Photocatalytic Degradation of Phenol with Ultrasonic Mist and Sunlight

Due to the toxicity and persistence of the phenolic compounds present in wastewater, their removal is necessary for the prevention of pollution and the recycling of wastewater. Photocatalytic treatment with the utilization of mist droplets generated by ultrasound has been proposed for enhancing the degradation of those compounds by avoiding the limitations such as light irradiation conditions and mass transfer. Previous studies have investigated the degradation of organic pollutants by applying photocatalysts, conventional ultraviolet lamps, and ultrasound with mist generation. For the reduction of energy use, it is of great interest to utilize sunlight as a renewable light source for photocatalytic reactions. In this study, the synergy of sunlight and the presence of the mist droplets on the photocatalytic degradation of phenol is investigated by using a reactor in which titanium oxide is used as the photocatalyst, ultrasound is applied for mist generation, and simulated sunlight is used for illumination. The phenol degradation increased, and the apparent rate constant was 23.5 % higher when the mist droplets were present in the reactor and illuminated with simulated sunlight. In addition, the effect of different irradiance levels was studied. The results of this study demonstrate that ultrasound, mist, and sunlight can be used for the promotion of photocatalytic reactions.