RhB PF00299804 a water soluble fluorescent xanthene dye widely used in textile industries for dyeing cotton, wool and silk. The dye is potentially toxic and carcinogenic to humans and animals and can cause irritation to the skin, eyes, gastrointestinal and respiratory tracts . Fig. 10A and B shows the plot of C/C0 versus time for the decolorization of hazardous RhB as a model dye at RT under UVA (370 nm) and Sunlight irradiation for a duration of 90 min. The decolorization efficiency of CeO2 NPs in the dark was less than 5 %, which indicated the value of dye removal by adsorption was insignificant compared to photocatalysis. The decreasing decolorization capacity and rate constant of the medulla catalysts were of the order under UVA irradiation: CeO2 NPs (S4 > S3 > S2 > S1) and under Sunlight irradiation: CeO2 NPs (S4 > S3 > S2 > S1) were tabulated inset (Fig. 10A and B) respectively. The photocatalytic efficiencies of the CeO2 NPs increased from 55 to highest activity of 73 % under UVA light irradiation and 61 % to highest activity of 80 % under Sunlight irradiation.