles. The synthesized nZVI particles were found to agglomerate, forming a porous structure that allows dye molecules to access the surface. It was determined that the main mechanism of the decolorization process involves the initial adsorption of RY-145 onto the nZVI surface, followed by a simultaneous reaction with hydrogen molecules formed on the surface. Experiments revealed that the highest decolorization efficiency (96.4%) was achieved under the most acidic conditions (pH 3.0), highlighting the importance of hydrogen molecule formation. Furthermore, increasing the amount of nZVI and decreasing the initial dye concentration enhanced both the decolorization rate and efficiency. The adsorption mechanism showed good compliance with the Langmuir isotherm model and was defined as a “favorable” process. However, due to the continuous dissolution of the nZVI surface during the reaction, it was concluded that the term "pseudo-adsorption" is more appropriate for this process. Kinetic analyses showed that the decolorization rate is best described by the pseudo-second-order kinetic model. The findings of this study highlight the potential of nZVI in wastewater treatment applications.