Calcium-containing materials as alternative catalysts in advanced oxidation process

Abstract In this work, four calcium-containing materials (calcium hydroxide, commercial hydrated lime, calcium oxide and calcium carbonate) were evaluated as catalysts in the photodegradation of Rhodamine 6G (Rh6G) under UV radiation. The effect of catalyst concentration, reaction time and pH were evaluated. Materials were characterized by X-ray powder diffraction, thermogravimetric analysis, Scanning Electron Microscopy and Diffuse Reflectance Spectroscopy. The X-ray powder patterns showed that Ca(OH) 2 , CaO and CaCO 3 samples presented pure crystalline phases while commercial hydrated lime consisted of a mixture of calcite and calcium hydroxide. Materials evaluation indicated that among the calcium-containing catalysts Ca(OH) 2 was the most active material showing a degradation and mineralization percentages of 50 and 61, respectively. Since Ca(OH) 2 band gap value was 5.69 eV, characteristic of an insulator material, the photocatalytic activity was attributed to an indirect dye sensitization.