Removal of air pollutants originating from stack gas with photocatalytic oxidation

Stacks are among the main sources of air pollutants released as a result of combustion processes. These pollutants can be of inorganic or organic origin. Inorganic pollutants include many pollutants such as sulfur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO), particulate matter (PM) while organic pollutants represent many different pollutants, including persistent toxic organics and volatile organic compounds (VOC). The VOC group includes about 150 different compounds, the majority of which are considered harmful and toxic to human health. Considering all these features, the removal of VOC is of great importance. According to the Industrial Air Pollution Control Regulation, VOCs in flue gases are classified into classes, and the limit value for the most dangerous group is specified as 20 mg/m3 according to the degree of damage. From past to present, many different removal technologies have been developed and continue to be developed. Removal of pollutants at low concentrations by conventional methods is more inadequate than those above certain concentrations. Photocatalytic oxidation is one of the technologies used for VOC removal recently. It has been determined that many different organic pollutants can be removed with this method. Within the scope of this thesis, the removal of benzene and toluene pollutants, which are two important VOCs frequently encountered in flue gases, by heterogeneous photocatalytic oxidation method has been studied. In this study, a new photocatalyst by doping silver (Ag), a noble metal, and nickel (Ni), one of the transition metals, on TiO2 particles was developed and laboratory scale reactor system was designed. Many experiments were carried out by changing the system parameters such as the light source (UVC and UVA), ambient temperature (120oC, 150oC, 180oC), humidity (25% and 50%) and percentage of Ag and Ni doping on TiO2 (0.5%, 1%, 2.5%, %5) and the most successful conditions for the removal of benzene and toluene contaminants were tried to be determined based on the results obtained. Considering all the experiments carried out within the scope of this study, the average removal efficiency for benzene was found as 82.79%, while the average removal efficiency for toluene was 90.02%. According to the results obtained, the most suitable conditions for the simultaneous removal of benzene and toluene pollutants by photocatalytic oxidation method were determined as 120oC temperature, 25% humidity and 0.5% doping photocatalyst under UVC light.