A novel catalyst of ceria-nanorods loaded on carbon xerogel for catalytic wet oxidation of methyl green dye

Abstract

In this study, promising catalysts of ceria nanorods-supported on the porous carbon xerogels via impregnation route were prepared. Three different molar concentrations of ceria catalysts (0.15, 0.25 and 0.50 mol/L) loaded onto carbon xerogels and denoted as follows 0.15Ce/CX, 0.25Ce/CX and 0.50Ce/CX were studied in the catalytic oxidation of methyl green (MG) dye. Nanorods-like shape of the CeO2 supported on the carbon xerogel was determined using both scanning electron microscope (SEM) and transmission electron microscope (TEM). Other techniques such as FTIR, XRD and N2 adsorption–desorption were investigated. The catalytic activity of the obtained samples was examined under various variables such as ceria loading, initial concentrations of dye, H2O2 dose and temperature to optimize the operating conditions. Catalytic wet oxidation experiments revealed that 0.25Ce/CX catalyst has the highest catalytic activity toward degradation of MG dye. The presence of ceria generated a large content of reactive basic oxygen species at the surface of CX and thus enhanced the catalytic oxidation of the pristine CX support. The optimal parameters showing efficient catalytic oxidation toward MG dye found to be 0.25 mol/L cerium loading, 0.139 mol/L H2O2 and temperature of 40 °C at pH 6.0 where 100% degradation of MG dye was obtained within 30 min. The maximum removal of dye through adsorption process only was reached to 54 and 42% onto CX and 0.25Ce/CX at 120 min. Conclusively, the studied catalytic system assessed that there was a synergetic effect as a result of a combination of basic oxygen groups and redox properties of CeO2 at the surface of CX which is effective for a heterogeneous Fenton-catalysis in liquid-phase processes.