Effect of surface fluorination of P25-TiO2 coated on nickel substrate for photocatalytic oxidation of methyl ethyl ketone in indoor environments

Abstract

Volatile organic compounds (VOCs) degradation via photocatalytic oxidation process (PCO) has been employed for air treatment in indoor environment application. However, the performance of PCO is hindered at high humidity conditions, due to the superhydrophilic surface of TiO2 and competition between VOCs and water molecules for adsorption on surface’s active sites. Herein, the photocatalytic activities of P25 and surface fluorinated P25 (F-P25) coated on nickel foam were evaluated for degradation of methyl ethyl ketone (MEK). Surface fluorination enhanced the UV light absorption and reduced the charge carrier recombination. Therefore, the photocatalytic efficiency and by-product generation rate of F-P25 are investigated in a continuous reactor operating at different inlet contaminant concentrations (200–1000 ppb), relative humidity levels (0–80%), light intensities (37 and 28 W/m2) and residence time (0.013-0.076 s). Results indicated that the surface fluorination of P25 enhanced the PCO efficiency of MEK removal in all tested conditions, compared to P25. The MEK removal efficiency under UV irradiation for three-layer and one-layer of F-P25 photocatalyst are 92% and 73%, respectively. Accordingly, by-products generation was considerably decreased using three layers of F-P25 photocatalyst. Moreover, the reaction mechanism for the photocatalytic oxidation of MEK is also proposed. The results of this research will ultimately lead to enhancing the efficiency of PCO process, especially in high humid condition.