Wastewater treatment using Fe-doped perovskite manganites by photocatalytic degradation of methyl orange, crystal violet and indigo carmine dyes in tungsten bulb/sunlight

Abstract

We documented (i) the decolorization of wastewater in visible light, which contains methyl orange, crystal violet and indigo carmine dyes, using La0.7Sr0.3Mn1–xFexO3 (x = 0.0, 0.05, 0.1 and 0.5) manganites and (ii) efficient separation of photocatalysts from water using magnetic field. These ceramic photocatalysts were sintered at 1050 °C for 12 h. Ceramics were characterized by X-ray diffraction (XRD), soft X-ray absorption spectroscopy (SXAS), Fourier transform infrared spectroscopy (FTIR) and UV–visible diffuse reflectance spectroscopy (DRS). SXAS studies show the presence of Mn (Mn3+/Mn4+) and Fe (Fe3+/Fe4+) mixes valences in Fe-doped compositions. Optical band gap is found in visible light range for La0.7Sr0.3Mn1–xFexO3 (x = 0.0, 0.05, 0.1) compositions. La0.7Sr0.3MnO3 degrades 94.6% methyl orange in 7 min, 81.9% crystal violet in 10 min and 99.1% indigo carmine in 5 min. La0.7Sr0.3Mn0.9Fe0.1O3 degrades the 92.6% methyl orange dye solution in 9 min, 94.8% crystal violet in 25 min and 97.1% indigo carmine in 3 min. Parent and Fe doped manganites can be separated in 60 s from wastewater.