Photocatalytic degradation of indigo carmine dye using alpha-Fe2O3/bentonite nanocomposite prepared by mechanochemical synthesis

Preparation of alpha-Fe2O3/bentonite nanocomposite has been successfully conducted by mechanochemical synthesis using iron sand from Syiah Kuala Beach, Banda Aceh and bentonite from Kuala Dewa, North Aceh as raw materials. The alpha-Fe2O3 was extracted using hydrochloric acid and precipitated using ammonium hydroxide as precipitation agent at pH 6 followed by calcination at high temperature in order to obtained alpha-Fe2O3. The alpha-Fe2O3/bentonite nanocomposite was prepared by milling the mixture of alpha-Fe2O3 and bentonite at 4: 1 ratio in a planetary mill for 2 hours without any solvent. The XRD results showed that the main component of iron sand was magnetite (Fe3O4), while in alpha-Fe2O3/bentonite nanocomposite the main component was alpha-Fe2O3 and SiO2. The photocatalytic activity of alpha-Fe2O3/bentonite nanocomposite was investigated on degradation of indigo carmine (IC) dye at various conditions of pH, photocatalyst mass, initial dye concentration and irradiation time. The results showed that the highest photocatalytic activity of alpha-Fe2O3/bentonite nanocomposite was obtained at the initial pH value of IC solution 1, 250 mg photocatalyst mass and initial concentration of IC 10 mg/L after irradiated for 90 minutes under ultra violet and solar light, respectively. The photocatalytic activity of alpha-Fe2O3/bentonite nanocomposite using UV light was almost the same as that of by solar light.