Preparation, characterization and performance of a novel visible light responsive spherical activated carbon-supported and Er 3+:YFeO 3-doped TiO 2 photocatalyst

Abstract

A novel spherical activated carbon (SAC) supported and Er 3+:YFeO 3-doped TiO 2 visible-light responsive photocatalyst (Er 3+:YFeO 3/TiO 2-SAC) was synthesized by a modified sol–gel method with ultrasonic dispersion. It was characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDS), powder X-ray diffractometer (XRD) and UV–vis diffuse reflectance spectrophotometer (DRS). The photocatalytic activity of Er 3+:YFeO 3/TiO 2-SAC was evaluated for degradation of methyl orange (MO) under visible light irradiation. The effects of calcination temperature and irradiation time on its photocatalytic activity were examined. The experimental results indicated that Er 3+:YFeO 3 could function as an upconversion luminescence agent, enabling photocatalytic degradation of MO by TiO 2 under visible light. The Er 3+:YFeO 3/TiO 2 calcinated at 700 °C showed the highest photocatalytic capability compared to those calcinated at other temperatures. The photocatalytic degradation of MO followed the Langmuir–Hinshelwood kinetic model. Although the photocatalyst showed a good physical stability and could tolerate a shear force up to 25 × 10 −3 N/g, its photocatalytic activity decreased over a four-cycle of reuse in concentrated MO solution, indicating that the decreased activity was ascribed to the fouling of catalyst surface by MO during the degradation process. However, the fouled Er 3+:YFeO 3/TiO 2-SAC could be regenerated through water rinsing-calcination or acid rinsing-calcination treatment.