HIERARCHICAL SYNTHESIS AND CHARACTERIZATION OF CERIUM OXIDE NANOMATERIAL FOR PHOTODEGRADATION OF METHYLENE BLUE

Ceria is a technologically important rare earth material widely used in catalytic oxidation processes due to its unique redox properties. Hydrothermal treatment method had been used to prepare ceria nanoparticles with the average size of 6-30 nm and surface area in the range of 46-62 m2/g in the presence of ionic liquid based on acetate anion, trifluoroacetate anion, dicyanamide anion as organic linker, cerium nitrate hexahydrate as precursor and ammonia. The ceria nanoparticles were characterized by X-ray diffraction techniques (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsoprtion-desorption technique, FTIR spectroscopy and electron energy loss spectroscopy (EELS) to evaluate the effect of ionic liquid organic linker on the textural and structural properties of ceria nanoparticles. It was found that the cerium oxide synthesized by acetate anion based ionic liquid has cube shape morphology and gradually form belt shape as the hydrothermal treatment temperature is increased. Cerium oxide synthesized by trifluoroacetate anion based ionic liquid remains its cubic morphology even at elevated temperature. Both show an increase in particle size at higher treatment temperature. Whereas for cerium oxide synthesized by dicyanamide anion based ionic liquid, ceria particles agglomerate and form irregular structures and the particle size increased with elevated treatment temperature. Catalytic photodegradation of azodye were carried out to investigate the catalytic activity of cerium oxide. Experimental kinetics were analyzed with pseudo first and five different type of pseudo-second order kinetic model. The study proved that ionic liquid-synthesized cerium oxide had better catalytic performance than commercial cerium oxide and pseudo-first order kinetic model best represents the methylene blue degradation for predicting kinetic rate constants.