Mechanism of Carbon Material to Enhance Removal of Azo-dye by Photo-Fenton Process

Abstract

A mechanism of decolorization of model colored wastewater by photo-Fenton process coupled with a carbon material was kinetically investigated. Decolorization process by photo-Fenton process could be divided into two established phases. At the beginning of the photo-Fenton process, the instantaneous and significant decrease in color of the solution was found. In the subsequent phase, the decolorization rate was decreased and then the decolorization was achieved. Therefore, the decolorization rate of the colored wastewater by photo-Fenton process can be expressed by two pseudo-first-order kinetics. On the other hand, the results of adsorption experiments revealed that adsorption of dyestuff in the colored wastewater onto the carbon material follows the Langmuir formula. The kinetic analysis revealed that the photo-Fenton process coupled with a carbon material had a synergistic effect. The synergistic effects could come from the reduction of ferric ions, which is the rate-limiting step in the photo-Fenton reaction, by reactions with hydroxyl groups on the carbon material and regeneration of reduction capacity of the carbon material. Our result facilitates to develop more efficient carbon material to enhance the photo-Fenton process.