Effect of Fe3O4 Pigment on the Photocatalytic Activity of TiO2 Coatings Deposited by HVOF Process

Among different methods which have been used for degradation of organic pollutants, photocatalytic process has received a remarkable attention due to its unique properties. In the present investigation, photocatalytic titanim dioxide (TiO2) and magnetite (Fe3O4) coatings were produced using HVOF thermal spraying process. Different weight percent of TiO2 (75vol. % anatase, 25vol. % rutile) and commercial Fe3O4 powders were mixed together and used as feedstock powder and precipitated on stainless steel 316 substrate. The structure, morphology, and photo-catalytic characteristics of TiO2-Fe3O4 coatings (using different Fe3O4 concentration) were investigated using scanning electron microscopy (SEM), X-ray diffractometer (XRD), and UV-Vis-NIR spectroscopy. Furthermore, the conversion rate of xylene under Vis and UV irradiation was also studied in order to evaluate the photo-catalytic efficiency of coatings in gas dynamic photoreactor. Results showed that the optimum value of Fe3O4 concentration affects the photocatalytic properties of TiO2-Fe3O4 coatings under UV and visible light irradiation. Addition of 7.5 weight percent of magnetite has resulted in an efficiency upper than 35 percent (under UV irradiation). Also addition of 10 weight percent of magnetite has resulted in an efficiency of approximate 4 percent, under visible light irradiation.