Effect of calcination temperature on structure of silica doped on zirconia for photodegradation of 2-chlorophenol

Abstract

Simple microwave assisted method was employed to prepare silica (SiO₂) doped zirconia (ZrO₂) that synthesized under different calcination temperature which are 350, 550 and 850 °C and denoted as Si/ZrO₂-350, Si/ZrO₂-550 and Si/ZrO₂-850, respectively for photodegradation of 2-chlorophenol (2-CP). The synthesized catalysts were characterized by X-ray diffraction, Fourier transform infrared and ultraviolet-visible diffuse reflectance spectroscopy. The results showed that higher calcination temperature and the presence of Si induced the tetragonal phase of ZrO₂ as well as narrowed the band gap energy, which affected the photocatalytic activity. The catalyst was subsequently tested for the photocatalytic activity on 2-CP degradation under various parameters such as pH, catalyst dosage and initial concentration of 2-CP under visible light irradiation. Si/ZrO₂-850 showed the highest photodegradation of 2-CP due to presence of tetragonal phase on ZrO₂ that resulting stabilize the structure. The photocatalytic performance of the catalysts towards degradation of 10 mgL^-1 of 2-CP at pH 3 and 0.125 g L^-1 catalyst under visible light after 240 minutes as following order: Si/ZrO₂-850 (88%) > Si/ZrO₂-550 (65%) > Si/ZrO₂- 350 (57%) > ZrO₂-850 (37%). The photodegradation followed the pseudofirst order Langmuir-Hinshelwood kinetic model. This study demonstrated that the Si/ZrO₂ has a potential to be used in photocatalytic degradation of various organic pollutant.