In this study, the effectiveness of iron powder, nanostructured iron, iron(III) oxide and V2O5/TiO2 catalysts to control emissions of selected pollutants was investigated. The focus of this study was the destruction of two classes of pollutants, namely, chloro-benzenes (CBz) and polychlorinated biphenyls (PCBs). The nanostructured V2O5/TiO2 catalyst (5% vanadia loading) was prepared by the wet incipient method. The iron nanoparticles used in this study were prepared by reducing ferric chloride solution with sodium borohydride. A PCB mix, Arochlor 1254, was used to investigate the potential of the proposed catalyst system to destroy PCB contaminants and 1, 2-dichlorobenzene was the CBz used in this study. The PCB or CBz mix was added to the reactor flow by placing the pollutant mix in the injector at room temperature and then heating the injector to 300°C. The reactor inlet concentration of pollutants was maintained at 1000 ppm. The transport efficiency of this sample introduction system has already been validated. For this study, the fixed bed reactor was made of 0.1 g of catalyst and the total reaction time was kept at 60 minutes. Air (combustion) or nitrogen (pyrolysis) was used as reactor gas during reaction time. The reactor exit gas was collected in a XAD trap held at room temperature. After each experiment, the catalyst and XAD trap were extracted separately by soxhlet extraction (solvent-dichloromethane) and then concentrated. The products were analyzed using gas chromatography-mass spectrometry (GC-MS). The results suggest that pollutants are destroyed more efficiently under combustion condition and that V2O5/TiO2, iron(III) oxide and nanostructured iron can all be effective in controlling emissions (destruction >80%) of PCB and CBZ emissions. As expected, iron powder was the least effective catalyst. The results also suggest that under the conditions of this study, deep oxidation and not dechlorination is the dominant pollutant destruction mechanism.
展开▼
