Activated carbon as carrier in fluidized bed reactor for Fenton oxidation of recalcitrant dye: Oxidation-adsorption synergy and surface interaction

In this work, we investigated the synergy of oxidation-adsorption and surface interaction in fluidized bed Fenton process with granular activated carbon (GAC) as carriers. Experiments were conducted to evaluate the synergy of oxidation and adsorption in the removal of a model pollutant, Reactive Black 5. The effects of carrier loading and solution pH on the process performance were investigated. To determine the nature of interaction between the carriers, Fenton's reagent and pollutant, the surface of the GAC was analyzed using FTIR, SEM/EDX, XPS and BET analyses. The highest COD and color removal obtained were 83% and 99% respectively, at 20 g carrier loading and pH 3. More than 28% of the initial COD was removed through adsorption by the carrier. The process performance increased with increase in carrier loading but decreased when the loading exceeded a certain threshold. Although the highest COD removal was obtained at pH 3, effective removal was still achieved at pH 7. The surface analysis of the carrier reveals that both Fenton's reagent and organic pollutant are adsorbed on the surface of the carrier, indicating that the removal of the pollutant is through both adsorption and oxidation. The performance of GAC in this study is superior to the commonly employed carrier, SiO2. This study shows that GAC can be used as an effective carrier in fluidized bed for Fenton process.