ABIOTIC REDUCTION OF NITRITE AND NITRATE BY CHEMOGENIC MAGNETITE NANOPARTICLES: IMPLICATIONS IN NITROGEN CYCLING AND GREENHOUSE GAS PRODUCTION
Iron oxides, such as lepidocrocite and ferrihydrite have been reported to reduce nitrite and nitrate to NO and N2O. In this study, the potential of magnetite nanoparticles to abiotically reduce nitrite and nitrate to other nitrogen species, such as NO, N2O, N2 and NH3, is investigated. This study examines the reactivity of chemogenic magnetite nanoparticles with nitrite and nitrate in bench-scale batch reactors by characterizing reaction kinetics and quantifying various product fractions. The study focuses on mass-fractions of NO and N2O that may be produced from nitrite and nitrate with above magnetite. The results thus far confirm that chemogenic magnetite is capable of rapidly degrading nitrite into N2O. Results thus far showed that 1.16 g L-1 magnetite in batch experiments under anaerobic conditions can degrade almost all of 0.025 mmoles of nitrite resulting in significant amounts of N2O in about 2 days. Further, experiments conducted with the same amount of magnetite but with 0.5 mmoles of nitrite shows degradation of 0.085 mmoles of nitrite that produced gaseous N2O. The influence of aqueous [Fe2+], dissolved O2, solution pH, surface area concentration, and size of the magnetite nanoparticles on the distribution of reaction products are under investigation.