Impact of metal ions (Cr+6/Mn+7) loaded CaCO3 extracted from tap water for adsorption/degradation of toxic pollutants under sunlight

The present work involves the extraction and characterization of highly efficient CaCO3 from tap water. The resulting white powder was sintered at 900 degrees C and study for the adsorption/degradation of Rhodamine-B (RB) dye. After sintering at a higher temperature, it was found that CaCO3 was decomposed into CaO and Ca(OH)(2) which results in the superior adsorption of RB dye relative to CaCO 3 dried at room temperature. The degradation efficiency of CaCO3 was further enhanced by loading two metal ions (Cr+6, Mn+7) having different oxidation states. The as-prepared composites were characterized by different techniques i.e., dynamic light scattering, X-ray diffraction, diffuse reflectance spectroscopy, scanning electron microscopy (SEM) and UV-Visible spectrophotometer and examined for photocatalytic degradation of Rhodamine-B (RB) dye under sunlight. The average hydrodynamic size of bare CaCO3 (900 degrees C) found to be 0.63 mu m which was increased to 1.34 mu m and 1.48 mu m after loading of Cr+6 and Mn+7 ions respectively. SEM images suggested the hierarchical morphology of CaCO 3 and energy dispersive X-ray spectroscopy (EDS)-mapping also confirms the presence of Cr6+ and Mn+7 ions on the surface CaCO3. It was observed that Mn+7-CaCO3 (900 degrees C) shows higher degradation efficiency of RB dye under solar radiation relative to bare and Cr+6 loaded CaCO3 and exhibited a higher rate constant of 4.6 x 10(-2) min(-1).