Catalytic denitration of drinking water

The interaction of a Pd catalyst with the reactants and potential reaction intermediates present during aqueous nitrate reduction, including NO3-, NO2- and NO in the presence of H2 and H2O were studied by infrared spectroscopy. Adsorbed NO, nitrite and nitrate could all be detected in the presence of water. It was found that in the presence of water/H2, nitrate is the most stable surface species followed by nitrite and then, highly reactive NO, which implies that the reduction of nitrate to nitrite, is the rate limiting step. The formation of ammonia is exclusively associated with reactions on the noble metal and its formation is dependent on the surface hydrogen availability and reaction media water. Photocatalytic removal of nitrates is very recent field of study but offers potentially viable alternative to the extensively studies hydrogenation process. The measured activities are generally one of two orders of magnitude higher than the catalysed hydrogenation reaction and the additional advantage is that the process does not require the use of noble metal catalysts. In this study, TiO2 was the chosen semiconductor, which was modified by the addition of a metal (Ag, Cu or Au). The addition of the metal led to an increase in the photocatalytic performances of the system with respect to the undoped titania. EPR and FTIR under UV irradiation revealed that the metal operates as an electron sink for the reaction which hinders, to a certain extent, the undesired charge recombination process.EThOS - Electronic Theses Online ServiceGBUnited Kingdo