Research Outputs
Synthesis of BiOI/Mordenite composites for photocatalytic treatment of organic pollutants present in agro-industrial wastewater
Recently, bismuth oxyiodide (BiOI) is an attractive semiconductor to use in heterogeneous photocatalysis processes. Unfortunately, BiOI individually shows limited photocatalytic efficiency, instability, and a quick recombination of electron/holes. Considering the practical application of this semiconductor, some studies show that synthetic zeolites provide good support for this photocatalyst. This support material permits a better photocatalytic efficiency because it prevents the quick recombination of photogenerated pairs. However, the optimal conditions (time and temperature) to obtain composites (BiOI/ synthetic zeolite) with high photocatalytic efficiency using a coprecipitation-solvothermal growth method have not yet been reported. In this study, a response surface methodology (RSM) based on a central composite design (CCD) was applied to optimize the synthesis conditions of BiOI/mordenite composites. For this purpose, eleven BiOI/mordenite composites were synthesized using a combined coprecipitation-solvothermal method under different time and temperature conditions. The photocatalytic activities of the synthesized composites were evaluated after 20 min of photocatalytic oxidation of caffeic acid, a typical organic pollutant found in agro-industrial wastewater. Moreover, BiOI/mordenite composites with the highest and lowest photocatalytic activity were physically and chemically characterized using nitrogen adsorption isotherms, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and diffuse reflectance spectroscopy (DRS). The optimal synthesis conditions prove to be 187 ◦C and 9 h. In addition, the changes applied to the experimental conditions led to surface property modifications that influenced the photocatalytic degradation efficiency of the BiOI/mordenite composite toward caffeic acid photodegradation.
A theoretical and experimental approach for photocatalytic degradation of caffeic acid using BiOBr microspheres
This study describes theoretical and experimental considerations to optimize the photocatalytic degradation of caffeic acid in water using 3D-BiOBr based materials under visible light irradiation. Three BiOBr materials were synthesized through the solvothermal method using different bromide sources, namely potassium bromide (KBr) and the ionic liquid (IL) 1-butyl-3-methylimidazolium bromide. Morphological and chemical changes were observed in IL based 3D-BiOBr materials. The theoretical optimization of the experimental conditions in heterogeneous photocatalysis tests (pH and dose of catalyst) were simulated using the MODDE 12.0.1 software. A central composite design (CCD) was applied to obtain a response surface to elucidate the optimal conditions. This model predicted that the maximum photocatalytic degradation can be achieved at pH of 6.7 and a photocatalyst dose of 344 mg L−1. The optimal experimental conditions were tested using the three synthesized 3D-BiOBr materials. The results showed that the highest degradation efficiency and mineralization yield were obtained using the BiOBr microspheres synthesized with the IL at 145 °C.